Sensorineural hearing loss in children

Characterization of the Expression and Role of Striatin-Interacting Protein 2 in Mouse Cochlea

HYPOTHESIS

In this study, we aimed to examine the cochlear expression pattern and function of Striatin-interacting protein 2 (STRIP2) by using animal models.

BACKGROUND

Sensorineural hearing loss often results from genetic defects in hair cell (HC) development and function. STRIP2 is a part of the striatin-interacting phosphatase and kinase (STRIPAK) complex, which plays important regulatory roles in cell fate determination, proliferation, cytoskeletal organization, and cell morphology. A recent study revealed Strip2 as the candidate gene that regulates positive selection in HC lineages. However, its role in the inner ear has not been identified.

METHODS

Strip2 knockout mouse model was used to examine the cochlear expression pattern and function of STRIP2. Auditory brainstem response test was used to evaluate the hearing function of mice. Immunostaining and scanning electron microscope were used to study hair cells, synapses, and stereocilia of cochlea.

RESULTS

Immunostaining showed that cytoplasmic STRIP2 expression in hair cells increased from postnatal day (P) 3 to P14. Despite having normal hearing thresholds, hair cell numbers, and stereocilia morphology until P90, the deletion of Strip2 resulted in a mild reduction in ribbon synapse density, suggesting a late onset of cochlear synaptic defects.

CONCLUSION

Our results revealed that STRIP2 was abundantly expressed in hair cells; however, the hearing function of Strip2-/- mice was comparable to that of control mice until P90, and a mild decrease in ribbon synapse number was detected at P60 and P90. Further studies on STRIP2 and its associated complexes will provide new insights into the pathways involved in inner ear development and function.

Metformin-induced mitophagy suppresses auditory hair cell apoptosis via AMPK pathway

Hearing loss is a pervasive issue affecting numerous individuals, and its etiology and categorization are multifaceted. Among these, sensorineural hearing loss (SNHL) emerges as the most prevalent variant among these. The primary causative factor underlying SNHL resides in the depletion of auditory hair cells within the cochlea, yet the pursuit of efficacious therapeutic interventions remains an ongoing challenge. Previous investigations have illuminated the role of mitochondrial dysfunction in precipitating cellular apoptosis, and mitophagy has emerged as a promising mechanism to ameliorate such dysfunction. Additionally, it has been noted that metformin possesses the specific ability to induce mitophagy. Herein, our objective is to explore the protective effects of metformin-induced mitophagy against apoptosis in auditory hair cells (HEI-OC1 cells) and explore its potential mechanisms. Our results revealed that metformin effectively triggered mitophagy in HEI-OC1 cells. Moreover, metformin treatment showed the ability to prevent tert-butyl hydroperoxide (TBHP) induced mitochondrial dysfunction and intrinsic apoptotic pathways. Mechanistically, we discovered that metformin activates AMP-activated protein kinase (AMPK) signaling in HEI-OC1 cells stimulated by TBHP, thereby triggering mitophagy. Overall, our results suggest that metformin may represent a promising and innovative therapeutic strategy for mitigating the onset of hearing loss.

Anatomical investigation of safety determining factors for keyhole drilling trajectories for robotic cochlear implant surgery

PURPOSE

Cochlear implants (CI) are the most successful bioprosthesis in medicine probably due to the tonotopic anatomy of the auditory pathway and of course the brain plasticity. Correct placement of the CI arrays, respecting the inner ear anatomy are therefore important. The ideal trajectory to insert a cochlear implant array is defined by an entrance through the round window membrane and continues as long as possible parallel to the basal turn of the cochlea. Image-guided surgery can directly drill with a robotic arm through the mastoid and execute an exact drilling of this precalculated most ideal trajectory. Here, we aim to identify critical anatomical structures determining the safest keyhole drilling trajectory by comparing easy and difficult CI surgeries performed with the HEARO Procedure: a robotic tool for image-guided surgery.

METHODS

Cone-beam computed tomography images of patients who underwent robot-assisted cochlear implantation surgery (RACIS) were included. Three of 25 cases had to be converted to conventional surgery because of the current safety mitigations based on anatomical distance. Radiological images in DICOM format were transferred to dedicated software (OTOPLAN® Cascination GMHB Bern Switzerland) for analyses. Surgical segmentation and previously planned trajectories were analyzed for these 25 cases by comparing cochlear sizes, facial recess sizes, round window sizes, and trajectory angles. In addition, facial recess angle, and cochlear orientation angles were measured with RadiAnt DICOM Viewer (Medixant, Pozan, Poland).

RESULTS

Facial recess size, facial recess angle, and distance between the facial nerve and safe trajectory were smaller in patient who converted from robotic surgery to conventional. A significant positive correlation existed between basal turn angle and in-plane angle (p = 0.001, r = 0.859). In addition, there was a significant negative correlation between the basal turn length and the last electrode insertion depth degree (p = 0.007, r = 0.545).

CONCLUSION

In our robotic surgery cases, we demonstrate that the limiting factors of anatomical relationships are constituted by the dimensions of the facial recess and the cochlear orientation. The findings of this study are considered to be a reference for future studies in achieving collision-free trajectory planning in robotic-assisted cochlear implant surgery.

Identification of novel CDH23 heterozygous variants causing autosomal recessive nonsyndromic hearing loss

BACKGROUND

Hearing loss adversely impacts language development, acquisition, and the social and cognitive maturation of affected children. The hearing loss etiology mainly includes genetic factors and environmental factors, of which the former account for about 50-60%.

OBJECTIVE

This study aimed to investigate the genetic basis of autosomal recessive non-syndromic hearing loss (NSHL) by identifying and characterizing novel variants in the CDH23 gene. Furthermore, it seeks to determine the pathogenic potential of the noncanonical splice site variant c.2398-6G > A.

METHODS

Comprehensive clinical evaluation and whole-exome sequencing (WES) were performed on the girl. The WES analysis revealed two novel variants in the CDH23 gene, associated with nonsyndromic deafness 12 (DFNB12). To further explore the pathogenicity of these variants, functional studies involving in vivo splicing analysis were performed on the novel noncanonical splice site variant, c.2398-6G > A, which was initially classified as a variant of uncertain significance (VUS).

RESULTS

Whole-exome sequencing of the patient identified two compound heterozygous variants in CDH23: c.2398-6G > A, a noncanonical splice site variant, and c.6068C > A (p. Ser2023Ter), a nonsense mutation. In vitro splicing assays demonstrated that c.2398-6G > A caused aberrant splicing, leading to a frameshift (p. Val800Alafs*6) and the production of a truncated protein, as confirmed by structural protein analysis. The study revealed novel mutations as likely pathogenic, linking both variants to autosomal recessive NSHL.

CONCLUSIONS

Our analyses revealed novel compound heterozygous mutations in CDH23 associated with autosomal recessive NSHL, thereby expanding the mutational landscape of CDH23-related hearing loss and increasing knowledge about the CDH23 splice site variants.

Disparities among Different Countries in Access for Diagnosis and Treatment of Pediatric Sensorineural Hearing Loss

OBJECTIVE

Timely diagnosis and management of pediatric sensorineural hearing loss (SNHL) is essential for best outcomes. This study evaluated the differences of health access among cochlear implant (CI) centers of countries with different health care systems.

STUDY DESIGN

Retrospective.

SETTING

Multicenter, tertiary pediatric CI referral center in four different countries: United States (USA), France (FR), Australia (AUS), and Brazil (BR).

PATIENTS

Pediatric (age 0-21 years (0-16 years AUS)) patients receiving CI between January 2017 and December 2019.

INTERVENTIONS

CI.

MAIN OUTCOME MEASURES

Primary outcome measures included age at milestones in CI process and age at implantation.

RESULTS

There were 1,673 patients who underwent CI surgery at four multinational designated institutions were identified (n = 143 AUS; 153 BRA; 1,158 FR; and 219 USA). Median age at time of hearing loss diagnosis ( p < 0.0001), median age at hearing aid (HA) fitting ( p < 0.0001), and CI evaluation ( p < 0.0001) differed between countries. However, age at CI surgery was not significantly different between countries. Time from diagnosis to HA fitting was impacted by country ( p < 0.0001) and language ( p = 0.01) but not by private compared with public insurance. There were 512 children with available data regarding onset of hearing loss as prelingual n = 358 (70%) and postlingual n = 154 (30%). In patients with prelingual severe to profound hearing loss, country and race/ethnic origin affected age at diagnosis ( p < 0.0001, p = 0.001), HA fitting ( p < 0.0001, p < 0.001), candidacy evaluation ( p = 0.0001, p = 0.02), and CI surgery ( p = 0.0027, p = 0.001).

CONCLUSIONS

Age at pediatric CI was comparable across the CI centers compared in the four countries. This is encouraging given the effect of neuroplasticity on pediatric CI outcomes, despite different health care expenditures and delivery systems in the four countries. Improvement in care access for certain populations may decrease disparities in pediatric CI access worldwide.

