Search Results (124)

GJB2-associated hearing loss is the most common form of non-syndromic hereditary deafness worldwide. However, it exhibits significant heterogeneity in terms of both clinical presentation and biological basis. This review focuses on mechanism-oriented therapeutic strategies for GJB2-associated hearing loss, investigating how different types of GJB2 variants correspond to distinct clinical phenotypes and underlying pathogenic mechanisms, and aims to determine appropriate treatments. Current evidence suggests that GJB2-associated hearing loss is not solely caused by channel dysfunction resulting from gap junction defects, but rather the result of multiple pathological processes, including impaired GJB2 transcriptional regulation, cochlear developmental abnormalities, sensory epithelial degeneration and secondary damage pathways such as inflammation. Consequently, emerging therapeutic approaches can be viewed as interventions targeting specific mechanisms, including gene therapy, restoration of protein transport and pharmacological modulation of damage to the cochlear microenvironment. Overall, this review highlights the importance of aligning therapeutic strategies with specific GJB2 variants, underlying pathogenic mechanisms, and the developmental window during which cochlear injury remains biologically reversible. Full article

Introduction: Recent advancements in genomic technologies have significantly improved the resolution of genetic variants driving rare genodermatoses, a heterogeneous group of inherited skin disorders caused by pathogenic variants affecting skin structure and function. However, many genodermatoses remain molecularly uncharacterized, particularly in Middle Eastern populations. Objectives: This study aimed to evaluate the diagnostic accuracy and inherent challenges of utilizing (WES) for genodermatoses within a Middle Eastern context. Methods: We performed WES on three unrelated Middle Eastern pediatric patients presenting with genodermatoses. Genetic variants were prioritized and adjudicated according to ClinVar and the American College of Medical Genetics and Genomics (ACMG) guidelines. Results: WES identified pathogenic variants in three pediatric cases presenting with genodermatoses. Findings included a GJB2 missense variant (c.148G>T; p.Asp50Asn) associated with keratitis–ichthyosis–deafness (KID) syndrome. This represents one of the first documented cases in a Middle Eastern population. Two additional patients presenting with epidermolysis bullosa harbored truncating variants in COL7A1 (c.497dup; p.Val168Glyfs12) and EXPH5 (c.5786del; p.Pro1929Leufs8), respectively; the latter also carried a KRT5 missense variant (c.1607G>A; p.Ser536Asn). Conclusions: WES is a robust diagnostic adjunct for resolving ambiguity in rare genodermatoses, though its efficacy remains contingent on the availability of regional genomic references. Within pediatric dermatology, systematic exome sequencing serves as a powerful facilitator for transitioning from clinical suspicion to definitive molecular characterization. Collectively, these findings highlight the essential role of regionally representative genomic datasets in the accurate interpretation of novel variants and the advancement of precision dermatology. Full article

Background/Objectives: Hearing impairment is a highly prevalent sensory disorder resulting from a variety of causes. A high proportion of autosomal recessive non-syndromic hearing impairment is linked to the GJB2 (OMIM 121011) gene which encodes for a gap junction protein, connexin-26. Alterations of genes that encode for connexins can lead to changes in cell ion content and cause hearing impairment. Methods: GJB2 gene polymorphisms (c.71G>A, p.Trp24*rs104894396; c.457G>A, p.Val153Ile, rs111033186; c.380G>A, p.Arg127His, rs111033196; c.109G>A, p.Val37Ile, rs72474224; and c.269T>C, p.Leu90Pro, rs80338945) were analyzed in the Roma population of Croatia. Loci were genotyped using the KASP method. Results: Altered alleles were detected on the loci c.71G>A, c.457G>A and c.380G>A and statistically significant differences in allele frequencies were noticed. Furthermore, in comparison to worldwide populations, the Roma population also shows statistically significant difference in allele frequency of these loci. Conclusions: This study reveals marked genetic differentiation among Croatian Roma particularly with respect to the c.71G>A variant. Characterizing such population-specific mutational heterogeneity is crucial for the accurate prevention, diagnosis, and clinical management of autosomal recessive nonsyndromic hearing loss. Full article

