Search Results (258)

Pathogenic variants in the MAP1B gene have been associated with neurological impairment, including intellectual disability, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, brain malformations, cognitive hearing loss, short stature, and dysmorphic features. However, few cases with detailed clinical characterization have been reported. We describe a 12-year-old boy carrying a loss-of-function MAP1B variant, presenting with severe elimination disorders despite normal intelligence. He was referred to the genetics service due to persistent elimination issues, including daytime urinary incontinence, nocturnal enuresis, and fecal incontinence. He had normal motor and cognitive development, with an IQ of 99; however, he also presented with ADHD, short stature, microcephaly, and myopia. Brain MRI revealed bilaterial subependymal periventricular nodular heterotopia (PVNH). Audiometry showed normal bilateral hearing. Testing fragile X syndrome (FXS) and karyotype analyses yielded normal results. Whole exome sequencing (WES) revealed a nonsense pathogenic variant in MAP1B (c.895 C>T; p.Arg299*). No other family members showed a similar phenotype; however, a great-uncle and a great-aunt had a history of nocturnal enuresis until age 10. The patient’s deceased mother had short stature and psychiatric disorders, and a history of consanguinity was reported on the maternal side. This case broadens the phenotypic spectrum associated with MAP1B syndrome, suggesting that elimination disorder, frequently reported in FXS, should also be evaluated in MAP1B pathogenic variant carriers. In addition, the presence of short stature also appears to be part of the syndrome. Full article

Transmembrane protein 43 (TMEM43 or LUMA) encodes a highly conserved protein found in the nuclear and endoplasmic reticulum membranes of many cell types and the intercalated discs and adherens junctions of cardiac myocytes. TMEM43 is involved in facilitating intra/extracellular signal transduction to the nucleus via the linker of the nucleoskeleton and cytoskeleton complex. Genetic mutations may result in reduced TMEM43 expression and altered TMEM43 protein cellular localization, resulting in impaired cell polarization, intracellular force transmission, and cell–cell connections. The p.S358L mutation causes arrhythmogenic right ventricular cardiomyopathy type-5 and is associated with increased absorption of lipids, fatty acids, and cholesterol in the mouse small intestine, which may promote fibro-fatty replacement of cardiac myocytes. Mutations (p.E85K and p.I91V) have been identified in patients with Emery–Dreifuss Muscular Dystrophy-related myopathies. Other mutations also lead to auditory neuropathy spectrum disorder-associated hearing loss and have a negative association with cancer progression and tumor cell survival. This review explores the pathogenesis of TMEM43 mutation-associated diseases in humans, highlighting animal and in vitro studies that describe the molecular details of disease processes and clinical, histologic, and molecular manifestations. Additionally, we discuss TMEM43 expression-related conditions and how each disease may progress to severe and life-threatening states. Full article

Background/Objectives: Congenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL) in children. In cases of severe-to-profound SNHL, cochlear implantation (CI) is a widely used intervention, but outcomes remain variable due to possible neurodevelopmental comorbidities. This study aimed to evaluate the long-term auditory and language outcomes in children with cCMV after CI and to explore clinical and radiological predictors of post-CI performance. Methods: Fifty-three children with cCMV and bilateral severe-to-profound SNHL who underwent CI at five tertiary referral centers in Italy were included in the study. Auditory and language outcomes were assessed pre- and post-implantation using the Categories of Auditory Performance II (CAP-II) scale, the Nottingham 3-Level Classification, and the Bates Language Development Scale. Brain MRI abnormalities were classified according to the Alarcón classification. Correlations were explored between outcome scores and symptomatic status at birth, MRI findings, and neurodevelopmental comorbidities. Results: At birth, 40 children (75.5%) were symptomatic and 13 (24.5%) asymptomatic. Neurodevelopmental comorbidities were present in 19 children (35.8%). MRI was normal in 15 (28.3%), mildly abnormal in 26 (49%), and moderately to severely abnormal in 12 (22.6%). Auditory and language outcomes improved significantly post-CI (p < 0.001), though the outcomes varied widely. Twenty-five children (47%) reached CAP level ≥ 6, and thirteen (23%) reached Bates Level 6. Symptomatic status at birth correlated weakly with worse CAP (ρ = −0.291, p = 0.038) and Bates (ρ = −0.310, p = 0.028) scores. Higher Alarcón scores were significantly associated with neurodevelopmental comorbidities, though not directly with post-CI auditory and language outcomes. Finally, the presence of neurodevelopmental disabilities was generally associated with lower results, even if without statistical significance. Conclusions: CI provides substantial auditory and language benefit in children with cCMV, even in cases of severe neurodevelopmental comorbidities. MRI and developmental assessments, as well as perinatal history for clinical signs and symptoms, are helpful in guiding expectations and personalizing post-implantation support. Full article