Viral-Mediated Connexin 26 Expression Combined with Dexamethasone Rescues Hearing in a Conditional Gjb2 Null Mice Model

GJB2 encodes connexin 26 (Cx26), the most commonly mutated gene causing hereditary non-syndromic hearing loss. Cx26 is mainly expressed in supporting cells (SCs) and fibrocytes in the mammalian cochlea. Gene therapy is currently considered the most promising strategy for eradicating genetic diseases. However, there have been no significant effects of gene therapy for GJB2 gene mutation-associated deafness because deficiency of Cx26 leads to expanded sensory epithelial damage. In this study, the AAV2.7m8 serotype combined with the gfaABC1D promoter targeted infection of SCs is identified. It is found that Gjb2 gene replacement therapy in wild-type mice results in sensory hair cells (HCs) deficits, excessive inflammatory responses, and hearing loss. This may be one of the key factors contributing to the hardship of GJB2 gene replacement therapy. Dexamethasone (DEX) shows promising results in inhibiting macrophage recruitment, with a protective effect against HC damage. Further, the combination of AAV2.7m8-Gjb2 with DEX shows a synergistic effect and enhances the gene therapy effect in a conditional Cx26 null mice model. These results indicate that the combination of gene therapy and medication will provide a new strategy for the treatment of hereditary deafness associated with GJB2 defects.

Classification and prediction of variants associated with hearing loss using sequence information in the vicinity of mutation sites

Hearing impairment is a major global health problem, affecting more than 5 % of the world's population at various ages, from neonates to the elderly. Among the common genetic variations in humans, single nucleotide variations and small insertions or deletions predominate. The study of hearing loss resulting from these variations is proving invaluable in the analysis and diagnosis of hearing disorders. The identification of pathogenic mutations is frequently a lengthy and laborious process. Existing computational prediction tools have been developed primarily for common diseases and genome-wide analyses, with less focus on deafness. This study proposes a novel approach that focuses on the regions surrounding mutation sites. Mutation sites associated with deafness and their flanking regions of different lengths were extracted from relevant databases and combined into seven distinct segments of different lengths. The information-theoretic features of these segments were computed. Five machine learning algorithms were then used for training, resulting in the construction of a model capable of classifying and predicting deafness-related mutations. For fragments encompassing the 250 bp regions upstream and downstream of the mutations, the average AUC of the five classifiers on the independent test set is 0.89 and the average ACC is 0.85, indicating that the model has a high recognition rate of the pathogenic deafness mutation site. An ensemble approach was also applied to predict variants of uncertain significance (VUS) that may be associated with deafness. These variants were then scored and ranked to assess their likelihood of contributing to the condition.

Case report: A novel nonsense mutation in the MARVELD2 gene causes nonsyndromic hearing loss in a China family

The MARVELD2 gene is located on chromosome 5q13.2 and is associated with autosomal recessive nonsyndromic hearing loss (OMIM: # 610572). In this study, we identified and reported a novel nonsense mutation in MARVELD2 c. 663G > A in a Chinese family. We collected peripheral venous blood from 19 members of the affected family and performed whole exome sequencing to analyze the mutation genotype. A single-nucleotide mutation was detected in MARVELD2. Five individuals in the family carried the MARVELD2 c.663G>A mutation; one of them was homozygous and showed severe congenital deafness and language impairment. The next-generation sequencing results were validated by Sanger sequencing. This study expands the spectrum of MARVELD2 mutations that cause nonsyndromic hearing loss and provides insights into the molecular pathogenesis underlying deafness. This finding has important implications for genetic screening, diagnosis, counseling, and research of deafness-related genes.

Hamartomas of the Tuber Cinereum Associated with X-Linked Deafness Show Signs of Pubertas Tarda Instead of Pubertas Praecox and No Gelastic Seizures-Long-Term Follow-Up of 12 Years

PURPOSE

Hamartomas of tuber cinereum present as ectopic tissue in the hypothalamic region. Clinically, the usual hypothalamic hamartomas manifest themself by gelastic seizures and pubertas praecox. We observed an increased coincidence of the presence of X-linked recessive deafness DFNX2 (DFN3) and a hamartoma of the tuber cinereum. Initially five patients presented with hearing loss in childhood, two additional were already adults, not showing any characteristic symptoms for a hamartoma but signs of delayed puberty.

METHODS

Seven patients who underwent computed tomography imaging due to a sensorineural hearing loss and had a hamartoma of the tuber cinereum in addition to X-linked deafness DFNX2 (DFN3) were included in a retrospective study. Patients underwent initial neurologic, endocrinologic, and genetic evaluation. Long-term follow-up was performed after 10 to 12 years.

RESULTS

The average age at the initial exam was 12.9 years (range 4-29). All patients genetically proven nonsyndromic, X-linked deafness associated with the POU3F4 gene. Three out of six patients presented signs of delayed puberty. None of all seven showed any evidence of pubertas praecox or gelastic seizures at mean age of 17 years (range 17-29 years) at any time.

CONCLUSION

Hamartomas of tuber cinereum are often coincident with DFNX2. Clinically, half of the cases are-in contrary to the usual pubertas praecox-associated with growth hormone deficiency and delayed puberty, in the sense of pubertas tarda, when coincident. Clinicians' and radiologists' knowledge and awareness of this rare combination are crucial to identify children early enough for hormone-sensitive treatment.

Management of Prenatal Expanded Genetic Carrier Screening Results for Autosomal Recessive Sensorineural Hearing Loss

OBJECTIVE

Expanded carrier screening (ECS) identified couples at-risk to have a baby with an autosomal recessive genetic condition. Several genes implicated in sensorineural hearing loss (SNHL) are included in prenatal or preconception genetics ECS testing. Early identification of SNHL risk may enable prognostication of hearing loss, early educational intervention, and minimization of unnecessary diagnostic testing. We sought to describe cases where ECS enabled early SNHL-risk identification.

STUDY DESIGN

Retrospective chart review.

SETTING

Maternal-Fetal Care Center and Otolaryngology department at an academic tertiary hospital.

METHODS

Medical records of parent-infant dyads with positive ECS results for variants in autosomal recessive SNHL genes were reviewed. Data regarding genetic diagnostic testing, newborn hearing screening, time to HL diagnosis, audiological evaluation, and clinical consultations were compiled.

RESULTS

Fifteen pregnant with positive ECS results for SNHL were referred for consultation with a pediatric otolaryngologist and genetic counselor. Generally, these couples were highly educated and adequately insured. 14 had pathogenic variants for GJB2 and 1 for USH2A. Four couples pursued prenatal genetic diagnosis via amniocentesis; 11 couples deferred genetic testing to the postnatal period or waited for initial hearing evaluation. Six babies inherited biallelic GJB2 mutations. Four were found to have SNHL on ABR by age 5 weeks and received follow-up management, 1 had a normal hearing evaluation despite being gene-positive, and 1 was lost to follow-up before hearing evaluation.

CONCLUSIONS

Carrier screening and confirmatory prenatal or neonatal genetic testing provided considerable lead time for early audiometric testing and appropriate intervention services including hearing aid fitting.

Comparison of Genetic, Auditory Features, and Systemic Clinical Phenotype in 14 Families with Syndromic Hearing Loss

Introduction

Syndromic hearing loss (SHL) is characterized by distinctive clinical phenotypes as well as genetic and phenotypic heterogeneity. More than 400 species of SHL have been described, the majority of which are autosomal dominant.

Methods

11 forms of SHL were obtained from 14 unrelated families with probands ranging in age from 5 to 78 months. The results of whole exome sequencing(WES), audiological characteristics, middle and inner ear radiological findings, and additional clinical phenotype characteristics were retrospectively analyzed.

Results

Fourteen people with SHL were found. Two of them had Waardenburg syndrome, two had Branchio-Oto-Renal syndrome, two had CHARGE syndrome, and one had Treacher Collins syndrome, Kleefstra syndrome, Muenke syndrome, Osteopathia Striata with Cranial Sclerosis, Ayme-Gripp syndrome, Tatton-Brown-Rahman syndrome, Stickler syndrome, or Stapes Ankylosis with Broad Thumbs and Toes. In this investigation, ten variants were first reported.

Discussion

The combination of a neonatal hearing screening and WES can diagnose syndrome-type hearing loss in infancy and childhood, according to our findings, expansion of the gene variant spectrum and phenotype for various age groups of SHL is essential and can provide valuable guidelines for clinical intervention decisions. It is imperative for medical practitioners to conduct diligent and prolonged patient monitoring due to the inherent variability in both the auditory impairment and the comprehensive clinical manifestation of SHL.

Polygenic Risk Scores and Hearing Loss Phenotypes in Children

Importance

Monogenic causes of childhood hearing loss are well established, as are polygenic risk contributions to age-related hearing loss. However, an untested possibility is that polygenic risk scores (PRS) also contribute to childhood hearing loss of all severities, alongside environmental and/or monogenic causes.

Objective

To examine the association between a PRS for adult hearing loss and childhood hearing loss phenotypes.

Design, Setting, and Participants

This cross-sectional study used a unique population-based dataset spanning normal hearing to profound loss, combining 2 contemporaneous population cohorts in Australia. This included the Child Health CheckPoint, a national population-based cross-sectional study nested within the Longitudinal Study of Australian Children, and the Victorian Childhood Hearing Longitudinal Databank (VicCHILD), a statewide population-based longitudinal data bank open to every child with congenital hearing loss in Victoria, Australia. The analysis took place from March to August 2023.

Exposures

Genotype data were generated from saliva- or blood-derived DNA using global single-nucleotide variations arrays. Based on genotype data, PRS was computed using published UK Biobank genome-wide association study results for self-reported hearing difficulty in individuals aged 40 to 69 years.

Main Outcomes and Measures

Hearing outcomes were classified by laterality (bilateral, unilateral), severity (mild, moderate, severe or worse) and types (sensorineural, conductive, mixed, auditory neuropathy, atresia). Analyses included multinominal logistic regressions of PRS with hearing outcomes.

