Machine learning-based longitudinal prediction for GJB2-related sensorineural hearing loss.

BACKGROUND: Recessive GJB2 variants, the most common genetic cause of hearing loss, may contribute to progressive sensorineural hearing loss (SNHL). The aim of this study is to build a realistic predictive model for GJB2-related SNHL using machine learning to enable personalized medical planning for timely intervention. METHOD: Patients with SNHL with confirmed biallelic GJB2 variants in a nationwide cohort between 2005 and 2022 were included. Different data preprocessing protocols and computational algorithms were combined to construct a prediction model. We randomly divided the dataset into training, validation, and test sets at a ratio of 72:8:20, and repeated this process ten times to obtain an average result. The performance of the models was evaluated using the mean absolute error (MAE), which refers to the discrepancy between the predicted and actual hearing thresholds. RESULTS: We enrolled 449 patients with 2184 audiograms available for deep learning analysis. SNHL progression was identified in all models and was independent of age, sex, and genotype. The average hearing progression rate was 0.61 dB HL per year. The best MAE for linear regression, multilayer perceptron, long short-term memory, and attention model were 4.42, 4.38, 4.34, and 4.76 dB HL, respectively. The long short-term memory model performed best with an average MAE of 4.34 dB HL and acceptable accuracy for up to 4 years. CONCLUSIONS: We have developed a prognostic model that uses machine learning to approximate realistic hearing progression in GJB2-related SNHL, allowing for the design of individualized medical plans, such as recommending the optimal follow-up interval for this population.

Structural basis for pathogenic variants of GJB2 and hearing levels of patients with hearing loss.

OBJECTIVES: The crystal structure of the six protomers of gap junction protein beta 2 (GJB2) enables prediction of the effect(s) of an amino acid substitution, thereby facilitating investigation of molecular pathogenesis of missense variants of GJB2. This study mainly focused on R143W variant that causes hearing loss, and investigated the relationship between amino acid substitution and 3-D structural changes in GJB2. METHODS: Patients with nonsyndromic hearing loss who appeared to have two GJB2 pathogenic variants, including the R143W variant, were investigated. Because the X-ray crystal structure of the six protomers of the GJB2 protein is known, R143W and structurally related variants of GJB2 were modeled using this crystal structure as a template. The wild-type crystal structure and the variant computer-aided model were observed and the differences in molecular interactions within the two were analyzed. RESULTS: The predicted structure demonstrated that the hydrogen bond between R143 and N206 was important for the stability of the protomer structure. From this prediction, R143W related N206S and N206T variants showed loss of the hydrogen bond. CONCLUSION: Investigation of the genotypes and clinical data in patients carrying the R143W variant on an allele indicated that severity of hearing loss depends largely on the levels of dysfunction of the pathogenic variant on the allele, whereas a patient with the homozygous R143W variant demonstrated profound hearing loss. We concluded that these hearing impairments may be due to destabilization of the protomer structure of GJB2 caused by the R143W variant.

Demographic analysis of hearing impairment based on various parameters in patients with cochlear implant.

Objectives: To analyse the demographic and clinical variables in children having undergone cochlear implant surgery because of deafness. METHODS: The cross-sectional study was conducted from January to November 2022 at the Centre for Research in Experimental and Applied Medicine laboratory of the Department of Biochemistry and Molecular Biology, Army Medical College, Rawalpindi, Pakistan, in collaboration with the Ear, Nose and Throat Department of Combined Military Hospital, Rawalpindi, and comprised children of eith gender aged up to 10 years who had received cochlear implant. Data was collected through questionnaire-based detailed interviews. Syndromic Hearing Loss, Non-Syndromic Hearing Loss, and Acquired Hearing Loss were identified among the subjects. Data was analysed using SPSS 22. RESULTS: Of the 250 cases, 147(58.8%) were boys, 146(58.4%) were aged 0-5 years, 219(87.6%) had prelingual onset of disease, and 202(80.8%) had a non-progressive disease course. In 203(81.2%) cases, normal developmental milestones were seen. Parental consanguinity was observed in 219(87.6%) cases. However, 63(25.2%) patients had a first-degree relative who had a history of deafness. In 170(68%) cases, hearing loss was hereditary, whereas in 80(32%) it was acquired. Meningitis was the most commonly identified risk factor 55(68.75%). Acquired risk factors and family history had significant association with hearing loss (p<0.05). Speech perception significantly improved in all 219(100%) patients with prelingual hearing loss who underwent cochlear implantation. CONCLUSIONS: Majority of the cases were found to be male, had a prelingual disease onset and a non-progressive disease course. Family history was a significant factor, while meningitis was the most common acquired cause of hearing loss.