Purpose: Hearing loss (HL) is a prevalent condition significantly impairing quality of life, with genetic mutations accounting for a substantial proportion of congenital cases, notably those involving the GJB2 gene encoding connexin 26. This study aims to analyze the current knowledge, feasibility, and challenges of gene therapy targeting GJB2-related HL, emphasizing both embryonic and postnatal interventions. Methods: A comprehensive scoping review was conducted across electronic databases up to October 2025, including studies focusing on GJB2-associated HL, gene therapy approaches, and the timing of interventions. Data extraction encompassed mutation types, animal models, delivery strategies, outcomes, and ethical considerations. Results: The results indicated over 467 GJB2 variants which could impair cochlear ion homeostasis and development. Animal models, mainly murine, demonstrated early-onset degeneration with limited recovery following delayed gene therapy, while early postnatal intervention showed greater efficacy. Viral vectors like AAV have been employed for targeted gene delivery via cochlear injections, achieving partial restoration of connexin expression and cochlear function, yet they have faced limitations including transduction efficiency, immune responses, and long-term stability. Challenges in translating these findings to humans have been compounded by anatomical, immunological, ethical, and safety issues, particularly regarding embryonic gene therapy and germline modifications. Ethical frameworks can vary internationally, highlighting the necessity for careful regulation. Conclusions: While promising advances in gene therapy for GJB2-related HL have been achieved in preclinical studies, significant scientific, technical, and ethical barriers must be addressed before clinical application, especially during embryogenesis. A multidisciplinary, cautious approach is essential to realize the potential of gene therapy in restoring natural hearing while safeguarding individual and societal interests. Full article

Abnormal refraction phenomena such as atmospheric ducts due to temperature inversions or rapid decreases in humidity often happen in the lower troposphere over the sea and coastal area, which can make low-elevation signals in the duct layer propagate beyond the horizon, and the ray trajectories extend horizontally over long distances. This paper uses ray tracing technology based on a second-order Taylor approximation to accurately predict the low-elevation ray trajectories within atmospheric ducts. The meteorologic parameters at the heights traversed by the rays are extracted to accumulate atmospheric absorption attenuation by line-by-line calculations, and a high-precision prediction method for atmospheric absorption attenuation in over-the-horizon propagation links is established; meanwhile, we also implement visualization of atmospheric absorption attenuation changes along the ray trajectories in atmospheric duct environments. By comparing the results of the atmospheric absorption attenuation models for horizontal terrestrial paths in the ITU-R P.676 recommendation and GJB Z87-1997 in atmospheric duct environments, we found that the high-precision model proposed in this paper can improve the prediction accuracy of atmospheric absorption attenuation by about 15% in surface ducts and 28% in elevated ducts, significantly improving the propagation performance of low-elevation signals under atmospheric ducts and other abnormal refraction conditions for electronic systems such as surveillance, detection, communication, and navigation. Full article

Studying epigenetic changes in cancer development can reveal the role of tumor suppressor genes and their regulation by DNA methylation. CpG islands, found in promoter regions, are of particular interest, as their hypermethylation can silence tumor suppressor gene expression. Here, we present a practical analysis pipeline for wet-lab biologists with the aim of identify novel epigenetically regulated tumor suppressors using freely available online tools. Bioinformatic platforms such as the R2 Genomics Analysis and Visualization Platform enable analysis of genomic organization, CpG islands, and regulatory elements. Differential methylation and gene expression analyses are based on datasets including TCGA, using tools such as MethSurv, TCGA Wanderer, and GEPIA2 to correlate DNA methylation with gene expression. This bioinformatic step is the basis for the tumor suppressor verification in the wet-lab. Using this pipeline, we identified CLDN10 and GJB2 as potential tumor suppressors in melanoma. Experimentally, our approach includes DNA methylation analysis based on DNA bisulfite conversion, combined bisulfite restriction analysis (CoBRA), pyrosequencing for specific CpG methylation quantification, and RT-PCR for RNA expression quantification. We verify these results in primary tumors, metastases, and cell line models. This approach supports efficient identification of novel epigenetically regulated tumor suppressors, providing practical research guidelines. Full article