Results

Overall, 1488 CheckPoint study children (49.8% boys, aged 11-12 years) and 527 VicCHILD study children (55.2% boys, aged 0-13 years) with hearing and genotype data were included. A 1-SD increment in PRS was associated with higher odds of mild (odds ratio [OR], 1.3; 95% CI, 1.0-1.6), moderate (OR, 5.1; 95% CI, 3.2-8.1), and severe or worse (OR, 5.3; 95% CI, 3.9-7.3) unilateral hearing loss compared with normal hearing. Similarly, the PRS was associated with increased odds of mild, moderate, and severe or worse bilateral hearing loss (per-SD ORs, 3.9-6.6) and all hearing loss types (per-SD ORs, 8.5-10.6).

Conclusions and Relevance

In this cross-sectional study, a PRS initially developed for adult hearing difficulty was associated with wide-ranging childhood hearing loss phenotypes, partly explaining hearing phenotype variations despite shared genetic and environmental factors (eg, preterm birth). Large-scale studies with objectively defined hearing phenotypes are crucial for refining PRS and predicting high-risk children.

Ventilation with hyperoxia promotes cochlear bleeding in rabbits with congenital diaphragmatic hernia

OBJECTIVE

The authors hypothesized that ventilation and hyperoxia may harm the cochlea vasculature in an experimental model of Congenital Diaphragmatic Hernia (CDH) performed in rabbits.

METHODS

New Zealand rabbits underwent CDH creation at 25 days of gestation (term = 30 days). CDH was created in fetuses (n = 15) and compared with Controls (n = 15). Six groups were studied: Control, Control Ventilated 21% FiO2 (Control 21%), Control Ventilated 100% FiO2 (Control 100%), CDH, CDH Ventilated 21% FiO2 (CDH 21%) and CDH Ventilated 100% FiO2 (CDH 100%). Dynamic Compliance (CRS), dynamic Elastance (ERS), and dynamic Resistance (RRS) were measured. The cochleae were then removed, and the apical, middle, and basal slopes of the cochleae were evaluated. Samples were graded using a scoring system for the severity of bleeding: 0 (absent), 1 (mild), 2 (moderate), and 3 (severe). Statistical analysis was performed by contingence and ANOVA.

RESULTS

There was no difference in the severity of cochlear bleeding between Controls and CDH without ventilation. Control 21% and 100% had average scores of 2 and 1.2 respectively; CDH 21% and 100% had average scores of 0.4 and 3.8 respectively; RR [CDH 100% / Control 100%] (95% CI) = 3.16 (p < 0.005).

CONCLUSIONS

The severity of bleeding was 3.16 times worse with 100% oxygenation in CDH. This information may be helpful for future therapeutic strategies for decreasing SNHL in CDH patients.

Gene therapy for hearing loss: Current status and future prospects of non-viral vector delivery systems

Current therapeutic options for hearing loss rely on hearing aids, ossiculoplasty or cochlear implants. These devices have limitations, particularly in noisy acoustic environments. Therefore, interest in exploring aetiological treatments to improve not only auditory perception but also the quality of life of those affected is increasing. Gene therapy is a promising aetiological treatment that can fully restore auditory function. The success of gene therapy relies on the efficient delivery of therapeutic genes or genetic modifications to the cells of the inner ear that are designed to repair or replace defective genes and restore normal hearing function. Two main strategies for gene therapy involve the use of recombinant viral vectors and nonviral delivery vehicles. Owing to their excellent diffusion properties and compatibility with sensory cells, recombinant viral vectors, particularly adeno-associated viruses (AAVs), have dominated gene therapy in the cochlea. However, recombinant viral vectors have several drawbacks, such as limited transgene size, immunogenicity (particularly in neonates), and potential need for repeat administration. Nonviral vectors, such as cationic lipids and polymeric nanoparticles, are potential attractive alternatives. Nonviral vectors have several advantages, including low immunogenicity and unlimited transgene size. Recent studies have demonstrated significant auditory recovery in vivo using nonviral vectors in murine models. However, nonviral vectors are not as efficient as viral vectors in transferring genetic material. An alternative to nanoparticles is the use of other methods, such as electroporation. The main advantage of electroporation is that it can be used in combination with cochlear implantation and can target surface cells, but this method has a risk of cell damage. The goal of this review is to provide valuable insights into the current state of research on nonviral vectors for inner ear gene therapy and propose the exploration of innovative and effective gene therapy strategies for the treatment of hearing loss.

Etiology of Childhood Profound Sensorineural Hearing Loss: The Role of Hearing Loss Gene Panel Testing

OBJECTIVE

Establishing the cause of hearing loss (HL) is important and rewarding, though not without its challenges. While our ability to identify the etiology for HL has improved with advances in scientific knowledge, a significant proportion of cases remain of unknown etiology. Recent protocol changes within the NHS Genomic Medicine Service support the utilization of the HL gene panel test, rather than individual gene tests. In light of these changes, determining the yield of these more extensive panel tests is important in informing future practice.

STUDY DESIGN

Retrospective study.

SETTING

The Cochlear Implant (CI) Department at Great Ormond Street Hospital (GOSH).

METHODS

Four hundred seventy-six children with profound HL were identified from a database of referrals to the GOSH CI Department. Data on etiology of HL including genetic diagnosis was collected from hospital notes on an electronic patient records system and hospital genetics database.

RESULTS

We identified a positive result in 163/476 (34%) cases through the gene panel test, representing an additional 19% yield to current level 1 investigations. Genetic HL, including both syndromic (including those not covered by the HL gene panel) and nonsyndromic (209/476, 44%) was the most common etiology in our cohort. Perinatal, intrauterine, ototoxicity, meningitis, and encephalitis categories altogether comprised 97/476 (20%) cases.

CONCLUSION

Gene panel testing provides significant additional yield over current level 1 investigations which include GJB2 testing only. This has far-reaching implications for how we optimize investigations into HL in children and counsel families, and for future early interventions.

A Survey of the Knowledge and Attitudes of First-Time Pregnant Women Regarding Infant Hearing Loss

OBJECTIVES

The aim of the present study was to investigate the knowledge and attitudes of first-time pregnant women regarding hearing loss in infants, and to identify the key factors that influence their perceptions.

METHODS

After validating and ensuring the reliability of a well-structured questionnaire consisting of 15 items, it was distributed to a total of 400 pregnant women who were experiencing their first pregnancies. Utilizing a cluster sampling method, participants were selected from both public hospitals and private gynecologist offices across diverse geographic regions in Tehran, Iran. Participants were asked to respond on a three-point scale (No, Not Sure, Yes). The results were analyzed using both descriptive and analytic statistics.

RESULTS

The translated questionnaire exhibited suitable face validity, test-retest reliability, and internal consistency. Findings revealed the highest maternal knowledge for "newborns can be born with hearing loss "(77.5%) and the lowest knowledge score was observed for "delayed birth cry can lead to hearing loss" (23.8%). Regarding attitudes, 72.5% of mothers scored above the mean of 5.65 out of 6, indicating a preference for early diagnosis and intervention. Several factors, such as education level and the mother's city of residence, showed a significant correlation with certain knowledge and attitude-related questions. Notably, individuals receiving care at public hospitals showed greater knowledge compared to those visiting private clinics.

CONCLUSIONS FOR PRACTICE

Mothers play a crucial role in child health and need to have a thorough understanding of pediatric diseases in order to make informed decisions. One particular condition that mothers should be well-informed about is hearing loss, as it has a significant impact on language development. However, this study reveals that there are gaps in maternal knowledge when it comes to the specific causes of hearing loss.

A novel CLRN2 variant: expanding the mutation spectrum and its critical role in isolated hearing impairment

BACKGROUND

Biallelic variants in the CLRN2 gene have been reported to cause autosomal recessive profound hearing impairment in humans. CLRN2 belongs to the clarin gene family that encodes a tetraspan protein that contains a cytosolic N-terminus, multiple helical transmembrane domains, and an endoplasmic reticulum membrane retention signal, TKGH, in the C-terminus. The encoded protein may be important in development and homeostasis of the inner ear and retina.

METHODS

Here, we present a consanguineous family suffering from autosomal recessive non-syndromic profound hearing impairment (HI). We employed state of the art Whole exome sequencing (WES), Sanger sequencing followed by routine bioinformatics filtration steps and homology modeling to elucidate the effect of mutation at the protein level.

RESULTS

ES followed by Sanger sequencing revealed a novel homozygous nonsense variant in the CLRN2 gene [c.414 C > A; p.Cys138*]. Furthermore, insilico protein modeling of the wildtype and mutated version of the CLRN2 protein revealed large-scale changes that predict to compromise the routine normal function of the protein.

CONCLUSION

Our finding further extends the mutations spectrum of CLRN2 gene and confirms its important role in hearing homeostasis and with developmental disorder in humans.

Lipid metabolism and hearing loss: association of non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) with adolescent hearing health

BACKGROUND

The ratio of non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol (NHHR) is a novel lipid measure for assessing the risk of cardiovascular disease. Lipid metabolism disorders are reportedly associated with hearing impairment. This study aimed to investigate the potential association between NHHR and hearing.

METHODS

The data used in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) cycles of 2005-2010 and 2017-2018, including 4,296 participants aged 6-19 years. The NHHR was calculated from lipid profiles, and hearing was assessed using pure-tone audiometry. Weighted multivariate logistic regression analyses were used to investigate the association between the NHHR and hearing loss. Subgroup and sensitivity analyses were performed to verify the robustness of the results.