Functional Studies of Deafness-Associated Pendrin and Prestin Variants.

Pendrin and prestin are evolutionary-conserved membrane proteins that are essential for normal hearing. Dysfunction of these proteins results in hearing loss in humans, and numerous deafness-associated pendrin and prestin variants have been identified in patients. However, the pathogenic impacts of many of these variants are ambiguous. Here, we report results from our ongoing efforts to experimentally characterize pendrin and prestin variants using in vitro functional assays. With previously established fluorometric anion transport assays, we determined that many of the pendrin variants identified on transmembrane (TM) 10, which contains the essential anion binding site, and on the neighboring TM9 within the core domain resulted in impaired anion transport activity. We also determined the range of functional impairment in three deafness-associated prestin variants by measuring nonlinear capacitance (NLC), a proxy for motor function. Using the results from our functional analyses, we also evaluated the performance of AlphaMissense (AM), a computational tool for predicting the pathogenicity of missense variants. AM prediction scores correlated well with our experimental results; however, some variants were misclassified, underscoring the necessity of experimentally assessing the effects of variants. Together, our experimental efforts provide invaluable information regarding the pathogenicity of deafness-associated pendrin and prestin variants.

Genetically modified pigs: Emerging animal models for hereditary hearing loss.

Hereditary hearing loss (HHL), a genetic disorder that impairs auditory function, significantly affects quality of life and incurs substantial economic losses for society. To investigate the underlying causes of HHL and evaluate therapeutic outcomes, appropriate animal models are necessary. Pigs have been extensively used as valuable large animal models in biomedical research. In this review, we highlight the advantages of pig models in terms of ear anatomy, inner ear morphology, and electrophysiological characteristics, as well as recent advancements in the development of distinct genetically modified porcine models of hearing loss. Additionally, we discuss the prospects, challenges, and recommendations regarding the use pig models in HHL research. Overall, this review provides insights and perspectives for future studies on HHL using porcine models.

[Genetic and phenotypic analysis of MYO15A rare variants associated with autosomal recessive hearing loss].

Objective:To analyze the phenotype and genotype characteristics of autosomal recessive hearing loss caused by MYO15A gene variants, and to provide genetic diagnosis and genetic counseling for patients and their families. Methods:Identification of MYO15A gene variants by next generation sequencing in two sporadic cases of hearing loss at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The sequence variants were verified by Sanger sequencing.The pathogenicity of these variants was determined according to the American College of Medical Genetics and Genomics（ACMG） variant classification guidelines, in conjuction with clinical data. Results:The probands of the two families have bilateral,severe or complete hearing loss.Four variants of MYO15A were identified, including one pathogenic variant that has been reported, two likely pathogenic variants,and one splicing variant of uncertain significance. Patient I carries c. 3524dupA（p. Ser1176Valfs*14）, a reported pathogenic variant, and a splicing variant c. 10082+3G>A of uncertain significance according to the ACMG guidelines. Patient I was treated with bilateral hearing aids with satisfactory effect, demonstrated average hearing thresholds of 37.5 dB in the right ear and 33.75 dB in the left ear. Patient Ⅱ carries c. 7441_7442del（p. Leu2481Glufs*86） and c. 10250_10252del（p. Ser3417del）,a pair of as likely pathogenic variants according to the ACMG guidelines. Patient Ⅱ, who underwent right cochlear implantation eight years ago, achieved scores of 9 on the Categorical Auditory Performance-Ⅱ（CAP-Ⅱ） and 5 on the Speech Intelligibility Rating（SIR）. Conclusion:This study's discovery of the rare c. 7441_7442del variant and the splicing variant c. 10082+3G>A in the MYO15A gene is closely associated with autosomal recessive hearing loss, expanding the MYO15A variant spectrum. Additionally, the pathogenicity assessment of the splicing variant facilitates classification of splicing variations.

