International Journal of Neonatal Screening doi: 10.3390/ijns12030067

Authors: Judit García-Villoria Rosa María López-Galera Carmen Delgado-Pecellín Dolores Rausell Félix Cristóbal Colón Hugo Rocha Belén Pérez Antonia Ribes María Luz Couce Domingo González-Lamuño

Background: Newborn screening (NBS) is a cornerstone of preventive medicine, enabling early diagnosis and treatment of severe congenital disorders. In Spain, despite the existence of a Basic Common Portfolio, the absence of a harmonized national panel has led to significant inter-regional variability, affecting equity in access to early diagnosis. Methods: The Spanish Uniform Screening Panel (SUSP) was developed through a structured nationwide consensus process involving all NBS centers in Spain, with additional input from Portugal. The process included a comprehensive survey of current practices, expert workshops, multiple consensus rounds, and predefined inclusion criteria. Disease nomenclature was standardized using OMIM and ORPHAcode identifiers. Conditions were classified as primary screening targets or secondary findings, and consensus was reached on confirmatory biochemical and genetic testing pathways. Results: The operational dataset comprised 48 biomarker-based screening entries. Because some conditions can be detected through multiple primary markers, duplicate analytical routes were retained but counted once, resulting in a total 189 unique clinical conditions, including 87 primary and 102 secondary conditions. Conclusions: The SUSP represents the first nationwide harmonized framework for newborn screening in Spain and constitutes a major step toward equitable and standardized implementation. It provides a scalable model that may inform other countries facing similar disparities.

International Journal of Neonatal Screening doi: 10.3390/ijns12030066

Authors: Amy Gaviglio Natasha Bonhomme Barbara Burton Norman Matthew Ellinwood Joseph Muenzer Kim Stephens Ravi Pathak Carolyn Schaeffer-Koziol

Mucopolysaccharidosis type II (MPS II; also known as Hunter syndrome), is a rare X-linked lysosomal disease that leads to progressive tissue and organ damage. Early treatment is essential as most symptoms of MPS II are not reversible. Consequently, MPS II has been added to many newborn screening (NBS) programs. This narrative literature review provides practical recommendations from a multidisciplinary expert panel on the US-based NBS for MPS II and its diagnosis and clinical management. Recommendations for NBS programs include aiming for universal access to NBS within their jurisdiction, implementing tiered testing to support diagnostic accuracy, and providing infrastructure for confirmatory testing and post-screening support for families. Recommendations for health care providers (HCPs) include communicating test results empathetically and alongside verbal and written information, allowing families to express their feelings, and consulting an MPS II specialist to support treatment recommendations. The NBS programs and HCPs should work together to ensure positive screening results are communicated effectively and to provide equitable access to treatment and long-term care. Such a coordinated and appropriately resourced effort involving NBS programs, HCPs, and patient advocates will ensure better support for families and the best possible outcomes for individuals with MPS II.

International Journal of Neonatal Screening doi: 10.3390/ijns12030065

Authors: Carolyn Mazariego Mahitha Ramanathan Deborah A. Johnston Zhicheng Li Brittany C. McGill Marina Okamura Lauren Kelada Ilona Juraskova Claire E. Wakefield Natalie Taylor

Informed consent is fundamental to Australian newborn bloodspot screening (NBS), but emerging genomic screening technologies pose new challenges to clinical care and research. Optimizing consent processes is necessary to support ethical practice and maintain public trust as NBS evolves. This study aimed to identify gaps and opportunities to improve NBS consent processes in Queensland, Australia, while also exploring preliminary insights into the evolving complexity of consent in the context of genomic NBS (gNBS) and NBS-related research. A qualitative study design was used, with two facilitated interest-holder workshops (a total of 12 h) involving 86 participants (healthcare professionals, policy-makers, researchers, genomics experts, and consumer representatives). Workshop 1 (n = 25) was held virtually, and Workshop 2 (n = 61) was held in person. Thematic analysis was used to identify practical recommendations and ethical considerations. Participants identified three priority domains for improving consent in Queensland’s NBS program: (1) revision of the Guthrie Card and consent statement, (2) development of consistent, antenatal information resources across healthcare providers, and (3) standardized consent delivery training for healthcare staff. Discussions also highlighted tensions around information requirements for informed consent, revealing growing complexities regarding layered consent models. While recommendations on research consent were not fully developed at the workshop, insights highlighted the growing complexity and divergence of views on layered consent models. Findings suggest that improving NBS consent requires both operational reform and reassessment of ethical standards, alongside broader interest-holder engagement and feasible, scalable models also suited to genomic technologies. A nationally consistent framework is needed.

International Journal of Neonatal Screening doi: 10.3390/ijns12030064

Authors: Sophie ter Braak Mette Nyegaard Christian Munch Hagen Marie Bækvad-Hansen Madara Auzenbaha François Boemer James R. Bonham Patricia Borde Ian Brincat David Cheillan Vera Frankova Leifur Franzson Ksenija Fumić Urh Groselj Tom L. G. M. van den Kerkhof Riikka Kurkijärvi Giancarlo la Marca Tatjana Milenković Olve Moldestad Vyacheslav Mitkin Florentina Moldovanu Marios Vogazianos Jürgen G. Okun Lene Sörensen Gulnara Svyatova Ildikó Szatmári Maja Raičević Karit Reinson Trine Tangeraas Alma Toromanović Laura Vilarinho Svetlana Vorslova Raquel Yahyaoui Maximillian Zeyda Dianne Webster Peter C. J. I. Schielen

Neonatal screening using Dried Blood Spot (DBS) cards is an important and successful public health facility in Europe, enabling early detection of congenital disorders for early treatment and prevention of overt disease. Biobanks of stored DBS cards offer significant potential for biomedical research. Biobanking and secondary use of DBS cards also raise ethical and legal issues, particularly concerning the rights of parents and children. This study provides a comprehensive overview of legislation and legal practices governing DBS biobanking across 29 European countries, based on a survey conducted in collaboration with the International Society for Neonatal Screening. Findings reveal a highly heterogeneous landscape: 15 countries have national legislation, five have regional guidelines, and nine lack formal regulations. Only four countries require explicit parental consent for DBS storage, with considerable variation in approval processes for research use. A harmonization of practices, with the European General Data Protection Regulation (GDPR) as a basis for future regulation, supplemented by clearer guidance on ‘public interest’ and robust safeguards for individual rights may lead to more transparent and consistent governance, which is essential to balance scientific progress with the protection of parental and children’s rights in DBS-based research across Europe.

International Journal of Neonatal Screening doi: 10.3390/ijns12030063

Authors: Chloe Miu Mak Hoi Ying Wu Ariel Ying Wong Felicite Enyu Song Toby Chun Hei Chan Cheuk Wing Fung Suet Na Wong Edgar Wai Lok Hau Matthew Chun Wing Yeung

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder and is associated with serious clinical consequences. While newborn screening (NBS) could facilitate early identification and timely intervention, its implementation for X-ALD remains controversial due to ethical concerns arising from its X-linked recessive inheritance pattern, particularly regarding female newborns. This study aims to explore the perspectives of healthcare professionals and the general public on NBS for X-ALD in Hong Kong. An online survey with 20 quantitative questions on ethical considerations was conducted from May to August 2024. Among a total of 259 responses, most respondents (99.2%) supported NBS for their male newborns, primarily because it facilitates early diagnosis and effective management. The majority of the respondents were in favor of offering NBS to female newborns, citing potential benefits for the management of adult-onset disease, enhanced family planning and support, and opportunities for extended family screening. However, some respondents expressed concerns regarding (1) psychological stress and anxiety from uncertain disease onset and frequent monitoring; (2) potential genetic discrimination and adverse impact on insurance premiums/coverage; (3) affordability and accessibility of expensive treatments, such as gene therapy; and (4) ethical issues regarding children’s “right to an open future”, particularly for late-onset female X-ALD. To address these concerns while respecting family autonomy, we propose an opt-in system with clear, balanced information for parents, combined with a three-tier screening algorithm. In summary, while inclusion of X-ALD in Hong Kong’s NBS program receives strong community support, targeted measures are needed to mitigate the identified ethical and practical barriers.

International Journal of Neonatal Screening doi: 10.3390/ijns12030062

Authors: Abena Adaboh Daem Celestin Alex Agyekum Nana Serwaa Osei Araba Mensah Sadath Sayeed Nana-Akyaa Yao

The adoption of pulse oximetry screening (POS) in low- and middle-income countries remains limited. We describe the development, implementation, and evaluation of a POS program at two of the leading tertiary centers in Accra, Ghana, based on a modified American Academy of Pediatrics protocol. Screening was conducted by trained research assistants. Operational experiences of research assistants were evaluated using a mixed-methods approach, including post-implementation surveys (n = 14) and focus group discussions (n = 10). Although participants felt comfortable with the level of instruction, they recommended incorporating simulation exercises to strengthen management of failed screens. Key challenges included difficulty locating newborns due to fragmented wards and paper-based records, equipment durability issues, and complex coordination for echocardiography following failed screens. Early discharge practices and high neonatal intensive care unit admissions reduced screening coverage among high-risk infants. Despite limited referral systems and surgical capacity, the POS pilot increased provider awareness, improved diagnostic clarity and demonstrated feasibility. Sustainable expansion will require more efficient referral networks as well as investment in pediatric cardiology training and cardiac surgical infrastructure.

International Journal of Neonatal Screening doi: 10.3390/ijns12030061

Authors: Qiongfang Yao Shuting Huang Fei Kong Min Wu Xiaolong Qiu Peiran Zhao Yinglin Zeng Jinying Luo Jinfu Zhou Liangpu Xu

Amino acid metabolic disorders (AAMs) are a group of inherited metabolic diseases caused by defects in enzymes or transporters involved in amino acid metabolism. This systematic review and meta-analysis aimed to evaluate the incidence, disease spectrum, and regional distribution of AAMs in China. A comprehensive search of PubMed, Embase, Web of Science, and major Chinese databases identified studies published between January 2002 and December 2025. After rigorous screening and quality assessment, 65 studies were included, encompassing 16,757,850 newborns and 2928 confirmed AAM cases. The most prevalent subtypes included hyperphenylalaninemia (HPA), hypermethioninemia (MET), citrin deficiency (CD), citrullinemia type 1 (CTLN1), maple syrup urine disease (MSUD), ornithine transcarbamylase deficiency (OTCD), and tyrosinemia (HT). The pooled incidence of AAMs was estimated at 184.0 (95% confidence interval 155.0–218.0) per million newborns. Significant regional differences were observed in the overall incidence of AAMs, with a higher incidence in northern China than southern China (287.0 vs. 126.0 per million, p < 0.0001). This difference was largely attributable to the substantially higher prevalence of HPA in northern China, whereas other major AAM subtypes showed no significant north–south differences. In contrast, no significant north–south differences were identified for other major subtypes. Additionally, the proportion of tetrahydrobiopterin deficiency (BH4D) among HPA cases was significantly higher in southern China (p < 0.001). These findings provide comprehensive epidemiological evidence on AAMs in China and highlight the importance of region-specific newborn screening strategies.

International Journal of Neonatal Screening doi: 10.3390/ijns12030060

Authors: Marci K. Sontag Susanna A. McColley

Newborn screening (NBS) for cystic fibrosis (CF) was first implemented almost 50 years ago, and many improvements have been made to the initial algorithms, educational approaches, and available therapies [...]

International Journal of Neonatal Screening doi: 10.3390/ijns12030059

Authors: Daniel R. Schecter Colleen Donnelly Amy White Hillary Raynes Gordon Heller Deepa Rajan Carlos A. Saavedra-Matiz Joseph Orsini Jaap-Jan Boelens Dietrich Matern Jaya Ganesh

Krabbe disease is an autosomal recessive leukodystrophy caused by a deficiency of the lysosomal enzyme galactosylceramidase (GALC), responsible for the degradation of galactolipids, resulting in toxic psychosine accumulation and progressive demyelination of the central and peripheral nervous systems. Newborn screening (NBS) has increased recognition of later-onset Krabbe disease, although interpretation of complex GALC genotypes remains challenging, particularly in the presence of “pseudodeficiency” and modifier alleles. In this case report, we describe a child with late-infantile Krabbe disease identified through NBS with markedly reduced GALC activity and a homozygous GALC haplotype containing c.956A>G (p.Tyr319Cys; Y319C) and c.1685T>C (p.Ile562Thr; I562T), in addition to other benign variants. Retrospective analysis of the newborn screening specimen demonstrated mild psychosine elevation. Despite preserved neurodevelopment, longitudinal surveillance demonstrated progressive cerebral white matter abnormalities by 3 years and 9 months of age and psychosine elevation in erythrocytes (14 pmol/g Hb; controls < 5), prompting umbilical cord blood transplantation (UCBT). Following transplantation, GALC enzyme activity normalized, psychosine levels decreased, and serial neuroimaging demonstrated radiographic stability without neurologic regression at last follow-up (9 years old). This case expands the phenotypic spectrum associated with homozygosity for the p.Tyr319Cys variant and highlights the role of p.Ile562Thr in amplifying the pathogenic potential when in cis with p.Tyr319Cys. This GALC haplotype illustrates how “pseudodeficiency” and modifier alleles may collectively influence biochemical, radiologic, and clinical disease expression. These findings emphasize the importance of integrating genotype, psychosine, enzyme activity, and longitudinal neuroimaging when evaluating infants with NBS results positive for Krabbe disease.

International Journal of Neonatal Screening doi: 10.3390/ijns12030058

Authors: Qingqing Ma Junxing Chen Yong Huang Yan Wang Wangsheng Song Hongyu Xu Yuhui Wan Haili Hu

Citrin deficiency (CD) is an autosomal recessive disorder and represents one of the urea cycle disorders. This study aims to analyze the detection rate, clinical features, and genetic mutation characteristics of neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) in the Hefei region of China. We conducted NICCD screening using tandem mass spectrometry (MS/MS) for infants born in Hefei City between January 2016 and December 2025. Screen-positive cases were subjected to genetic testing via next-generation sequencing (NGS), with subsequent validation by Sanger sequencing. Clinical manifestations, biochemical parameters, and genetic mutation profiles of confirmed cases were systematically analyzed. A total of 924,676 newborns underwent screening, identifying 17 cases of NICCD, yielding a detection rate of 1/54,393, with two false-negative cases identified. The most prevalent mutation site is c.852_855del (p.M285Pfs*2). Following diagnosis, health education, dietary guidance, and symptomatic treatment were administered, resulting in favorable outcomes in the majority of cases. However, one infant exhibited significant growth retardation despite early therapeutic intervention that normalized biochemical parameters. Furthermore, an infant was found to have gallstones at birth and subsequently diagnosed with a liver hemangioma at one year of age. Some patients may experience missed screenings due to delayed elevations in citrulline levels. Therefore, even for newborns with negative screening results, timely assessments of liver function, MS/MS, and genetic testing are recommended for infants experiencing prolonged jaundice. This approach enables early identification and intervention. The combination of MS/MS with genetic screening may serve as a reliable strategy to reduce false-negative results in NICCD screening.

International Journal of Neonatal Screening doi: 10.3390/ijns12030057

Authors: Megan Honor Pesch Laura C. Taylor Sean P. McKenzie Gail Demmler-Harrison

Congenital cytomegalovirus (cCMV) is characterized by highly variable outcomes; how diagnostic information is communicated to families is critical, yet parent experiences of communication following a cCMV diagnosis are not well described. The objective was to examine parent experiences of communication following a cCMV diagnosis and identify opportunities to improve communication in the setting of clinical uncertainty. The method used was semi-structured interviews with 41 mothers of children with cCMV explored communication of diagnostic results, interactions with healthcare providers, and perceptions of information clarity, timing, and adequacy. Transcripts were analyzed using thematic analysis. Participants described variability in diagnostic communication, including differences in timing, modality, and content. Some received in-person counseling, whereas others learned of the diagnosis through phone calls, written communication, or electronic health portals prior to provider contact. Many reported limited explanation, insufficient anticipatory guidance, and inconsistent or incomplete information across providers. These communication gaps contributed to confusion, increased reliance on external information sources, and diminished trust in the healthcare system. Participants emphasized the importance of clear, compassionate communication that acknowledges uncertainty while providing actionable guidance. Communication surrounding cCMV diagnosis is inconsistent and often does not meet family needs. Diagnostic disclosure should function as a clinical intervention requiring clear, patient-centered, longitudinal communication to support families navigating uncertainty.

International Journal of Neonatal Screening doi: 10.3390/ijns12030056

Authors: Bennett O. V. Shum Carel Pretorius Ilya Henner Emre Basar Urs Wilgen Glenn Bennett Jacobus P. J. Ungerer

Newborn screening benefits children with rare diseases by enabling early detection and intervention, which improves health outcomes. False-positive results are one harm of screening, with infants subject to further testing to resolve a positive screen and parents susceptible to psychosocial distress while awaiting the results. Newborn bloodspot screening (NBS) for severe combined immunodeficiency (SCID) using quantitative polymerase chain reaction (qPCR) and cystic fibrosis (CF) screening using immunoreactive trypsinogen (IRT) have high false-positive rates, with more than five infants screening positive and unaffected, for each child diagnosed. We used first-tier targeted gene sequencing (TGS) to prospectively screen 3025 newborns for CF, SCID and spinal muscular atrophy (SMA) and compared the results to current screening protocols using multiplex qPCR and IRT. TGS identified one infant with CF, missed by the IRT assay, and detected an infant with SMA, who screened positive with multiplex qPCR. TGS had zero false-positive results for SCID, CF and SMA. By contrast, multiplex qPCR and IRT screening protocols had approximately nine false positives for each child diagnosed with CF (positive predictive value, PPV 10.00%) and SCID (PPV 10.13%). Replacing current SCID and CF screening protocols with TGS would reduce NBS false positives and may result in a higher sensitivity for CF. TGS sensitivity and specificity would be comparable to qPCR for SMA. A larger trial is required to determine TGS sensitivity and cost-effectiveness.

International Journal of Neonatal Screening doi: 10.3390/ijns12030055

Authors: Anita Krishnan Carolyn Sommer Chinenyenwa Mpamaugo Sonia Voleti Chivukula Lisa A. Hom Gerard R. Martin Mary T. Donofrio

Congenital heart disease is the most common birth defect worldwide. Perinatal detection, either in utero or prior to hospital discharge is important for planning delivery, ordering adjunct testing, and planning for surgical or medical care. In countries with access to ultrasound screening, prenatal detection is highly accurate though with variable sensitivity and specificity around the world. Pulse oximetry screening, in some cases coupled with murmur auscultation in the nursery can also reach very high degrees of sensitivity for critical congenital heart disease. Use of the modalities per guidelines and recommendations is an important aspect of decreasing infant mortality and morbidity worldwide.