RESULTS

Univariate analysis revealed significant associations between the NHHR and hearing threshold at all categorized frequency (low, speech, or high-frequency) (P < 0.001). Three models were used: an unadjusted model, a model adjusted for age, sex, and race, and a model further adjusted for PIR, BMI, and diabetes. Multiple regression analysis confirmed these associations consistently across all models. When considered as a continuous variable, NHHR had a significant association with enhanced hearing thresholds at all categorized frequencies: low-frequency (β:0.56, 95% CI: 0.36-0.75), speech-frequency (β:0.55, 95% CI: 0.36-0.7), and high-frequency (β:0.55, 95% CI: 0.36-0.74). The adjusted models showed persistent positive correlations after controlling for covariates. The NHHR was consistently positively associated with hearing loss. The NHHR and auditory thresholds showed a general dose-response association across all frequencies.

CONCLUSIONS

NHHR is a promising biomarker for predicting adolescent hearing threshold shifts and hearing loss. The study highlights the importance of early lipid monitoring and management as strategies to prevent or reduce hearing impairment.

Clinical and genetic characterisation of childhood-onset sensorineural hearing loss reveal associated phenotypes and enrichment of pathogenic founder mutations in the Finnish population

OBJECTIVE

To examine the clinical and genetic characteristics of childhood-onset bilateral sensorineural hearing loss (SNHL) in Finland.

DESIGN

Retrospective analysis.

STUDY SAMPLE

A total of 249 children younger than 18 years were diagnosed with bilateral SNHL in Oulu University Hospital, Finland, from 2017 to 2022.

RESULTS

Pathogenic or likely pathogenic gene variants or chromosome abnormalities explaining SNHL were identified in 41% (N = 101/249) of children. Likely causative variants were more commonly identified in patients with severe SNHL than in those with moderate or mild SNHL. Our study identified likely causative gene variants in 24 different genes and six different likely causative chromosome abnormalities, demonstrating the genetic heterogeneity of SNHL. Population-enriched founder mutations were identified in the CABP2, CLRN1, MYO7A, SUCLA2, TMC1, and TWNK genes. A significant number of patients had associated phenotypes, including global developmental delay or intellectual disability (16%), language disorder (20%), ophthalmological abnormalities (16%), or malformations other than those involving the ear (10%).

CONCLUSIONS

SNHL is genetically and clinically heterogeneous. Pathogenic variants in GJB2 were the most common. Several population-enriched variants were identified as causing SNHL in the northern Finnish population. Associated medical phenotypes are common and should be taken into account in patients' follow-up and treatment.

Intratympanic injection of MSC-derived small extracellular vesicles protects spiral ganglion neurons from degeneration

Sensorineural hearing loss is one of the most prevalent sensory deficits. Spiral ganglion neurons (SGNs) exhibit very limited regeneration capacity and their degeneration leads to profound hearing loss. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) have been demonstrated to repair tissue damage in various degenerative diseases. However, the effects of MSC-sEV on SGN degeneration remain unclear. In this study, we investigated the efficacy of MSC-sEV for protection against ouabain-induced SGN degeneration. MSC-sEV were derived from rat bone marrow and their components related to neuron growth were determined by proteomic analysis. In primary culture SGNs, MSC-sEV significantly promoted neurite growth and growth cone development. The RNA-Seq analysis of SGNs showed that enriched pathways include neuron development and axon regeneration, consistent with proteomics. In ouabain induced SGN degeneration rat model, MSC-sEV administration via intratympanic injection significantly enhanced SGN survival and mitigated hearing loss. Furthermore, after ouabain treatment, SGNs displayed evident signs of apoptosis, including nuclei condensation and fragmentation, with numerous cells exhibiting TUNEL-positive. However, administration of MSC-sEV effectively decreased the number of TUNEL-positive cells and reduced caspase-3 activation. In conclusion, our findings demonstrate the potential of MSC-sEV in preventing SGN degeneration and promoting neural growth, suggesting intratympanic injection of MSC-sEV is a specific and efficient strategy for neural hearing loss.

Genomic and phenotypic landscapes of X-linked hereditary hearing loss in the Chinese population

BACKGROUND

Hearing loss (HL) is the most common sensory birth deficit worldwide, with causative variants in more than 150 genes. However, the etiological contribution and clinical manifestations of X-linked inheritance in HL remain unclear within the Chinese HL population. In this study, we focused on X-linked hereditary HL and aimed to assess its contribution to hereditary HL and identify the genotype-phenotype relationship.

METHODS

We performed a molecular epidemiological investigation of X-linked hereditary HL based on next-generation sequencing and third-generation sequencing in 3646 unrelated patients with HL. We also discussed the clinical features associated with X-linked non-syndromic HL-related genes based on a review of the literature.

RESULTS

We obtained a diagnostic rate of 52.72% (1922/3646) among our patients; the aggregate contribution of HL caused by genes on the X chromosome in this cohort was ~ 1.14% (22/1922), and POU3F4 variants caused ~ 59% (13/22) of these cases. We found that X-linked HL was congenital or began during childhood in all cases, with representative audiological profiles or typical cochlear malformations in certain genes. Genotypic and phenotypic analyses showed that causative variants in PRPS1 and AIFM1 were mainly of the missense type, suggesting that phenotypic variability was correlated with the different effects that the replaced residues exert on structure and function. Variations in SMPX causing truncation of the protein product were associated with DFNX4, which resulted in typical audiological profiles before and after the age of 10 years, whereas nontruncated proteins typically led to distal myopathy. No phenotypic differences were identified in patients carrying POU3F4 or COL4A6 variants.

CONCLUSIONS

Our work constitutes a preliminary evaluation of the molecular contribution of X-linked genes in heritable HL (~ 1.14%). The 15 novel variants reported here expand the mutational spectrum of these genes. Analysis of the genotype-phenotype relationship is valuable for X-linked HL precise diagnostics and genetic counseling. Elucidation of the pathogenic mechanisms and audiological profiles of HL can also guide choices regarding treatment modalities.

Splice-altering variant of PJVK gene in a Mauritanian family with non-syndromic hearing impairment

PJVK gene was recently shown to create hypervulnerability to sound in humans and was the first human gene implicated in non-syndromic hearing impairment due to neural defect. Targeted next-generation sequencing of over 150 known deafness genes was performed in the proband. Sanger sequencing was used to validate the PJVK variant and confirm familial segregation of the disease. A minigene-based assay has been performed to assess the impact of the variant on splicing. We identified a novel c.550-6A > G acceptor splice-site variant in the PJVK gene in the homozygous state in a Mauritanian child with severe to profound congenital deafness. The substitution was located in intron 4. The effect of the variation was demonstrated by a minigene assay which showed that the variation, an insertion of an additional 5 bp, created a new splice site resulting in the appearance of a premature stop codon (p.Phe184Tyrfs*26) and likely a truncated protein. This result constitutes a new splice-site variant report in the PJVK gene leading to DFNB59 type associated with autosomal recessive non-syndromic hearing impairment (ARNSHI).

Prevalence and Profiles of Late-Onset Hearing Loss in Preschool Children with Autism Spectrum Disorder Who Passed Newborn Hearing Screening in a South East Asian Population

Prevalence of hearing loss in children with autism spectrum disorder (ASD) is uncertain, as it is more challenging to assess hearing function in children with developmental difficulties (DD). We aimed to determine the prevalence and profiles of hearing loss in preschool children with ASD in a Southeast-Asian population who passed newborn hearing screening. A retrospective study of preschool children with DD (ASD, Global Developmental Delay (GDD), and Speech and Language Delay (SLD)) attending the Child Development Unit (CDU) at our hospital was performed. Three hundred and thirty-three children (ASD: n = 129; GDD: n = 110; and SLD: n = 94) underwent hearing assessments. Of these, 10.8% of children (n = 36, comprising 15 with ASD, 12 with GDD and 9 with SLD) had confirmed hearing loss. Hearing loss was predominantly bilateral in children with ASD and GDD; in those with SLD, unilateral and bilateral hearing loss were equally common. Conductive hearing loss occurred as frequently as sensorineural hearing loss in children with ASD and SLD, but was the dominant subtype in those with GDD. Moderate to severe hearing loss (n = 2) was noted only in children with ASD. Children with ASD and GDD required significantly more audiology visits and procedures to obtain conclusive hearing test results, compared to those with SLD. The need to identify hearing loss and monitor for resolution is particularly important in vulnerable populations with communication deficits, such as in those with ASD.

