Frameshift mutation of Timm8a1 gene in mouse leads to an abnormal mitochondrial structure in the brain, correlating with hearing and memory impairment.

BACKGROUND: Deafness-dystonia-optic neuronopathy (DDON) syndrome is a progressive X-linked recessive disorder characterised by deafness, dystonia, ataxia and reduced visual acuity. The causative gene deafness/dystonia protein 1 (DDP1)/translocase of the inner membrane 8A (TIMM8A) encodes a mitochondrial intermembrane space chaperon. The molecular mechanism of DDON remains unclear, and detailed information on animal models has not been reported yet. METHODS AND RESULTS: We characterized a family with DDON syndrome, in which the affected members carried a novel hemizygous variation in the DDP1 gene (NM_004085.3, c.82C>T, p.Q28X). We then generated a mouse line with the hemizygous mutation (p.I23fs49X) in the Timm8a1 gene using the clustered regularly interspaced short palindromic repeats /Cas9 technology. The deficient DDP1 protein was confirmed by western blot assay. Electron microscopic analysis of brain samples from the mutant mice indicated abnormal mitochondrial structure in several brain areas. However, Timm8a1I23fs49X/y mutation did not affect the import of mitochondria inner member protein Tim23 and outer member protein Tom40 as well as the biogenesis of the proteins in the mitochondrial oxidative phosphorylation system and the manganese superoxide dismutase (MnSOD / SOD-2). The male mice with Timm8a1I23fs49X/y mutant exhibited less weight gain, hearing impairment and cognitive deficit. CONCLUSION: Our study suggests that frameshift mutation of the Timm8a1 gene in mice leads to an abnormal mitochondrial structure in the brain, correlating with hearing and memory impairment. Taken together, we have successfully generated a mouse model bearing loss-of-function mutation in Timm8a1.

Multi-level evidence of an allelic hierarchy of USH2A variants in hearing, auditory processing and speech/language outcomes.

Language development builds upon a complex network of interacting subservient systems. It therefore follows that variations in, and subclinical disruptions of, these systems may have secondary effects on emergent language. In this paper, we consider the relationship between genetic variants, hearing, auditory processing and language development. We employ whole genome sequencing in a discovery family to target association and gene x environment interaction analyses in two large population cohorts; the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK10K. These investigations indicate that USH2A variants are associated with altered low-frequency sound perception which, in turn, increases the risk of developmental language disorder. We further show that Ush2a heterozygote mice have low-level hearing impairments, persistent higher-order acoustic processing deficits and altered vocalizations. These findings provide new insights into the complexity of genetic mechanisms serving language development and disorders and the relationships between developmental auditory and neural systems.

GWAS Identifies 44 Independent Associated Genomic Loci for Self-Reported Adult Hearing Difficulty in UK Biobank.

Age-related hearing impairment (ARHI) is the most common sensory impairment in the aging population; a third of individuals are affected by disabling hearing loss by the age of 65. It causes social isolation and depression and has recently been identified as a risk factor for dementia. The genetic risk factors and underlying pathology of ARHI are largely unknown, meaning that targets for new therapies remain elusive, yet heritability estimates range between 35% and 55%. We performed genome-wide association studies (GWASs) for two self-reported hearing phenotypes, using more than 250,000 UK Biobank (UKBB) volunteers aged between 40 and 69 years. Forty-four independent genome-wide significant loci (p < 5E-08) were identified, considerably increasing the number of established trait loci. Thirty-four loci are novel associations with hearing loss of any form, and only one of the ten known hearing loci has a previously reported association with an ARHI-related trait. Gene sets from these loci are enriched in auditory processes such as synaptic activities, nervous system processes, inner ear morphology, and cognition, while genetic correlation analysis revealed strong positive correlations with multiple personality and psychological traits for the first time. Immunohistochemistry for protein localization in adult mouse cochlea implicate metabolic, sensory, and neuronal functions for NID2, CLRN2, and ARHGEF28. These results provide insight into the genetic landscape underlying ARHI, opening up novel therapeutic targets for further investigation. In a wider context, our study also highlights the viability of using self-report phenotypes for genetic discovery in very large samples when deep phenotyping is unavailable.

Perceived Gaps in Genetics Training Among Audiologists and Speech-Language Pathologists: Lessons From a National Survey.