International Journal of Neonatal Screening doi: 10.3390/ijns12030054

Authors: Miaomiao Wei Yaoyao Dong Ciren Zhuoma Lin Peng Youping Tian Qing Gu Sheng Wei Bianba Zhuoma Xiaojing Hu Guoying Huang

The peripheral perfusion index (PPI) is a non-invasive indicator of peripheral tissue perfusion in neonates. However, reference values for the PPI at different postnatal time points in healthy neonates residing at high altitudes, as well as early perfusion characteristics in infants with congenital heart disease (CHD) in these settings, remain inadequately defined. The primary aim was to determine the dynamic changes in and percentile-based reference values of the PPI in healthy neonates during the first 6–72 h after birth in the high-altitude region of Tibet. A secondary, exploratory aim was to observe PPI patterns in neonates with CHD born during the same period and to compare the two groups, given the limited number of CHD cases enrolled. A longitudinal cohort study was conducted among consecutively born neonates in a high-altitude region of Tibet. The PPI was measured in the right hand (pre-ductal) and either foot (post-ductal) at 6, ~12, ~24, ~48, and ~72 h after birth. Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used to construct percentile reference curves for healthy neonates. Generalized Estimating Equations (GEE) were applied to evaluate differences in the PPI across time points, measurement sites, and between groups (healthy vs. CHD). A total of 1043 neonates were enrolled, including 1034 in the healthy group and only 9 CHD cases. In healthy neonates, the PPI increased progressively within the first 72 h, with a rapid rise from 6 to 24 h, a slower increase from 24 to 48 h, and stabilization between 48 and 72 h. At all time points, the lower-limb PPI was significantly higher than the upper-limb PPI (p < 0.001). The 50th percentile (P50) values for the upper-limb PPI at 6, 12, 24, 48, and 72 h were 2.32, 2.46, 2.62, 2.63, and 2.77, respectively; corresponding values for the lower-limb PPI were 2.53, 2.64, 2.76, 2.77, and 2.90. Compared to the healthy group, neonates with CHD at high altitudes had similar PPI at 6 h. However, their PPI was significantly lower between 12 and 48 h. At 72 h, no statistically significant difference was found between the groups, likely due to the small sample size of CHD infants. Conclusions: This study provides a reference for routine perfusion assessment in stable neonates born at high altitudes. Due to the limited sample size (only 9 CHD cases), our findings on PPI changes in neonates with CHD remain preliminary. The normative PPI percentile curves established in this study offer objective baseline perfusion data for stable neonates living in high-altitude areas. Future large-scale cohort studies are still needed to validate the clinical value of the PPI as a perfusion monitoring tool in infants with CHD.

International Journal of Neonatal Screening doi: 10.3390/ijns12030053

Authors: Andrew K. Ewer

Pulse oximetry screening (POS) is a simple non-invasive tool which enables the early detection of critical congenital heart defects (CCHDs). POS has moderate sensitivity and high specificity; it is cost-effective, readily accepted by parents and healthcare professionals, and its introduction significantly reduces mortality from CCHDs. As a result, most high-income countries and many middle-income countries have introduced, or are considering introducing, POS. Despite the international uptake of POS, there is still no consensus regarding the most appropriate screening algorithm, although several have been described. In addition, this review will consider the variations—and their relative advantages and disadvantages—between POS algorithms and also explore how modifications to existing algorithms—such as the addition of a perfusion index or the incorporation of machine learning—may have the potential to improve future detection of CCHDs.

International Journal of Neonatal Screening doi: 10.3390/ijns12030052

Authors: Niko Kohmer Lena Mistry Thorsten Mosler Sabine Kramer Annette Weiß Alfred Lennart Bissinger Nora Doberschuetz Ulrich Rochwalsky Holger F. Rabenau Horst Buxmann

Congenital Cytomegalovirus (cCMV) infection is the leading non-genetic cause of sensorineural hearing loss in newborns. Systematic nationwide screening programmes are lacking. Antiviral valganciclovir therapy could improve auditory outcomes if initiated within the first 30 days of life, making timely diagnosis crucial. To address this, we investigated whether a hearing screening-based protocol is suitable. Between 2015 and 2019, newborns, aged ≤21 days, with repeated abnormal newborn hearing screening (NHS) were prospectively enrolled at University Hospital Frankfurt. Oral mucosal swabs were tested for CMV DNA by real-time PCR, with confirmatory urine and blood diagnostics in positive cases. Of 2741 infants presenting for repeat NHS, 2059 (75.1%) showed normal bilateral findings. Of the 682 (24.9%) with abnormal results, 575 (84.3%) were aged >21 days and thus ineligible. A total of 107 infants (3.9%) met both criteria—abnormal NHS and aged ≤21 days—of whom 100 entered per-protocol analysis. Two (2%) were confirmed as cCMV-positive and received valganciclovir. Among the 48 infants who additionally underwent DBS testing, diagnostic sensitivity and specificity were 100%. The presented NHS-driven cCMV protocol reliably identified cCMV-infected newborns to offer timely antiviral therapy. In the absence of universal cCMV screening, this targeted approach offers a challenging but WHO screening-criteria-compliant strategy to enable timely antiviral intervention.

International Journal of Neonatal Screening doi: 10.3390/ijns12030051

Authors: Gulzada Abdushukurova Alken Auyelova Banu Kadyrbayeva Ardak Ayazbekov Dina Mussayeva Ainash Oshibayeva Kumissay Babayeva Liliya Khairullina Karlygash Sadykova Gulnaz Nuskabaeva

The early detection of Severe Combined Immunodeficiency (SCID) and X-linked agammaglobulinemia (XLA) prevents fatal outcomes. This study presents the first pilot TREC/KREC newborn screening (NBS) program in southern Kazakhstan, a high-birth-rate region, to establish local reference ranges and assess operational viability. A multiplex real-time PCR assay was used to quantify T-cell (TREC) and kappa-deleting recombination excision circles (KRECs) from dried blood spots of 5000 unselected neonates. Biomarkers were normalized to copies per 106 cells using albumin as a diploid reference gene. Regional 0.5th percentile cut-offs were established (TREC < 3165 copies/106 cells and KREC < 2554 copies/106  cells), and gender and gestational age did not significantly impact biomarker levels. While a low birth weight (≤2500 g) significantly reduced KREC levels, the extreme lower distribution tails remained unaffected, validating the use of universal, unstratified thresholds. Applying these cut-offs yielded an optimal 1.0% initial recall rate. Consistent with global incidence rates, no true positive cases were identified. The established assay and universal percentile cut-offs demonstrate high levels of analytical reliability and demographic stability. This pilot confirms the regional pediatric healthcare infrastructure’s readiness for a routine, population-based NBS program without the need for complex algorithms.

International Journal of Neonatal Screening doi: 10.3390/ijns12030050

Authors: Diogo Nani Rodrigo Holanda Mendonça Felipe Franco da Graça Vitoria Regia Pereira Pinheiro Mirella Carneireiro Bruna Glaucia Farah Marcondes Cavalcante França Carmen Silvia Gabetta Graziela Polido Cristina Iwabe Frederico Monfardini Alulin Tácio Quadros Santos Monteiro Fonseca Paulo Breinis Carmela Maggiuzzo Grindler Carlos Eugenio Fernandez de Andrade Athene Maria de Marco França Mauro Edmar Zanoteli Wilson Marques Léa Maria Zanini Maciel Acary Souza Bulle Oliveira Maria da Penha Ananias Morita Edward Yang Vanessa Luiza Romanelli Tavares

5q spinal muscular atrophy (5q-SMA) is a leading genetic cause of infant mortality. Presymptomatic intervention with disease-modifying therapies significantly improves motor outcomes, but effectiveness depends on early detection through newborn screening (NBS). Despite global 5q-SMA NBS expansion and recent Brazilian federal legislation, regional disparities and a lack of systematic monitoring hinder access to timely diagnosis and care. This study addresses these gaps by evaluating a statewide pilot program in São Paulo. We used multiplex real-time PCR to detect SMN1 exon 7 deletions in dried blood spots, confirming SMN1/2 copy numbers via MLPA in positive cases. Under real-world conditions, timeliness key performance indicators were evaluated to assess operational efficiency. 194,714 newborns were screened with 14 positive cases, yielding a prevalence of 1:13,908. First-tier results and treatment initiation occurred at a median of 10.8 and 28 days of life, respectively. Notably, 78.6% of patients had two SMN2 copies, of which approximately half were symptomatic by the first evaluation, highlighting the critical need for rapid screening to prevent irreversible motor decline. Screening achieved 100% specificity. This pilot demonstrates the feasibility of 5q-SMA NBS within the Brazilian public health system, providing essential evidence to overcome logistical and socioeconomic barriers and support nationwide expansion.

International Journal of Neonatal Screening doi: 10.3390/ijns12030049

Authors: Alessandra Vasco Andrea Meta Clarissa Berardo Davide Camerlengo Francesca Fumagalli Davide Tonduti Iris Fiamingo Cristina Montrasio Diana Postorivo Manuela Rizzetto Sabrina Fede MLD-NBS Study Group MLD-NBS Study Group Roberto Bozic Francisco Ferron Valeria Calbi Gianvincenzo Zuccotti Alessandro Aiuti Giancarlo la Marca Stephana Carelli Cristina Cereda

Metachromatic leukodystrophy (MLD) is a rare, autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme arylsulfatase A (ARSA, MIM #250100), which leads to progressive demyelination in the central and peripheral nervous systems, resulting in severe neurodegeneration and premature death. With the recent approval of the first ex vivo gene therapy for MLD, newborn screening (NBS) programs have begun to implement pilot studies for early detection, as identifying affected individuals during the pre-symptomatic therapeutic window is crucial. We present the analytical workflow and the NBS algorithm developed during the first year of MLD screening in Lombardy. The screening strategy comprised a first-tier test (1TT) using mass spectrometry to quantify sulfatide concentrations, a second-tier test (2TT) measuring ARSA enzymatic activity, and a third-tier test (3TT) based on whole-exome sequencing. A total of 16,130 newborns were screened for MLD. Of these, 6.41% required retesting (1TT), 1.53% underwent duplicate 2TT, and 0.36% proceeded to 3TT. No neonates were recalled, and no cases of MLD were identified through the screening program. The first-year implementation of MLD NBS in Lombardy demonstrates that a mass spectrometry-based sulfatide assay combined with a multi-tiered screening algorithm is feasible and reliable. Incorporating genetic analysis alongside expanded validation of additional sulfatide species may enhance specificity, reduce false positives, and facilitate timely identification of infants affected by MLD.

International Journal of Neonatal Screening doi: 10.3390/ijns12030048

Authors: Nika Eržen Jernej Kovač Barbka Repič Lampret Urh Grošelj Aneta Soltirovska Šalamon Gregor Nosan

Congenital cytomegalovirus infection (cCMV) is the most common congenital infection and an important cause of sensorineural hearing loss and neurodevelopmental impairment, yet many affected infants remain undetected under selective screening approaches. We conducted a prospective national pilot study to evaluate the feasibility and diagnostic yield of universal dried blood spot (DBS)-based screening for cCMV within the Slovenian newborn screening program. DBS samples collected within 72 h of life were tested by polymerase chain reaction (PCR), and screen-positive newborns underwent confirmatory urine PCR within 21 days together with standardized clinical evaluation. Among 5556 screened newborns, 13 (0.23%) screened positive and cCMV was confirmed in 10, corresponding to a lower-bound birth prevalence of 1.80 per 1000 live births (95% confidence interval, 0.98–3.31), because confirmatory testing was limited to DBS-positive newborns. None of the confirmed cases were clinically suspected at birth, and all passed newborn hearing screening. Six infants met protocol-defined criteria for symptomatic cCMV and received valganciclovir. Historical registry-based clinical case ascertainment in Slovenia corresponded to 0.09 detected cases per 1000 live births. These findings demonstrate the feasibility of universal DBS-based cCMV screening within an established newborn screening infrastructure and suggest substantial under-ascertainment under selective clinical detection pathways.

International Journal of Neonatal Screening doi: 10.3390/ijns12030047

Authors: Yuki Ueda Shinsuke Hirabayashi Masayuki Miura Satoshi Yamada Sachiko Nakakubo Midori Nakajima Takeru Goto Jutaro Abe Yukayo Terashita Atsushi Manabe Torayuki Okuyama Kiyoshi Egawa

Enzyme replacement therapy (ERT) for central nervous system symptoms and newborn screening (NBS) is available in Japan for patients with mucopolysaccharidosis type II (MPS II). Of 12 suspected cases identified through the NBS program, 3 patients were diagnosed with neuronopathic MPS II (2 directly from the screened cohort and 1 affected sibling). We reviewed the clinical courses of these patients, who were treated with intracerebroventricular (ICV) ERT using idursulfase beta (Hunterase®) followed by umbilical cord blood transplantation (CBT). Heparan sulfate (HS) in the cerebrospinal fluid (CSF) was longitudinally measured as a therapeutic biomarker, and developmental age was evaluated. All patients achieved successful engraftment with no severe complications, except for one patient with sinusoidal obstruction syndrome. The CSF HS concentration showed a temporary increase during the ERT discontinuation period, which can be attributed to CBT, and a subsequent reduction after the resumption of ICV-ERT. The patients exhibited age-appropriate development. The pattern of change in HS indicates the importance of continuing ICV-ERT even after hematopoietic stem cell transplantation. The study results demonstrate that the combination of ICV-ERT and CBT may yield promising outcomes in patients with neuronopathic MPS II, underscoring the importance of early intervention through NBS.

International Journal of Neonatal Screening doi: 10.3390/ijns12030046

Authors: Victory Oghenetega Samuel Abdullahi Adeyinka Adejare Ushotanefe Useh

Newborn screening initiatives have the potential to mitigate childhood morbidity in Africa, but they also have special ethical, legal, and social implications (ELSI) that are influenced by issues with the health system, cultural diversity, and limited resources. This scoping review explores the ELSI of newborn screening across Africa to identify key challenges, gaps, and future research needs. A systematic search identified 27 peer-reviewed studies published between 2008 and 2025, covering 12 African countries. Data were extracted on study characteristics, disease types, and ELSI dimensions from African Journals Online (AJOL), Scopus, PubMed, Web of Science, and BMJ Journals. Thematic analysis mapped recurring ethical, legal, and social concerns. Most studies examined ethical and social dimensions, while legal frameworks were rarely addressed. South Africa, Tanzania, and Ghana contributed the largest number of publications. Sickle cell disease (52%) and hearing screening (30%) were the dominant foci. Common ethical issues included informed consent, privacy, and justice; legal gaps centered on the absence of data protection and frameworks; and social concerns involved stigma, awareness, and cultural perceptions of hereditary disease. Ethical and social issues dominate NBS discourse in Africa, whereas legal oversight remains limited. To guarantee fair, reliable, and long-lasting newborn screening programs, national policy guidelines, community involvement, and context-specific ethical frameworks must be strengthened.

International Journal of Neonatal Screening doi: 10.3390/ijns12030045

Authors: Alia Zainudin Thin Thin Aye Chloe Chen Sze Yun Gaayathri Kumarasamy Adli Ali

Severe Combined Immunodeficiency (SCID), Spinal Muscular Atrophy (SMA), and X-Linked Agammaglobulinemia (XLA) are rare but life-threatening genetic disorders in infants that can lead to severe infections, progressive neuromuscular degeneration, or severe immune dysfunction associated with significant morbidity and mortality if not diagnosed early. Advances in newborn screening (NBS) technologies have enabled pre-symptomatic detection of these conditions, allowing early initiation of life-saving interventions such as hematopoietic stem cell transplantation, gene therapy, and immunoglobulin replacement therapy. However, the absence of a standardized national clinical pathway linking screening, confirmatory testing, and specialist referral in Malaysia continues to contribute to delayed diagnosis and suboptimal patient outcomes. This review examines and synthesizes current evidence on the clinical pathways for early diagnosis and management of SCID, SMA, and XLA, with particular emphasis on diagnostic workflows, screening technologies, and healthcare system challenges within the Malaysian context. The review examines disease epidemiology, consequences of delayed diagnosis, and the role of expanded NBS under the Screening for Health, Intervention, Nurturing of Every Child (SHINE) program in improving early diagnosis and management. In addition, the paper outlines the current NBS landscape, the use of multiplex real-time polymerase chain reaction (PCR) assays for simultaneous detection of T-cell receptor excision circles (TREC), kappa-deleting recombination excision circles (KREC), and survival motor neuron 1 (SMN1) gene deletion of exon 7 from dried blood spot (DBS) samples. A structured diagnostic framework incorporating screening interpretation, confirmatory testing, and urgency-based referral pathways is also proposed. By addressing current operational barriers and coordinating laboratory referral systems, expanding NBS programs could significantly improve early diagnosis and long-term outcomes for infants affected by SCID, SMA, and XLA in Malaysia.

International Journal of Neonatal Screening doi: 10.3390/ijns12020044

Authors: Raquel Yahyaoui Pilar Quijada-Fraile Javier Blasco-Alonso Inmaculada Vives David Gil Ortega Maria-Luz Couce Paula Sánchez-Pintos M. Concepción García Jiménez Silvia Meavilla Olivas Camila García Volpe Mariela de los Santos Mercedes Ángels García-Cazorla Ana Felipe-Rucián Lucy Dougherty-de Miguel Ana Morais López Ana Bergua Martínez José David Andrade Guerrero Sinziana Stanescu Amaya Belanger Mercedes Gil-Campos María José Comino Monroy Marcello Bellusci Patricia Pérez-Mohand Delia Barrio-Carreras Belén Pérez Elena Martín-Hernández

Urea cycle disorders (UCDs) are rare inherited metabolic diseases associated with toxic hyperammonemia, leading to severe neurological damage and early mortality. Early diagnosis of distal UCDs through newborn screening (NBS) enables presymptomatic intervention; however, comparative real-world outcome data remain limited. We conducted a retrospective, multicenter study using data from the Spanish UCD Registry to describe the clinical characteristics and compare health outcomes between patients diagnosed through NBS (n = 40) and those diagnosed after clinical presentation (n = 53). Patients identified by NBS showed a markedly more favorable clinical prognosis, with a mortality rate of 2.5% compared with 15.1% in the unscreened cohort, as well as significantly lower rates of neurological involvement, fewer hospital admissions due to metabolic decompensation, and a reduced need for liver transplantation. Screening also identified a high prevalence of argininosuccinate synthetase deficiency (ASS1D) cases with attenuated biochemical profiles, highlighting the relevance of sensitive screening cutoffs. These findings provide real-world evidence that presymptomatic diagnosis through NBS is associated with improved survival and long-term neurological outcomes in patients with distal UCDs.