Unraveling the Diversity of GJB2 Mutations in Nonsyndromic Hearing Loss: A Comprehensive Study in the Moroccan Population.

INTRODUCTION: Despite the high genetic heterogeneity of hearing loss, mutations in the GJB2 gene are a major cause of autosomal recessive nonsyndromic hearing loss (NSHL) worldwide. However, the mutation profile of GJB2 in NSHL is under-investigated in Morocco, especially among simplex cases. This study aimed to identify the spectrum and frequency of GJB2 mutations in the Moroccan population among simplex and multiplex families with NSHL. METHODS: Moroccan families with NSHL were selected according to well-defined criteria. Selected families were screened for GJB2 gene variants using direct sequencing of the entire coding region of GJB2. RESULTS: A total of 145 affected individuals from 115 families with NSHL were included in this study (49 simplex, 66 multiplex). Mutations in the GJB2 gene were noted in 28.69% of the families (33/115), of which 75.75% were multiplex families and 24.24% were simplex. In total, seven different mutations were detected: c.35delG(p.G12fs), c.551G>A(p.R184Q), c.139G>T(p.E47X), c.109G>A(p.V37I), c.167delT(p.L56fs), c.617A>G(p.N206S), c.94C>T(p.R32C). The last three mutations have not previously been reported in Morocco. The most common GJB2 mutation was c.35delG (21.73%), followed by p.V37I (2.60%) and p.E47X (1.73%). CONCLUSIONS: Our study confirms a high prevalence of GJB2 variants in the Moroccan population, particularly the c.35delG mutation. Additionally, we have identified previously unreported or rarely reported mutations, revealing a greater diversity of GJB2 mutations. These findings emphasize the importance of comprehensive screening beyond the 35delG mutation for patients with NSHL, regardless of their family history. Integrating this approach into clinical care will enhance diagnosis and management of hearing loss in the Moroccan population.

Genetic and phenotypic analysis of MYO15A rare variants associated with autosomal recessive hearing loss / 临床耳鼻咽喉头颈外科杂志

Objective:To analyze the phenotype and genotype characteristics of autosomal recessive hearing loss caused by MYO15A gene variants, and to provide genetic diagnosis and genetic counseling for patients and their families. Methods:Identification of MYO15A gene variants by next generation sequencing in two sporadic cases of hearing loss at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The sequence variants were verified by Sanger sequencing.The pathogenicity of these variants was determined according to the American College of Medical Genetics and Genomics（ACMG） variant classification guidelines, in conjuction with clinical data. Results:The probands of the two families have bilateral,severe or complete hearing loss.Four variants of MYO15A were identified, including one pathogenic variant that has been reported, two likely pathogenic variants,and one splicing variant of uncertain significance. Patient I carries c. 3524dupA（p. Ser1176Valfs*14）, a reported pathogenic variant, and a splicing variant c. 10082+3G>A of uncertain significance according to the ACMG guidelines. Patient I was treated with bilateral hearing aids with satisfactory effect, demonstrated average hearing thresholds of 37.5 dB in the right ear and 33.75 dB in the left ear. Patient Ⅱ carries c. 7441_7442del（p. Leu2481Glufs*86） and c. 10250_10252del（p. Ser3417del）,a pair of as likely pathogenic variants according to the ACMG guidelines. Patient Ⅱ, who underwent right cochlear implantation eight years ago, achieved scores of 9 on the Categorical Auditory Performance-Ⅱ（CAP-Ⅱ） and 5 on the Speech Intelligibility Rating（SIR）. Conclusion:This study's discovery of the rare c. 7441_7442del variant and the splicing variant c. 10082+3G>A in the MYO15A gene is closely associated with autosomal recessive hearing loss, expanding the MYO15A variant spectrum. Additionally, the pathogenicity assessment of the splicing variant facilitates classification of splicing variations.