Purpose The aim of this study was to assess knowledge, self-rated confidence, and perceived relevance of genetics in the clinical practice of audiologists and speech-language pathologists (SLPs) toward a better understanding of the need for genetics education, given that genetics plays a growing role in the diagnosis of hearing impairment and communication disorders. Method A survey consisting of 8 demographic items and 16 content questions was returned by 233 audiologists and 283 SLPs. Knowledge of applied genetics was queried with clinical scenarios in a multiple-choice format. Self-assessment of clinical confidence and perceived relevance of genetics in one's field was queried with questions and statements rated on 5-point Likert scales. The benefit of additional training in genetics was rated with a yes/no question, and if answered with yes, suggested topics were entered. Results A large significant gap between confidence in one's own genetics skills and the perceived relevance of genetics was evident, regardless of professional group. Over one third of the audiologists and over two thirds of the SLPs indicated low or somewhat low confidence in their own ability to implement principles of genetics, whereas over two thirds of both groups agreed that genetics is relevant for their field. Regardless of group, confidence scores were significantly and positively associated with relevance scores. Over 80% of respondents in both groups indicated that they would benefit from additional training in genetics. Most commonly suggested topics included genetic causes, general information about genetics, and making referrals. Conclusion Both audiologists and SLPs felt that genetics is relevant for their fields and that additional training in genetics would be beneficial. Future studies should evaluate the effect of genetics training on patient outcomes and the need for incorporating genetics more extensively into audiology and speech-language pathology training programs.

Genes Involved in the Development and Physiology of Both the Peripheral and Central Auditory Systems.

The genetic approach, based on the study of inherited forms of deafness, has proven to be particularly effective for deciphering the molecular mechanisms underlying the development of the peripheral auditory system, the cochlea and its afferent auditory neurons, and how this system extracts the physical parameters of sound. Although this genetic dissection has provided little information about the central auditory system, scattered data suggest that some genes may have a critical role in both the peripheral and central auditory systems. Here, we review the genes controlling the development and function of the peripheral and central auditory systems, focusing on those with demonstrated intrinsic roles in both systems and highlighting the current underappreciation of these genes. Their encoded products are diverse, from transcription factors to ion channels, as are their roles in the central auditory system, mostly evaluated in brainstem nuclei. We examine the ontogenetic and evolutionary mechanisms that may underlie their expression at different sites.

Neural crest contributions to the ear: Implications for congenital hearing disorders.

Congenital hearing disorders affect millions of children worldwide and can significantly impact acquisition of speech and language. Efforts to identify the developmental genetic etiologies of conductive and sensorineural hearing losses have revealed critical roles for cranial neural crest cells (NCCs) in ear development. Cranial NCCs contribute to all portions of the ear, and defects in neural crest development can lead to neurocristopathies associated with profound hearing loss. The molecular mechanisms governing the development of neural crest derivatives within the ear are partially understood, but many questions remain. In this review, we describe recent advancements in determining neural crest contributions to the ear, how they inform our understanding of neurocristopathies, and highlight new avenues for further research using bioinformatic approaches.

Decreased Expression of TRPV4 Channels in HEI-OC1 Cells Induced by High Glucose Is Associated with Hearing Impairment.

PURPOSE: Previous reports have shown that hyperglycemia-induced inhibition of transient receptor potential vanilloid sub type 4 (TRPV4), a transient receptor potential ion channel, affects the severity of hearing impairment (HI). In this study, we explored the role of TRPV4 in HI using HEI-OC1 cells exposed to high glucose (HG). MATERIALS AND METHODS: HEI-OC1 cells were cultured in a HG environment (25 mM D-glucose) for 48 hours, and qRT-PCR and Western blotting were used to analyze the expression of TRPV4 at the mRNA and protein level. TRPV4 agonist (GSK1016790A) or antagonist (HC-067047) in cultured HEI-OC1 cells was used to obtain abnormal TRPV4 expression. Functional TRPV4 activity was assessed in cultured HEI-OC1 cells using the MTT assay and a cell death detection ELISA. RESULTS: TRPV4 agonists exerted protective effects against HG-induced HI, as evidenced by increased MTT levels and inhibition of apoptosis in HEI-OC1 cells. TRPV4 overexpression significantly increased protein levels of phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK), while TRPV4 antagonists had the opposite effect. Our results indicated that TRPV4 is a hyperglycemia-related factor that can inhibit cell proliferation and promote cell apoptosis by activating the MAPK signaling pathway in HEI-OC1 cells. CONCLUSION: Our results show that the overexpression of TRPV4 can attenuate cell death in HEI-OC1 cells exposed to HG.