Usher syndrome, a rare genetic disorder causing both hearing and vision loss, presents significant diagnostic and therapeutic challenges due to its complex genetic basis. The identification of reliable biomarkers for early detection and intervention is crucial for improving patient outcomes. In this study, we present a machine learning-based hybrid sequential feature selection approach to identify key mRNA biomarkers associated with Usher syndrome. Beginning with a dataset of 42,334 mRNA features, our approach successfully reduced dimensionality and identified 58 top mRNA biomarkers that distinguish Usher syndrome from control samples. We employed a combination of feature selection techniques, including variance thresholding, recursive feature elimination, and Lasso regression, integrated within a nested cross-validation framework. The selected biomarkers were further validated using multiple machine learning models, including Logistic Regression, Random Forest, and Support Vector Machines, demonstrating robust classification performance. To assess the biological relevance of the computationally identified mRNA biomarkers, we experimentally validated candidates from the top 10 selected mRNAs using droplet digital PCR (ddPCR). The ddPCR results were consistent with expression patterns observed in the integrated transcriptomic metadata, reinforcing the credibility of our machine learning-driven biomarker discovery framework. Our findings highlight the potential of machine learning-driven biomarker discovery to enhance the detection of Usher syndrome. Full article

Waardenburg syndrome (WS) is a rare genetic disorder that affects both hearing and pigmentation. The wide divergence of WS poses significant diagnostic and management challenges. This study investigated type 4 WS within an underrepresented Mongolian population. Whole-exome sequencing revealed that two unique heterozygous variants were identified in the SOX10 gene: c.393C>G (p.Asn131Lys) in a five-year-old female patient presenting with profound sensorineural hearing loss (SNHL), dystopia canthorum, and a white forelock; and c.535A>T (p.Lys179Ter) in a nine-year-old male patient presenting with profound SNHL, dystopia canthorum, and Hirschsprung’s disease. Temporal bone imaging revealed abnormalities in the inner ear structure in both patients. The genotypic and phenotypic characteristics were meticulously delineated, incorporating the deleterious effects of these variants, as evaluated by multiple predictive tools and the American College of Medical Genetics and Genomics (ACMG) criteria. In addition, structural characterizations were also presented using AlphaFold. The findings of this study contribute valuable genetic data to the limited literature on type 4 WS within this ethnic group and highlight the importance of genetic testing and multidisciplinary care for this rare disorder in settings with limited resources. Full article

Background: Syndromic inherited retinal diseases (IRDs) are a clinically and genetically heterogeneous group of disorders, involving the retina and additional organs. Over 80 forms of syndromic IRD have been described. Methods: We aimed to phenotypically and genotypically characterize a cohort of 171 individuals from 140 Israeli families with syndromic IRD. Ophthalmic examination included best corrected visual acuity, fundus examination, visual field testing, retinal imaging and electrophysiological evaluation. Most participants were also evaluated by specialists in fields relevant to their extra-retinal symptoms. Genetic analyses included haplotype analysis, homozygosity mapping, Sanger sequencing and next-generation sequencing. Results: In total, 51% of the families in the cohort were consanguineous. The largest ethnic group was Muslim Arabs. The most common phenotype was Usher syndrome (USH). The most common causative gene was USH2A. In 29% of the families, genetic analysis led to a revised or modified clinical diagnosis. This included confirmation of an atypical USH diagnosis for individuals with late-onset retinitis pigmentosa (RP) and/or hearing loss (HL); diagnosis of Heimler syndrome in individuals with biallelic pathogenic variants in PEX6 and an original diagnosis of USH or nonsyndromic RP; and diagnosis of a mild form of Leber congenital amaurosis with early-onset deafness (LCAEOD) in an individual with a heterozygous pathogenic variant in TUBB4B and an original diagnosis of USH. Novel genotype–phenotype correlations included biallelic pathogenic variants in KATNIP, previously associated with Joubert syndrome (JBTS), in an individual who presented with kidney disease and IRD, but no other features of JBTS. Conclusions: Syndromic IRDs are a highly heterogeneous group of disorders. The rarity of some of these syndromes on one hand, and the co-occurrence of several syndromic and nonsyndromic conditions in some individuals, on the other hand, complicates the diagnostic process. Genetic analysis is the ultimate way to obtain an accurate clinical diagnosis in these individuals. Full article