International Journal of Neonatal Screening doi: 10.3390/ijns12020043

Authors: Raquel Yahyaoui Lúcia Mamede Martin Zach James Taylor Claire Booth Rosalind Fisher Věra Franková Adli Ali Johan Prevot Martine Pergent Roberta Anido de Pena Elizabeth Rivers

The Ethics Session of the International Primary Immunodeficiency Congress (IPIC), held in November 2025 and organised by the International Patient Organisation for Primary Immunodeficiencies (IPOPI), examined one of the most challenging developments emerging from genomic-enhanced newborn screening: the identification of serious, non-treatable disorders as incidental detection in programmes originally designed to detect severe combined immunodeficiency (SCID). Using a fictionalised clinical scenario based on the recent literature, the session explored the early diagnosis of ataxia–telangiectasia (AT) detected through TREC-based screening. The discussion highlighted the clinical value and psychological risks associated with presymptomatic detection, the persistent shortcomings in parental consent processes, the systemic pressures created by expanding genomic testing, and the ethical challenges surrounding the reporting and management of incidental findings in screening. The debate underscored the need for internationally coordinated frameworks to guide the management of incidental detection in newborn screening as genomic technologies become more deeply embedded in routine public health practice.

International Journal of Neonatal Screening doi: 10.3390/ijns12020042

Authors: Umma A. Ibrahim Aisha B. Musa Oiza O. Aliu-Isah Hauwa A. Inuwa Zubaida L. Farouk Khadija Bulama Aisha Mukaddas Khadija Kamal Rifkatu N. Auta Nafiu Hussaini Aisha A. Galadanci Yusuf D. Jobbi Bilya S. Musa Yvonne Carroll Lauren J. Klein Ibrahim M. Idris Michael R. DeBaun Muktar H. Aliyu

In sub-Saharan Africa, where approximately 75% of newborns with sickle cell disease (SCD) are born, under-five mortality remains high, partly due to the absence of newborn screening (NBS) and delayed linkage to comprehensive care. We conducted a prospective, quasi-experimental study involving two sequential newborn screening cohorts at Aminu Kano Teaching Hospital (AKTH), Kano, Nigeria (December 2022–December 2025), to evaluate the feasibility of integrating newborn screening (NBS) with early comprehensive SCD care and to identify barriers to enrollment before 3 months of age. Following an initial implementation period with suboptimal follow-up, a structured family-centered enrollment and communication strategy was introduced to improve early linkage to comprehensive care. During the pre-intervention period, 277 newborns were enrolled (33 with SCD and 244 without SCD [NSCD]), with early enrollment (≤3 months) occurring in 46.5% overall, higher among SCD than NSCD infants (72.8% vs. 43.0%). Delayed enrollment (>6 months) was more frequent among SCD infants. Following the implementation of family-centered communication strategies, 60 additional newborns were enrolled (16 SCD, 44 NSCD), and early enrollment increased to 91.7%. These findings demonstrate that low-cost, family-centered communication and tracking strategies can substantially improve early linkage to comprehensive SCD care following newborn screening in low-resource settings. Early enrollment is a critical step toward reducing morbidity and mortality among children with SCD in low-resource settings.

International Journal of Neonatal Screening doi: 10.3390/ijns12020041

Authors: Rachel S. Carling Zoe J. Barclay Sophie C. Ward Marie Appleton Robert Barski Harry Benn Kelly Chambers Paul Coakley Helena Kemp Nicola Crabbe Sarah Dowden Toby Greenfield Sarah L. Hogg Saima Hussein Rhiannon Marr Oliver Parkes Darren Powell Tejswurree Ramgoolam Joshua Ssali Nazia Taj Katherine Wright Teresa H. Y. Wu James R. Bonham

Newborn screening in England is a national program with laboratories adhering to common screening algorithms. Until recently, screening for inherited metabolic disorders was provided by ten laboratories using laboratory-developed tests (LDTs) and three using commercial assays: harmonization of results proved challenging. Introduction of hereditary tyrosinemia type 1 screening meant LDTs required modification to include the measurement of succinylacetone, and subsequent re-validation. This provided an opportunity to implement a single commercial reagent kit in all laboratories. It was anticipated that this would improve analytical performance and harmonization. This study aimed to determine whether these goals were achieved. Verification across the 13 laboratories revealed that the commercial kit reduced inter-laboratory variation for all analytes demonstrating improved harmonization. However, this was achieved by applying instrument-specific correction factors to all analytes, the magnitude of which were significant, indicating a lack of standardization. Performance of succinylacetone was limited by instrument-dependent background interference from the methionine stable isotope label, underscoring the need to establish evidence-based screening cut-off values (COV) rather than adopting published thresholds. This study emphasizes the need for traceable reference materials to improve laboratory quality and the value of screening outcome data.

International Journal of Neonatal Screening doi: 10.3390/ijns12020040

Authors: Elya Courtney Samantha L. Isenberg Timothy Lim C. Austin Pickens Rachel Lee Carla Cuthbert Konstantinos Petritis

Lysosomal diseases (LDs, or Lysosomal Storage Disorders) have become increasingly visible in the newborn screening community, with the addition of mucopolysaccharidosis type II (MPS-II) into the Recommended Uniform Screening Panel in August 2022 and Infantile Krabbe disease in June 2024. As more LDs are expected to be considered for screening adoption, the ability to multiplex conditions and expand proficiency testing (PT) using quality control materials is essential. This study examines the use of recombinant enzymes to produce first-tier PT materials for mucopolysaccharidosis type I, MPS-II, Gaucher, Fabry, Krabbe, Pompe, and Niemann–Pick A/B (acid sphingomyelinase deficiency)—adding four disorders to the CDC’s Newborn Screening Quality Assurance Program (NSQAP) LD PT panel. Through an iterative process that included two prototype phases, two pilot phases, and external testing by up to 31 external laboratories, a new manufacturing process was developed for producing high-performing dried blood spot-based LD PT specimens. Materials were evaluated using several methods commonly employed by newborn screening laboratories, including tandem mass spectrometry with flow injection and liquid chromatography, digital microfluidics, and fluorometric assays. This novel process for producing LD PT materials offers several advantages over previous manufacturing methods that relied on immortalized cell lines from affected patients. Improved scalability, for example, has enabled NSQAP to expand LD PT enrollment internationally. Furthermore, the new process makes it easier to support future expansions of the LD screening panel. The updated specimens and expanded program were launched in January 2025.

International Journal of Neonatal Screening doi: 10.3390/ijns12020039

Authors: Tomoko Lee Miki Matsui Yoko Yokoyama Ryosuke Bo Hiroyuki Awano Dai Kataoka Masaaki Ueda Toshinori Minato Hironori Kobayashi Yuki Hasegawa Kei Murayama Yasuhiro Takeshima

Proximal urea-cycle disorders (PUCDs), including N-acetylglutamate synthase deficiency (NAGSD), ornithine transcarbamylase deficiency (OTCD), and carbamoyl phosphate synthase 1 deficiency (CPS1D), cause hyperammonemia and impair neurological outcomes. Early detection of late-onset forms allows presymptomatic intervention to prevent hyperammonemia; however, reliable newborn screening (NBS) markers are lacking. This prospective pilot study in Hyogo Prefecture, Japan, evaluated hypocitrullinemia as a screening marker for late-onset PUCDs. Newborns with citrulline levels below the 0.05th percentile on NBS between June 2020 and May 2024 were enrolled in the study. Confirmatory diagnosis of PUCDs was performed using plasma amino acids, urinary organic acids, and genetic testing. During the first period (101,172 newborns), 11 newborns exhibited hypocitrullinemia; 10 underwent further evaluation. One newborn was diagnosed with CPS1D (compound heterozygous CPS1 variants); another was later diagnosed with Leigh syndrome. The remaining eight cases were false positives, often associated with prematurity, poor feeding, or gastrointestinal disorders. A second dried blood spot (DBS) card protocol was introduced in the second period (34,694 newborns), reducing false positives. One neonatal-onset OTCD case was detected, and citrulline levels were normalized in six of the seven other cases. In summary, hypocitrullinemia can identify presymptomatic PUCDs, and requesting a second DBS card reduces false positives, supporting its feasibility for incorporation into NBS programs.

International Journal of Neonatal Screening doi: 10.3390/ijns12020038

Authors: Iulia Coliban Natalia Usurelu Igor Opalco Sergiu Gladun Victoria Sacara

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder in which presymptomatic treatment substantially improves survival and motor outcomes, yet newborn screening for SMA remains unevenly implemented across Europe, and evidence from lower-resource health systems is needed to guide scale-up. In this study, we assessed the feasibility, diagnostic performance, and public health implications of implementing neonatal SMA screening in the Republic of Moldova within an established national newborn screening framework. A pilot genetic screening program was conducted using dried blood spot (DBS) samples collected through routine newborn screening workflows; SMN1 exon 7 deletion testing was performed by real-time polymerase chain reaction (qPCR), and positive findings were confirmed by multiplex ligation-dependent probe amplification (MLPA), alongside the evaluation of operational integration and system-level requirements. Screening was operationally feasible within existing DBS processes and demonstrated high analytical performance, consistent with published international experience, although performance results should be interpreted cautiously due to the limited sample size. Two SMA cases were confirmed in a small cohort, enabling early diagnosis and timely referral for disease-modifying therapy, and integration into the existing program was practical and resource-efficient. These findings support the incorporation of SMA into national newborn screening panels using DBS-based molecular methods, highlighting an implementable model for introducing advanced genetic testing within routine public health services.

International Journal of Neonatal Screening doi: 10.3390/ijns12020037

Authors: Aihua Xia Hongfei Chen Fuhua Lu Ping Xu Peixiao Shen Wei Wei Chunrong Gui Juliang Liu Dan Wei Haipeng Qin Yan Huang Ju Long Baoheng Gui

Thalassemia is one of the most common inherited diseases in Guangxi, China. Early identification of thalassemia by neonatal screening is beneficial for effective clinical management and treatment. A total of 3671 newborns from multiple centers of Guangxi were prospectively recruited and screened for thalassemia using single molecule real-time (SMRT) sequencing technology. A total of 36 types of variants of globin genes were identified, including 16 common variants and 20 rare variants in the Chinese population. In total, 956 (26.04%) newborns were identified to carry thalassemia variants, including 672 (18.31%) α-thalassemia, 228 (6.21%) β-thalassemia, 55 (1.50%) combined α/β-thalassemia and 1 (0.03%) δ-thalassemia. In addition, this study showed that the carrier rates of structural variants of α-globin genes and abnormal hemoglobin variants were 1.28% and 0.93% respectively. Phenotypically, 12 newborns with hemoglobin H disease and 2 cases with intermedia β-thalassemia were found, two of whom would be misdiagnosed by conventional genetic analysis methods. Collectively, this study characterized the complexity and diversity of thalassemia gene variants in newborns of Guangxi, and further achieved early identification of newborns with intermedia thalassemia, which facilitated precision prevention of thalassemia in this region. Also, SMRT provided a powerful tool for neonatal thalassemia screening, especially in prevalent regions.

International Journal of Neonatal Screening doi: 10.3390/ijns12020036

Authors: Go Tajima Nobuyuki Ishige Junji Hanai Keiko Konomura

False-positive results are known to occur frequently in newborn screening (NBS) for carnitine palmitoyltransferase II (CPT II) deficiency, highlighting the need to identify appropriate screening markers. The present study aimed to compare the performance of two markers currently used in NBS for CPT II deficiency, (C16 + C18:1)/C2 and C14/C3, with two promising alternative markers, C12/C0 and C12/C2. We analyzed non-patient data from the 2023 fiscal year NBS program together with patient data for CPT II deficiency and very-long-chain acyl-CoA dehydrogenase deficiency derived from previously reported case series. Marker performance was assessed using precision–recall curves, including an analysis in which patients with the myopathic form of CPT II deficiency who passed NBS using (C16 + C18:1)/C2 and C14/C3 were reclassified as true positives. The area under the precision–recall curve values for C12/C2 and C14/C3 were 0.711 (95% confidence interval, 0.492–0.923) and 0.569 (0.341–0.779), respectively, indicating superior performance compared with the other markers. When cases with the myopathic form of CPT II deficiency were included as true positives, the performance of all markers decreased markedly. Although some patients with the myopathic form are still likely to be missed, C12/C2 appears to be an effective marker for reducing false-positive results.

International Journal of Neonatal Screening doi: 10.3390/ijns12020035

Authors: Ahmed H. Mujamammi

The Saudi Arabia National Newborn Screening (NBS) program is a pillar of public health, offering timely detection of treatable, life-threatening, or disabling conditions in neonates. This comprehensive review critically examines the current laboratory diagnostic practices employed for metabolite analysis within this program. It focuses primarily on biochemical NBS conducted via dried blood spot testing and evaluates the methodologies, technical challenges, and stringent quality assurance measures that underpin successful screening. This review examines the critical role of tandem mass spectrometry, sample integrity protocols, and the establishment of robust cutoff values. Furthermore, this review explores persistent challenges such as false-positive and false-negative results, ethical and logistical hurdles in global implementation, and the transformative potential of recent advancements, including the integration of genomics and high-resolution metabolomics. In addition, this review explores the future of the program, highlighting the transformative potential of high-resolution metabolomics and the integration of genomic sequencing to ensure early diagnosis and intervention.

International Journal of Neonatal Screening doi: 10.3390/ijns12020034

Authors: Pru Holder Chloe Musa Jim B. Chilcott Anju D. Keetharuth Louise Moody Ellinor K. Olander Fiona Ulph Jane Chudleigh

Background: In 2021, the UK National Screening Committee commissioned an evaluation of newborn bloodspot screening for severe combined immunodeficiency (SCID) in England. This paper describes the experiences of parents who received an SCID or non-SCID T-cell lymphopenia (non-SCID TCL) result for their baby during the evaluation. Methods: A qualitative exploratory design was employed using semi-structured interviews with 12 parents (n = 5 who had received an SCID outcome and n = 7 who had received a non-SCID TCL following SCID NBS). Results: The impact on parents whose baby was diagnosed with SCID was complex, reflecting the experience of receiving a presymptomatic diagnosis. Parents of babies who had been diagnosed with a non-SCID TCL viewed their baby’s result in terms of risk; while their baby might still have a serious immunological condition, it was not considered to be as serious as SCID. All parents reported that they valued their participation in the SCID screening evaluation. Conclusions: Support for families following a positive screening result for SCID needs to be considered. This includes tailored psychosocial support, given their experiences will not be the same as those of parents of non-screened babies with SCID.

International Journal of Neonatal Screening doi: 10.3390/ijns12020033

Authors: Daniel Pfurtscheller Carola Ganzer Ena Suppan Melina Winkler Bernhard Schwaberger Lisa Sallmon Gerhard Pichler Benno Kohlmaier

Background: Conjugated hyperbilirubinemia in early infancy is a critical indicator of hepatobiliary dysfunction. Prompt and accurate identification is essential to diagnose cholestatic liver disease (CLD), particularly biliary atresia. Current guidelines define conjugated bilirubin (CB) ≥ 1 mg/dL as abnormal, irrespective of total bilirubin (TB). This study aimed to evaluate whether combining absolute and relative CB thresholds improves diagnostic performance for CLD. Methods: We retrospectively analyzed all infants aged ≤6 months of chronological age with CB ≥ 1 mg/dL admitted to the Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Austria, between January 2004 and February 2025. During that period, 116,104 infants were born at our hospital catchment area; 3119 of these underwent bilirubin fractionation, and 257 infants (0.2% of total births) had a CB ≥ 1 mg/dL and were included in the analysis. Clinical and biochemical data were extracted. Diagnostic performance of the absolute (CB ≥ 1 mg/dL) and in combination with the relative (CB ≥ 20% of TB) thresholds was assessed using receiver operating characteristic (ROC) analysis for the detection of CLD. Results: Among 257 infants, 47 (18%) were diagnosed with CLD. The median age at the time of blood sampling was 18 days (IQR 9–31). The combined criterion (CB ≥ 1 mg/dL and ≥20% of TB) achieved 100% sensitivity and 61.2% specificity (AUC = 0.82, 95% CI 0.79–0.92; p < 0.001). Implementation of the combined cut-off reduced the number needed to screen from 5.5 to 2.7, representing nearly a twofold improvement in diagnostic efficiency. Conclusions: Applying both absolute (≥1 mg/dL) and relative (≥20% of total bilirubin) CB thresholds substantially improves detection of neonatal CLD in early infancy. This combined approach maintains full sensitivity while reducing false positives and unnecessary investigations, thereby enhancing diagnostic efficiency in early infancy.

International Journal of Neonatal Screening doi: 10.3390/ijns12020032

Authors: Yuko Matsumoto Yuko Kushihashi Akiko Suwa Go Tajima

Newborn mass screening improves outcomes for inborn errors of metabolism (IEM); nonetheless, home-based dietary therapy imposes a substantial parental burden. In this study, we explored differences in parents’ health coping behaviors, assessed using the Coping Health Inventory for Parents (CHIP), based on the presence of dietary therapy, child age group, and diagnostic category. A 21-item, CHIP-based questionnaire was distributed via the JaSMIn registry to parents of children with IEM up to school age. Overall, 201 valid responses (56.1% response rate) were analyzed regarding the implementation and perceived usefulness of coping behaviors, stratified by child age, enrollment, diagnosis, and dietary therapy. Parents in the dietary-therapy group reported more coping behaviors than did those in the non-dietary-therapy group. Notably, parents of children aged 1–3 years (not yet in preschool) and those of children with organic acid metabolism disorders rated “daily home practice of treatments” as a highly useful coping behavior. Health-related coping behaviors among parents of children with IEM vary substantially according to child age and disease characteristics. Therefore, family support strategies should be tailored to specific developmental stages and treatment requirements.

International Journal of Neonatal Screening doi: 10.3390/ijns12020031

Authors: Lisa A. Hom Gerard R. Martin

Congenital heart disease (CHD) remains the number one cause of mortality due to congenital defects in children under the age of one [...]