Familial misophonia or selective sound sensitivity syndrome: evidence for autosomal dominant inheritance? / Misofonia familiar ou síndrome da sensibilidade seletiva a sons: evidência de herança autossômica dominante?

Abstract Introduction: Misophonia is a recently described, poorly understood and neglected condition. It is characterized by strong negative reactions of hatred, anger or fear when subjects have to face some selective and low level repetitive sounds. The most common ones that trigger such aversive reactions are those elicited by the mouth (chewing gum or food, popping lips) or the nose (breathing, sniffing, and blowing) or by the fingers (typing, kneading paper, clicking pen, drumming on the table). Previous articles have cited that such individuals usually know at least one close relative with similar symptoms, suggesting a possible hereditary component. Objective: We found and described a family with 15 members having misophonia, detailing their common characteristics and the pattern of sounds that trigger such strong discomfort. Methods: All 15 members agreed to give us their epidemiological data, and 12 agreed to answer a specific questionnaire which investigated the symptoms, specific trigger sounds, main feelings evoked and attitudes adopted by each participant. Results: The 15 members belong to three generations of the family. Their age ranged from 9 to 73 years (mean 38.3 years; median 41 years) and 10 were females. Analysis of the 12 questionnaires showed that 10 subjects (83.3%) developed the first symptoms during childhood or adolescence. The mean annoyance score on the Visual Analog Scale from 0 to 10 was 7.3 (median 7.5). Individuals reported hatred/anger, irritability and anxiety in response to sounds, and faced the situation asking to stop the sound, leaving/avoiding the place and even fighting. The self-reported associated symptoms were anxiety (91.3%), tinnitus (50%), obsessive-compulsive disorder (41.6%), depression (33.3%), and hypersensitivity to sounds (25%). Conclusion: The high incidence of misophonia in this particular familial distribution suggests that it might be more common than expected and raises the possibility of having a hereditary etiology.

Resumo Introdução: A misofonia é uma condição recentemente descrita, mal compreendida e negligenciada. É caracterizada por fortes reações negativas de ódio, raiva ou medo quando os indivíduos precisam enfrentar alguns sons repetitivos seletivos e de baixa intensidade. Os mais comuns que desencadeiam tais reações aversivas são aqueles provocados pela boca (mascar goma ou mastigar comida, estalar os lábios) ou nariz (respirando, cheirando e soprando) ou pelos dedos (digitando, amassando papel, clicando a caneta, tamborilando na mesa). Artigos anteriores citam que esses indivíduos geralmente conhecem pelo menos um parente próximo com sintomas semelhantes, sugerindo um possível componente hereditário. Objetivo: Encontramos e descrevemos uma família com 15 membros com misofonia, detalhando suas características comuns e o padrão de sons que desencadeiam um desconforto tão forte. Método: Todos os 15 membros concordaram em nos fornecer seus dados epidemiológicos e 12 concordaram em responder a um questionário específico que investigou os sintomas, sons de gatilho específicos, principais sentimentos evocados e atitudes adotadas por cada participante. Resultados: Os 15 membros pertencem a três gerações da família. A idade variou de 9 a 73 anos (média de 38,3 anos, mediana de 41 anos) e 10 eram mulheres. A análise dos 12 questionários mostrou que 10 indivíduos (83,3%) desenvolveram os primeiros sintomas durante a infância ou a adolescência. A média do escore de irritação na Escala Visual Analógica de 0 a 10 foi de 7,3 (mediana 7,5). Os indivíduos relataram sentimentos de ódio/raiva, irritabilidade e ansiedade em resposta a sons, e enfrentaram a situação pedindo para interromper o som, deixando/evitando o lugar e até mesmo discutindo. Os sintomas associados auto-relatados foram ansiedade (91,3%), zumbido (50%), transtorno obsessivo-compulsivo (41,6%), depressão (33,3%) e hipersensibilidade aos sons (25%). Conclusão: A alta incidência de misofonia nessa distribuição familiar em particular sugere que possa ser mais comum do que o esperado e suscita a possibilidade de haver uma etiologia hereditária.