Muscle biopsy has long been regarded as the cornerstone for diagnosing pediatric muscular disorders; however, it is invasive and may be limited by sampling error and inconclusive histopathological findings. This study aimed to evaluate whether whole-exome sequencing (WES) can effectively replace muscle biopsy as a first-line diagnostic approach in children with suspected neuromuscular disorders. Between January 2018 and December 2025, we prospectively enrolled 47 pediatric patients presenting with clinical features suggestive of muscular disorders at a tertiary medical center in Taiwan. The cohort included patients with suspected muscular dystrophies (n = 21), congenital myopathies (n = 23), and multiplex ligation-dependent probe amplification (MLPA)-negative Duchenne muscular dystrophy (DMD; n = 3). All patients underwent WES as the initial diagnostic test without prior muscle biopsy. Trio-based analysis using parental samples was performed in 29.8% of cases. Variant interpretation followed the American College of Medical Genetics and Genomics (ACMG) guidelines. WES identified a definitive molecular diagnosis in 72.3% of patients (34/47). Diagnostic yields varied by subgroup: 100% (3/3) in MLPA-negative DMD, 71.4% (15/21) in muscular dystrophies, and 69.6% (16/23) in congenital myopathies. Pathogenic or likely pathogenic variants were detected in 31 distinct genes, including COL6A1 and COL6A3, which are associated with Ullrich congenital muscular dystrophy. Notably, 58.8% of diagnosed patients (20/34) received molecular diagnoses that differed from their initial clinical impression, encompassing conditions such as ZSWIM6-associated neurodevelopmental disorders, GJB2-related hearing loss, OCRL-associated Lowe syndrome, and various metabolic or syndromic disorders. In all three MLPA-negative DMD cases, WES identified point mutations amenable to mutation-specific therapies. No patient required a muscle biopsy for diagnostic confirmation during the study period. First-tier WES demonstrates high diagnostic utility in pediatric muscular disorders while avoiding invasive muscle biopsy. The high rate of diagnostic reclassification underscores the substantial phenotypic overlap between primary neuromuscular diseases and other neurological or systemic conditions. These findings support the early implementation of genetic testing to enable accurate diagnosis and timely initiation of targeted therapies. Full article

Nonsyndromic hearing loss (NSHL) is a highly prevalent, genetically heterogeneous condition, yet its molecular basis in the Singaporean population remains underexplored. We performed whole-exome sequencing and integrative bioinformatics analysis in 115 patients with NSHL to define population-specific genetic biomarkers. A molecular diagnosis was achieved in 57% of cases, with 76% of identified variants classified as pathogenic or likely pathogenic and 24% exhibiting high pathogenic potential. Common East Asian NSHL genes, including GJB2, SLC26A4, and OTOF, were frequently detected alongside less prevalent genes such as ACTG1, CEACAM16, COL11A2, DIAPH1, KCQN4, MYH14, MYO6, MYO7A, MYO15A, SLC17A8, SMPX, STRC, TJP2, TMC1, TMPRSS3, highlighting extensive genetic heterogeneity. Notably, multiple novel variants, including MYO6 c.554-2A>G, and TNC p.N750Y, were identified, expanding the known mutational spectrum of NSHL. Genotype–phenotype correlations revealed that GJB2 variants were primarily associated with mild to moderate hearing loss, whereas SLC26A4 variants correlated with severe to profound phenotypes in the Singaporean populations. Collectively, our study provides important insights into the genetic architecture of NSHL in Singapore’s population. In addition, it supports improved molecular diagnosis yield and informed clinical management decisions as well as the advancement of precision medicine approaches aimed at reducing the burden of hearing loss in the region. Full article

Cochlear implantation (CI) is a well-established intervention for improving auditory and speech development in children with severe-to-profound hearing loss. Nonetheless, postoperative rehabilitation outcomes exhibit substantial individual variability. This review synthesizes contemporary evidence on predictors of rehabilitation success following pediatric CI. A robust set of general factors is consistently linked to more favorable outcomes, including earlier age at implantation (with particular benefit within the first year of life), stronger preoperative receptive language skills and speech recognition, higher developmental quotient and nonverbal intelligence, and higher parental educational level. Regarding hearing-specific variables, later-onset deafness, a shorter duration of deafness, and identifiable etiologies (notably specific genetic mutations such as GJB2 and OTOF) exert significant influence. Furthermore, bilateral CI demonstrates superior outcomes compared to unilateral CI, with the surgical timing (simultaneous versus sequential) and factors such as electrode array selection and placement being critical determinants. Overall, postoperative outcomes arise from a complex interplay of biological, developmental, and environmental factors. Full article

