Search Results (13)

Fabry disease (FD) is an X-linked genetic disease caused by deficient α galactosidase A activity, leading to a lysosomal storage disorder of globotriaosylceramide, causing organ damages. There are two most common clinical manifestations of the disease: classic FD with a typical onset of symptoms in childhood in males, and later-onset variants which may include female heterozygotes. The highly heterogeneous and nonspecific nature of FD’s symptoms and limited physicians’ awareness result in a significant diagnostic and therapeutic delay. Even though the implementation of newborn screening (NBS) gives us an opportunity for early diagnosis and timely treatment, it has not yet been universally adopted. Over twenty pilot studies and screening programs worldwide have been published, showing that FD is more prevalent than previously estimated, exceeding 1 in 40,000 males, mainly due to the high incidence of variants of unknown significance (VUSs). They also raised controversies regarding the diagnostic methods, results interpretation, ethical issues, clinical approach, and economic burden. This review analyzes recent studies of NBS for FD; examines the screening methods, prevalence findings, and natural history data; and assesses the benefits and risks of NBS. We conclude with suggestions for the screening program design and research priorities to ensure that screening leads to improved health outcomes with acceptable costs and psychosocial impact. Full article

Newborn screening laboratories are increasingly adding lysosomal storage disorders (LSDs), such as Mucopolysaccharidosis I (MPS I) and Pompe disease, to their screening panels. Without newborn screening, LSDs are frequently diagnosed only after the onset of symptoms; late detection can lead to profound and irreversible organ damage and mortality. While screening of these disorders has accelerated over the past five years, there is little published information regarding the potential correlation of demographic variables (age at sample collection, birthweight, gestational age, gender, etc.) with lysosomal enzyme activity. The Missouri State Public Health Laboratory prospectively screened more than 475,000 newborns for MPS I, Pompe disease, Gaucher disease, and Fabry disease between 15 January 2013 and 15 May 2018. This report investigates trends between several demographic variables and activities of four lysosomal enzymes: α-L-iduronidase (IDUA), acid α-glucosidase (GAA), acid β-glucocerebrosidase (GBA), and acid α-galactosidase (GLA). This information provides a valuable resource to newborn screening laboratories for the implementation of screening for lysosomal storage disorders and the establishment of screening cutoffs. Full article

Fabry disease is a lysosomal storage disorder caused by a significant decrease in the activity or absence of the enzyme α-galactosidase A. The diagnostics of Fabry disease during newborn screening are reasonable, due to the availability of enzyme replacement therapy. This paper presents an electrochemical method using complementary metal-oxide semiconductor (CMOS)-compatible ion-sensitive field effect transistors (ISFETs) with hafnium oxide-sensitive surfaces for the detection of α-galactosidase A activity in dried blood spot extracts. The capability of ISFETs to detect the reaction catalyzed by α-galactosidase A was demonstrated. The buffer composition was optimized to provide suitable conditions for both enzyme and ISFET performance. The use of ISFET structures as sensor elements allowed for the label-free detection of enzymatic reactions with melibiose, a natural substrate of α-galactosidase A, instead of a synthetic fluorogenic one. ISFET chips were packaged with printed circuit boards and microfluidic reaction chambers to enable long-term signal measurement using a custom device. The packaged sensors were demonstrated to discriminate between normal and inhibited GLA activity in dried blood spots extracts. The described method offers a promising solution for increasing the widespread distribution of newborn screening of Fabry disease. Full article

In the last two decades, the development of high-throughput diagnostic methods and the availability of effective treatments have increased the interest in newborn screening for lysosomal storage disorders. However, long-term follow-up experience is needed to clearly identify risks, benefits and challenges. We report our 8-year experience of screening and follow-up on about 250,000 neonates screened for four lysosomal storage diseases (Pompe disease, mucopolysaccharidosis type I, Fabry disease, Gaucher disease), using the enzyme activity assay by tandem mass spectrometry, and biomarker quantification as a second-tier test. Among the 126 positive newborns (0.051%), 51 infants were confirmed as affected (positive predictive value 40%), with an overall incidence of 1:4874. Of these, three patients with infantile-onset Pompe disease, two with neonatal-onset Gaucher disease and four with mucopolysaccharidosis type I were immediately treated. Furthermore, another four Gaucher disease patients needed treatment in the first years of life. Our study demonstrates the feasibility and effectiveness of newborn screening for lysosomal storage diseases. Early diagnosis and treatment allow the achievement of better patient outcomes. Challenges such as false-positive rates, the diagnosis of variants of uncertain significance or late-onset forms and the lack of treatment for neuronopathic forms, should be addressed. Full article