Mutant MRPS5 affects mitoribosomal accuracy and confers stress-related behavioral alterations.

The 1555 A to G substitution in mitochondrial 12S A-site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease. Here, we recapitulate the suggested A1555G-mediated pathomechanism in an experimental model of mitoribosomal mistranslation by directed mutagenesis of mitoribosomal protein MRPS5. We first establish that the ratio of cysteine/methionine incorporation and read-through of mtDNA-encoded MT-CO1 protein constitute reliable measures of mitoribosomal misreading. Next, we demonstrate that human HEK293 cells expressing mutant V336Y MRPS5 show increased mitoribosomal mistranslation. As for immortalized lymphocytes of individuals with the pathogenic A1555G mutation, we find little changes in the transcriptome of mutant V336Y MRPS5 HEK cells, except for a coordinated upregulation of transcripts for cytoplasmic ribosomal proteins. Homozygous knock-in mutant Mrps5 V338Y mice show impaired mitochondrial function and a phenotype composed of enhanced susceptibility to noise-induced hearing damage and anxiety-related behavioral alterations. The experimental data in V338Y mutant mice point to a key role of mitochondrial translation and function in stress-related behavioral and physiological adaptations.

Branchiootorenal syndrome: A case report.

Branchiootorenal syndrome is a rare autosomal dominant disorder characterised by branchial arch anomaly, hearing loss, renal anomalies and other otologic manifestations. We report a case of apparent de novo mutation that presented with hearing loss, branchial sinus and other manifestations of the disease. It is extremely rare in the West African region, and we suggest a high index of suspicion in a patient presenting with branchial sinus and/or hearing loss.

Transcriptomic analysis of chicken cochleae after gentamicin damage and the involvement of four signaling pathways (Notch, FGF, Wnt and BMP) in hair cell regeneration.

Unlike mammalian hair cells, which are essentially unable to regenerate after damage, avian hair cells have a robust capacity for regeneration. The prerequisite for understanding the above difference is knowing the genetic programming of avian hair cell regeneration. Although the major processes have been known, the precise molecular signaling that induces regeneration remains unclear. To address this issue, we performed a high-throughput transcriptomic analysis of gene expression during hair cell regeneration in the chick cochlea after antibiotic injury in vivo. A total of 16,588 genes were found to be expressed in the cochlea, of which about 1000 genes were differentially expressed among the four groups studied, i.e., 2 days (d) or 3 d post-treatment with gentamicin or physiological saline. The differentially expressed genes were distributed across approximately one hundred signaling pathways, including the Notch, MAPK (FGF), Wnt and TGF-ß (BMP) pathways that have been shown to play important roles in embryonic development. Some differentially expressed genes (2-3 in each pathway) were further verified by qRT-PCR. After blocking Notch, FGF or BMP signaling, the number of regenerating hair cells and mitotic supporting cells increased. However, the opposite effect was observed after suppressing the Wnt pathway or enhancing BMP signaling. To our knowledge, the present study provided a relatively complete dataset of candidate genes and signaling pathways most likely involved in hair cell regeneration and should be a useful start in deciphering the genetic circuitry for inducing hair cell regeneration in the chick cochlea.

Familial misophonia or selective sound sensitivity syndrome : evidence for autosomal dominant inheritance?

INTRODUCTION: Misophonia is a recently described, poorly understood and neglected condition. It is characterized by strong negative reactions of hatred, anger or fear when subjects have to face some selective and low level repetitive sounds. The most common ones that trigger such aversive reactions are those elicited by the mouth (chewing gum or food, popping lips) or the nose (breathing, sniffing, and blowing) or by the fingers (typing, kneading paper, clicking pen, drumming on the table). Previous articles have cited that such individuals usually know at least one close relative with similar symptoms, suggesting a possible hereditary component. OBJECTIVE: We found and described a family with 15 members having misophonia, detailing their common characteristics and the pattern of sounds that trigger such strong discomfort. METHODS: All 15 members agreed to give us their epidemiological data, and 12 agreed to answer a specific questionnaire which investigated the symptoms, specific trigger sounds, main feelings evoked and attitudes adopted by each participant. RESULTS: The 15 members belong to three generations of the family. Their age ranged from 9 to 73 years (mean 38.3 years; median 41 years) and 10 were females. Analysis of the 12 questionnaires showed that 10 subjects (83.3%) developed the first symptoms during childhood or adolescence. The mean annoyance score on the Visual Analog Scale from 0 to 10 was 7.3 (median 7.5). Individuals reported hatred/anger, irritability and anxiety in response to sounds, and faced the situation asking to stop the sound, leaving/avoiding the place and even fighting. The self-reported associated symptoms were anxiety (91.3%), tinnitus (50%), obsessive-compulsive disorder (41.6%), depression (33.3%), and hypersensitivity to sounds (25%). CONCLUSION: The high incidence of misophonia in this particular familial distribution suggests that it might be more common than expected and raises the possibility of having a hereditary etiology.