This review integrates molecular, clinical, and translational data to provide an updated understanding of GJB2-related deafness and its emerging treatment landscape. Truncating mutations in GJB2 typically cause severe-profound hearing loss (HL) phenotypes, whereas non-truncating alleles are often associated with milder or progressive phenotypes. Geographic variation in variant prevalence contributes to regional differences in disease burden. Beyond the coding region, deletions and cis-regulatory mutations within the DFNB1 locus, including GJB6 and CRYL1, can influence HL severity when compounded with other pathogenic GJB2 variants. DFNB1 hearing loss generally presents as symmetric, bilateral, and flat to gently sloping across frequencies, with preserved cochlear neurons that support excellent cochlear implant (CI) outcomes. Early implantation CI in GJB2-positive children yields superior speech and language development compared with non-GJB2 etiologies. Emerging therapies include dual-AAV (AAV1 + AAV-ie/ScPro) delivery, achieving cell-specific Cx26 restoration, adenine base-editing for dominant-negative variants, and allele-specific suppression using RNA interference or antisense oligonucleotides. Concurrent progress in human iPSC-derived cochlear organoids provides a physiologic model to advance toward clinical trials. By integrating genotype-phenotype correlations, natural history insights, and advances in molecular therapeutics, this review presents a comprehensive update on GJB2-related HL and highlights how gene-based strategies are poised to change the treatment of this condition. Full article

Hereditary polyneuropathies represent a genetically and clinically heterogeneous group of disorders affecting the peripheral nervous system, characterized by progressive motor, sensory, and autonomic impairment. Advances in molecular genetics have identified key causative genes, including PMP22, MPZ, MFN2, TTR, EGR2, and CX32 (GJB1), which are implicated in Charcot–Marie–Tooth disease, Dejerine–Sottas syndrome, and related neuropathies. These conditions display substantial allelic and locus heterogeneity. Pathogenetically, mechanisms involve impaired myelin maintenance, disrupted axonal transport, mitochondrial dysfunction, and aberrant Schwann cell biology. Despite these insights, therapeutic options remain limited, and there is a pressing need to translate genetic findings into effective interventions. This review aims to provide a comprehensive synthesis of current knowledge compiling all known mutations resulting in hereditary polyneuropathies. In addition, it underscores the molecular pathomechanisms of hereditary polyneuropathies and evaluates emerging therapeutic strategies, including adeno-associated virus mediated RNA interference, CRISPR-based gene editing, antisense oligonucleotide therapy, and small-molecule modulators of axonal degeneration. Furthermore, the integration of precision diagnostics, such as next-generation sequencing and functional genomic approaches, is discussed in the context of personalized disease management. Collectively, this review underscores the need for patient-centered approaches in advancing care for individuals with hereditary polyneuropathies. Full article

Background/Objectives: This study reports on findings from the first preconception screening performed in Russia and provides a comprehensive discussion of the significant results and challenges faced during the implementation of the project. Methods: Using a targeted sequencing panel of 33 genes (associated with 29 autosomal recessive and 4 X-linked diseases), we analyzed 165 couples considering pregnancy. The screening design also included analysis of the frequent pathogenic variants in the SMN1, DMD, CFTR, and CYP21A2 genes that may not be detected through the next-generation sequencing approach. The sequential screening protocol, wherein the female partner was tested first, was used. Results: The results revealed that 35.8% of women (n = 59) were carriers of at least one pathogenic or likely pathogenic (P/LP) variant, with 7.9% of women (n = 13) carrying variants in two or more genes. Notably, the analysis identified 5 deletions of exon 7 in the SMN1 gene, 1 deletion of the CYP21A2 gene, and 1 large duplication in the DMD gene in female participants. The most frequently identified pathogenic variants occurred in the CYP21A2, GJB2, SERPINA1, and ATP7B genes. The screening identified six couples (3.6% of the cohort) at high risk of having a child with an autosomal recessive or X-linked genetic disorder. Conclusions: This pilot study confirms the high clinical utility of the gene panel, effectively evaluating reproductive risk in couples without a known family history of monogenic diseases. The findings indicate that the observed frequencies of identified gene variants differ from those theoretically expected, with a notable percentage of identified couples being at relatively high risk. Furthermore, these results highlight the indispensable role of comprehensive genetic counseling both before and after testing to ensure an appropriate preconception testing algorithm and informed reproductive decision-making. Full article