Coalition for Global Hearing Health Hearing Care Pathways Working Group: Guidelines for Clinical Guidance for Readiness and Development of Evidence-Based Early Hearing Detection and Intervention Programs

Editor's Note: The following article discusses the timely topic Clinical Guidance in the areas of Evidence-Based Early Hearing Detection and Intervention Programs. This article aims to discuss areas of services needed, guidance to countries/organizations attempting to initiate early hearing detection and intervention systems. Expert consensus and systematic/scoping reviews were combined to produce recommendations for evidence-based clinical practice. In Ear and Hearing, our long-term goal for the Point of View article is to stimulate the field's interest in and to enhance the appreciation of the author's area of expertise. Hearing is an important sense for children to develop cognitive, speech, language, and psychosocial skills. The goal of universal newborn hearing screening is to enable the detection of hearing loss in infants so that timely health and educational/therapeutic intervention can be provided as early as possible to improve outcomes. While many countries have implemented universal newborn hearing screening programs, many others are yet to start. As hearing screening is only the first step to identify children with hearing loss, many follow-up services are needed to help them thrive. However, not all of these services are universally available, even in high-income countries. The purposes of this article are (1) to discuss the areas of services needed in an integrated care system to support children with hearing loss and their families; (2) to provide guidance to countries/organizations attempting to initiate early hearing detection and intervention systems with the goal of meeting measurable benchmarks to assure quality; and (3) to help established programs expand and improve their services to support children with hearing loss to develop their full potential. Multiple databases were interrogated including PubMed, Medline (OVIDSP), Cochrane library, Google Scholar, Web of Science and One Search, ERIC, PsychInfo. Expert consensus and systematic/scoping reviews were combined to produce recommendations for evidence-based clinical practice. Eight essential areas were identified to be central to the integrated care: (1) hearing screening, (2) audiologic diagnosis and management, (3) amplification, (4) medical evaluation and management, (5) early intervention services, (6) family-to-family support, (7) D/deaf/hard of hearing leadership, and (8) data management. Checklists are provided to support the assessment of a country/organization's readiness and development in each area as well as to suggest alternative strategies for situations with limited resources. A three-tiered system (i.e., Basic, Intermediate, and Advanced) is proposed to help countries/organizations at all resource levels assess their readiness to provide the needed services and to improve their integrated care system. Future directions and policy implications are also discussed.

Concordance of Cytomegalovirus Saliva and Urine Testing in Infants for the Detection of Congenital Infection

Congenital cytomegalovirus is a leading cause of neurodevelopmental impairment and sensorineural hearing loss. We evaluated infants ≤21 days postnatal age who had both urine and saliva cytomegalovirus testing and determined concordance between the 2 tests and influence of very low birth weight on concordance. Discordance was low overall between urine and saliva testing; however, discordance was high in very low birth weight infants.

Tissue engineering strategies for spiral ganglion neuron protection and regeneration

Cochlear implants can directly activate the auditory system's primary sensory neurons, the spiral ganglion neurons (SGNs), via circumvention of defective cochlear hair cells. This bypass restores auditory input to the brainstem. SGN loss etiologies are complex, with limited mammalian regeneration. Protecting and revitalizing SGN is critical. Tissue engineering offers a novel therapeutic strategy, utilizing seed cells, biomolecules, and scaffold materials to create a cellular environment and regulate molecular cues. This review encapsulates the spectrum of both human and animal research, collating the factors contributing to SGN loss, the latest advancements in the utilization of exogenous stem cells for auditory nerve repair and preservation, the taxonomy and mechanism of action of standard biomolecules, and the architectural components of scaffold materials tailored for the inner ear. Furthermore, we delineate the potential and benefits of the biohybrid neural interface, an incipient technology in the realm of implantable devices. Nonetheless, tissue engineering requires refined cell selection and differentiation protocols for consistent SGN quality. In addition, strategies to improve stem cell survival, scaffold biocompatibility, and molecular cue timing are essential for biohybrid neural interface integration.

High prevalence of m.1555A > G in patients with hearing loss in the Baikal Lake region of Russia as a result of founder effect

Mitochondrial forms account approximately 1-2% of all nonsyndromic cases of hearing loss (HL). One of the most common causative variants of mtDNA is the m.1555A > G variant of the MT-RNR1 gene (OMIM 561000). Currently the detection of the m.1555A > G variant of the MT-RNR1 gene is not included in all research protocols. In this study this variant was screened among 165 patients with HL from the Republic of Buryatia, located in the Baikal Lake region of Russia. In our study, the total contribution of the m.1555A > G variant to the etiology of HL was 12.7% (21/165), while the update global prevalence of this variant is 1.8% (863/47,328). The m.1555A > G variant was notably more prevalent in Buryat (20.2%) than in Russian patients (1.3%). Mitogenome analysis in 14 unrelated Buryat families carrying the m.1555A > G variant revealed a predominant lineage: in 13 families, a cluster affiliated with sub-haplogroup A5b (92.9%) was identified, while one family had the D5a2a1 lineage (7.1%). In a Russian family with the m.1555A > G variant the lineage affiliated with sub-haplogroup F1a1d was found. Considering that more than 90% of Buryat families with the m.1555A > G variant belong to the single maternal lineage cluster we conclude that high prevalence of this variant in patients with HL in the Baikal Lake region can be attributed to a founder effect.

Genetic analysis of 106 sporadic cases with hearing loss in the UAE population

BACKGROUND

Hereditary hearing loss is a rare hereditary condition that has a significant presence in consanguineous populations. Despite its prevalence, hearing loss is marked by substantial genetic diversity, which poses challenges for diagnosis and screening, particularly in cases with no clear family history or when the impact of the genetic variant requires functional analysis, such as in the case of missense mutations and UTR variants. The advent of next-generation sequencing (NGS) has transformed the identification of genes and variants linked to various conditions, including hearing loss. However, there remains a high proportion of undiagnosed patients, attributable to various factors, including limitations in sequencing coverage and gaps in our knowledge of the entire genome, among other factors. In this study, our objective was to comprehensively identify the spectrum of genes and variants associated with hearing loss in a cohort of 106 affected individuals from the UAE.

RESULTS

In this study, we investigated 106 sporadic cases of hearing impairment and performed genetic analyses to identify causative mutations. Screening of the GJB2 gene in these cases revealed its involvement in 24 affected individuals, with specific mutations identified. For individuals without GJB2 mutations, whole exome sequencing (WES) was conducted. WES revealed 33 genetic variants, including 6 homozygous and 27 heterozygous DNA changes, two of which were previously implicated in hearing loss, while 25 variants were novel. We also observed multiple potential pathogenic heterozygous variants across different genes in some cases. Notably, a significant proportion of cases remained without potential pathogenic variants.

CONCLUSIONS

Our findings confirm the complex genetic landscape of hearing loss and the limitations of WES in achieving a 100% diagnostic rate, especially in conditions characterized by genetic heterogeneity. These results contribute to our understanding of the genetic basis of hearing loss and emphasize the need for further research and comprehensive genetic analyses to elucidate the underlying causes of this condition.

A novel cell-free therapy using exosomes in the inner ear regeneration

Cellular and molecular alterations associated with hearing loss are now better understood with advances in molecular biology. These changes indicate the participation of distinct damage and stress pathways that are unlikely to be fully addressed by conventional pharmaceutical treatment. Sensorineural hearing loss is a common and debilitating condition for which comprehensive pharmacologic intervention is not available. The complex and diverse molecular pathology that underlies hearing loss currently limits our ability to intervene with small molecules. The present review focuses on the potential for the use of extracellular vesicles in otology. It examines a variety of inner ear diseases and hearing loss that may be treatable using exosomes (EXOs). The role of EXOs as carriers for the treatment of diseases related to the inner ear as well as EXOs as biomarkers for the recognition of diseases related to the ear is discussed.

Identification of novel MYH14 variants in families with autosomal dominant sensorineural hearing loss

Autosomal dominant sensorineural hearing loss (ADSNHL) is a genetically heterogeneous disorder caused by pathogenic variants in various genes, including MYH14. However, the interpretation of pathogenicity for MYH14 variants remains a challenge due to incomplete penetrance and the lack of functional studies and large families. In this study, we performed exome sequencing in six unrelated families with ADSNHL and identified five MYH14 variants, including three novel variants. Two of the novel variants, c.571G > C (p.Asp191His) and c.571G > A (p.Asp191Asn), were classified as likely pathogenic using ACMG and Hearing Loss Expert panel guidelines. In silico modeling demonstrated that these variants, along with p.Gly1794Arg, can alter protein stability and interactions among neighboring molecules. Our findings suggest that MYH14 causative variants may be more contributory and emphasize the importance of considering this gene in patients with nonsyndromic mainly post-lingual severe form of hearing loss. However, further functional studies are needed to confirm the pathogenicity of these variants.

Contiguous Gene Syndromes and Hearing Loss: A Clinical Report of Xq21 Deletion and Comprehensive Literature Review

Given the crucial role of the personalized management and treatment of hearing loss (HL), etiological investigations are performed early on, and genetic analysis significantly contributes to the determination of most syndromic and nonsyndromic HL cases. Knowing hundreds of syndromic associations with HL, little comprehensive data about HL in genomic disorders due to microdeletion or microduplications of contiguous genes is available. Together with the description of a new patient with a novel 3.7 Mb deletion of the Xq21 critical locus, we propose an unreported literature review about clinical findings in patients and their family members with Xq21 deletion syndrome. We finally propose a comprehensive review of HL in contiguous gene syndromes in order to confirm the role of cytogenomic microarray analysis to investigate the etiology of unexplained HL.

The Segregation of p.Arg68Ter-CLDN14 Mutation in a Syrian Deaf Family, Phenotypic Variations, and Comparative Analysis with the GJB2 Gene

Hearing impairment, a rare inherited condition, is notably prevalent in populations with high rates of consanguinity. The most common form observed globally is autosomal recessive non-syndromic hearing loss. Despite its prevalence, this genetic disorder is characterized by a substantial genetic diversity, making diagnosis and screening challenging. The emergence of advanced next-generation sequencing (NGS) technologies has significantly advanced the discovery of genes and variants linked to various conditions, such as hearing loss. In this study, our objective was to identify the specific variant causing hearing loss in a family from Syria using clinical exome sequencing. The proband in the family exhibited profound deafness as shown by pure-tone audiometry results. The analysis of the different variants obtained by NGS revealed the presence of a nonsense mutation within the CLDN14 gene. Through Sanger sequencing, we verified that this variant segregates with the disease and was not present in the control population. Moreover, we conducted a comprehensive review of all reported deafness-related CLDN14 mutations and their associated phenotypes. Furthermore, we endeavored to carry out a comparative analysis between the CLDN14 and GJB2 genes, with the objective of identifying potential factors that could explain the notable discrepancy in mutation frequency between these two genes.