Stable long-term outcomes after cochlear implantation in subjects with TMPRSS3 associated hearing loss: a retrospective multicentre study.

BACKGROUND: The spiral ganglion hypothesis suggests that pathogenic variants in genes preferentially expressed in the spiral ganglion nerves (SGN), may lead to poor cochlear implant (CI) performance. It was long thought that TMPRSS3 was particularly expressed in the SGNs. However, this is not in line with recent reviews evaluating CI performance in subjects with TMPRSS3-associated sensorineural hearing loss (SNHL) reporting overall beneficial outcomes. These outcomes are, however, based on variable follow-up times of, in general, 1 year or less. Therefore, we aimed to 1. evaluate long-term outcomes after CI implantation of speech recognition in quiet in subjects with TMPRSS3-associated SNHL, and 2. test the spiral ganglion hypothesis using the TMPRSS3-group. METHODS: This retrospective, multicentre study evaluated long-term CI performance in a Dutch population with TMPRSS3-associated SNHL. The phoneme scores at 70 dB with CI in the TMPRSS3-group were compared to a control group of fully genotyped cochlear implant users with post-lingual SNHL without genes affecting the SGN, or severe anatomical inner ear malformations. CI-recipients with a phoneme score ≤ 70% at least 1-year post-implantation were considered poor performers and were evaluated in more detail. RESULTS: The TMPRSS3 group consisted of 29 subjects (N = 33 ears), and the control group of 62 subjects (N = 67 ears). For the TMPRSS3-group, we found an average phoneme score of 89% after 5 years, which remained stable up to 10 years post-implantation. At both 5 and 10-year follow-up, no difference was found in speech recognition in quiet between both groups (p = 0.830 and p = 0.987, respectively). Despite these overall adequate CI outcomes, six CI recipients had a phoneme score of ≤ 70% and were considered poor performers. The latter was observed in subjects with residual hearing post-implantation or older age at implantation. CONCLUSION: Subjects with TMPRSS3-associated SNHL have adequate and stable long-term outcomes after cochlear implantation, equal to the performance of genotyped patient with affected genes not expressed in the SGN. These findings are not in line with the spiral ganglion hypothesis. However, more recent studies showed that TMPRSS3 is mainly expressed in the hair cells with only limited SGN expression. Therefore, we cannot confirm nor refute the spiral ganglion hypothesis.

Preclinical evaluation of the efficacy and safety of AAV1-hOTOF in mice and nonhuman primates.

Pathogenic mutations in the OTOF gene cause autosomal recessive hearing loss (DFNB9), one of the most common forms of auditory neuropathy. There is no biological treatment for DFNB9. Here, we designed an OTOF gene therapy agent by dual-adeno-associated virus 1 (AAV1) carrying human OTOF coding sequences with the expression driven by the hair cell-specific promoter Myo15, AAV1-hOTOF. To develop a clinical application of AAV1-hOTOF gene therapy, we evaluated its efficacy and safety in animal models using pharmacodynamics, behavior, and histopathology. AAV1-hOTOF inner ear delivery significantly improved hearing in Otof-/- mice without affecting normal hearing in wild-type mice. AAV1 was predominately distributed to the cochlea, although it was detected in other organs such as the CNS and the liver, and no obvious toxic effects of AAV1-hOTOF were observed in mice. To further evaluate the safety of Myo15 promoter-driven AAV1-transgene, AAV1-GFP was delivered into the inner ear of Macaca fascicularis via the round window membrane. AAV1-GFP transduced 60%-94% of the inner hair cells along the cochlear turns. AAV1-GFP was detected in isolated organs and no significant adverse effects were detected. These results suggest that AAV1-hOTOF is well tolerated and effective in animals, providing critical support for its clinical translation.