Background: Wolfram syndrome (WFS), also known as DIDMOAD, is a rare monogenic neurodegenerative disorder characterized by four key components: non-autoimmune insulin-dependent diabetes mellitus (DM), optic atrophy, sensorineural hearing loss, and diabetes insipidus. Although it significantly affects quality of life, gonadal dysfunction, particularly hypogonadism, remains underrecognized. Methods: In total, 45 patients (25 men, 20 women) with genetically confirmed WFS from a single tertiary-care center were prospectively followed to assess gonadal function. Men underwent hormonal evaluations, semen analysis, imaging tests, and testicular biopsies. In women, data on age at menarche, menstrual irregularities, and age at menopause were recorded. Hormonal analyses, including anti-Müllerian hormone (AMH) levels, and imaging tests were also conducted. Results: Hypogonadism was identified in 19 men (76.0%), of whom 17 (68.0%) had hypergonadotropic hypogonadism and 2 (8.0%) had hypogonadotropic hypogonadism. Testicular biopsies showed seminiferous tubule damage, Sertoli cell predominance, and reduced Leydig cells. Azoospermia was observed in 12 patients, whereas others presented with oligozoospermia, teratozoospermia, or asthenozoospermia. Most patients exhibited low testosterone levels along with elevated LH and FSH, suggesting primary testicular failure, except for two cases of hypogonadotropic hypogonadism. Correlations between biomarkers, onset age and severity have been analyzed and provide important insights regarding medical treatment. In women, menstrual irregularities were universal, with 20% experiencing premature menopause. Four patients had low AMH levels, with ovarian atrophy in three and a postmenopausal uterus in two, indicating early hypogonadism risk. Conclusions: Gonadal dysfunction is a significant yet overlooked feature of WFS, requiring systematic evaluation during puberty and beyond. Proper management is essential to mitigate metabolic disturbances and psychological impacts, including infertility distress, relationship challenges, and quality of life concerns. Addressing sexual health is crucial as WFS patients live longer and aspire to establish relationships or start families. Full article

Disorders of vesicular trafficking and genetic defects in autophagy play a critical role in the development of metabolic and neurometabolic diseases. These processes govern intracellular transport and lysosomal degradation, thereby maintaining cellular homeostasis. In this article, we present two siblings with a novel homozygous variant in VPS51 (Vacuolar protein sorting 51) gene (c.1511C>T; p.Thr504Met), exhibiting developmental delay, a thin corpus callosum, severe intellectual disability, epilepsy, microcephaly, hearing loss, and dysphagia. This study aimed to investigate the effects of the novel VPS51 gene variation at the RNA and protein level in fibroblasts derived from patients. A comparative proteomic analysis, which has not been previously elucidated, was performed to identify uncharacterized proteins associated with vesicular trafficking. Furthermore, the impact of disrupted pathways on mitochondria–lysosome contact sites was assessed, offering a thorough pathophysiological evaluation of GARP/EARP (Golgi Associated Retrograde Protein / Endosome Associated Retrograde Protein) complex dysfunction. An analysis of mRNA expression indicated decreased levels of the VPS51 gene, alongside modifications in the expression of autophagy-related genes (LC3B, p62, RAB7A, TBC1D15). Western blotting demonstrated a reduction in VPS51 and autophagy-related protein levels. Proteomic profiling revealed 585 differentially expressed proteins, indicating disruptions in vesicular trafficking, lysosomal function, and mitochondrial metabolism. Proteins involved in mitochondrial β-oxidation and oxidative phosphorylation exhibited downregulation, whereas pathways related to glycolysis and lipid synthesis showed upregulation. Live-cell confocal microscopy revealed a notable increase in mitochondria–lysosome contact sites in patient fibroblasts, suggesting that VPS51 protein dysfunction contributes to impaired organelle communication. The findings indicate that the novel VPS51 gene variation influences intracellular transport, autophagy, and metabolic pathways, offering new insights into its involvement in neurometabolic disorders. Full article