The Association between Prenatal Nicotine Exposure and Offspring's Hearing Impairment

OBJECTIVES

The objective of this study is to evaluate whether there is an association between in-utero exposure to nicotine and subsequent hearing dysfunction.

MATERIALS AND METHODS

Secondary analysis of a multicenter randomized trial to prevent congenital cytomegalovirus (CMV) infection among gravidas with primary CMV infection was conducted. Monthly intravenous immunoglobulin hyperimmune globulin therapy did not influence the rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in one or more ears defined as abnormal distortion product otoacoustic emissions (DPOAEs; 1 to 8 kHz) that were measured within 42 days of birth. DPOAEs were interpreted using optimized frequency-specific level criteria. Cotinine was measured via enzyme-linked immunosorbent assay kits in maternal urine collected at enrollment and in the third trimester (mean gestational age 16.0 and 36.7 weeks, respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/mL at either time point was defined as in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome and with the exposure (p < 0.05) in univariate analysis.

RESULTS

Of 399 enrolled patients in the original trial, 150 were included in this analysis, of whom 46 (31%) were exposed to nicotine. The primary outcome occurred in 18 (12%) newborns and was higher in nicotine-exposed infants compared with those nonexposed (15.2 vs. 10.6%, odds ratio [OR] 1.52, 95% confidence interval [CI] 0.55-4.20), but the difference was not significantly different (adjusted odds ratio [aOR] = 1.0, 95% CI 0.30-3.31). This association was similar when exposure was stratified as heavy (>100 ng/mL, aOR 0.72, 95% CI 0.15-3.51) or mild (5-100 ng/mL, aOR 1.28, 95% CI 0.33-4.95). There was no association between nicotine exposure and frequency-specific DPOAE amplitude.

CONCLUSION

In a cohort of parturients with primary CMV infection, nicotine exposure was not associated with offspring hearing dysfunction assessed with DPOAEs.

KEY POINTS

· Nicotine exposure was quantified from maternal urine.. · Nicotine exposure was identified in 30% of the cohort.. · Exposure was not associated with offspring hearing dysfunction..

Comprehensive Genetic Evaluation in Patients with Special Reference to Late-Onset Sensorineural Hearing Loss

Hearing loss (HL) is a common and multi-complex etiological deficit that can occur at any age and can be caused by genetic variants, aging, toxic drugs, noise, injury, viral infection, and other factors. Recently, a high incidence of genetic etiologies in congenital HL has been reported, and the usefulness of genetic testing has been widely accepted in congenital-onset or early-onset HL. In contrast, there have been few comprehensive reports on the relationship between late-onset HL and genetic causes. In this study, we performed next-generation sequencing analysis for 91 HL patients mainly consisting of late-onset HL patients. As a result, we identified 23 possibly disease-causing variants from 29 probands, affording a diagnostic rate for this study of 31.9%. The highest diagnostic rate was observed in the congenital/early-onset group (42.9%), followed by the juvenile/young adult-onset group (31.7%), and the middle-aged/aged-onset group (21.4%). The diagnostic ratio decreased with age; however, genetic etiologies were involved to a considerable degree even in late-onset HL. In particular, the responsible gene variants were found in 19 (55.9%) of 34 patients with a familial history and progressive HL. Therefore, this phenotype is considered to be a good candidate for genetic evaluation based on this diagnostic panel.

Characterization of Vestibular Phenotypes in Patients with Genetic Hearing Loss

Background: The vestibular phenotypes of patients with genetic hearing loss are poorly understood. Methods: we performed genetic testing including exome sequencing and vestibular function tests to investigate vestibular phenotypes and functions in patients with genetic hearing loss. Results: Among 627 patients, 143 (22.8%) had vestibular symptoms. Genetic variations were confirmed in 45 (31.5%) of the 143 patients. Nineteen deafness genes were linked with vestibular symptoms; the most frequent genes in autosomal dominant and recessive individuals were COCH and SLC26A4, respectively. Vestibular symptoms were mostly of the vertigo type, recurrent, and persisted for hours in the genetically confirmed and unconfirmed groups. Decreased vestibular function in the caloric test, video head impulse test, cervical vestibular-evoked myogenic potential, and ocular vestibular-evoked myogenic potential was observed in 42.0%, 16.3%, 57.8%, and 85.0% of the patients, respectively. The caloric test revealed a significantly higher incidence of abnormal results in autosomal recessive individuals than in autosomal dominant individuals (p = 0.011). The genes, including SLC26A4, COCH, KCNQ4, MYH9, NLRP3, EYA4, MYO7A, MYO15A, and MYH9, were heterogeneously associated with abnormalities in the vestibular function test. Conclusions: In conclusion, diverse vestibular symptoms are commonly concomitant with genetic hearing loss and are easily overlooked.

Microstructural Changes in the Brainstem Auditory Pathway in Children With Hearing Loss

OBJECTIVE

To assess the utility of diffusion tensor imaging of the auditory pathway in children with sensorineural hearing loss (SNHL).

STUDY DESIGN

Retrospective cohort study.

SETTING

A single academic tertiary children's hospital.

PATIENTS

Sixteen pediatric patients with bilateral SNHL of at least moderate severity in the poorer ear (eight male; mean age, 5.3 ± 4.9 yrs). Controls consisted of age- and sex-matched children with normal hearing who were imaged for nonotologic, non-neurologic medical concerns and found to have normal magnetic resonance imaging (MRI).

INTERVENTIONS

Three Tesla MRI scanners were used for diffusion tensor imaging.

MAIN OUTCOME MEASURES

Quantitative diffusion tensor metrics were extracted from the superior olivary nucleus (SON), inferior colliculus (IC), and ipsilateral fiber tracts between the SON and IC delineated by tractography.

RESULTS

We identified differences in fractional anisotropy of the SON between the SNHL cohort and controls (0.377 ± 0.056 vs. 0.422 ± 0.052; p = 0.009), but not in the IC. There were no differences in the mean diffusivity (MD) values in the IC and SON. Among younger children (≤5 yrs), MD was decreased in the SNHL cohort compared with controls in the IC (0.918 ± 0.051 vs. 1.120 ± 0.142; p < 0.001). However, among older children (>5 yrs), there were no differences in MD (1.124 ± 0.198 vs. 0.997 ± 0.103; p = 0.119). There were no differences in MD or fractional anisotropy in the white matter fibers of the IC-SON tract.

CONCLUSIONS

Our results suggest abnormal neural tracts along the central auditory pathway among children with SNHL. Longitudinal studies should assess the prognostic value of these MRI-based findings for assessing long-term outcomes and determining intervention efficacy.

Genetic diagnosis of childhood sensorineural hearing loss

INTRODUCTION

Congenital/early-onset sensorineural hearing loss (SNHL) is one of the most common hereditary disorders in our environment. There is increasing awareness of the importance of an etiologic diagnosis, and genetic testing with next-generation sequencing (NGS) has the highest diagnostic yield. Our study shows the genetic results obtained in a cohort of patients with bilateral congenital/early-onset SNHL.

MATERIALS AND METHODS

We included 105 children with bilateral SNHL that received genetic testing between 2019 and 2022. Genetic tests were performed with whole exome sequencing, analyzing genes related to hearing loss (virtual panel with 244 genes).

RESULTS

48% (50/105) of patients were genetically diagnosed. We identified pathogenic and likely pathogenic variants in 26 different genes, and the most frequently mutated genes were GJB2, USH2A and STRC. 52% (26/50) of variants identified produced non-syndromic hearing loss, 40% (20/50) produced syndromic hearing loss, and the resting 8% (4/50) could produce both non-syndromic and syndromic hearing loss.

CONCLUSIONS

Genetic testing plays a vital role in the etiologic diagnosis of bilateral SNHL. Our cohort shows that genetic testing with NGS has a high diagnostic yield and can provide useful information for the clinical workup of patients.

PKHD1L1, a gene involved in the stereocilia coat, causes autosomal recessive nonsyndromic hearing loss

Identification of genes associated with nonsyndromic hearing loss is a crucial endeavor given the substantial number of individuals who remain without a diagnosis after even the most advanced genetic testing. PKHD1L1 was established as necessary for the formation of the cochlear hair-cell stereociliary coat and causes hearing loss in mice and zebrafish when mutated. We sought to determine if biallelic variants in PKHD1L1 also cause hearing loss in humans. Exome sequencing was performed on DNA of four families segregating autosomal recessive nonsyndromic sensorineural hearing loss. Compound heterozygous p.[(Gly129Ser)];p.[(Gly1314Val)] and p.[(Gly605Arg)];p[(Leu2818TyrfsTer5)], homozygous missense p.(His2479Gln) and nonsense p.(Arg3381Ter) variants were identified in PKHD1L1 that were predicted to be damaging using in silico pathogenicity prediction methods. In vitro functional analysis of two missense variants was performed using purified recombinant PKHD1L1 protein fragments. We then evaluated protein thermodynamic stability with and without the missense variants found in one of the families and performed a minigene splicing assay for another variant. In silico molecular modeling using AlphaFold2 and protein sequence alignment analysis were carried out to further explore potential variant effects on structure. In vitro functional assessment indicated that both engineered PKHD1L1 p.(Gly129Ser) and p.(Gly1314Val) mutant constructs significantly reduced the folding and structural stabilities of the expressed protein fragments, providing further evidence to support pathogenicity of these variants. Minigene assay of the c.1813G>A p.(Gly605Arg) variant, located at the boundary of exon 17, revealed exon skipping leading to an in-frame deletion of 48 amino acids. In silico molecular modeling exposed key structural features that might suggest PKHD1L1 protein destabilization. Multiple lines of evidence collectively associate PKHD1L1 with nonsyndromic mild-moderate to severe sensorineural hearing loss. PKHD1L1 testing in individuals with mild-moderate hearing loss may identify further affected families.