Maturation arrest in early postnatal sensory receptors by deletion of the miR-183/96/182 cluster in mouse.

The polycistronic miR-183/96/182 cluster is preferentially and abundantly expressed in terminally differentiating sensory epithelia. To clarify its roles in the terminal differentiation of sensory receptors in vivo, we deleted the entire gene cluster in mouse germline through homologous recombination. The miR-183/96/182 null mice display impairment of the visual, auditory, vestibular, and olfactory systems, attributable to profound defects in sensory receptor terminal differentiation. Maturation of sensory receptor precursors is delayed, and they never attain a fully differentiated state. In the retina, delay in up-regulation of key photoreceptor genes underlies delayed outer segment elongation and possibly mispositioning of cone nuclei in the retina. Incomplete maturation of photoreceptors is followed shortly afterward by early-onset degeneration. Cell biologic and transcriptome analyses implicate dysregulation of ciliogenesis, nuclear translocation, and an epigenetic mechanism that may control timing of terminal differentiation in developing photoreceptors. In both the organ of Corti and the vestibular organ, impaired terminal differentiation manifests as immature stereocilia and kinocilia on the apical surface of hair cells. Our study thus establishes a dedicated role of the miR-183/96/182 cluster in driving the terminal differentiation of multiple sensory receptor cells.

Global Analysis of Protein Expression of Inner Ear Hair Cells.

The mammalian inner ear (IE) subserves auditory and vestibular sensations via highly specialized cells and proteins. Sensory receptor hair cells (HCs) are necessary for transducing mechanical inputs and stimulating sensory neurons by using a host of known and as yet unknown protein machinery. To understand the protein composition of these unique postmitotic cells, in which irreversible protein degradation or damage can lead to impaired hearing and balance, we analyzed IE samples by tandem mass spectrometry to generate an unbiased, shotgun-proteomics view of protein identities and abundances. By using Pou4f3/eGFP-transgenic mice in which HCs express GFP driven by Pou4f3, we FACS purified a population of HCs to analyze and compare the HC proteome with other IE subproteomes from sensory epithelia and whole IE. We show that the mammalian HC proteome comprises hundreds of uniquely or highly expressed proteins. Our global proteomic analysis of purified HCs extends the existing HC transcriptome, revealing previously undetected gene products and isoform-specific protein expression. Comparison of our proteomic data with mouse and human databases of genetic auditory/vestibular impairments confirms the critical role of the HC proteome for normal IE function, providing a cell-specific pool of candidates for novel, important HC genes. Several proteins identified exclusively in HCs by proteomics and verified by immunohistochemistry map to human genetic deafness loci, potentially representing new deafness genes. SIGNIFICANCE STATEMENT: Hearing and balance rely on specialized sensory hair cells (HCs) in the inner ear (IE) to convey information about sound, acceleration, and orientation to the brain. Genetically and environmentally induced perturbations to HC proteins can result in deafness and severe imbalance. We used transgenic mice with GFP-expressing HCs, coupled with FACS sorting and tandem mass spectrometry, to define the most complete HC and IE proteome to date. We show that hundreds of proteins are uniquely identified or enriched in HCs, extending previous gene expression analyses to reveal novel HC proteins and isoforms. Importantly, deafness-linked proteins were significantly enriched in HCs, suggesting that this in-depth proteomic analysis of IE sensory cells may hold potential for deafness gene discovery.

Electroconvulsive shock attenuated microgliosis and astrogliosis in the hippocampus and ameliorated schizophrenia-like behavior of Gunn rat.