This case study presents the long-term management of a 14-year-old male diagnosed with 18q deletion syndrome, also known as de Grouchy Syndrome, highlighting the challenges of treating rare chromosomal disorders in rural Romania. Background and Clinical Significance: 18q deletion syndrome, also known as de Grouchy syndrome, is a chromosomal disorder caused by the deletion of a part of the long arm of chromosome 18. This syndrome is seen in one out of 10,000 live births. The main features of the syndrome are short stature, hearing loss, hypotonia, mental retardation, endocrine disorders, and autoimmunity. Case Presentation: The patient’s condition was initially suspected at birth due to abnormal features and was later confirmed through genetic testing, revealing a 46,XY,del(18) karyotype. Key clinical features include craniofacial dysmorphism, delayed growth, congenital cardiac anomalies, developmental delay, severe neurological impairment, and multiple comorbidities such as endocrine dysfunction, dental anomalies, and orthopedic deformities. Despite early interventions such as cardiac surgery, the patient’s management has been challenged by limited access to specialized care. Conclusions: The case underscores the importance of timely genetic testing, early multidisciplinary care, and the role of family support in managing complex disorders. This report also addresses the gaps in healthcare accessibility in rural settings and emphasizes the need for improved infrastructure and genetic services. By comparing this case with the existing literature, the study explores the variability in clinical presentations of 18q deletion syndrome and advocates for more precise genetic testing to better understand its phenotypic spectrum. The patient’s ongoing challenges with medical and socio-economic factors emphasize the critical need for coordinated care and family support in managing rare genetic conditions. Full article

Background/Objectives: Pathogenic recessive GJB2 variants are the main genetic cause of non-syndromic sensorineural hearing loss. However, following GJB2 testing, a significant proportion of deaf patients are only found to be heterozygous carriers of pathogenic GJB2 alleles. Five large deletions not affecting GJB2 but encompassing a minimal common 62 kb region within the neighbouring CRYL1 gene have been described to cause loss of cis GJB2 expression and, as a result, produce hearing loss when in trans with pathogenic GJB2 variants. We describe the identification and characterization of a novel deletion of this type in deaf patients from northwestern Spain. Methods: We used panel NGS sequencing to detect the deletion, MLPA to validate it, whole-genome sequencing to map its breakpoints, PCR + Sanger sequencing to finely characterize it and triple-primer PCR to screen for it. Results: We identified a novel 200 kb deletion spanning the whole CRYL1 gene in two unrelated deaf patients from Asturias (in northwestern Spain) who were heterozygous for the pathogenic GJB2 c.35delG variant. Although the large deletion was absent from gnomAD v4.1.0 and 2052 local control alleles, screening for it in 20 additional deaf carriers of monoallelic pathogenic GJB2 variants detected it in another patient from Galicia (also in northwestern Spain). The novel deletion, termed del(200 kb)insATTATA, explained hearing loss in 3/43 (7%) deaf patients from our cohort that were otherwise heterozygous for pathogenic GJB2 variants. Conclusions: This work highlights the importance of comprehensively testing all genomic regions known to be clinically relevant for a given genetic condition, including thorough CRYL1 CNV screening for DFNB1A diagnostics. Full article

Background: Primary ciliary dyskinesia (PCD) is a rare hereditary disorder caused by defective motile cilia, predominantly affecting the respiratory system. Conductive hearing loss (CHL) due to chronic otitis media with effusion (OME) is a typical feature of PCD, particularly in childhood. However, the underlying mechanisms contributing to sensorineural hearing loss (SNHL) in patients with PCD remain unclear. Methods: We present the case of a 52-year-old male with a clinical diagnosis of PCD, confirmed by the presence of situs inversus, chronic respiratory symptoms, and ultrastructural ciliary defects. Results: Despite a history of recurrent acute otitis media (AOM), the patient developed severe bilateral SNHL, a relatively uncommon and poorly understood manifestation of PCD. Genetic testing revealed a pathogenic SH3TC2 variant, a gene classically associated with Charcot–Marie–Tooth disease type 4C (CMT4C), raising the possibility of an alternative or contributory genetic etiology for the patient’s auditory dysfunction. Conclusions: This case highlights the importance of comprehensive audiological and genetic evaluations in PCD patients, particularly those presenting with progressive or atypical HL. The presence of a pathogenic SH3TC2 mutation suggests a potential neuropathic component to the patient’s HL, underscoring the need for further research into the intersection between ciliary dysfunction and genetic neuropathies. Early identification and intervention are critical to optimizing auditory outcomes and quality of life in affected individuals. Full article

There is significant inter-individual variability in the prevalence and severity of cisplatin-induced ototoxicity, which is greatly influenced by genetic and non-genetic factors that predispose the patient to the development of hearing loss. Currently, the focus should be on identifying patients who are more likely to develop ototoxicity based on genetic and non-genetic factors, as therapies to combat ototoxicity are limited or still under study. The severity of hearing loss and the time of its onset may be influenced by certain genetic polymorphisms or the dose administered, age, sex, diet, the administration of other drugs with ototoxic potential, and association with radiotherapy of the head and neck. Knowing the risk factors allows the doctor to manage each case in a personalized manner, preventing hearing damage, especially in the long term. With the help of PubMed and Scopus, we searched for relevant studies documenting the genetic and non-genetic risk in patients treated with cisplatin. This review article is a synthesis of the literature that points out the importance of these factors, encouraging genetic screening and improving quality of life in patients treated with cisplatin. Full article