International Journal of Neonatal Screening doi: 10.3390/ijns12020030

Authors: Samuel Stanovský Josef Bártl Petr Chrastina Viktor Kožich Jakub Krijt Kristýna Nelicová Jitka Sokolová Truong An Nguyen Richard Plavka Květa Pelinková Drahomíra Springer Klára Berková Zbyněk Straňák Jan Janota Katarína Tichá Jiří Zach Tomáš Honzík

Neonatal vitamin B12 (B12) deficiency can cause neurodevelopmental harm, and newborn screening (NBS) may enable early detection and treatment. We conducted a multicenter pilot project in four Prague university hospitals between 1 June 2022 and 30 June 2025. Algorithms included the determination of propionylcarnitine-derived primary markers using flow-injection tandem mass spectrometry and second-tier methylmalonic acid (MMA), with total homocysteine measured only when MMA was increased. Of 34,302 screened newborns with consent, 1365 (3.98%) triggered second-tier testing; 9 had MMA > 2.5 µmol/L, of which 8 met the case definition after confirmatory testing, giving a birth frequency of 1:4228 (95% CI 1:2176–1:9931). Positive predictive value was 0.59% (95% CI 0.25–1.15%) and 88.89% (95% CI 51.75–99.72%) for the primary test and second-tier MMA, respectively, with a false positive rate of 0.00292% (95% CI 0.000074–0.01625%). All affected infants were treated orally with cyanocobalamin. Maternal work-up identified confirmed B12 deficiency in four of eight mothers and premalignant gastric changes in two of four positive women. These data support the feasibility, low cost, and clinical utility of incorporating B12 deficiency into Czech NBS, with benefits extending beyond newborn health.

International Journal of Neonatal Screening doi: 10.3390/ijns12020029

Authors: Karin Engström Rolf H. Zetterström Anna Wedell Anna Nordenström

Newborn screening for congenital adrenal hyperplasia (CAH) is effective in identifying patients with severe forms before a potentially lethal crisis, but has a relatively high false-positive rate. The aim of this study was to improve the national neonatal screening program in Sweden and the positive predictive value by implementing LC-MS/MS second-tier testing. A combination of two independent parameters, the steroid hormone ratio (androstenedione+17-hydroxyprogesterone)/cortisol and the concentration of 21-deoxycortisol and adjustment of cut-off levels resulted in an increase in the positive predictive value (PPV) from 14% to 84% for full-term infants. In total, the false-positive screening cases decreased by 88%. CYP21A2 genotyping was used to determine the severity of CAH in identified cases. We report on the stepwise approach that was used to optimize the cut-off levels for full-term and preterm infants in order not to miss any true cases in the process.

International Journal of Neonatal Screening doi: 10.3390/ijns12020028

Authors: Toby Greenfield Lesley Tetlow James R. Bonham Catherine Collingwood Laura Wainwright Liz Robinson Dave Wright Beverly Hird Tejswurree Ramgoolam Caroline Griffith Lynette Shakespeare Mehdi Mirzazadeh Rachelle Garstone Deborah Finnerty Nick Flynn Nazia Taj Maya Desai

Increasing ethnic diversity raises potential inequalities within screening programmes. In the UK, newborns are screened for CF by initially measuring IRT. Dried blood spot IRT levels above a set cut-off require follow-up testing to establish a screening result. Variation exists in IRT levels between different ethnicities and therefore impacts the number of potentially false positive results obtained from ethnic groups. Over a 4-year period, IRT data was collected, and the 99.5th centile was calculated for different ethnic groups. Significant differences were noticed between ethnic groups, and the CF outcome data over a 10-year period were then analysed to establish the effect this had on positive predictive values. The largest difference in IRT 99.5th centile values was seen between the White British and Black African groups. Positive predictive values for Black African and Indian ethnic groups were much lower than the other groups. Rather than try to incorporate ethnicity into the UK CF screening algorithm, we suggest making CF clinicians aware of the differences between different ethnic groups to inform counselling families who receive screen-positive results.

International Journal of Neonatal Screening doi: 10.3390/ijns12020027

Authors: Mark de Hora Natasha Heather Dianne Webster Benjamin B. Albert Paul Hofman

21-deoxycortisol is a sensitive and specific blood marker for congenital adrenal hyperplasia (CAH). We postulated that 21-deoxycortisone, the 11β-hydroxysteroid dehydrogenase metabolite of 21-deoxycortisol, may also be an accurate bloodspot marker of CAH. Measurement of 21-deoxycortisone was performed on 42 residual NBS specimens with a true positive result for CAH, 11 with a false negative result, and 439 specimens with a false positive result. For this study, the test was considered positive if 21-deoxycortisone was detected. The sensitivity and specificity of 21-deoxycortisone as a marker for classical CAH was calculated and compared to 21-deoxycortisol data from a previous New Zealand study. The method for 21-deoxycortisone measurement was linear to 1000 nmol/L and precision was 7.3–10.3%. The lower limit of quantification was 2 nmol/L, and recovery was 99%. 21-deoxycortisone was ≥2 nmol/L in all 42 true positive samples and in 10 false negative samples, and was not detected in the false positive group of specimens. The sensitivity of 21-deoxycortisone was 98.1%, and specificity was 100%. In a previous study, the sensitivity of 21-deoxycortisol was 88.7% and specificity was 99.8% in 1910 newborn screening tests carried out between 2018 and 2021. Incorporating 21-deoxycortisone into a second-tier test and adjustment of primary screening protocols could improve the accuracy of newborn screening for CAH. Longer term prospective studies on the performance of 21-deoxycortisone are warranted.

International Journal of Neonatal Screening doi: 10.3390/ijns12020026

Authors: Pru Holder Chloe Musa Anju Keetharuth Fiona Ulph Jim B. Chilcott Louise Moody Ellinor K. Olander Jane Chudleigh

The project aimed to explore the psychosocial impact on parents of receiving a false-positive outcome following a positive newborn bloodspot screening (NBS) result for SCID for their child. A mixed-methods design was employed using semi-structured interviews and standardised health-related questionnaires (EQ-5D-5L, ITQOL-47, and GAD-7). The participants were recruited from six National Health Service hospital trusts in England involved in the NHS England In-Service Evaluation of Screening for SCID. A total of 22 interviews were conducted with 28 parents. Health-related questionnaire data were collected from 26 of these parents. The interviews were analysed using a reflexive deductive approach to thematic analysis. For the health-related questionnaire data, a comparison of group means against population norms was undertaken using t-tests with unequal variances. The findings from the interviews showed that receiving a false-positive outcome following a positive NBS SCID result could cause parents to have an enhanced view of their child’s vulnerability in the short term. However, negative sequelae were largely mitigated as parents viewed their child’s exposure to ‘normal’ infections as evidence of a functional immune system. The health-related questionnaire data showed that the parents had significantly worse health than the population norm (as indicated by EQ-VAS: p = 0.0296); however, all the other measures were non-significant. More research is needed to explore the potential longer-term psychosocial impact of a false-positive screening result for SCID on parents beyond their child’s first year of life.

International Journal of Neonatal Screening doi: 10.3390/ijns12020025

Authors: Zinandré Stander Amy L. White Matthew Lynch David Coman Justin Rosati Diana Bailey Jessica Johnson Bo Hoon Lee ChinTo Fong Joseph Orsini Matthew J. Schultz Devin Oglesbee Dimitar Gavrilov Dietrich Matern Patricia L. Hall Silvia Tortorelli

COASY-related disorders (CRDs) are a spectrum of autosomal recessive conditions caused by the dysfunction of CoA synthase, an enzyme responsible for the final steps of CoA synthesis. Clinical manifestations of CRDs are highly variable, ranging from perinatal lethal pontocerebellar hypoplasia to childhood-onset neurodegenerative brain iron accumulation, which is often recognized after clinical regression. Recent reports have described a few individuals with CRD who screened positive for carnitine palmitoyltransferase-I deficiency by newborn screening (NBS). However, heterogeneous clinical presentations, conflicting biochemical/molecular sequencing of CPT1A, and a lack of metabolic characterization have led to lengthy, costly diagnostic journeys. To address some of these aspects, this investigation retrospectively evaluated NBS acylcarnitine patterns in five CRD cases using Collaborative Laboratory Integrated Reports (CLIR). A total of 25 metabolites/ratios were identified to deviate significantly from reference ranges and were primarily composed of elevated free carnitine and reduced long-chain acylcarnitine levels. While low acylcarnitine concentrations are often not reported due to a lack of lower reference cutoffs, ratios involving these metabolites relative to short-chain acylcarnitines could aid in identifying CRD cases via NBS. When comparing this pattern to CPT-Ia cases, we confirmed a nearly identical acylcarnitine pattern between these, and thus support the need to consider CRD in cases with NBS results suggestive of CPT-Ia. This study is the first case series to characterize NBS patterns in patients with CRD and highlights the unique opportunity for early detection, particularly in cases that are neonatally asymptomatic and have unremarkable confirmatory biochemical results.

International Journal of Neonatal Screening doi: 10.3390/ijns12020024

Authors: Tunganege Matipa Elia Nyangi Agnes Jonathan Mwashungi Ally Lulu Chirande Asteria Mpoto Emmanuel Balandya Gladys Reuben Mahiti

Sickle cell disease (SCD) is a major public health concern in Tanzania where approximately 11,000 children are born with the condition annually. Newborn screening (NBS) enables early diagnosis and timely intervention. Despite the proven effectiveness of NBS in reducing early mortality from SCD, implementation in Tanzania remains limited to pilot programs at facilities such as Temeke and Amana Regional Referral Hospitals (RRHs) in the city of Dar-es-salaam. This study evaluated the implementation of NBS for the SCD Program at Temeke and Amana RRHs. An explanatory mixed-methods process evaluation was conducted between January 2022 and December 2024. Quantitative data were extracted from hospital registries and REDCap, while qualitative data were obtained from key informant interviews with 17 healthcare workers. Quantitative data were analyzed using SPSS v29.0, while qualitative transcripts were thematically analyzed using NVivo software version 15 to explore operational factors influencing implementation. A total of 10,711 newborns were screened across the two hospitals. Seventy-four (0.70%) newborns had homozygous SCD (HbS/S), whereas 1325 (12.53%) had sickle cell trait (HbA/S). Enrolment of infants diagnosed with SCD into comprehensive care declined substantially over time, from 65.6% in 2022 to 10.5% in 2024 at Temeke RRH, while Amana RRH recorded no enrolments beyond the first year of implementation. Qualitative findings highlighted facilitators for NBS such as maternal awareness, interdepartmental collaboration, and the availability of trained staff. However, implementation was hindered by inadequate refresher training, delayed staff incentives, supply shortages, and parental hesitancy influenced by cultural beliefs. This evaluation found a substantial decline in enrolment of newborns diagnosed with SCD into comprehensive care, driven by key operational challenges. Although early implementation benefited from trained, committed staff and interdepartmental collaboration, sustainability was limited by inadequate refresher training, delayed incentives, supply shortages, and parental hesitancy. Addressing these gaps through regular capacity building, strengthened supply chains, timely incentives, and culturally sensitive community education is critical to improving enrolment, continuity of care, and informing national scale-up of NBS for SCD in Tanzania.

International Journal of Neonatal Screening doi: 10.3390/ijns12020023

Authors: Emily Cheves Hannah E. Frawley Angela You Gwaltney Ana N. Forsythe Samantha Scott John Colin Mathews Jake Dibble Tanya Reeve Vesselina Bakalov Manisha Dass Heidi L. Cope Curt Scharfe Holly Peay

Research programs can interface with public health programs to generate innovation, yet it is critical to ensure processes that support research activities without infringing on protected data. Genomic newborn screening (gNBS) research programs require reliable methods to link parental consents to the correct newborn screening (NBS) specimen. Early Check is a gNBS research program in North Carolina that uses the residual dried bloodspot (DBS) samples stored at the North Carolina State Laboratory of Public Health (NCSLPH) to screen babies for serious health conditions. Early Check created a systematic approach to match research consents with NBS DBS samples utilizing a fuzzy matching algorithm and manual review of prospective matches utilizing a decision tree. Between 28 September 2023, and 10 June 2025, Early Check received parental consents for 4279 newborns. Of those, 614 (14%) had discrepancies that required further review. More than half of these (349, 57%) required outreach to the consenting parent to resolve differences in information such as name, infant sex, or contact details. The use of probabilistic matching, a decision tree, and structured staff review provides a feasible approach for accurately identifying samples from consented NBS participants.

International Journal of Neonatal Screening doi: 10.3390/ijns12020022

Authors: Akie Kato Atsuko Noguchi Hiroyuki Adachi Kiichi Takahashi Masato Ito Tomoo Ito Shozo Ota Hirokazu Arai

Acid sphingomyelinase deficiency (ASMD) is currently treatable with olipudase alfa, increasing the need for early newborn screening (NBS). We conducted a two-center pilot cohort study to characterize dried blood spot (DBS) acid sphingomyelinase (ASM) activity in Japanese neonates in the neonatal intensive care unit (NICU). ASM activity was measured by flow injection-tandem mass spectrometry in 244 NICU-admitted neonates (gestational age 25–41 weeks; birth weight 773–4201 g); longitudinal paired samples were available in 34 neonates with birth weight < 2000 g and concurrent hematology in 43 neonates. The mean ASM activity was 3.7 ± 1.2 μmol/h/L (95% confidence interval, 3.54–3.84; range, 1.7–11.6), with a right-skewed distribution. ASM activity correlated positively with birth weight (r = 0.184, p = 0.0039), gestational age (r = 0.219, p = 0.0006), and lymphocyte count (ρ = 0.394, p = 0.0089) and negatively with hematocrit (ρ = −0.372, p = 0.014). In neonates with a birth weight < 2000 g, ASM increased significantly on repeat sampling (mean difference, 1.60 μmol/h/L; p < 0.0001; Cohen’s d = 0.912). These findings support NICU-specific reference ranges, hematology-informed interpretations, repeat testing after maturation, and the use of second-tier biomarkers for ASMD NBS implementation in Japan.

International Journal of Neonatal Screening doi: 10.3390/ijns12020021

Authors: Keiko Konomura Motoko Tanaka Go Tajima Eri Hoshino

We conducted a cost-effectiveness analysis of a universal newborn screening (NBS) program for infantile-onset Pompe disease (IOPD) compared with clinical identification in newborns. The analytical model combined a decision tree and a Markov model. The incremental cost-effectiveness ratio (ICER) was estimated over a lifetime horizon, applying a 2% annual discount rate from the public healthcare payer’s perspective. In a cohort of 727,288 individuals, 2.4 patients were expected to have IOPD. The cumulative quality-adjusted life years (QALYs) gained per patient were estimated to be 7.9 when clinically diagnosed and treated with enzyme replacement therapy, and 28.9 when identified through universal NBS. The ICER was 174 million JPY per QALY. Sensitivity and scenario analyses indicated that the parameters most affecting the ICER were the NBS test cost, the quality-of-life value for ambulatory patients, the prevalence of IOPD, and the cost of enzyme replacement therapy. Although considerable uncertainty exists in the analysis, the findings suggest that implementing NBS solely for detecting infantile-onset cases poses challenges in terms of cost-effectiveness, primarily due to the rarity of the disease and the high costs associated with testing and treatment.

International Journal of Neonatal Screening doi: 10.3390/ijns12020020

Authors: Lawrence Greed James Pitt Ronda F. Greaves Kate Coleman Gabrielle Crisp Enzo Ranieri Mark de Hora Dianne Webster Natasha Heather

Newborn screening (NBS) bloodspots are primarily used to test for a defined panel of conditions, yet screening expansion has necessitated the implementation of new tests. Integral to test implementation across all clinical laboratories is the need to evaluate the method with clinical samples, and a common secondary use of residual bloodspots, which are samples that remain following conventional screening, is validating new testing methods by establishing “normal” analyte concentrations and setting action decision limits for NBS protocols prior to implementation. Analysis of de-identified residual bloodspots may potentially reveal an infant with a treatable condition, and re-identification and clinical notification of the infant may then be prudent. However, consent to test residual samples for conditions under implementation may not have been obtained. This ethical dilemma risks the inclusion of residual bloodspots in test development being declined by over-arching NBS authorities. Consequently, the Human Genetics Society of Australasia (HGSA) NBS Committee issued a survey to the Australasian NBS laboratories regarding the current practices of the use of residual bloodspots for new test implementation. The questionnaire revealed a consistent requirement for residual NBS bloodspot analysis to determine reference ranges and screening cutoffs for biochemical variants. If using de-identified residual samples as a component of test validation, re-identification of infants with out-of-range results for clinical referral was considered ethically justified for potentially treatable conditions. The survey results will be used to develop a consensus approach in the region that is both ethically and scientifically valid.

International Journal of Neonatal Screening doi: 10.3390/ijns12020019

Authors: Saskia G. Smits Suzanne M. Onstwedder Tessel Rigter Wendy Rodenburg Lidewij Henneman

Interest in the genomic sequencing of healthy newborns has raised a discussion on whether this technology should be introduced into existing newborn screening (NBS) programs. This qualitative study explores a multi-stakeholder perspective on the future of genomic sequencing in NBS. Semi-structured interviews were conducted with 26 professionals involved in NBS or in clinical genome sequencing in the Netherlands. Participants highlighted opportunities such as the possibility to use one test for a wide range of genetic conditions, reducing diagnostic odyssey, expanding the scope of NBS, and increasing program efficiency. Challenges were raised regarding genetic variant interpretation, expected increased parental anxiety, data privacy issues, difficulties with information provision, and high costs. Three areas of tension between participants’ perspectives were identified: screening strategy, screening performance, and roles and responsibilities. It was emphasized that implementing genomic sequencing should not risk reducing the current high NBS participation, and that enhancing knowledge, communication, and collaboration between all stakeholders is needed. Although most participants did not believe genomic sequencing as a first-tier test is currently desirable and feasible, they acknowledged it has a role to play in the future of NBS. Future decision-making should consider the potential impact on the participation rate, program quality, and balancing benefits and harms.