Functional Consequences of Pathogenic Variants of the GJB2 Gene (Cx26) Localized in Different Cx26 Domains.

One of the most common forms of genetic deafness has been predominantly associated with pathogenic variants in the GJB2 gene, encoding transmembrane protein connexin 26 (Cx26). The Cx26 molecule consists of an N-terminal domain (NT), four transmembrane domains (TM1-TM4), two extracellular loops (EL1 and EL2), a cytoplasmic loop, and a C-terminus (CT). Pathogenic variants in the GJB2 gene, resulting in amino acid substitutions scattered across the Cx26 domains, lead to a variety of clinical outcomes, including the most common non-syndromic autosomal recessive deafness (DFNB1A), autosomal dominant deafness (DFNA3A), as well as syndromic forms combining hearing loss and skin disorders. However, for rare and poorly documented variants, information on the mode of inheritance is often lacking. Numerous in vitro studies have been conducted to elucidate the functional consequences of pathogenic GJB2 variants leading to amino acid substitutions in different domains of Cx26 protein. In this work, we summarized all available data on a mode of inheritance of pathogenic GJB2 variants leading to amino acid substitutions and reviewed published information on their functional effects, with an emphasis on their localization in certain Cx26 domains.

Autosomal dominant non-syndromic hearing loss caused by a novel mutation in MYO7A: A case report and review of the literature.

BACKGROUND: Variants in the MYO7A gene commonly result in Usher syndrome, and in rare cases lead to autosomal dominant non-syndromic deafness (DFNA11). Currently, only nine variants have been reported to be responsible for DFNA11 and their clinical phenotypes are not identical. Here we present a novel variant causing DFNA11 identified in a three-generation Chinese family. CASE SUMMARY: The proband was a 53-year-old Han male who presented with post-lingual bilateral symmetrical moderate sensorineural hearing loss. We learned from the patient's medical history collection that multiple family members also had similar hearing loss, generally occurring around the age of 40. Subsequent investigation by high-throughput sequencing identified a novel MYO7A variant. To provide evidence supporting that this variant is responsible for the hearing loss in the studied family, we performed Sanger sequencing on 11 family members and found that the variant co-segregated with the deafness phenotype. In addition, the clinical manifestation of the 11 affected family members was found to be late-onset bilateral slowly progressive hearing loss, inherited in this family in an autosomal dominant manner. None of the affected family members had visual impairment or vestibular symptoms; therefore, we believe that this novel MYO7A variant is responsible for the rare DFNA11 in this family. CONCLUSION: We report a novel variant leading to DFNA11 which further enriches the collection of MYO7A variants, and our review of the nine previous variants that have been identified to cause DFNA11 provides a reference for clinical genetic counseling.

Unraveling haplotype errors in the DFNA33 locus.

Genetic heterogeneity makes it difficult to identify the causal genes for hearing loss. Studies from previous decades have mapped numerous genetic loci, providing critical supporting evidence for gene discovery studies. Despite widespread sequencing accessibility, many historically mapped loci remain without a causal gene. The DFNA33 locus was mapped in 2009 and coincidentally contains ATP11A, a gene recently associated with autosomal dominant hearing loss and auditory neuropathy type 2. In a rare opportunity, we genome-sequenced a member of the original family to determine whether the DFNA33 locus may also be assigned to ATP11A. We identified a deep intronic variant in ATP11A that showed evidence of functionally normal splicing. Furthermore, we re-assessed haplotypes from the originally published DFNA33 family and identified two double recombination events and one triple recombination event in the pedigree, a highly unlikely occurrence, especially at this scale. This brief research report also serves as a call to the community to revisit families who have previously been involved in gene mapping studies, provide closure, and resolve these historical loci.