Radiotherapy-induced hearing impairment significantly affects patients’ quality of life, yet its genetic basis remains poorly understood. This study seeks to identify genetic variants associated with radiotherapy-induced tinnitus and hearing loss and explore their functional implications. A genome-wide association study (GWAS) was conducted to identify single-nucleotide polymorphisms (SNPs) associated with radiotherapy-induced tinnitus and hearing loss. Protein–protein interaction networks and functional enrichment analyses were performed to explore underlying biological pathways. A phenome-wide association study (PheWAS) analysis across five databases examined associations between identified SNPs and various phenotypes. The GWAS identified 97 SNPs significantly associated with radiotherapy-induced tinnitus and 76 SNPs with hearing loss. Tinnitus-associated variants were enriched in pathways involving Wnt signaling and telomerase RNA regulation, while hearing-loss-associated variants were linked to calcium-dependent cell adhesion and neurotransmitter receptor regulation. The PheWAS analysis revealed significant associations between these hearing-impairment-related SNPs and metabolic phenotypes, particularly BMI and metabolic disorders. A chromosomal distribution analysis showed concentrated significant SNPs on chromosomes 1, 2, 5, and 10. This study identified distinct genetic architectures underlying radiotherapy-induced tinnitus and hearing loss, revealing different molecular pathways involved in their pathogenesis. The unexpected association with metabolic phenotypes suggests potential interactions between metabolic status and susceptibility to radiotherapy-induced hearing complications. These findings provide insights for developing genetic screening tools and targeted interventions to prevent or mitigate radiotherapy-related hearing damage. Full article

Inherited metabolic disorders (IMDs) are genetic disorders that occur in as many as 1:2500 births worldwide. Nevertheless, they are quite rare individually and even more rare is the co-occurrence of two IMDs in one individual. To better understand the metabolic cross-talk between glycosylation changes and deficient energy metabolism, and its potential effect on outcomes, we evaluated patient fibroblasts with likely pathogenic variants in PGM1 and pathogenic variants in NDUFA13 derived from a patient who passed away at 16 years of age. The patient presented with characteristic of PGM1-CDG including bifid uvula, muscle involvement, abnormal glycosylation in blood, and elevated liver transaminases. In addition, hearing loss, seizures, elevated plasma and CSF lactate and a Leigh-like MRI brain pattern were present, which are commonly associated with Leigh syndrome. PGM1-CDG has been reported in about 70 individuals, while NDUFA13 deficiency has so far only been reported in 13 patients. As abundant energy is essential for glycosylation, and both PGM1 and NDUFA13 are linked to energy metabolism, we sought to better understand the underlying biochemical cause of the patient’s clinical presentation. To do so, we performed extensive investigations including tracer metabolomics, lipidomics and enzymatic studies on the patient’s fibroblasts. We found a profound depletion of UDP-hexoses, consistent with PGM1-CDG. Complex I enzyme activity and mitochondrial function were also impaired, corroborating complex I deficiency and Leigh syndrome. Further, lipidomics analysis showed similarities with both PGM1-CDG and OXPHOS-deficient patients. Based on our results, the patient was diagnosed with both PGM1-CDG and Leigh syndrome. In summary, we present the first case of combined CDG and Leigh syndrome, caused by (likely) pathogenic variants in PGM1 and NDUFA13, and underline the importance of considering the synergistic effects of multiple disease-causing variants in patients with complex clinical presentation, leading to the patient’s early demise. Full article

The Universal Neonatal Hearing Screening (UNHS) program is crucial for the early detection and treatment of hearing impairment in newborns. Poland has successfully implemented a nationwide UNHS program, adhering to international standards. Research indicates that hearing loss affects approximately 2–4 per 1000 infants, with sensorineural hearing loss being the most prevalent. Major risk factors include genetic alterations, craniofacial anomalies, prematurity, hyperbilirubinemia, and congenital infections such as cytomegalovirus. Despite the program’s success, challenges related to limited parental awareness and disparities in access highlight the need for continuous improvement in screening and follow-up procedures. Additionally, gene therapy is emerging as a promising treatment for hearing loss. While still experimental, gene therapy could become a key complementary treatment option in the future, offering new hope for those with hearing impairments. Full article