Hidden hearing loss: Fifteen years at a glance

Hearing loss affects approximately 18% of the population worldwide. Hearing difficulties in noisy environments without accompanying audiometric threshold shifts likely affect an even larger percentage of the global population. One of the potential causes of hidden hearing loss is cochlear synaptopathy, the loss of synapses between inner hair cells (IHC) and auditory nerve fibers (ANF). These synapses are the most vulnerable structures in the cochlea to noise exposure or aging. The loss of synapses causes auditory deafferentation, i.e., the loss of auditory afferent information, whose downstream effect is the loss of information that is sent to higher-order auditory processing stages. Understanding the physiological and perceptual effects of this early auditory deafferentation might inform interventions to prevent later, more severe hearing loss. In the past decade, a large body of work has been devoted to better understand hidden hearing loss, including the causes of hidden hearing loss, their corresponding impact on the auditory pathway, and the use of auditory physiological measures for clinical diagnosis of auditory deafferentation. This review synthesizes the findings from studies in humans and animals to answer some of the key questions in the field, and it points to gaps in knowledge that warrant more investigation. Specifically, recent studies suggest that some electrophysiological measures have the potential to function as indicators of hidden hearing loss in humans, but more research is needed for these measures to be included as part of a clinical test battery.

The Importance of Mitochondrial Disease Testing in Young Adults With New Onset Sensorineural Hearing Loss

OBJECTIVES

Sensorineural hearing loss (SNHL) occurs commonly as part of mitochondriopathies and varies in severity and onset. In this study, we characterized hearing with specific consideration for hearing loss as a potential early indicator of mitochondrial disease (MD). We hypothesize that genetic testing at the earliest detection of SNHL may lead to an earlier MD diagnosis.

DESIGN

We reviewed the clinical and audiometric data of 49 patients undergoing genetic testing for MD.

RESULTS

One-third of individuals with molecularly confirmed MD presented with SNHL. On average, patients had hearing loss at least 10 years before genetic testing. The collective audiometric profile includes mild to moderate SNHL at lower frequencies and moderate SNHL at 2 kHz and higher frequencies.

CONCLUSIONS

This study suggests that screening for SNHL could be an early indicator of MD. We propose that the audiometric profile for those with a MD diagnosis may have clinical triage utility.

Effects of the BalanCI on Working Memory and Balance in Children and Young Adults With Cochleovestibular Dysfunction

OBJECTIVES

This study aimed to: (1) determine the interaction between cognitive load and balance in children and young adults with bilateral cochleovestibular dysfunction who use bilateral cochlear implants (CIs) and (2) determine the effect of an auditory balance prosthesis (the BalanCI) on this interaction. Many (20 to 70%) children with sensorineural hearing loss experience some degree of vestibular loss, leading to poorer balance. Poor balance could have effects on cognitive resource allocation which might be alleviated by the BalanCI as it translates head-referenced cues into electrical pulses delivered through the CI. It is hypothesized that children and young adults with cochleovestibular dysfunction will demonstrate greater dual-task costs than typically-developing children during dual balance-cognition tasks, and that BalanCI use will improve performance on these tasks.

DESIGN

Study participants were 15 typically-developing children (control group: mean age ± SD = 13.6 ± 2.75 years, 6 females) and 10 children and young adults who use bilateral CIs and have vestibular dysfunction (CI-V group: mean age ± SD=20.6 ± 5.36 years, 7 females). Participants completed two working memory tasks (backward auditory verbal digit span task and backward visuospatial dot matrix task) during three balance conditions: seated, standing in tandem stance with the BalanCI off, and standing in tandem stance with the BalanCI on. Working memory performance was quantified as total number of correct trials achieved. Postural stability was quantified as translational and rotational path length of motion capture markers worn on the head, upper body, pelvis, and feet, normalized by trial time.

RESULTS

Relative to the control group, children and young adults in the CI-V group exhibited poorer overall working memory across all balance conditions ( p = 0.03), poorer translational postural stability (larger translational path length) during both verbal and visuospatial working memory tasks ( p < 0.001), and poorer rotational stability (larger rotational path length) during the verbal working memory task ( p = 0.026). The CI-V group also exhibited poorer translational ( p = 0.004) and rotational ( p < 0.001) postural stability during the backward verbal digit span task than backward visuospatial dot matrix task; BalanCI use reduced this stability difference between verbal and visuospatial working memory tasks for translational stability overall ( p > 0.9), as well as for rotational stability during the maximum working memory span (highest load) participants achieved in each task ( p = 0.91).

CONCLUSIONS

Balance and working memory were impaired in the CI-V group compared with the control group. The BalanCI offered subtle improvements in stability in the CI-V group during a backward verbal working memory task, without producing a negative effect on working memory outcomes. This study supports the feasibility of the BalanCI as a balance prosthesis for individuals with cochleovestibular impairments.

Adult Neurogenesis of the Medial Geniculate Body: In Vitro and Molecular Genetic Analyses Reflect the Neural Stem Cell Capacity of the Rat Auditory Thalamus over Time

Neural stem cells (NSCs) have been recently identified in the neonatal rat medial geniculate body (MGB). NSCs are characterized by three cardinal features: mitotic self-renewal, formation of progenitors, and differentiation into all neuroectodermal cell lineages. NSCs and the molecular factors affecting them are particularly interesting, as they present a potential target for treating neurologically based hearing disorders. It is unclear whether an NSC niche exists in the rat MGB up to the adult stage and which neurogenic factors are essential during maturation. The rat MGB was examined on postnatal days 8, 12, and 16, and at the adult stadium. The cardinal features of NSCs were detected in MGB cells of all age groups examined by neurosphere, passage, and differentiation assays. In addition, real-time quantitative polymerase chain reaction arrays were used to compare the mRNA levels of 84 genes relevant to NSCs and neurogenesis. In summary, cells of the MGB display the cardinal features of NSCs up to the adult stage with a decreasing NSC potential over time. Neurogenic factors with high importance for MGB neurogenesis were identified on the mRNA level. These findings should contribute to a better understanding of MGB neurogenesis and its regenerative capacity.

Spectrum of genetic variants in bilateral sensorineural hearing loss

Background: Hearing loss (HL) is an impairment of auditory function with identified genetic forms that can be syndromic (30%) or non-syndromic (70%). HL is genetically heterogeneous, with more than 1,000 variants across 150 causative genes identified to date. The genetic diagnostic rate varies significantly depending on the population being tested. Countries with a considerably high rate of consanguinity provide a unique resource for studying rare forms of recessive HL. In this study, we identified genetic variants associated with bilateral sensorineural HL (SNHL) using whole-exome sequencing (WES) in 11 families residing in the United Arab Emirates (UAE). Results: We established the molecular diagnosis in six probands, with six different pathogenic or likely pathogenic variants in the genes MYO15A, SLC26A4, and GJB2. One novel nonsense variant, MYO15A:p.Tyr1962Ter*, was identified in a homozygous state in one family, which has not been reported in any public database. SLC26A4 and GJB2 were found to be the most frequently associated genes in this study. In addition, six variants of uncertain significance (VUS) were detected in five probands in the genes CDH23, COL11A1, ADGRV1, NLRP3, and GDF6. In total, 12 variants were observed in eight genes. Among these variants, eight missense variants (66.7%), three nonsense variants (25.0%), and one frameshift (8.3%) were identified. The overall diagnostic rate of this study was 54.5%. Approximately 45.5% of the patients in this study came from consanguineous families. Conclusion: Understanding the genetic basis of HL provides insight for the clinical diagnosis of hearing impairment cases through the utilization of next-generation sequencing (NGS). Our findings contribute to the knowledge of the heterogeneous genetic profile of HL, especially in a population with a high rate of consanguineous marriage in the Arab population.

Audiological Phenotypes of Connexin Gene Mutation Patterns: A Glance at Different GJB2/GJB6 Gene Mutation Profiles

GJB2 mutations are the most common cause of autosomal-recessive non-syndromic sensorineural hearing loss (SNHL). The available evidence shows large phenotypic variability across different genotypes and allelic variants. The aim of this study was to investigate the clinical and audiological features of a cohort of subjects with different GJB2/GJB6 gene mutation profiles from a tertiary referral center in Northeastern Italy. We considered 57 patients with GJB2/GJB6 mutations presenting with congenital, non-syndromic SNHL, mainly coming from the Veneto region (Italy). The samples were screened for mutations in exons 1 and 2 of the GJB2 gene and for the GJB6 gene deletion del (GJB6-D13S1830). Free-field and air-conduction frequency-specific thresholds and the pure-tone average (PTA) were considered in the statistical analysis. Five patients (8.87%) had connexin gene mutations in simple heterozygosis, 15 (26.31%) in compound heterozygosis, 34 (59.64%) in homozygosis, and 3 (5.26%) with digenic patterns. The frequency-specific air-conduction thresholds showed significantly different mean values across the different genotypes (Roy's largest-root test, p = 0.0473). Despite the evidence already available on genetic SNHL, many new insights are to be expected. Further large-scale prospective studies including different populations are necessary to confirm these preliminary findings about the clinical and audiological features of patients with different GJB2/GJB6 gene mutation patterns.