Comprehensiveness of online sources for patient education on hereditary hearing impairment.

Introduction: The present study aimed at investigating the readability of online sources on hereditary hearing impairment (HHI). Methods: In August 2022, the search terms "hereditary hearing impairment", "genetic deafness", hereditary hearing loss", and "sensorineural hearing loss of genetic origin" were entered into the Google search engine and educational materials were determined. The first 50 websites were determined for each search. The double hits were removed and websites with only graphics or tables were excluded. Websites were categorized into either a professional society, a clinical practice or a general health information website. The readability tests to evaluate the websites included: Flesch Reading Ease, Flesch-Kincaid grade level, Gunning-Fog Index, Simple Measure of Gobbledygook, Coleman-Liau Index, Automated Readability Index. Results: Twentynine websites were included and categorized as from 4 professional societies, 11 from clinical practices and 14 providing general information. All analyzed websites required higher reading levels than sixth grade. On average 12-16 years of education is required to read and understand the websites focused on HHI. Although general health information websites have better readability, the difference was not statistically significant. Discussion: The readability scores of every type of online educational materials on HHI are above the recommended level indicating that not all patients and parents can comprehend the information they seek for on these websites.

Role of mitochondrial dysfunction and oxidative stress in sensorineural hearing loss.

Sensorineural hearing loss (SNHL) can either be genetically inherited or acquired as a result of aging, noise exposure, or ototoxic drugs. Although the precise pathophysiological mechanisms underlying SNHL remain unclear, an overwhelming body of evidence implicates mitochondrial dysfunction and oxidative stress playing a central etiological role. With its high metabolic demands, the cochlea, particularly the sensory hair cells, stria vascularis, and spiral ganglion neurons, is vulnerable to the damaging effects of mitochondrial reactive oxygen species (ROS). Mitochondrial dysfunction and consequent oxidative stress in cochlear cells can be caused by inherited mitochondrial DNA (mtDNA) mutations (hereditary hearing loss and aminoglycoside-induced ototoxicity), accumulation of acquired mtDNA mutations with age (age-related hearing loss), mitochondrial overdrive and calcium dysregulation (noise-induced hearing loss and cisplatin-induced ototoxicity), or accumulation of ototoxic drugs within hair cell mitochondria (drug-induced hearing loss). In this review, we provide an overview of our current knowledge on the role of mitochondrial dysfunction and oxidative stress in the development of SNHL caused by genetic mutations, aging, exposure to excessive noise, and ototoxic drugs. We also explore the advancements in antioxidant therapies for the different forms of acquired SNHL that are being evaluated in preclinical and clinical studies.

Preimplantation genetic testing for hereditary hearing loss in Chinese population.

PURPOSE: To evaluate the clinical validity of preimplantation genetic testing (PGT) to prevent hereditary hearing loss (HL) in Chinese population. METHODS: A PGT procedure combining multiple annealing and looping-based amplification cycles (MALBAC) and single-nucleotide polymorphisms (SNPs) linkage analyses with a single low-depth next-generation sequencing run was implemented. Forty-three couples carried pathogenic variants in autosomal recessive non-syndromic HL genes, GJB2 and SLC26A4, and four couples carried pathogenic variants in rare HL genes: KCNQ4, PTPN11, PAX3, and USH2A were enrolled. RESULTS: Fifty-four in vitro fertilization (IVF) cycles were implemented, 340 blastocysts were cultured, and 303 (89.1%) of these received a definite diagnosis of a disease-causing variant testing, linkage analysis and chromosome screening. A clinical pregnancy of 38 implanted was achieved, and 34 babies were born with normal hearing. The live birth rate was 61.1%. CONCLUSIONS AND RELEVANCE: In both the HL population and in hearing individuals at risk of giving birth to offspring with HL in China, there is a practical need for PGT. The whole genome amplification combined with NGS can simplify the PGT process, and the efficiency of PGT process can be improved by establishing a universal SNP bank of common disease-causing gene in particular regions and nationalities. This PGT procedure was demonstrated to be effective and lead to satisfactory clinical outcomes.