Fabry disease is an X-linked progressive lysosomal disorder, due to α-galactosidase A deficiency. Patients with a classic phenotype usually present in childhood as a multisystemic disease. Patients presenting with the later onset subtypes have cardiac, renal and neurological involvements in adulthood. Unfortunately, the diagnosis is often delayed until the organ damage is already irreversibly severe, making specific treatments less efficacious. For this reason, in the last two decades, newborn screening has been implemented to allow early diagnosis and treatment. This became possible with the application of the standard enzymology fluorometric method to dried blood spots. Then, high-throughput multiplexable assays, such as digital microfluidics and tandem mass spectrometry, were developed. Recently DNA-based methods have been applied to newborn screening in some countries. Using these methods, several newborn screening pilot studies and programs have been implemented worldwide. However, several concerns persist, and newborn screening for Fabry disease is still not universally accepted. In particular, enzyme-based methods miss a relevant number of affected females. Moreover, ethical issues are due to the large number of infants with later onset forms or variants of uncertain significance. Long term follow-up of individuals detected by newborn screening will improve our knowledge about the natural history of the disease, the phenotype prediction and the patients’ management, allowing a better evaluation of risks and benefits of the newborn screening for Fabry disease. Full article

Fabry disease (FD) is an X-linked inherited disorder caused by mutations in the GLA gene, which encodes the lysosomal enzyme α-galactosidase A (α-Gal A). FD detection in patients at an early stage is essential to achieve sufficient treatment effects, and high-risk screening may be effective. Here, we performed high-risk screening for FD in Japan and showed that peripheral neurological manifestations are important in young patients with FD. Moreover, we reviewed the literature on high-risk screening in patients with renal, cardiac, and central neurological manifestations. Based on the results of this study and review of research abroad, we believe that FD can be detected more effectively by targeting individuals based on age. In recent years, the methods for high-risk screening have been ameliorated, and high-risk screening studies using GLA next-generation sequencing have been conducted. Considering the cost-effectiveness of screening, GLA sequencing should be performed in individuals with reduced α-Gal A activity and females with certain FD manifestations and/or a family history of FD. The findings suggest that family analysis would likely detect FD patients, although GLA sequencing of asymptomatic family members requires adequate genetic counseling. Full article

Lysosomal storage diseases (LSDs) are a heterogeneous group of approximately 70 monogenic metabolic disorders whose diagnosis represents an arduous challenge for clinicians due to their variability in phenotype penetrance, clinical manifestations, and high allelic heterogeneity. In recent years, the approval of disease-specific therapies and the rapid emergence of novel rapid diagnostic methods has opened, for a set of selected LSDs, the possibility for inclusion in extensive national newborn screening (NBS) programs. Herein, we evaluated the clinical utility and diagnostic validity of a targeted next-generation sequencing (tNGS) panel (called NBS_LSDs), designed ad hoc to scan the coding regions of six genes (GBA, GAA, SMPD1, IDUA1, GLA, GALC) relevant for a group of LSDs candidate for inclusion in national NBS programs (MPSI, Pompe, Fabry, Krabbe, Niemann Pick A-B and Gaucher diseases). A standard group of 15 samples with previously known genetic mutations was used to test and validate the entire flowchart. Analytical accuracy, sensitivity, and specificity, as well as turnaround time and costs, were assessed. Results showed that the Ion AmpliSeq and Ion Chef System-based high-throughput NBS_LSDs tNGS panel is a fast, accurate, and cost-effective process. The introduction of this technology into routine NBS procedures as a second-tier test along with primary biochemical assays will allow facilitating the identification and management of selected LSDs and reducing diagnostic delay. Full article

Fabry disease (FD) is a progressive multisystemic lysosomal storage disease. Early diagnosis by newborn screening (NBS) may allow for timely treatment, thus preventing future irreversible organ damage. We present the results of 5.5 years of NBS for FD by α-galactosidase A activity and globotriaosylsphingosine (lyso-Gb₃) assays in dried blood spot through a multiplexed MS/MS assay. Furthermore, we report our experience with long-term follow-up of positive subjects. We screened more than 170,000 newborns and 22 males were confirmed to have a GLA gene variant, with an incidence of 1:7879 newborns. All patients were diagnosed with a variant previously associated with the later-onset phenotype of FD or carried an unclassified variant (four patients) or the likely benign p.Ala143Thr variant. All were asymptomatic at the last visit. Although lyso-Gb₃ is not considered a reliable second tier test for newborn screening, it can simplify the screening algorithm when its levels are elevated at birth. After birth, plasma lyso-Gb₃ is a useful marker for non-invasive monitoring of all positive patients. Our study is the largest reported to date in Europe, and presents data from long-term NBS for FD that reveals the current incidence of FD in northeastern Italy. Our follow-up data describe the early disease course and the trend of plasma lyso-Gb₃ during early childhood. Full article

Newborn screening for one or more lysosomal disorders has been implemented in several US states, Japan and Taiwan by multiplexed enzyme assays using either tandem mass spectrometry or digital microfluidics. Another multiplex assay making use of immunocapture technology has also been proposed. To investigate the potential variability in performance of these analytical approaches, we implemented three high-throughput screening assays for the simultaneous screening for four lysosomal disorders: Fabry disease, Gaucher disease, mucopolysaccharidosis type I, and Pompe disease. These assays were tested in a prospective comparative effectiveness study using nearly 100,000 residual newborn dried blood spot specimens. In addition, 2nd tier enzyme assays and confirmatory molecular genetic testing were employed. Post-analytical interpretive tools were created using the software Collaborative Laboratory Integrated Reports (CLIR) to determine its ability to improve the performance of each assay vs. the traditional result interpretation based on analyte-specific reference ranges and cutoffs. This study showed that all three platforms have high sensitivity, and the application of CLIR tools markedly improves the performance of each platform while reducing the need for 2nd tier testing by 66% to 95%. Moreover, the addition of disease-specific biochemical 2nd tier tests ensures the lowest false positive rates and the highest positive predictive values for any platform. Full article