International Journal of Neonatal Screening doi: 10.3390/ijns12010018

Authors: Yiming Lin Jinping Zhong Weilin Peng Faming Zheng Xudong Wang

Organic acidemias (OADs) are a group of inherited metabolic disorders with a high false-positive rate in newborn screening. In this study, we aimed to evaluate the clinical performance of next-generation sequencing (NGS) as a combined genetic test for OADs. From September 2022 to August 2025, 154,634 newborns underwent primary screening using tandem mass spectrometry (MS/MS). Among them, 151 neonates with suspected OADs underwent combined genetic screening using a pre-designed NGS panel. Of these, 55 cases tested positive on genetic screening, and 17 were ultimately diagnosed with OADs, yielding a prevalence of 1 in 9096. The positive predictive value of NGS was 30.91% (17/55). The genotypes of nine patients (9/17, 52.9%) were identified through NGS screening. Notably, one case of methylmalonic acidemia that would have been missed by MS/MS screening was successfully identified using the combined genetic screening. Additionally, 37 neonates with positive biochemical screening results were confirmed to be either carriers or unaffected individuals. Two cases of Wilson’s disease were also identified through combined genetic screening. Therefore, integrating NGS into conventional MS/MS-based screening can significantly reduce the false-positive rate and shorten the time from screening to definitive diagnosis. This approach provides a valuable model for improving the efficiency and accuracy of newborn genetic screening.

International Journal of Neonatal Screening doi: 10.3390/ijns12010017

Authors: Yiming Lin Yanru Chen Weihua Lin Faming Zheng

Functional analysis of SLC22A5 variants can improve diagnostic accuracy in patients with primary carnitine deficiency (PCD). Herein, we performed a genetic analysis of three neonates with PCD. Two of the patients harbored a novel synonymous SLC22A5 variant that has not been previously reported, and the other patient harbored a classical splice site variant. The splicing patterns of the two SLC22A5 variants were evaluated using three in silico tools, and in vitro minigene analysis was performed to verify the impact of variants on RNA splicing mechanisms. All three in silico tools predicted that both SLC22A5 variants could alter normal RNA splicing. Functional studies using minigene assays demonstrated that the c.450C>T (p.F150=) leads to partial exon 2 skipping, and c.394-1G>A leads to intron 1 retention and exon 2 skipping. Intron 1 retention of 65 nucleotides and exon 2 skipping were confirmed by sequencing cDNA amplification products. These results, along with functional evidence, led to reclassification of c.450C>T (p.F150=) and c.394-1G>A as likely pathogenic and pathogenic, respectively. This is the first reported synonymous variant in the SLC22A5 gene that has been functionally validated to affect RNA splicing, thus enriching the variant spectrum of SLC22A5 and aiding accurate PCD diagnosis.

International Journal of Neonatal Screening doi: 10.3390/ijns12010016

Authors: Ilaria Bitetti Rosa Iannaccone Giovanna Margiotta Antonio Varone

Spinal muscular atrophy (SMA) is a rare neuromuscular disorder causing progressive muscle weakness. Severe SMA forms are typically observed up to six months postnatally. Disease-modifying therapies provide significant benefits, making newborn screening (NBS) essential for timely diagnosis and treatment initiation. The NBS programme evaluated infants born between April 2023 and October 2024 in the Campania region, Italy. DNA was amplified to detect homozygous deletion of the SMN1 gene by RT-PCR and SMN2 copy number using multiplex ligation-dependent probe amplification. Following treatment, motor functions were assessed using CHOP-INTEND and Bayley III scales. Among 62,801 infants screened for SMA, thirteen (11 females, 2 males) tested positive. The distribution of SMN2 copy numbers was as follows: eight patients had two copies, one patient had three, and four patients had four copies. One year after treatment, motor outcome data were available for four of the eight patients with two SMN2 copies. Among these patients, one achieved the milestones of walking without support, and three were standing with support. At 24 months, three of these patients were walking independently. Pre-symptomatic treatment markedly improves motor function development. This underscores the urgent need for large-scale newborn screening to prevent diagnostic delays and ensure timely, effective therapy. Validated care protocols must be established to facilitate early diagnosis and intervention.

International Journal of Neonatal Screening doi: 10.3390/ijns12010015

Authors: Rithika Thampy Nishitha R. Pillai Michael Evans Chester B. Whitley Paul J. Orchard Matthew Ellinwood Amy Gaviglio

Mucopolysaccharidosis type I (MPS I) results in the accumulation of glycosaminoglycans (GAG) and, for the purposes of newborn screening, is differentiated into two forms: severe (Hurler syndrome) versus attenuated (encompassing Scheie and Hurler-Scheie syndromes). MPS I was added to the federal Recommended Uniform Screening Panel for newborn screening (NBS) in 2016, and as of December 2025, 45 of 54 programs in the United States (US) screen for MPS I. Within the newborn screening program, a second-tier analysis of GAG is thought to reduce false-positive rates, particularly through mitigating the detection of pseudodeficiency. However, there have been some concerns that the use of second-tier GAG analysis might inadvertently result in missed detection of attenuated cases. A survey of all US NBS programs was conducted requesting data on the total number of screen-positive NBS results for MPS I as well as the final diagnostic outcome from these results. Diagnostic outcomes after screening were classified as false-positive, pseudodeficiency, severe MPS I, attenuated MPS I, and MPS I of undetermined phenotype. Additionally, information on testing methodologies and dates of MPS I NBS implementation was collected. Responses were obtained from 32 NBS programs. The cohort of screening programs utilizing second-tier blood spot GAG determinations detected a higher proportion of severe cases than those not using this second-tier test (48% vs. 29%). The proportion of attenuated cases remained consistent between both groups (13% vs. 14%). The proportion of pseudodeficiency detection was only slightly lower in the cohort using second-tier GAG analysis (85% vs. 91%). Second-tier GAG analysis appears to reduce the detection of false-positive cases and improves the resolution of severe MPS I cases, though the proportion of pseudodeficiency was only slightly lower compared to the programs that do not use second-tier GAG analysis. Currently, the proportion of attenuated cases is comparable between the two cohorts, but the higher number of “undetermined phenotype” cases may eventually shift the balance toward states not using GAG analysis once the type is determined.

International Journal of Neonatal Screening doi: 10.3390/ijns12010014

Authors: Nika Požun Daša Perko Violeta Anastasovska Ivo Barić Mihail Baša Tadej Battelino Iva Bilandžija Ian Brincat Miloš Brkušanin Maja Djordević Ivanka Dimova Ana Drole Torkar Ksenija Fumić Sergiu Gladun Panagiotis Girginoudis Ildikó Szatmári Ivana Kavečan Jasmina Katanić Vjosa Kotori Nina Marić Jelena Martić Olja Manđarelo Tatjana Milenković Matej Mlinarič Florentina Moldovanu Michaela Nanu Péter Monostori Iskra Modeva Branka Opančina Dimitris Platis Maja Raičević Žiga Iztok Remec Barbka Repič Lampret Alexey Savov Anastasia Skouma Aleksandar Sovtić Iva Stoeva Alma Toromanović Domen Trampuž Natalia Usurelu Jelena Višekruna Marios Vogazianos Maximillian Zeyda Mojca Žerjav Tanšek Urh Grošelj

Newborn screening (NBS) is a well-established public health program that enables early detection and treatment of rare disorders in newborns, preventing severe complications or death. Despite its recognized importance, the scope and implementation of NBS programs vary across Southeastern (SE) and Central Europe. This study aimed to evaluate the current status of NBS in 16 countries of SE and Central Europe and assess progress since the previous survey in 2021. A structured questionnaire was distributed to national experts between April and December 2025, collecting data on program organization, coverage, diseases included, laboratory methods, confirmatory testing, consent practices, and future expansion plans. All countries reported universal screening for congenital hypothyroidism, except Kosovo, where a national NBS is in the process of being established. Expanded NBS using tandem mass spectrometry was available in Austria, Bulgaria, Croatia, Cyprus, Greece, Hungary, North Macedonia, Romania, and Slovenia. Spinal muscular atrophy screening became universal in Austria, Croatia, Hungary, Serbia, and Slovenia. Most countries reported plans for further expansion, with congenital adrenal hyperplasia, severe combined immunodeficiency, spinal muscular atrophy, and cystic fibrosis being the most frequently targeted conditions. Although notable infrastructural progress has been achieved, financial constraints, lack of staff, and organizational barriers remain key challenges. The study’s assessment of program effectiveness was further limited by the absence of region-wide systems for capturing end-to-end performance indicators, such as the age of the infant at treatment initiation or missed cases. Regional collaboration and adoption of best practices are therefore vital to ensure equitable access and continuous advancement of NBS programs.

International Journal of Neonatal Screening doi: 10.3390/ijns12010013

Authors: Ekaterina Y. Zakharova Galina V. Baydakova Polina V. Baranova Darya Y. Aleksandrova Olga A. Shchagina Yulia S. Itkis Natalya V. Milovanova Tatyana S. Nagornova Olga N. Ivanova Yana D. Nazarenko Sergey V. Voronin Alena L. Chukhrova Varvara A. Kadnikova Ekaterina E. Lotnik Nina V. Ryadninskaya Aleksander V. Polyakov Kirill V. Savostyanov Fanil S. Bilalov Alexander L. Koroteev Dmitry Y. Trofimov Tatyana A. Bairova Gulnara N. Seitova Sergei V. Mordanov Svetlana A. Matulevich Elena B. Nikolaeva Sergey I. Kutsev

In 2023, the Russian Federation expanded its national newborn screening (NBS) program from 5 to 36 conditions, 29 of which are inherited metabolic diseases (IMDs). This study presents the first nationwide results and outcomes of the expanded NBS program. Between January 2023 and December 2024, dried blood spots from 2,466,615 newborns (98.53% of the birth cohort) were analyzed for IMDs using MS/MS. Screen-positive cases were referred to the national reference center for confirmatory testing, which included biochemical (MS/MS and GC-MS) and genetic analyses (NGS). A total of 41,728 neonates (1.69%) screened positive, of whom 37,733 underwent confirmatory testing. It resulted in 834 confirmed diagnoses of IMDs (1 in 2900 live births). Phenylketonuria was the most prevalent IMD (n = 538; 1 in 4600), followed by MCADD (n = 99; 1 in 25,000). Distinct regional and ethnic variations were observed, including a high prevalence of tyrosinemia type 1 in the Chechen Republic and MCADD in North Ossetia. The integration of NGS was essential for resolving complex cases, such as identifying heterozygous carriers and dual diagnoses. These findings underscore the program’s clinical utility, highlight unique epidemiological patterns, and identify challenges such as false positives and diagnostic complexities, which will guide future refinements.

International Journal of Neonatal Screening doi: 10.3390/ijns12010012

Authors: Hussien Abdo Babiker Turki Omaish Alotaibi Hiba Hassan Sulaiman Almohaimeed Shadin Alamrah Asalah Alhazmi Abdulwahab H. Alharbi

Critical congenital heart disease (CCHD) is a major cause of neonatal morbidity and mortality. Pulse oximetry screening enables early detection, potentially reducing complications and improving outcomes. This study evaluated pediatric residents’ knowledge, attitudes, and practices (KAP) related to CCHD screening in Saudi Arabia. A cross-sectional survey was distributed to pediatric residents across Saudi Arabia. The questionnaire assessed knowledge, attitude, and practice regarding CCHD screening. A total of 123 pediatric residents in training were included in the study. Of these, 57 (46.3%) were male, and 66 (53.7%) were female. A progressive increase in mean scores was observed with advancing training years (p = 0.010). A significant difference was observed in knowledge scores based on completion of a cardiology rotation (p = 0.006). A progressive increase in attitude scores was observed with each successive year of training. Current year in training showed a statistically significant association with attitude scores (p < 0.001). Completion of a newborn nursery or NICU rotation was also significantly associated with higher attitude scores (p = 0.027). Similarly, attitude scores were significantly higher among those who had completed a cardiology rotation (mean = 12.99, SD = 1.52) compared to those who had not (mean = 11.60, SD = 1.84; p < 0.001). While practice scores were not statistically different across most groups, senior residents demonstrated better adherence to screening. Residents exhibit increasing awareness and positive attitudes with experience; however, practical implementation remains inconsistent. Targeted education and standardized protocols are necessary to improve outcomes. A positive correlation was observed between knowledge and attitude scores (r = 0.346, p < 0.001).

International Journal of Neonatal Screening doi: 10.3390/ijns12010011

Authors: Louis Domenach Adrien Pagin Camille Cisterne Marie-Pierre Audrezet Laure Couderc Laetitia Monteil Léa Roditis Marlène Murris Julie Macey Michael Fayon Stéphanie Bui Marie-Pierre Reboul

CFTR modulators have transformed the clinical evolution of patients with CF. The number of pregnancies is increasing in women with CF, most of whom are now treated with CFTR modulators such as elexacaftor/tezacaftor/ivacaftor (ETI) or Tezacaftor/Ivacaftor. This raises some questions as we still lack data on foetal and maternal safety. The preliminary data seem to support the continuation of modulators. Some of these mothers may also give birth to newborns with CF and this raises more questions. We report here four cases of CF newborns whose mothers were treated with CFTR modulators throughout pregnancy to help refine potential foetal outcomes of in utero administration of CF modulators. No maternal or foetal complications could be attributed to CFTR modulators. Three CF newborns were exposed to ETI and were false negative of the newborn screening. Two of them were pancreatic sufficient at birth. The remaining patient, exposed to Tezacaftor/Ivacaftor (TI) alone, showed elevated immunoreactive trypsin (IRT) and severe pancreatic insufficiency at birth. These cases highlight that in utero administration of ETI could potentially improve neonatal outcomes of CF newborns and cause newborn screening false negative.

International Journal of Neonatal Screening doi: 10.3390/ijns12010010

Authors: Emine A. Rahiman Rajendra Prasad Anne Rajasekharan P. Warrier

Newborn screening helps identify sickle cell disorder (SCD) early and to promptly initiate effective measures. It is estimated that India accounts for approximately 16% of global annual births with SCD. Multiple reports of screening for SCD in India have emerged in the last decade. Our aim was to pool the birth prevalence of SCD and sickle cell trait (SCT). A systematic review of published evidence on nontargeted, universal screening for SCD or SCT in newborns was performed (16 studies). The pooled prevalence of SCD was 1100 per 100,000 (10 studies, 88,276 neonates, 95% CI: 432, 1768), while that of SCT was 9639 per 100,000 (7 studies, 72,702 neonates, 95% CI: 6283, 12,995) in endemic regions. Limited data exist from nonendemic regions. Only three studies had data on follow-up and confirmatory genetic diagnosis. Sparse data exist on cost-effectiveness, long-term follow-up, and the impact of early screening on mortality. Concerted ongoing efforts in the identification of the burden are needed. The needs of the hour are universalization of NBS, integration into existing health systems, and maintenance of birth cohorts with early introduction of penicillin prophylaxis, hydroxyurea, parental education, appropriate immunization, and continued follow-up by an experienced medical team.

International Journal of Neonatal Screening doi: 10.3390/ijns12010009

Authors: Scott D. Grosse Kai Hong Golriz K. Yazdanpanah Ashley Nash Amy Gaviglio Marcus Gaffney Kendra A. K. Lawrence Jennifer M. Kwon

Screening for spinal muscular atrophy (SMA) was adopted by all US state newborn screening programs between 2018 and 2024; by the end of 2022, 48 states were screening for SMA. We assessed trends in health insurance records of SMA diagnoses to quantify improvements in the timeliness of SMA identification following the adoption of screening. We used nationally representative Medicaid claims data for approximately half of US births covered by public insurance and a convenience sample of employer-sponsored health plans. We analyzed records for birth cohorts with at least 1 full year of follow-up (i.e., through the end of the following calendar year). For 2017 births, 1.3 per 100,000 infants had SMA codes first recorded by 1 month of age; this increased to 6.6 per 100,000 among publicly insured newborns born in 2022. The rollout of SMA newborn screening across US states was also followed by improvements in the timely detection of SMA. The proportion of infants with SMA detected by 1 month increased from 18% in 2017 to 61% in 2021 and is projected to reach 75% in 2022. Growth in timely detection was even greater in the employer-insured sample. Timely diagnosis of SMA can enable the initiation of treatment prior to the irreversible loss of motor function.

International Journal of Neonatal Screening doi: 10.3390/ijns12010008

Authors: Bradford L. Therrell

Newborn bloodspot screening (NBS) began in Guthrie’s laboratory in 1961 for phenylketonuria. A federal study the following year formed the basis for expanding NBS as a public health function. Diseases detectable through NBS gradually expanded, eventually including sickle cell anemia, which was included in the screening panel in New York in 1975. Universal inclusion of full population screening for sickle cell anemia was included in all US NBS programs by 2006. Through the years, NBS for sickle cell anemia has expanded to include other clinically significant hemoglobin disorders (both hemoglobinopathies and thalassemias). While NBS programs exist in most high-income countries, their implementation in low- and middle-income settings has been slow, with the inclusion of hemoglobin disorders occurring even more slowly. It is particularly noteworthy that the low-resource settings with the highest incidences of sickle cell diseases (Sub-Saharan Africa, the Caribbean Islands, and India) and therefore the greatest potential for benefitting from NBS, continue to struggle with its implementation. Recent advances in curative treatments further emphasize the importance of NBS in early disease identification. This report reviews some of the history of newborn screening for hemoglobinopathies and thalassemias and provides an update of related activities currently ongoing globally.

International Journal of Neonatal Screening doi: 10.3390/ijns12010007

Authors: Lisanne Vonk Paula van Dommelen Iris Eekhout Noëlle N. Uilenburg Paul H. Verkerk Catharina (Kitty) P. B. van der Ploeg

In The Netherlands, preventive child healthcare (PCHC) has been carrying out neonatal hearing screening in well-babies since 2006. The aim of this study was to examine the relationship between the age of newborns and the false positive referral rate of the first hearing screening using a transient evoked otoacoustic emission (OAE) test, to identify the most efficient timing for OAE screening. Additionally, we investigated the relationship between the type of OAE screening device (Echoscreen (ES)I/II versus ESIII) and the referral rate during the first screening. We used data from the Dutch universal well-baby neonatal hearing screening programme by PCHC between 2013 and 2023. Multilevel logistic regression analyses were performed to estimate the probability of a referral in 2023 for newborns screened in 2022 and 2023. We included a total of 1,650,506 newborns for 2013–2022 and 323,194 newborns for 2022–2023. The lowest false positive referral rates were found between days five and thirteen, ranging from 3.3 to 3.9%. ESIII significantly increased the probability of a referral compared to ESI/II (odds ratio = 1.84, 95% confidence interval = 1.65–2.06). In conclusion, the timing of neonatal hearing screening significantly impacts the false positive referral rate. Furthermore, the likelihood of a referral is significantly higher when using the ESIII compared to the ESI/II.