BACKGROUND: Although electroconvulsive therapy (ECT) is regarded as one of the efficient treatments for intractable psychiatric disorders, the mechanism of therapeutic action remains unclear. Recently, many studies indicate that ECT affects the immune-related cells, such as microglia, astrocytes, and lymphocytes. Moreover, microglial activation and astrocytic activation have been implicated in the postmortem brains of schizophrenia patients. We previously demonstrated that Gunn rats showed schizophrenia-like behavior and microglial activation in their brains. The present study examined the effects of electroconvulsive shock (ECS), an animal counterpart of ECT, on schizophrenia-like behavior, microgliosis, and astrogliosis in the brain of Gunn rats. METHODS: The rats were divided into four groups, i.e., Wistar sham, Wistar ECS, Gunn sham, and Gunn ECS. ECS groups received ECS once daily for six consecutive days. Subsequently, prepulse inhibition (PPI) test was performed, and immunohistochemistry analysis was carried out to determine the activation degree of microglia and astrocytes in the hippocampus by using anti-CD11b and anti-glial fibrillary acidic protein (GFAP) antibody, respectively. RESULTS: We found PPI deficit in Gunn rats compared to Wistar rats, and it was significantly improved by ECS. Immunohistochemistry analysis revealed that immunoreactivity of CD11b and GFAP was significantly increased in Gunn rats compared to Wistar rats. ECS significantly attenuated the immunoreactivity of both CD11b and GFAP in Gunn rats. CONCLUSIONS: ECS ameliorated schizophrenia-like behavior of Gunn rats and attenuated microgliosis and astrogliosis in the hippocampus of Gunn rats. Accordingly, therapeutic effects of ECT may be exerted, at least in part, by inhibition of glial activation. These results may provide crucial information to elucidate the role of activated glia in the pathogenesis of schizophrenia and to determine whether future therapeutic interventions should attempt to up-regulate or down-regulate glial functions.

Prevalence and audiological profiles of GJB2 mutations in a large collective of hearing impaired patients.

Mutations in the GJB2 gene are known to represent the commonest cause of hereditary and congenital hearing loss. In this study, a complete sequencing of the GJB2 gene in a cohort of 506 patients from a single, large cochlear implant program in Europe was performed. Audiological testing for those patients who could actively participate was performed using pure tone audiometry (PTA). Those unable to undergo PTA were measured using click-auditory brainstem response (ABR). Data analysis was performed to determine genotype-phenotype correlations of the mutational status vs. audiological profiles and vs. age at the time of presentation. An overall prevalence of biallelic mutations of 13.4% was found for the total collective. When subsets of younger patients were examined, the prevalence increased to 27% of those up to age 18 and 35% of those up to age 5 at the time of testing, respectively. This increase was found to be highly significant (p < 0.001). Analysis of the mean PTA thresholds revealed a strong correlation between allele combination status and mean PTA (p = 0.021). The prevalence of simple heterozygotes was found to be approximately 10.1%, which is around 3.3 times the value expected in the general population. As GJB2 follows a recessive pattern of inheritance, the question arises as to why such a large fraction of simple heterozygotes was observed among the hearing impaired patients included in this study.

High frequency of OTOF mutations in Chinese infants with congenital auditory neuropathy spectrum disorder.

Auditory neuropathy spectrum disorder (ANSD) is one of the most common diseases leading to hearing and speech communication barriers in infants and young children. The OTOF gene is the first gene identified for autosomal recessive non-syndromic ANSD, and patients with OTOF mutations have shown marked improvement of auditory functions from the cochlear implantation, but the true involvement of OTOF mutations in Chinese ANSD patients is still unknown which precludes the effective management of this disease. Here, we investigated the contribution of OTOF mutations to congenital ANSD patients in China. In all, 37 infants and young Children with ANSD were screened for all the exons of OTOF gene, of them 34 patients had no neonatal risk factors who were considered as congenital ANSD. The clinical manifestation and audiometric features were also investigated and compared in patients with and without OTOF mutations. In all, 14 of these subjects were shown to carry two or three mutant alleles of OTOF with the high frequency of 41.2% in congenital ANSD patients. In total, 15 novel pathogenic mutations and 10 reported mutations were identified. Our results confirmed that mutations in OTOF gene were a major cause of congenital ANSD in China. Identification of OTOF mutations can facilitate diagnosis, clinical intervention and counseling for congenital ANSD.