The increasing availability of treatments and the importance of early intervention have stimulated interest in newborn screening for lysosomal storage diseases. Since 2015, 112,446 newborns in North Eastern Italy have been screened for four lysosomal disorders—mucopolysaccharidosis type I and Pompe, Fabry and Gaucher diseases—using a multiplexed tandem mass spectrometry (MS/MS) assay system. We recalled 138 neonates (0.12%) for collection of a second dried blood spot. Low activity was confirmed in 62 (0.06%), who underwent confirmatory testing. Twenty-five neonates (0.02%) were true positive: eight with Pompe disease; seven with Gaucher disease; eight with Fabry disease; and two with Mucopolysaccharidosis type I. The combined incidence of the four disorders was 1 in 4497 births. Except for Pompe disease, a second-tier test was implemented. We conclude that newborn screening for multiple lysosomal storage diseases combined with a second-tier test can largely eliminate false-positives and achieve rapid diagnosis. Full article

Early diagnosis of lysosomal storage diseases (LSDs) through newborn screening (NBS) has been adapted widely. The National Taiwan University Hospital Newborn Screening Center launched the four-plex tandem mass spectrometry LSD newborn screening test in 2015. The test determined activities of acid α-glucosidase (GAA; Pompe), acid α-galactosidase (GLA; Fabry), acid β-glucocerebrosidase (ABG; Gaucher), and acid α-l-iduronidase (IDUA; MPS-I) in dried blood spots (DBS). Through 2017, 64,148 newborns were screened for these four LSDs. The screening algorithm includes enzyme activity/ratio as the cutoffs for the first screening test and a second-tier test for Pompe disease screening. The second-tier Pompe disease screening test measured activity inhibition by acarbose. Twenty-nine newborns required a confirmatory test; six were confirmed to have Pompe disease, and nine were confirmed to have Fabry disease. The screen-positive rate for Pompe disease was 0.031%. Therefore, in Pompe disease newborn screening, a validated 2nd tier test is necessary to decrease false positives. Full article

Prospective full-population newborn screening for multiple lysosomal storage disorders (LSDs) is currently practiced in a few NBS programs, and several others are actively pursuing this course of action. Two platforms suitable for multiple LSD screening—tandem mass spectrometry (MS/MS) and digital microfluidic fluorometry (DMF)—are now commercially available with reagent kits. In this article, we review the methods currently used for prospective NBS for LSDs and objectively compare their workflows and the results from two programs in the United States that screen for the same four LSDs, one using MS/MS and the other DMF. The results show that the DMF platform workflow is simpler and generates results faster than MS/MS, enabling results reporting on the same day as specimen analysis. Furthermore, the performance metrics for both platforms while not identical, are broadly similar and do not indicate the superior performance of one method over the other. Results show a preponderance of inconclusive results for Pompe and Fabry diseases and for Hurler syndrome, due to genetic heterogeneity and other factors that can lead to low enzyme activities, regardless of the screening method. We conclude that either platform is a good choice but caution that post-analytical tools will need to be applied to improve the positive predictive value for these conditions. Full article

Anderson-Fabry disease (AFD) is an Xlinked lysosomal storage disorder of glycosphingolipid catabolism, due to deficiency or absence of a galactosidase A (α-gal A) enzyme. The disease may affect males and females, the latter with an average 10 years delay. Metabolites storage (mostly Gb3 and lyso-Gb3) leads to progressive cellular and multiorgan dysfunction, with either early and late onset variable clinical manifestations that usually reduce quality of life and life expectancy. Heart and kidney failure, stroke and sudden death are the most devastating complications. AFD is always been considered a very rare disease, although new epidemiologic data, based on newborn screening, showed that AFD prevalence is probably underestimated and much higher than previously reported, especially for late-onset atypical phenotypes. Currently, the diagnosis may be easier and simpler by evaluating α-gal A enzyme activity and genetic analysis for GLA gene mutations on dried blood spot. While a marked α-gal A deficiency leads to diagnosis of AFD in hemizygous males, the molecular analysis is mandatory in heterozygous females. However, referral to a center with an expert multidisciplinary team is highly advisable, in order to ensure careful management and treatment of patients, based also on accurate molecular and biochemical data interpretation. While long-term efficacy of enzyme replacement therapy (ERT) in advanced stage is still debated, increasing evidence shows greater efficacy of early treatment initiation. Concomitant, organ-specific therapy is also needed. New treatment approaches, such as chemical chaperone therapy, alone or in combination with ERT, are currently under investigation. The present review illustrates the major features of the disease, focusing also on biochemical and genetic aspects. Full article