International Journal of Neonatal Screening doi: 10.3390/ijns12010006

Authors: Madalina Cristina Leanca Gelu Onose Georgiana Nicolae Elena Neagu Daniela Vasile Ecaterina Bercu Oana Mirabela Balanescu Andrei Capitanescu Constantin Munteanu Cristina Popescu Andrada Mirea

Spinal muscular atrophy (SMA) is a severe genetic neuromuscular disorder caused by bi-allelic deletions or pathogenic SMN1 variants. Early diagnosis through neonatal screening is essential for timely therapeutic intervention, significantly improving clinical outcomes. In August 2022, a pilot neonatal screening program for SMA was launched in Romania, aiming to assess feasibility and impact. Objectives are to present the preliminary results of the ongoing SMA neonatal screening pilot program in Romania, evaluating its effectiveness in early detection and referral for treatment. The program started in August 2022 with four maternity hospitals and has progressively expanded to 28 maternity hospitals nationwide. Dried blood spot samples from newborns were analyzed for SMN1 gene deletions using real-time PCR. Positive results were confirmed through genetic testing, and affected infants, along with their families, were referred for further medical evaluation and early therapeutic intervention. Approximately 60,000 newborns have been screened since the program’s inception, and 12 newborns tested positive for SMN1 deletions, resulting in an estimated incidence rate of 1 in 5125 live births. All confirmed cases were promptly referred for specialized care, with early access to disease-modifying therapies. The program has faced challenges in logistics, parental awareness, and equitable access to treatment, but its expansion from 4 to 28 maternities demonstrates increasing feasibility, suitability, and acceptance. Conclusions: The Romanian pilot neonatal screening program for SMA has successfully identified affected infants early, proving its feasibility and clinical impact. The ongoing expansion suggests a strong foundation for a future national program, which could significantly improve early SMA diagnosis and patient outcomes in Romania.

International Journal of Neonatal Screening doi: 10.3390/ijns12010005

Authors: Olumuyiwa S. Folayan Bose E. Orimadegun Adejumoke I. Ayede Baba P. Inusa Marika K. Kase John I. Anetor

Newborn screening (NBS) is a cost-effective public health strategy for the early detection of congenital disorders that cause neonatal/infant morbidity and mortality. It is standard care in many high-income and emerging economies. Nigeria, despite its high birth number, has no newborn screening (NBS) programme for any disorder, causing missed opportunities for early therapy. This manuscript is a workshop report and expert consensus of a three-day national workshop organised by the Newborn Screening Consortium–Nigeria (NSC-N) in conjunction with The Federal Ministry of Health Nigeria, Revvity, and international partners. The first meeting comprised experts in different fields of newborn screening and newborn care who reviewed priority congenital disorders, implementation barriers, and national NBS needs in Nigeria. Experts presented pilot data, opinions, and global best practice evidence. Contributions were examined and debated and conclusions were reached by guided discussions and consensus agreement for a pragmatic nationwide NBS plan. The key outcomes were the urgency for Nigeria to begin an integrated, comprehensive NBS programme. Based on standard prioritisation criteria, sickle cell disease and congenital hypothyroidism were selected. Key implementation strategies included integration into routine maternal and child health services, establishing a national screening database, and developing a robust legislative and policy framework. The NBS workshop developed a framework to commence and incorporate integrated NBS into the Nigerian healthcare system. Two conditions were selected to kickstart the programme and establish a foundation for future expansion. This would improve neonatal health outcomes and reduce the long-term burden of congenital disorders.

International Journal of Neonatal Screening doi: 10.3390/ijns12010004

Authors: Lisa Marie Shook Russell E. Ware

Newborn screening (NBS) for sickle cell disease (SCD) has been performed in the United States (US) for decades, significantly reducing infant morbidity and mortality. A landmark clinical trial demonstrated that early identification of SCD enabled timely and life-saving prophylactic penicillin; this led to recommendations for universal NBS across the US. Early use of hydroxyurea as a safe and effective treatment for SCD further improved clinical outcomes by preventing acute and chronic disease complications. These advances add to the importance of early diagnosis through NBS, providing an opportunity for early treatment intervention. In recent years, high-resource countries—including those in Europe, the UK, and Canada—have adopted NBS for SCD using diverse strategies. Simultaneously, pilot programs in lower-resource settings such as Africa, Brazil, and India have demonstrated local feasibility and impact through implementation efforts. An overarching equity gap for achieving global NBS for SCD is the variable access to simple, accurate, and affordable testing. Other challenges include timing of NBS testing, targeted populations, laboratory methods, and parental education with genetic counseling. Questions remain about the equitable enrollment of affected infants worldwide into comprehensive care to ensure early treatment. These challenges raise concerns about sustainability, underscore the need for long-term funding and a strategic plan, and highlight persistent inequities from the lack of global NBS standards.

International Journal of Neonatal Screening doi: 10.3390/ijns12010003

Authors: Praveen Thokala Alice Bessey Rachel Knowles John Marshall Cristina Visintin Miranda Lawton Silvia Lombardo

Spinal muscular atrophy (SMA) is a genetic condition that causes the degeneration of motor neurons in the spinal cord. Newborn blood spot (NBS) screening can potentially enable diagnosis before symptoms, and presymptomatic treatment is considered to be more effective than symptomatic treatment. In this paper, we present an overview of a cost-effectiveness model of NBS screening for SMA in the UK, informed by key clinical trials and the relevant published literature. Our analyses suggest that implementing screening could result in better outcomes and lower costs compared to the current approach of no screening plus treatment. However, several uncertainties and limitations of the model remain. These include uncertainty in the reimbursement status of nusinersen and risdiplam in the future; the ‘actual’ costs of treatments, as they are under confidential commercial agreements; uncertainty in the long-term effectiveness of presymptomatic and symptomatic treatment; and uncertainty around the incidence of SMA and the costs and the accuracy of NBS screening. An SMA in-service evaluation (ISE) that could capture data specific to the UK is under consideration, and an appropriately designed ISE with ongoing data collection could support periodic updates of clinical and cost-effectiveness estimates of NBS screening for SMA in the UK.

International Journal of Neonatal Screening doi: 10.3390/ijns12010002

Authors: Mairéad Bracken-Scally Anna O’Loughlin Heather Burns

The aim of the evaluation was to gather information on parents’ experiences and attitudes towards the Irish National Newborn Bloodspot Screening Programme (NNBSP). An interviewer-administered survey was completed by 151 parents whose babies underwent newborn bloodspot screening (NBS) between 2023 and 2025 and for whom the screening result was normal. Results suggest that NBS is highly acceptable to parents, with 100% glad their baby underwent screening. The majority (95%) felt they were provided the information needed to understand the importance of NBS for their baby, and 93% are in favour of screening for more conditions. Positive aspects of NBS reported by parents included the following: blood sampling being undertaken in the home, the sample-taker being very nice and being advised in advance to keep the baby’s heel warm to ease the sampling process. Negative aspects of NBS reported included the following: having to return to the hospital for sampling, the baby becoming distressed, not receiving adequate information and not receiving the screening results. Parents were more likely to report negative experiences if the sample was not taken at home and if the sample was taken by a healthcare professional other than a public health nurse. Parents offered recommendations for improvements to the programme. This study provides important insights into parents’ experiences and attitudes towards NBS in Ireland.

International Journal of Neonatal Screening doi: 10.3390/ijns12010001

Authors: Nils W. F. Meijer Hidde H. Huidekoper Klaas Koop Sabine A. Fuchs M. Rebecca Heiner Fokkema Charlotte M. A. Lubout Andrea B. Haijer-Schreuder Wouter F. Visser Rendelien K. Verschoof-Puite Eugènie Dekkers Annet M. Bosch Rose E. Maase Monique G. M. de Sain-van der Velden

In the Netherlands, the newborn screening (NBS) program includes screening for propionic aciduria (PA) and methylmalonic aciduria (MMA). When initial screening reveals elevated C3 concentrations or abnormal ratios (C3/C2, C3/C16), a second-tier test measuring methylcitric acid (MCA) for PA and methylmalonic acid (MMAmb) for MMA is performed. While this two-tier approach reduces false positives effectively, it can delay referral from the NBS program and diagnosis of propionic aciduria. We describe four early-onset PA cases in which the current Dutch screening algorithm negatively impacted clinical outcomes, highlighting the need for expedited referral. We investigated different alternative screening strategies to identify the most effective approach for improving timeliness, while maintaining the high specificity of Dutch PA NBS. This revised approach prioritizes the evaluation of the C3/C2 ratio in first-tier screening. Specifically, samples with a C3/C2 ratio ≥ 0.75 should be referred directly for medical consultation and confirmatory testing. For all other samples with less pronounced biochemical abnormalities, the existing two-tier screening algorithm remains an appropriate NBS protocol. To position our approach internationally, a survey of European NBS programs was conducted to compare screening and referral protocols for PA across the region.

International Journal of Neonatal Screening doi: 10.3390/ijns11040116

Authors: Xuefang Jia Ting Xie Xiang Jiang Fang Tang Minyi Tan Qianyu Chen Sichi Liu Yonglan Huang Li Tao

This study was designed to assess the effectiveness of neonatal congenital adrenal hyperplasia (CAH) screening in Guangzhou, China. A total of 818,417 newborns were screened for CAH by measuring 17-hydroxyprogesterone (17-OHP) concentrations. Cut-off values were stratified based on gestational age (GA) and the timing of sample collection. Neonates with initial positive results (17-OHP ≥ cut-off value) were recalled for a second dried blood spot sample to reassess 17-OHP levels. Confirmatory testing involved biochemical analyses, Sanger sequencing, and multiplex ligation-dependent probe amplification of the CYP21A2 gene. From 2018 to 2024, a total of 40 patients with classical 21-hydroxylase deficiency were identified, including 28 cases (70%) of the salt-wasting form and 12 cases (30%) of the simple virilizing form. The overall incidence of CAH was 1 in 20,653 (95% confidence interval: 1:34,928, 1:14,661). No statistically significant differences in prevalence were observed between sexes or between preterm and full-term infants (p > 0.05). 17-OHP concentrations are influenced by GA and the timing of sample collection. The screening efficiency for CAH could be improved by adopting a multitiered cut-off value system adjusted for GA and collection time.

International Journal of Neonatal Screening doi: 10.3390/ijns11040115

Authors: Vincenza Gragnaniello Giacomo Gaiga Chiara Cazzorla Elena Porcù Daniela Gueraldi Andrea Puma Christian Loro Mara Doimo Leonardo Salviati Alberto B. Burlina

3-Methylcrotonyl-CoA carboxylase deficiency (3-MCCD) is a metabolic disorder with a wide clinical spectrum ranging from asymptomatic individuals to severe metabolic decompensation. Following the introduction of expanded newborn screening, a high number of asymptomatic individuals with 3-MCCD were identified, prompting debates about its inclusion in screening panels. In order to inform policy and healthcare decisions regarding the inclusion of 3-MCCD in newborn screening programs, we evaluated the long-term outcomes for newborns with positive results over a decade of screening experience in North-East Italy, as well as the psychological impact on their parents. Of the 336,668 newborns screened between 2014 and 2025, 9 were confirmed to be affected. These infants underwent annual clinical and biochemical assessments, including dried blood spot acylcarnitine profile, plasma free carnitine, and urinary organic acids assays. An emergency protocol was provided to all affected children to manage intercurrent illnesses. An ad hoc survey was developed to assess the psychological impact of the disease on parents. During follow-up (mean age at last visit: 4.2 years), one patient experienced metabolic decompensation during an intercurrent illness, which was promptly treated. One patient presented with growth retardation and another with transient psychomotor delay. Five patients developed carnitine deficiency, requiring supplementation. Psychological assessments revealed an initial high level of parental psychological impact, which decreased over time. All parents strongly supported the screening program. Newborn screening for 3-MCCD enabled the early identification and management of affected individuals, thereby avoiding severe metabolic decompensation. Although there is an initial psychological burden on parents, it significantly decreases over time. Therefore, the long-term benefits of newborn screening for 3-MCCD seem to outweigh the psychological drawbacks.

International Journal of Neonatal Screening doi: 10.3390/ijns11040114

Authors: Uta Nennstiel Inken Brockow Birgit Odenwald Carola Marzi Marianne Hanauer Esther Maier Wulf Röschinger Ralph Fingerhut Bernhard Liebl

The German federal state of Bavaria implemented newborn screening (NBS) using dried blood spots (DBS) as an integrated public health programme with centralised coordination. The Bavarian NBS Centre collaborates with NBS laboratories, obstetric and paediatric facilities, specialised centres of expertise, and parents. It is responsible for coordination, evaluation, quality assurance, and a long-term follow-up study. In this paper, an analysis of NBS in Bavaria from 1999 to 2023 and a long-term follow-up for the birth cohort until 2013 is presented. Of the 2,854,190 babies screened, 2500 were diagnosed and treated early thanks to NBS. An NBS coverage rate of 99.83% was achieved, with 99.09% of all requested repeat tests completed. Around 87% of infants with time-sensitive conditions underwent a clinical intervention within the first 14 days of life. Systematic tracking enabled all but 54 NBS-positive results to be clarified and 122 newborns to be diagnosed in due time. The results of the long-term follow-up study demonstrate that almost all the children identified through NBS receive ongoing medical care, and that NBS has contributed to the age-appropriate development of most affected children. This 25-year evaluation of NBS in Bavaria shows that near-universal participation in NBS and follow-up of almost all positive NBS results can be achieved through centralised coordination and ongoing cooperation of all those involved.

International Journal of Neonatal Screening doi: 10.3390/ijns11040113

Authors: Shuting Huang Qiongfang Yao Fei Kong Min Wu Xiaolong Qiu Peiran Zhao Yinglin Zeng Jinying Luo Liangpu Xu Jinfu Zhou

Organic acid disorders (OADs) are inherited metabolic defects in the enzymes and cofactors involved in metabolic pathways. This systematic review and meta-analysis investigated the incidence and regional differences in OADs between the northern and southern regions of China. Searches of the PubMed, Embase, Web of Science, and Chinese databases (CNKI, Veipu, and Wanfang) revealed 1784 studies indexed between January 2002 and December 2024. After quality assessment and data extraction, the meta-analysis was conducted on OAD screening data from 57 studies involving 13,314,056 newborns and 1501 OAD cases in China. The seven most prevalent OADs were methylmalonic acidemia (MMA), 3-methylcrotonyl-CoA carboxylase deficiency, glutaric acidemia type I, isobutyryl-CoA dehydrogenase deficiency, isovaleric acidemia, 2-methylbutyryl-CoA dehydrogenase deficiency (2-MBD), and propionic acidemia. The meta-analysis revealed an OAD prevalence of 112.38 (95% confidence interval 106.70–118.07) per 1,000,000 newborns. The incidence of OADs and MMA was significantly higher in northern China than in southern China, whereas the incidence of 2-MBD was significantly lower in northern China than in southern China (p < 0.0001). Additionally, the ratio of MMA combined with homocystinuria to MMA was higher in northern China than in southern China (p < 0.05). These results provide valuable epidemiological insights and guidance for newborn screening for OADs in China.

International Journal of Neonatal Screening doi: 10.3390/ijns11040112

Authors: Jariya Upadia Grace Noh Kea Crivelly Elise Aziz Amy Cunningham Hans C. Andersson

This study evaluates the incidence of metabolic disorders detected from January 2005 to December 2024 and their clinical outcomes. Data were retrospectively collected from the Louisiana Newborn Screening database. Clinical outcomes were obtained through review of corresponding medical records. In addition, an electronic questionnaire assessing educational attainment and neurodevelopmental disorders was sent to the patients’ families. Of 1,230,356 infants screened, 478 were diagnosed with metabolic disorders, corresponding to an incidence of 1 in 2574 live births. The three most commonly identified conditions were biotinidase deficiency, phenylketonuria (PKU), and medium-chain acyl-CoA dehydrogenase deficiency (MCADD). During the study period, at least 11 patients died. The program demonstrated a false-positive rate of 0.93%. Twelve patients (7%) were symptomatic before or at the time of NBS result notification. Recurrent metabolic decompensations occurred in 3 of 4 maple syrup urine disease (MSUD) cases, 7 of 7 methylmalonic acidemia (MMA) cases, 1 of 4 propionic acidemia (PA) cases and 1 of 7 urea cycle defect cases. Regarding long-term outcomes, 45.7% of survey respondents reported adverse neurodevelopmental outcomes of varying severity. Early detection and timely intervention have contributed to normal or near-normal outcomes in many cases. However, the morbidity and mortality observed in some patients despite early diagnosis highlights the severity and complexity of certain metabolic conditions. Additionally, the relatively high false positive rate underscores the need for ongoing efforts to improve the specificity of screening protocols to reduce unnecessary follow-ups and mitigate potential stress for families.

International Journal of Neonatal Screening doi: 10.3390/ijns11040111

Authors: Harvey L. Levy

This book by Dr [...]

International Journal of Neonatal Screening doi: 10.3390/ijns11040110

Authors: Jianjun Li Bo Wu Wenlan Liu

This study aims to investigate the genotype characteristics of newborns with biallelic GJB2 mutations and their correlation with hearing phenotypes, providing a basis for clinical genetic counseling and hearing management. A retrospective study was conducted on 652 newborns with biallelic GJB2 mutations detected at the Newborn Diseases Screening Center of Shenzhen Maternal and Child Health Care Hospital from January 2022 to December 2024. The differences in mutation types, hearing screening, and diagnostic results were analyzed and compared between the homozygous and compound heterozygous mutation groups to assess their correlation with hearing phenotypes. Genotype analysis identified 543 cases of homozygous mutations, mainly the c.109G>A/c.109G>A genotype (98.90%). Compound heterozygous mutations were identified in 109 cases, with the majority being c.109G>A/c.235delC (76.15%). Following two-stage hearing screening, 227 (34.82%) of the 652 cases were referred, with bilateral failure accounting for the majority (81.94%) of these cases. The referral rates showed no significant difference between the homozygous (35.54%) and compound heterozygous (31.19%) groups (p > 0.05). The overall hearing loss detection rate was 6.90% (45/652); among these, eight infants who had initially passed the newborn hearing screening were later found to have hearing loss between 2.5 and 6 months of age. Among the 45 confirmed deaf children, hearing loss was mainly mild to moderate (87.50%), and profound deafness was only seen in the homozygous mutation group (10.29%, 7/68 ears). Most newborns with biallelic GJB2 mutations passed the two-stage hearing screening, and associated hearing loss was typically mild to moderate. Long-term auditory monitoring remains essential for all genetically confirmed infants to monitor late-onset progression.