Background/Objectives: X-linked hypohidrotic ectodermal dysplasia (XLHED) is a rare monogenic disorder characterized by hypohidrosis, hypotrichosis, and hypodontia, caused primarily by pathogenic variants in the EDA gene. XLHED predominantly affects males due to its X-linked recessive inheritance, while female carriers may exhibit variable phenotypes due to random X-inactivation. Early diagnosis is critical for timely counseling and emerging therapeutic interventions. We report a rare prenatal diagnosis of XLHED in dizygotic dichorionic male twins during a dichorionic diamniotic pregnancy. At 24 weeks’ gestation, ultrasonographic anomalies—facial dysmorphisms, oligodontia, and hypoechogenic skin—raised suspicion for ectodermal dysplasia. Methods: Non-invasive prenatal test and targeted next-generation sequencing (NGS) of Cell-free DNA identified an hemizygous EDA deletion (c.612_629del; p.Ile205_Gly210del) with 52% variant allele frequency. Results: This in-frame deletion affects a highly conserved region in the TNF homology domain of ectodysplasin-A1, likely compromising protein function. The variant was confirmed in both fetuses via genetic analysis on amniotic fluid and in the heterozygous state in the mother, consistent with X-linked recessive inheritance. Family history revealed a maternal uncle with XLHED. Additional heterozygous variants were also identified in CPT2, GBA1, GJB2, and SMN1 genes. Following comprehensive genetic counseling, the mother opted for abortion. Conclusions: This case underscores the value of applying advanced genomic technologies—cfDNA-based NGS—for prenatal diagnosis of rare genetic disorders. The identification of apathogenic EDA variant expands the mutational spectrum of XLHED and supports early diagnosis for informed reproductive decisions and potential access to emerging prenatal therapies. Broader application of such technologies may improve outcomes in future pregnancies at risk for monogenic disorders. Full article

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. Full article

Autosomal recessive (AR) disorders represent a significant public health challenge, as asymptomatic carriers are often unaware of their reproductive risks. This study provides the first comprehensive assessment of AR gene variant frequencies and their molecular landscape in a fertile Western Romanian population. Genetic results from 604 unrelated, unaffected Caucasian individuals of reproductive age, tested at a single genetic center between 2020 and 2024, were retrospectively analyzed. Next-generation sequencing (NGS) with a multi-gene panel targeting 300 AR-associated genes was used for molecular profiling. Variants were identified in 156 genes, with 75% of individuals carrying at least one AR variant (mean 1.77 variants/person). A subgroup with >3 pathogenic variants comprised 7.5%, posing a notable risk for future offspring. The most frequent variants were detected in HFE (1:5), CFTR (1:9), BTD (1:16), GJB2 (1:17), and CYP21A2 (1:19). Four variants (HFE, c.187C>G; BTD, c.1330G>C; CFTR, c.1210-34TG[11]T[5]; GALT, c.-119_-116del) were particularly prevalent, each exceeding 3% frequency. Considerable allelic heterogeneity was observed for distrinctive variants in CFTR (14), PAH (12), USH2A (12), and ATP7B (9). Several variants were linked to severe disorders, with CFTR, GALT, ATP7B, and SMN1 identified as “red zone” genes associated with high morbidity and mortality. Low-frequency variants formed a “long tail” (83.9%), reflecting marked population heterogeneity and potential hidden disease risks. The study reveals high allelic diversity and a strong prevalence of AR variants in Western Romania. Variant-based gene classification supports population-level screening, highlighting the public health value of a national program to identify carriers and prevent severe inherited disorders. Full article