Hearing Loss: Genetic Testing, Current Advances and the Situation in Latin America

Congenital hearing loss is the most common birth defect, estimated to affect 2-3 in every 1000 births, with ~50-60% of those related to genetic causes. Technological advances enabled the identification of hundreds of genes related to hearing loss (HL), with important implications for patients, their families, and the community. Despite these advances, in Latin America, the population with hearing loss remains underdiagnosed, with most studies focusing on a single locus encompassing the GJB2/GJB6 genes. Here we discuss how current and emerging genetic knowledge has the potential to alter the approach to diagnosis and management of hearing loss, which is the current situation in Latin America, and the barriers that still need to be overcome.

Congenital toxoplasmosis and audiological outcome: from a case series to a suggestion of patient-based schedule

Introduction

Sensorineural hearing loss (SNHL) has been suggested to be possibly related to congenital toxoplasmosis (CT), although its prevalence varies from 0% to 26%. This variance appears to be dependent especially on early timing of treatment. However, the available data are based on outdated studies conducted on small groups of patients that lack homogeneity. Therefore, to establish evidence-based guidelines for audiologic monitoring in CT, we conducted a comprehensive evaluation of a large case series over a long period of time.

Patients and methods

This is a single-center, retrospective cohort that enrolled all infants and children who were exposed in utero to Toxoplasma gondii and/or congenitally infected between September 1980 and December 2022. They underwent standard serial audiological evaluations to detect possible SNHL at an early stage. The first evaluation was performed during the initial assessment to define the onset of congenital toxoplasmosis, with another evaluation conducted at least at 12 months of life.

Results

We collected data from 1,712 patients, and 183 (10.7%) were diagnosed with CT. Among these cases, 78 children (42.6%) presented with symptomatic CT at the onset, exhibiting ocular findings (21.1%), clinical cerebral manifestations (6.1%), and/or abnormal findings on neuroimaging (35.5%). Therapy was administrated at the onset in 164 patients (89.6%) with 115 of them starting treatment prior to 2.5 months of age (0-388, median 32.00 ± 92.352 days of life). Only one patient presented with SNHL at the onset, but this was apparently unrelated to CT. The median number of audiological assessments was 2.2 ± 1.543 (2-10). No patients developed any grade of delayed hearing loss, both in treated and untreated groups. The median age at last audiological evaluation was 2.3 ± 2.18 years (1-8), although the median follow-up period was 12.4 years (±6.3), ranging from 1 to 27 years.

Conclusions

Based on these data, it appears that SNHL may be less frequent in CT than previously assumed. We recommend conducting an audiological assessment at the onset (within the first 2.5 months of life) to comprehensively define the type of CT onset, and then conducting another evaluation within 9 months of life.

Characteristics of vestibular-evoked myogenic potentials in children with vestibular malformation and severe sensorineural hearing loss

BACKGROUND

With the increasing clinical focus on the safety of bilateral cochlear implantation (CI) and the potential risk of bilateral vestibular dysfunction, evaluating vestibular end-organ function in patients with vestibular malformations with accompanying abnormalities has been strongly recommended.

OBJECTIVES

To identify the vestibular-evoked myogenic potential (VEMP) values among children with sensorineural hearing loss (SNHL) with vestibular malformation and assess the effectiveness of VEMP testing for inner ear malformations (IEM) diagnosis.

METHODS

This study included 96 children (192 ears), including those with vestibular malformations (48 ears), large vestibular aqueduct syndrome (LVAS) (50 ears), and SNHL without IEM (94 ears; control group). All groups underwent ocular and cervical VEMP (oVEMP and cVEMP, respectively) testing. The response rates, VEMP parameters, and wave characteristics were compared.

RESULTS

The cVEMP response rates were 37.5 %, 64 %, and 58.51 % and the oVEMP response rates were 42.86 %, 78.95 %, and 77.27 % in the vestibular malformation, LVAS, and control groups, respectively, and significantly differed between groups (cVEMP: X2 = 18.228, P<0.001) (oVEMP: X2 = 7.528, P = 0.023). Significant inter-group differences were observed for the cVEMP and oVEMP latency and amplitude (P < 0.05). The LVAS group's waveform exhibited a prolonged latency and increased amplitude compared with that of the other groups.

CONCLUSION

Patients with SNHL were highly susceptible to otolith dysfunction, regardless of comorbid vestibular malformation presence. Measuring VEMPs is an effective and rapid evaluation technique for vestibular function and could provide a basis for vestibular rehabilitation training.

Laterality and otorhinolaryngology: a review

BACKGROUND

Laterality of paired organs involves the function of the eyes, ears, hands and feet. Whilst most people have a right-handed preference, about 10 per cent are left-handed. Similarly, the right eye is usually preferred to the left. Medicine is both taught and practised for those with right hand and eye preference, and left-handed medical students and doctors must negotiate the right-handed world.

OBJECTIVE

This brief review looks at society's attitudes, medical training and the practice of otolaryngology in the UK towards laterality and handedness.

METHOD

Literature review.

RESULTS

Studies suggest that left-handers are more versatile and so are more ambidextrous. Conversely, this may result in problems when a right-hander tries to undertake a procedure with the non-dominant hand.

CONCLUSION

Cultures and attitudes are changing towards those who are left-handed. Left-handed surgeons may encounter difficulties in the clinical environment throughout their training.

PKHD1L1, A Gene Involved in the Stereocilia Coat, Causes Autosomal Recessive Nonsyndromic Hearing Loss

Identification of genes associated with nonsyndromic hearing loss is a crucial endeavor given the substantial number of individuals who remain without a diagnosis after even the most advanced genetic testing. PKHD1L1 was established as necessary for the formation of the cochlear hair-cell stereociliary coat and causes hearing loss in mice and zebrafish when mutated. We sought to determine if biallelic variants in PKHD1L1 also cause hearing loss in humans. Exome sequencing was performed on DNA of four families segregating autosomal recessive nonsyndromic sensorineural hearing loss. Compound heterozygous p.[(Gly129Ser)];p.[(Gly1314Val)] and p.[(Gly605Arg)];p[(Leu2818TyrfsTer5)], homozygous missense p.(His2479Gln) and nonsense p.(Arg3381Ter) variants were identified in PKHD1L1 that were predicted to be damaging using in silico pathogenicity prediction methods. In vitro functional analysis of two missense variants was performed using purified recombinant PKHD1L1 protein fragments. We then evaluated protein thermodynamic stability with and without the missense variants found in one of the families and performed a minigene splicing assay for another variant. In silico molecular modelling using AlphaFold2 and protein sequence alignment analysis were carried out to further explore potential variant effects on structure. In vitro functional assessment indicated that both engineered PKHD1L1 p.(Gly129Ser) and p.(Gly1314Val) mutant constructs significantly reduced the folding and structural stabilities of the expressed protein fragments, providing further evidence to support pathogenicity of these variants. Minigene assay of the c.1813G>A p.(Gly605Arg) variant, located at the boundary of exon 17, revealed exon skipping leading to an in-frame deletion of 48 amino acids. In silico molecular modelling exposed key structural features that might suggest PKHD1L1 protein destabilization. Multiple lines of evidence collectively associate PKHD1L1 with nonsyndromic mild-moderate to severe sensorineural hearing loss. PKHD1L1 testing in individuals with mild-moderate hearing loss may identify further affected families.

Predicting the Impact of OTOF Gene Missense Variants on Auditory Neuropathy Spectrum Disorder

Auditory neuropathy spectrum disorder (ANSD) associated with mutations of the OTOF gene is one of the common types of sensorineural hearing loss of a hereditary nature. Due to its high genetic heterogeneity, ANSD is considered one of the most difficult hearing disorders to diagnose. The dataset from 270 known annotated single amino acid substitutions (SAV) related to ANSD was created. It was used to estimate the accuracy of pathogenicity prediction using the known (from dbNSFP4.4) method and a new one. The new method (ConStruct) for the creation of the protein-centric classification model is based on the use of Random Forest for the analysis of missense variants in exons of the OTOF gene. A system of predictor variables was developed based on the modern understanding of the structure and function of the otoferlin protein and reflecting the location of changes in the tertiary structure of the protein due to mutations in the OTOF gene. The conservation values of nucleotide substitutions in genomes of 100 vertebrates and 30 primates were also used as variables. The average prediction of balanced accuracy and the AUC value calculated by the 5-fold cross-validation procedure were 0.866 and 0.903, respectively. The model shows good results for interpreting data from the targeted sequencing of the OTOF gene and can be implemented as an auxiliary tool for the diagnosis of ANSD in the early stages of ontogenesis. The created model, together with the results of the pathogenicity prediction of SAVs via other known accurate methods, were used for the evaluation of a manually created set of 1302 VUS related to ANSD. Based on the analysis of predicted results, 16 SAVs were selected as the new most probable pathogenic variants.