International Journal of Neonatal Screening doi: 10.3390/ijns11040109

Authors: Eri Sakai Takahiro Yamada Takashi Hamazaki Go Tajima Toshiyuki Seto

Following Newborn Screening (NBS), parents receiving positive results experience various psychosocial effects upon learning their child’s genetic information or unexpected findings. These factors warrant careful consideration. The Japanese Medical Association’s Guidelines for Genetic Testing and Diagnosis in Medical Care highlight the importance of genetic counseling (GC) in NBS; however, its current implementation status remains unclear. This study aimed to determine current approaches to GC following positive NBS results in Japan. A questionnaire was conducted with pediatric metabolic specialists responsible for treating individuals who screen positive through NBS results to evaluate GC implementation and their views on its provision. GC was provided at most referral centers for NBS (although not routinely at approximately half of the facilities). In over 70% of cases, GC was performed by a metabolic specialist, regardless of clinical geneticist certification. Furthermore, some metabolic specialists may be reluctant to provide GC due to limited understanding or time constraints. Raising awareness that all parents are eligible for GC, regardless of their child’s diagnosis or health status, is essential. In addition, a GC system incorporating multidisciplinary and multidepartmental collaboration is important for the multifaceted support of patients and families.

International Journal of Neonatal Screening doi: 10.3390/ijns11040108

Authors: Eman Abdelbadei Ahmed Mustafa Abir Omara Wafaa Shehata-Dieler Mohamed Hassany

Universal newborn hearing screening (UNHS) has become widely adopted worldwide as a standard of care for the early detection of congenital hearing loss. The Egyptian UNHS program started as a presidential initiative by the Ministry of Health in November 2019. The program was initiated in 1346 primary health care units (PHCUs) located throughout the 26 governorates. A retrospective study was conducted to assess the performance of the Egyptian Program during the period from November 2019 to July 2023. Quality measures recommended by the Joint Committee on Infant Hearing including coverage rate, rate of referral to a second screening, follow up rate of attendance of second screening, referral for diagnosis rate, and follow up rate of attendance of diagnostic assessment, were analyzed. Over a period of 3 years and 9 months, more than five and half million infants underwent a first screening. The coverage rate was initially 39% and increased to reach 82% in 2023. The rate of referral to a second screen was 7.2% in 2019 and reached 5.2% in 2023. The follow-up rate of attendance of a second screening improved throughout the study period, from 75.5% to 92.1% but did not reach the benchmark of 95%. The rate of referrals for diagnosis was less than 1.7% and rate of attendance of a diagnostic assessment was initially 20% and improved to more than 65% in 2023. The very low rate of attendance of diagnostic assessment in 2020 and 2021 was attributed to the effects of the COVID pandemic.

International Journal of Neonatal Screening doi: 10.3390/ijns11040107

Authors: Houyem Ouragini Nizar Ben Halim Sana Zitouni Dorra Chaouachi Imen Boudrigua Naima Saidani Imen Kraiem Amira Ayachi Salem Abbes Mechaal Mourali Samia Menif

Hemoglobinopathies represent a major public health concern in Tunisia. Although early diagnosis is essential, systemic neonatal screening has not yet been implemented at the national level. We conducted a screening study in Northern Tunisia (Bizerte region) using cord blood samples. Complete blood counts and hemoglobin analysis by capillary electrophoresis were performed. Samples showing abnormal profiles (HbBart’s, HbS, HbC, or HbA < 20%) underwent molecular testing. Correlations between hematological parameters, hemoglobin fractions, and β mutation types were assessed. Among 328 neonatal cord blood samples analyzed, we detected 3 silent α+-thalassemia, 6 β+-thalassemia traits, 3 β0-thalassemia traits, 7 HbS traits, 2 HbC traits, and 1 compound heterozygous for α+-thalassemia/HbC. No homozygous cases were identified. The heterozygous frequency was estimated at 1.2%, 2.7%, and 2.1% for α-thalassemia, β-thalassemia, and sickle cell disease, respectively. HbF levels were significantly associated with the β-thalassemia trait. This study represents the first hemoglobinopathy screening in Northern Tunisia using cord blood, highlighting the feasibility and reliability of this approach. While pilot programs have already been initiated in some regions, our findings reinforce the need for broader implementation to ensure early and accurate diagnosis across the country.

International Journal of Neonatal Screening doi: 10.3390/ijns11040106

Authors: Margaret M. Brennan Aoife O’Connell Loretta O’Grady Mohamed Elsammak Jennifer J. Brady Paul Marsden Heather Burns Abigail Collins

Severe combined immunodeficiency (SCID) and spinal muscular atrophy (SMA) are being added to the Newborn Bloodspot Screening (NBS) programme in the Republic of Ireland. To support this expansion, we conducted a scoping review to identify reported timeframes for implementing national, regional or state-wide expanded NBS programmes. We performed a scoping review of the literature published between 2015 and 2025. Eligible articles described the timeframes for implementation of expanded NBS programmes for SCID, SMA or additional metabolic conditions. Sources included PubMed, Embase, citation searching, the International Journal of Neonatal Screening and grey literature. A narrative synthesis was undertaken. Fourteen articles met the inclusion criteria, describing the addition of new conditions—SCID (N = 7), SMA (N = 4), or multiple conditions (N = 3) to expanded NBS programmes in the United States (US), Europe (Belgium, Catalonia, the Czech Republic, Estonia, Germany, Norway, Poland, Portugal, Slovakia, Slovenia, Sweden, and Tuscany), Hong Kong and New Zealand. In most jurisdictions, the implementation of NBS programmes for new conditions took two to six years. The implementation of NBS for new conditions requires considerable time and coordinated efforts. Further research providing greater detail on the specific implementation steps, along with associated timelines, would provide valuable guidance for jurisdictions aiming to expand NBS programmes globally.

International Journal of Neonatal Screening doi: 10.3390/ijns11040105

Authors: Nitash Zwaveling-Soonawala Anju Virmani Aman Pulungan Joseph Haddad Sirisha Boddu Feyza Darendeliler A. van Trotsenburg

Newborn screening (NBS) for congenital hypothyroidism (CH) facilitates early diagnosis and treatment and prevents permanent intellectual disability. Sadly, 50 years after the first introduction of NBS for CH, only 29.6% of newborns worldwide are screened. Africa and Asia, the continents with the highest birth rates, have very limited screening coverage. Most NBS programs measure TSH in a dried-blood spot taken from a heel-prick on a filter paper after 24 to 72 h of life. Implementing national NBS programs is logistically complex and expensive, requiring parental consent, specialized laboratories, and excellent infrastructure. In limited-resource settings, introducing such a complex program is often impossible. We propose universal decentralized cord blood TSH screening, offered as routine delivery care for all newborns in limited-resource settings. TSH measurement may be performed by local laboratories using widely available, inexpensive radioimmunoassay kits, with the report available within a few hours. Since the TSH report would be available before discharge, suitable clinical decision making would be possible, with a minimal need for recall, thus minimizing the parental, medical, and financial burden and improving developmental outcomes. The most important requirement is to change to a grassroots approach, with the education of obstetricians and pediatricians worldwide to perform routine cord blood TSH and make sure the TSH result is available before the baby is discharged.

International Journal of Neonatal Screening doi: 10.3390/ijns11040104

Authors: Terence Diane Fabella Joery den Hoed Lidewij Henneman Wendy Rodenburg Johannes C. F. Ket Jan Schouten Erik A. Sistermans

Newborn screening (NBS) is evolving as novel technologies offer the opportunities to include a broader range of treatable disorders in its programs. Multiplexable, high-throughput DNA-based technologies such as next-generation sequencing (NGS) are being explored to improve and expand disease detection, although several issues have been raised with its use. This scoping review aimed to identify multiplexable, high-throughput, DNA-based technologies that were used for screening or confirmatory testing of newborn disorders in published studies. Available evidence on the appropriateness of technologies in the NBS context was extracted. A literature search (Medline, Embase, and Web of Science) was performed from inception up to April 2024 in collaboration with a medical information specialist. After selection, 26 journal articles were included that used these technologies for either screening (n = 12) or confirmatory testing (n = 14). Five technologies were identified: whole-genome sequencing, whole-exome sequencing, targeted gene sequencing (TGS), quantitative polymerase chain reaction, and MassARRAY. The majority used TGS (n = 19, 73.08%). The data extracted concern mainly technical aspects, and these suggest that a combined approach, i.e., testing via NGS plus a biochemical test, in parallel or reflex, emerges as the optimal option. Ethical and economic evidence is limited and rarely reported in the reviewed articles.

International Journal of Neonatal Screening doi: 10.3390/ijns11040103

Authors: Lucia Laugwitz Andrew Shenker Erica F. Sluys Stéphane Pintat David Whiteman Charlotte Chanson

A systematic literature review was conducted to evaluate the emerging evidence on newborn screening (NBS) for metachromatic leukodystrophy (MLD; MIM #250100). The review focuses on (1) screening assay performance, (2) diagnostic confirmation methods and care pathways, (3) feasibility of population-based identification, and (4) the impact of early diagnosis and treatment on health outcomes. Electronic databases were searched in February 2025, and supplementary searches were performed up to 17 June 2025, for articles referencing NBS for MLD and treatments for MLD; 52 publications were eligible for inclusion. Nationwide NBS for MLD is currently carried out in Norway and large prospective pilots are running in Germany, Austria, Italy and the US. MLD meets established Wilson and Jungner criteria, with a reliable screening algorithm, established confirmatory diagnostics, and actionable care pathways. There is ongoing work to develop tools to predict disease severity and subtype. Early intervention—via gene therapy for early-onset MLD and hematopoietic stem cell transplantation (HSCT) for late-onset forms—significantly improves outcomes when initiated before symptom onset. This review provides the first comprehensive synthesis of the evidence supporting MLD for inclusion in NBS programs, underscoring the public health value of early identification and intervention.

International Journal of Neonatal Screening doi: 10.3390/ijns11040102

Authors: Riccardo Masson Serena Gaballo Raffaella Caravita Stefano Parravicini

We read with interest the recent study by Zaidman et al [...]

International Journal of Neonatal Screening doi: 10.3390/ijns11040101

Authors: Macie Hricovec Amy Gaviglio Christina Mealwitz Michelle Merrill Aaron J. Goldenberg

The goal of newborn screening (NBS) has remained the same despite its significant expansion from its inception as a public health initiative. This goal is to identify infants that are at risk for a set list of conditions and to implement a care plan to prevent, delay, or mitigate adverse health outcomes for those affected. The role of genetic counselors (GCs) in the NBS space is currently evolving, and there is limited research on parental experiences with genetic counseling for more recently added conditions on a list approved by the U.S. Secretary of Health and Human Services called the Recommended Uniform Screening Panel (RUSP). This qualitative study interviewed parents who have spoken to a genetic counselor after their child was diagnosed with one of three following conditions in the past five years: Pompe disease, X-linked Adrenoleukodystrophy, and Spinal Muscular Atrophy. A total of 13 interviews were conducted and results were organized into five thematic areas: (1) NBS/Results Disclosure, (2) Diagnostic Process after NBS, (3) Treatment/Follow-Up, (4) Communication, and (5) Holistic Support. The findings of this study highlighted parental preferences for early involvement of genetic counselors, provider, and parent education on NBS, and the provision of family support beyond genetic resources.

International Journal of Neonatal Screening doi: 10.3390/ijns11040100

Authors: Christopher Connolly Rachel Fisher Chen Yang Susan Schelley Bryce A. Mendelsohn Chung Lee Ayesha Ahmad

Accurate variant classification is crucial for newborn screening (NBS) to prevent missed diagnoses or unnecessary interventions. The IDUA gene variant denoted as c.250G>A (p.Gly84Ser) has been identified in individuals with positive NBS for Mucopolysaccharidosis Type I (MPS I). This variant has conflicting pathogenicity reports including one publication classifying this variant as associated with a severe MPS I phenotype; therefore, we aim to clarify the clinical significance of this variant by presenting a case series describing three individuals, each homozygous for c.250G>A (p.Gly84Ser), identified in Michigan and California. All patients in this case series had low alpha-iduronidase (IDUA) enzyme activity with normal or mildly elevated glycosaminoglycans (GAGs) in blood or urine not falling into the range or pattern seen for affected individuals. None of these patients have developed clinical features of MPS I during follow-up ranging up to 3.5 years of age. Review of functional and population data supports a pseudodeficiency effect, resulting in no need for treatment. Based on our experience with three patients all homozygous for c.250G>A (p.Gly84Ser), despite causing low in vitro IDUA activity, homozygosity for the IDUA gene variant denoted as c.250G>A (p.Gly84Ser), does not cause symptoms of MPS I and may represent a pseudodeficiency allele. Caution should be exercised in newborns with this variant to help reduce unnecessary interventions and alleviate the psychosocial and economic consequences of false-positive NBS results, particularly for the South Asian population.

International Journal of Neonatal Screening doi: 10.3390/ijns11040099

Authors: Péter Monostori Ildikó Szatmári Ákos Baráth János Bókay Marianna Csenki Zsolt Galla Balázs Gellén Nóra Grecsó Eszter Gyüre Zita Halász Krisztina Hegedűs Judit Kincs Erika Kiss Magdolna Kósa István Lénárt Andrea Pálmay Gábor Rácz Hajnalka Szabó Léna Szabó Viktória Tőkési Andrea Xue Petra Zsidegh Attila József Szabó Csaba Bereczki

Newborn screening (NBS), one of the most important public health care prevention programs, aims at the early identification of asymptomatic newborns at increased risk for inherited disorders, facilitating timely intervention to reduce morbidity and mortality. NBS in Hungary is celebrating the 50th anniversary of the nationwide implementation of screening for phenylketonuria and galactosemia, as well as the 40th anniversary of congenital hypothyroidism screening. The present paper reviews the early years, the present situation, and future perspectives for the Hungarian NBS program. Today, screening for 27 disorders (opt-out) plus spinal muscular atrophy (opt-in) is supported by two centralized and well-equipped laboratories in Budapest and Szeged, in-depth laboratory knowledge, a robust follow-up system, and governmental financial support. Since 1975, 3,289 patients have been confirmed with a screened condition from over 5.6 million newborns screened. The 50-year anniversary of the Hungarian NBS program highlights the dedication of both past and current professionals, ongoing advancements in analytical methods and laboratory information management systems, and alignment with international standards. The equitable provision of screening services continues to be prioritized for all newborns nationwide and within the broader Euro-regional context.

International Journal of Neonatal Screening doi: 10.3390/ijns11040098

Authors: Yajie Su Xifeng Lei Ayijiamali Muhetaer Jinfeng He Long Li

This long-term observational study aimed to define the spectrum of genetic variation in a congenital hypothyroidism (CH) cohort and investigate the correlations between specific genotypes and clinical phenotypes, including treatment requirements and outcomes. We analyzed the maintenance dose of L-thyroxine (L-T4) at 6, 12, 18, and 24 months, alongside clinical outcomes after 3 years. Data were collected from the Neonatal Disease Screening Center at our hospital between January 2011 and March 2024. Of 247 patients with confirmed CH, 119 had available genetic testing and complete clinical information. The genetic positivity rate was 56.3% (67/119). DUOX2 was the most frequently mutated gene (28.57%), followed by TPO, TG, and TSHR. Phenotypic correlation analysis revealed that patients with DUOX2 variants had significantly lower initial screening TSH levels and required lower L-T4 maintenance doses at 12 months compared to those with TPO or TSHR variants. Patients with TPO and TSHR variants exhibited more severe clinical phenotypes and a higher prevalence of thyroid enlargement on ultrasound. Notably, no significant differences in biochemical data, L-T4 doses, or clinical outcomes were observed between patients with monoallelic and biallelic DUOX2 variations, or among the negative, monogenic, and oligogenic variation groups. This study establishes a high genetic diagnostic yield for CH in the studied cohort, with DUOX2 as the predominant genetic etiology. The findings demonstrate significant genotype–phenotype correlations, where variations in different genes are associated with distinct biochemical severities and treatment demands. Crucially, the lack of correlation between the number of affected DUOX2 alleles and disease severity highlights the complex genetic and phenotypic heterogeneity of CH. These results provide valuable insights for the precise management and prognostic counseling of patients with CH.

International Journal of Neonatal Screening doi: 10.3390/ijns11040097

Authors: Chloe Miu Mak Timothy Yiu Cheong Ho Man Kwan Yip Felicite Enyu Song Raymond Chiu Mo Tam Leanne Wing Ying Yu Ann Anhong Ke Eric Chun Yiu Law Toby Chun Hei Chan Matthew Chun Wing Yeung

Newborn screening (NBS) for spinal muscular atrophy (SMA) and severe combined immunodeficiency (SCID) faces challenges. Accurate and precise SMN1 and SMN2 copy number determination, confirmed by two orthogonal methods, are vital for SMA prognostication and treatment. Single SMN1 copy detection also enables the further feasibility to screen for compound heterozygotes. In SCID, low-level T-cell receptor excision circle (TREC) quantification by quantitative PCR is imprecise, necessitating replicates for reliable results. An assay with enhanced accuracy, precision, and high throughput is warranted for NBS SMA and SCID. False positive of SMN1 deletions due to allele dropout are also a potential pitfall in PCR-based methods. We evaluated a first-tier fully automated quadruplex droplet digital PCR (ddPCR) assay detecting SMN1, SMN2, TREC, and RPP30 using dried blood spots together with a second-tier Sanger sequencing to exclude SMN1 allele dropout. Five proficiency test samples and six patient samples with known SMN1 and SMN2 copy numbers confirmed by multiplex ligation-dependent probe amplification were used for accuracy evaluation with full concordance. The ddPCR assay showed high precision for SMN1 and SMN2 (<7% coefficient of variation (CV) for ≥0 copy) and TREC (14.6% CV at 37 copies/µL blood). Second-tier Sanger sequencing identified all SMA cases with homozygous deletions. Accuracy for TREC classification was concordant with 10 proficiency samples. The reference interval of TREC concentration was established for newborns ≥ 34 weeks (n = 1812) and the 2.5th percentile was 57 copies/µL blood. A two-tiered approach with fully automated quadruplex ddPCR and Sanger sequencing delivers accurate and precise quantitation for NBS SMA and SCID, enabling early treatment and counseling.