Molecular Mechanisms and Clinical Phenotypes of GJB2 Missense Variants.

The GJB2 gene is the most common gene responsible for hearing loss (HL) worldwide, and missense variants are the most abundant type. GJB2 pathogenic missense variants cause nonsyndromic HL (autosomal recessive and dominant) and syndromic HL combined with skin diseases. However, the mechanism by which these different missense variants cause the different phenotypes is unknown. Over 2/3 of the GJB2 missense variants have yet to be functionally studied and are currently classified as variants of uncertain significance (VUS). Based on these functionally determined missense variants, we reviewed the clinical phenotypes and investigated the molecular mechanisms that affected hemichannel and gap junction functions, including connexin biosynthesis, trafficking, oligomerization into connexons, permeability, and interactions between other coexpressed connexins. We predict that all possible GJB2 missense variants will be described in the future by deep mutational scanning technology and optimizing computational models. Therefore, the mechanisms by which different missense variants cause different phenotypes will be fully elucidated.

Single Versus Multigene Testing for Hereditary Hearing Loss: Use and Costs in a Commercially Insured Cohort.

OBJECTIVE: The objectives of this study were to describe trends in single-gene GJB2/6 (connexin 26/30) and multigene hearing loss panel (HLP) testing for hereditary hearing loss using real-world evidence. STUDY DESIGN: Retrospective study using insurance claims data. SETTING: Optum Data Mart database from 2015 to 2020. METHODS: Rates of overall and hearing-specific genetic testing and costs to insurers and patients were reported. Linear regression models were used to assess the proportion of single-gene GJB2/6 testing over time. Additional linear regression models were used to assess changes in costs over time. RESULTS: From 2015 to 2020, 91,986 children received genetic testing for any indication, of which 601 (0.65%) received hearing-specific tests. The proportion of single-gene GJB2/6 testing remained similar over time (mean difference [MD]: -1.3% per year; 95% confidence interval [CI]: -4.3%, 1.7%), while multigene HLP use increased over time (MD: 4.0% per year; 95% CI: 0.4%, 7.5%). The median charge for single-gene GJB2/6 testing remained constant during the study period (MD: -$34; 95% CI: -$86, $18), while the median charge for multigene HLP decreased during the study period (MD: -$145 per year; 95% CI: -$278, -$12). CONCLUSION: Compared to molecular testing for GJB2/6, HLPs are becoming more common for hereditary hearing loss. The comprehensiveness of HLP and decreasing costs provide justification for its more widespread adoption moving forward.

The Enigmatic Genetic Landscape of Hereditary Hearing Loss: A Multistep Diagnostic Strategy in the Italian Population.

Hearing loss is the most frequent sensorineural disorder, affecting approximately 1:1000 newborns. Hereditary forms (HHL) represent 50-60% of cases, highlighting the relevance of genetic testing in deaf patients. HHL is classified as non-syndromic (NSHL-70% of cases) or syndromic (SHL-30% of cases). In this study, a multistep and integrative approach aimed at identifying the molecular cause of HHL in 102 patients, whose GJB2 analysis already showed a negative result, is described. In NSHL patients, multiplex ligation probe amplification and long-range PCR analyses of the STRC gene solved 13 cases, while whole exome sequencing (WES) identified the genetic diagnosis in 26 additional ones, with a total detection rate of 47.6%. Concerning SHL, WES detected the molecular cause in 55% of cases. Peculiar findings are represented by the identification of four subjects displaying a dual molecular diagnosis and eight affected by non-syndromic mimics, five of them presenting Usher syndrome type 2. Overall, this study provides a detailed characterisation of the genetic causes of HHL in the Italian population. Furthermore, we highlighted the frequency of Usher syndrome type 2 carriers in the Italian population to pave the way for a more effective implementation of diagnostic and follow-up strategies for this disease.