International Journal of Neonatal Screening doi: 10.3390/ijns11040096

Authors: Jim Chilcott Alice Bessey James R. Bonham Iván Castilla-Rodríguez Sarah Davis David Elliman Sara Hunt Chris Hyde Silvia Lombardo Jason Madan John Marshall Joan Morris Katherine Payne Oliver Rivero-Arias Bethany Shinkins Graham Shortland Susan Spillane Anthea Sutton Sian Taylor-Phillips Cristina Visintin

This methodological review identifies challenges in the development of health economic evaluations of newborn bloodspot screening (NBS) interventions and their consideration in NBS policy making. A systematic review of health economics methodological studies in NBS and stakeholder consultation was undertaken. The intervention under examination was defined as health economic decision analytic modelling used as decision support to NBS policy makers. An iterative search strategy was used to identify studies, and a data extraction framework was based upon a simple decision analytic model structure for the NBS decision problem. Synthesis was facilitated by two stakeholder workshops, which focused on ensuring the complete identification of challenges and developing recommendations. Sixteen methodological studies were identified. Data were extracted on challenges in decision criteria, decision variables, decision problem scope, defining model structure, selecting modelling method, the target condition, the screening test/protocol, outcome nodes, and other categories. Recommendations are made concerning supporting NBS decision making, NBS economic model structure and methods, data and estimation of model parameters, and overarching considerations. Recommendations for decision processes and methods research are put forward for the consideration of NBS policy makers and commissioners of research.

International Journal of Neonatal Screening doi: 10.3390/ijns11040095

Authors: Ijaz ul Haq Muhammad Imran Khan Amir Muhammad Majid Ali Xiaojing Hu Guo-Ying Huang

Early and timely screening for congenital heart disease (CHD) is one of the key challenges for healthcare professionals (HPs). This study aimed to identify barriers to the screening of CHD among healthcare professionals in Khyber Pakhtunkhwa, Pakistan. A qualitative cross-sectional study was conducted among HPs working in public and private hospitals, and data were analyzed thematically using NVivo 10.0 software until saturation following Braun and Clarke’s framework. Data were reported according to the Standards for Reporting Qualitative Research (SRQR). Participants reported critical gaps in CHD screening, including scarce resources such as a lack of pulse oximeters and echocardiography machines, inadequate training, and overburdened staff struggling with high patient volumes. Emotional distress was common when diagnosing severe CHDs, compounded by parental reluctance due to low awareness and socioeconomic barriers, including costs and travel distances. Operational inefficiencies, such as inconsistent protocols, weak referral systems, and paper-based record-keeping, further delayed diagnoses. Despite these challenges, HPs emphasized the potential of standardized screening tools, interdisciplinary coordination, and community education to improve detection rates. CHD screening in Pakistan is impeded by resource limitations, systemic fragmentation, and sociocultural factors. Prioritizing equipment procurement, HP training, public awareness campaigns, and policy-mandated screening protocols could enhance early detection.

International Journal of Neonatal Screening doi: 10.3390/ijns11040094

Authors: Deanna M. Green Jean Polasky Mark Weatherly Heather Stalker Colleen Blanchard Cheryl Kushner Marisa Couluris Patricia Ryland Iruvanti Sunitha Joseph Fong Sandra Crump Emily Reeves Kristin Barnette

Cystic fibrosis (CF) is an autosomal recessive genetic condition affecting nearly 1 in 4000 newborns. Early diagnosis and treatment have been shown to improve the care of individuals with CF, which is enhanced through newborn screening (NBS). The state of Florida has been performing CF NBS since 2007, and in 2022, Florida implemented enhanced next generation sequencing (NGS). The goal of this change was to identify individuals from under-represented racial and ethnic groups, who may have rare or de novo variants. NBS screening for CF involved a first tier with immunoreactive trypsinogen (IRT) ≥ 50 or the top 4% of daily specimens, whichever is lower, reflexing to a second tier. As of 2022, the second tier has evolved to an expanded sequence with an Agena 74-variant panel. Single variants would then reflex to the third tier utilizing NGS. NGS is able to confirm what is detected in second-tier testing, adding variants not included in the Agena panel, and refining the TG replications for Poly-T variants to determine pathogenicity of 5T results. When there is a variant of varying clinical consequence between the two databases, the most conservative classification is selected. Individuals with variants would then be referred to one of the contracted CF NBS referral centers for confirmatory sweat chloride testing (sweat). With implementation of NGS, referrals nearly tripled in 2022–2024, with 538 referrals in 2019; 485 in 2020; and 805 in 2021; followed by 1223 referrals made in 2022; 1146 in 2023; and 1294 in 2024. In 2022–2024, 71% of referrals to the contracted NBS CF referral centers were for single variant results, and no cases of CF were identified from these referrals. The number of CF cases remained about the same, ranging from 23 to 40 through the years 2019–2024. The number of CRMS/CFSPID cases, however, tripled going from 10 to 12 in 2019–2022 to over 100 in 2024. The reason for this change seems to be related to complex heterozygous genetic variants as opposed to abnormal sweat. Implementation of NGS for CF in Florida led to a significant increase in the identification of CFTR variants which affected all aspects of the NBS CF process, from an increased workload on the NBS laboratory and follow-up staff, to an increase in referrals to the NBS CF referral centers. The majority of referrals were for single-variant results, which meant the infants had a very low likelihood of having CF. It is recommended that when an algorithm involving NGS is utilized, one should verify that there are appropriate processes for sweat, including the manner in which single-variant CF results are handled, avoiding unnecessary healthcare utilization.

International Journal of Neonatal Screening doi: 10.3390/ijns11040093

Authors: Ernest M. Post Natasha L. Heather

Newborn screening (NBS) for congenital hypothyroidism (CH) has been going on for more than fifty years, but we are still learning more about the process and the disease(s) [...]

International Journal of Neonatal Screening doi: 10.3390/ijns11040092

Authors: Eva Thimm Anselma Riederer Jerry Vockley Dries Dobbelaere Monique Williams Anita MacDonald Katharina Dokoupil Ulrich A. Schatz Regina Ensenauer

Isovaleric acidemia (IVA, OMIM 243500) is an inherited disorder of leucine metabolism caused by a deficiency of isovaleryl-CoA dehydrogenase (IVD), leading to an accumulation of isovaleric acid and its derivates 3-hydroxyisovaleric acid, isovaleryl (C5)-carnitine and isovalerylglycine in body fluids. The clinical presentation is highly variable, ranging from life-threatening metabolic crises with metabolic acidosis and hyperammonemia to a clinically asymptomatic only biochemical phenotype. Newborn screening for IVA has been established in many countries. Treatment consists of a protein-restricted diet combined with supplementation of carnitine and/or glycine and emergency treatment in catabolic episodes. Still, evidence-based recommendations for the diagnosis and management of IVA patients with various phenotypes are lacking. Therefore, a systematic search and review of the literature was conducted to make suggestions for the care of patients with IVA based on both the available scientific evidence and consensus-derived expert conclusions. Based on a comprehensive set of literature data published between 1966 and 2024, 15 statements were phrased on the presentation, diagnosis, management, and outcome of IVA involving clinical, biochemical, and nutrition expertise. These statements can serve as a basis for more standardized care for IVA.

International Journal of Neonatal Screening doi: 10.3390/ijns11040091

Authors: Kristine Hovhannesyan Laura Helou Benoit Charloteaux Valerie Jacquemin Flavia Piazzon Myriam Mni Charlotte Flohimont Corinne Fasquelle Davood Mashhadizadeh Tamara Dangouloff Vincent Bours Laurent Servais Leonor Palmeira François Boemer

Newborn screening (NBS) has evolved significantly since its inception, yet many treatable rare diseases remain unscreened due to technical limitations. The BabyDetect study used gene panel sequencing to expand NBS to treatable conditions not covered by conventional biochemical screening. We present here the analytical validation of this workflow, assessing sensitivity, precision, and reproducibility using dried blood spots from newborns. We implemented strict quality control thresholds for sequencing, coverage, and contamination, ensuring high reliability. Longitudinal monitoring confirmed consistent performance across more than 5900 samples. Automation of DNA extraction improved scalability, and a panel redesign enhanced the coverage and selection of targeted regions. By focusing on known pathogenic/likely pathogenic variants, we minimized false positives and maintained clinical actionability. Our findings demonstrate that gene panel sequencing-based NBS is feasible, accurate, and scalable, addressing critical gaps in current screening programs.

International Journal of Neonatal Screening doi: 10.3390/ijns11040090

Authors: Sakura Morishima Yumi Shimada Kenji Ihara

Neonatal screening programs for inborn errors of metabolism are essential for early diagnosis and intervention. However, false-positive results can cause unnecessary psychological stress for caregivers. This study investigated the emotional impact on a small number of caregivers in Oita Prefecture in Japan, whose infants received false-positive screening results for very long-chain acyl-CoA dehydrogenase deficiency (VLCADD). Particular attention was given to caregivers’ concerns regarding episodes of transient fasting suggestive of nutritional deficiency, as well as their perspectives on appropriate feeding practices for newborns. Nineteen infants in Oita Prefecture were identified as having elevated acylcarnitines, which were later confirmed as false positives. Of these cases, 11 mothers consented to participate in a survey and long-term growth evaluation using health check records. Thirty children with normal screening results were included as controls. While no differences in physical growth were found between groups by 3.5 years of age, some mothers of false-positive infants reported persistent anxiety. Their concerns included regret for inadequate breastfeeding and latent adverse effects on long-term growth or development. Conversely, caregivers’ anxiety diminished over time as they directly observed their infants’ normal growth and development. No regret was expressed regarding breastfeeding, and concerns about VLDCAD were not observed. Caregivers’ responses may help reduce their psychological burden.

International Journal of Neonatal Screening doi: 10.3390/ijns11040089

Authors: Emilie Groulx-Boivin Ariane Belzile Cam-Tu Émilie Nguyen Amélie Gauthier Nicolas Chrestian Catherine Michaud-Gosselin Yves Giguère Marie-Thérèse Berthier Jean-François Soucy Anne-Marie Laberge Maryam Oskoui

Clinical trials in spinal muscular atrophy (SMA) have shown that early treatment improves outcomes, prompting inclusion in newborn screening (NBS) programs worldwide. The province of Quebec launched its SMA NBS program in October 2023, with a rapidly progressive implementation. We describe the program’s first-year experience, focusing on screening yield, birth prevalence, clinical outcomes, and challenges. In the first year, 6 of 67,933 newborns screened positive for SMA, all subsequently confirmed by diagnostic testing. Of these, 4 newborns (67%) had two SMN2 copies and 2 newborns (33%) had four copies. Additionally, one symptomatic compound heterozygote infant presented during this period, indicating a provincial birth prevalence of 1 in 9705 live births (95% CI: 1:20,032–1:4701). Two newborns with two SMN2 copies were symptomatic at initial consultation; one transitioned to palliative care and died at 43 days of life. Surviving newborns initiated treatment at a median age of 30 days (range: 9–103 days), with four receiving onasemnogene abeparvovec and one nusinersen. Motor outcomes at three or six months were stable or improved among treated infants. Overall, the Quebec SMA NBS pilot program successfully identified affected newborns, facilitated early access to therapy, and provided the first provincial estimate of SMA birth prevalence. Improved sample shipping and processing times are needed to maximize the program’s impact, which is expected with full automation.

International Journal of Neonatal Screening doi: 10.3390/ijns11040088

Authors: Philip M. Farrell

The morbidity/mortality risks of cystic fibrosis (CF) with a delayed diagnosis have made newborn screening (NBS) attractive for the past 50 years. Initial efforts focused on meconium analyses, but these proved unsatisfactory. After dried blood spot specimens became valuable for NBS applied to other genetic disorders and immunoassay methods became routine, the discovery of immunoreactive trypsinogen (IRT) led to numerous CF NBS programs around the world. Excellent laboratorians led the way, but CF clinicians rightly questioned the benefit–risk relationship and unanswered questions about IRT. These issues were resolved by the combination of a positive randomized clinical trial and the discovery of the cystic fibrosis transmembrane conductance regulator gene (CFTR) and its principal pathogenic variant, F508del. Recommendations for universal screening and then the proliferation of IRT/DNA screening programs followed. But more knowledge has brought more complexity, including an enigmatic, distracting condition known as cystic fibrosis transmembrane conductance regulator-related metabolic syndrome (CRMS) or cystic fibrosis screen positive, inconclusive diagnosis (CFSPID). Recently, with the recognition that CF is not a “white person’s disease,” and that over 1000 CFTR pathogenic variants occur, attention has turned to achieving equity and timeliness for all babies. Continuous quality improvement has characterized the past decade, as greatly expanded CFTR panels in the DNA tier through next-generation sequencing offer promise and raise the prospect of a primary genetic screening test.

International Journal of Neonatal Screening doi: 10.3390/ijns11040087

Authors: Brittany Truitt Eileen Barr Angela Wittenauer Andrew Jergel Shasha Bai Rossana Sanchez Russo Kathryn E. Oliver Kathleen McKie Rachel W. Linnemann

Early diagnosis by newborn screening (NBS) has contributed to improved outcomes in children with cystic fibrosis (CwCF). Georgia’s two-tiered algorithm consists of a fixed immunoreactive trypsinogen (IRT) cut-off followed by a 39-variant CFTR genetic panel. We conducted a retrospective review of CwCF born in Georgia from 2007 to 2022 to evaluate false negative NBS frequency. We characterized CwCF whose diagnosis was delayed beyond 28 days of age despite positive NBS. Six cases were detailed demonstrating the impact of missed and delayed diagnoses. We examined IRT trends from 2018 to 2022 and cut-off approaches. Missed case detection by expanded CFTR variant assays was assessed. Of 390 CwCF born in Georgia, 18 (4.6%) had false negative NBS—6 due to lack of CFTR variant detection and 12 due to low IRT values. Thirty children had delayed diagnosis, with the majority related to sweat testing. Minoritized children made up 19% of the population but 43% of missed and 44% of delayed diagnoses. Black and Hispanic infants had higher odds of missed or delayed diagnosis compared to non-Hispanic White infants (OR = 2.7, p = 0.027 and OR = 6.1, p < 0.001, respectively). Average IRT values varied across kits and were lower in warmer seasons. Expanded CFTR assays would reduce missed cases. Our results informed recommendations for improvement at multiple steps in the NBS process.

International Journal of Neonatal Screening doi: 10.3390/ijns11040086

Authors: Margherita Ruoppolo Cristina Cereda Teresa Giovanniello Sabrina Malvagia Sara Boenzi Francesca Teofoli on behalf of the SIMMESN Italian Newborn Screening Group on behalf of the SIMMESN Italian Newborn Screening Group Alberto Burlina

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive disorder of fatty acid oxidation that can have life-threatening consequences if not promptly treated. Early diagnosis by means of newborn screening (NBS) has the potential to reduce morbidity and mortality. This study investigates the incidence and molecular characteristics of MCADD in Italy over a five-year period within the framework of the expanded NBS program. Between January 2019 and December 2023, a total of 1,976,473 newborns were screened. Ninety unrelated neonates were diagnosed with MCADD, providing an estimated incidence of 1/21,960 live births (95% CI: 1:17,780–1:27,200), comparable to rates reported in other Mediterranean populations. Molecular analysis identified c.985A>G (p.Lys329Glu) as the most frequent pathogenic ACADM gene variant, observed in 56 patients (63%), including eighteen patients (20%) who were homozygous and thirty-eight (43%) who were compound heterozygotes for this variant. To our knowledge, this study represents the first comprehensive investigation to document the high prevalence of MCADD among the Italian population.

International Journal of Neonatal Screening doi: 10.3390/ijns11040085

Authors: Eileen Barr Brittany Truitt Andrew Jergel Shasha Bai Kathleen McKie Rossana Sanchez Russo Kathryn E. Oliver Rachel W. Linnemann

Cystic fibrosis (CF) newborn screening (NBS) aims to improve outcomes through early diagnosis, yet disparities in time to diagnosis remain. This study examines CFTR allele frequencies and variant panel performance among a diverse CF population in Georgia to inform recommendations for updating the NBS algorithm and improving equity. This cross-sectional study includes 969 people with CF (PwCF) from Georgia’s accredited CF centers. CFTR variant frequencies were calculated according to race and ethnicity. Panel performance was evaluated for Georgia’s current Luminex-39 variant test and three expanded panels. Statistical analyses compared detection rates across panels and demographic groups. Georgia’s diverse CF population demonstrates a unique CFTR allelic variability compared to national data. Increasing panel size enhances case identification. A panel including 719 CF-causing variants from the CFTR2 database significantly improves case detection from 93% to 97% (p = 0.002), as well as two-variant detection from 69% to 86% (p < 0.001). Detection of minoritized PwCF also improves with increasing panel size. However, even using the 719-variant panel, detection of non-Hispanic Black PwCF remains significantly lower compared to non-Hispanic White PwCF (case detection: p = 0.003; two-variant detection: p < 0.001). In conclusion, the use of expanded CFTR panels for NBS in Georgia would enhance timely diagnosis and improve equity.

International Journal of Neonatal Screening doi: 10.3390/ijns11040084

Authors: Eleonora Bonaventura Fabio Bruschi Luisella Alberti Clara Antonello Filippo Arrigoni Marina Balestriero Barbara Borsani Laura Cappelletti Elisa Cattaneo Matilde Ferrario Giulia Fiore Maria Iascone Giana Izzo Simona Lucchi Cecilia Parazzini Michela Perrone Donnorso Luigina Spaccini Ylenia Vaia Pierangelo Veggiotti Elvira Verduci Gianvincenzo Zuccotti Cristina Cereda Davide Tonduti XALD-NBS Study Group XALD-NBS Study Group

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder, caused by mutations in the ABCD1 gene. Early diagnosis is critical to manage adrenal insufficiency and cerebral forms of the disease. Since 2021, a pilot newborn screening (NBS) program for X-ALD has been launched in Lombardy, Italy. From September 2021 to June 2025, 138,116 newborns (≥37 weeks’ gestational age) were screened for elevated C26:0-lysophosphatidylcholine (C26:0-LPC) levels using a two-tier algorithm. Genetic testing was performed in non-negative cases. Males found to be ABCD1 variant carriers were enrolled in multidisciplinary follow-up, including neurological, endocrinological, and nutritional assessments. Eleven individuals (six males, five females) carried pathogenic or likely pathogenic ABCD1 variants. Three males were diagnosed with adrenal insufficiency and started hydrocortisone therapy between 1 and 2 years of age. Growth parameters were within normal range overall, but two children showed signs of stunting associated with poor dietary compliance. Additionally, three patients were diagnosed with Zellweger spectrum disorders (ZSDs). No patients affected with Aicardi-Goutières Syndrome were identified. Newborn screening for X-ALD in Italy is feasible and enables early detection and intervention. Biochemical markers and genetic analysis are reliable tools for identifying affected males and female carriers. Multidisciplinary management is essential to address medical and psychosocial challenges during follow-up.