MYO15A variants are responsible for human non-syndromic autosomal recessive deafness (DFNB3). The majority of MYO15A variants are associated with a congenital severe-to-profound hearing loss phenotype, except for MYO15A variants in exon 2, which cause a milder auditory phenotype, suggesting a genotype-phenotype correlation of MYO15A. However, MYO15A variants not in exon 2 related to a milder phenotype have also been reported, indicating that the genotype-phenotype correlation of MYO15A is complicated. This study aimed to provide more cases of MYO15A variation with diverse phenotypes to analyse this complex correlation. Fifteen Chinese autosomal recessive non-syndromic hearing loss (ARNSHL) individuals with MYO15A variants (8 males and 7 females) from 14 unrelated families, identified by targeted gene capture of 127 known candidate deafness genes, were recruited. Additionally, we conducted a review of the literature to further analyses all reported MYO15A genotype-phenotype relationships worldwide. We identified 16 novel variants and 12 reported pathogenic MYO15A variants in 15 patients, two of which presented with a milder phenotype. Interestingly, one of these cases carried two reported pathogenic variants in exon 2, while the other carried two novel variants not in exon 2. Based on our literature review, MYO15A genotype-phenotype correlation analysis showed that almost all domains were reported to be correlated with a milder phenotype. However, variants in the N-terminal domain were more likely to cause a milder phenotype. Using next-generation sequencing (NGS), we also found that the number of known MYO15A variants with milder phenotypes in Southeast Asia has increased in recent years. Our work extended the MYO15A variant spectrum, enriched our knowledge of auditory phenotypes, and tried to explore the genotype-phenotype correlation in different populations in order to investigate the cause of the complex MYO15A genotype-phenotype correlation.

Background: Previous studies have shown that patients with acoustic neuroma (AN) sometimes present with sudden sensorineural hearing loss (SSNHL) as an initial symptom. The purpose of this research was to investigate the clinical characteristics, diagnosis, and treatment of AN in patients initially diagnosed with SSNHL.Materials and methods: We reviewed retrospectively the medical records of all patients who were treated as SSNHL initially and were later diagnosed with AN after undergoing magnetic resonance imaging (MRI) at our hospital between 2008 and 2021. Patient demographics, associated complaints (mostly tinnitus and vertigo), the severity of hearing loss, audiogram configurations, auditory brainstem response (ABR), and MRI examination were reviewed and analyzed. In addition, treatment outcomes and management protocols were also included in this study.Results: A total of 10 (0.7%, 10/1,383) patients presented with SSNHL as the initial symptom and were diagnosed as AN by MRI finally. Of the 10 patients enrolled in this study, four were men and six were women. The average age at the time of diagnosis of SSNHL was 46.2 ± 13.16 years. These patients exhibited varying severity of hearing loss and a variety of audiogram configurations. All patients showed an abnormal ABR. According to the Koos grading standard, there were 5 grade I (intracanalicular [IAC]) tumors, 3 grade II tumors, and 2 grade III tumors. The treatment outcome revealed that 2 patients exhibited recovery of the average hearing of impaired frequency by more than 15 dB, and 6 patients showed no recovery. Furthermore, four patients were referred to undergo surgical treatment after being diagnosed with AN, 1 patient accepted stereotactic radiation therapy, and the remaining 5 patients were on a “wait and scan” strategy.Conclusion: The hearing loss of patients with AN presented with SSNHL may improve with drug treatment. Hearing recovery for SSNHL does not exclude the presence of AN, and all patients initially diagnosed with SSNHL should undergo MRI and ABR to prevent misdiagnosis and delays in potential treatment.

Mohr-Tranebjaerg syndrome (MTS) is a rare X-linked recessive neurodegenerative disorder resulting in early-onset hearing impairment, gradual dystonia and optic atrophy. MTS is caused by variations in the nuclear TIMM8A gene, which is involved in mitochondrial transport of metabolites. This study aimed to identify the pathogenic gene variations in three Chinese families associated with predicted MTS with or without X-linked agammaglobulinaemia. Otologic examinations, vestibular, neurological, optical and other clinical evaluations were conducted on the family members. Targeted genes capture combining next generation sequencing (NGS) was performed, and then Sanger sequencing was used to confirm the causative variation. A novel variation, c.232_233insCAAT, in TIMM8A was identified as the pathogenic variation in one Chinese family. This variation co-segregated with the most frequent phenotypic deafness and was absent in the 1000 Genomes Project, ExAC and 1751 ethnicity-matched controls. Clinically, otological examinations illustrated the typical postsynaptic auditory neuropathy for the proband without the symptoms of dystonia or optic atrophy. MRI demonstrated abnormal small cochlear symmetric nerves, while the vestibular function appeared to be less influenced. Furthermore, we found another two TIMM8A variations, the deletion c.133_135delGAG and a copy number variation (CNV) including the TIMM8A gene, in two independent case, when we performed NGS on an auditory neuropathy population. We identified two novel variations in the TIMM8A gene (c.232_233insCAAT and c.133_135delGAG) and a CNV including the TIMM8A gene in three independent Chinese families with predicted MTS. To our knowledge, this is the first report of TIMM8A variations being identified in a Chinese population. Our results enrich the variation spectrum of TIMM8A and clinical heterogeneity of MTS. Genetic detection and diagnosis is a powerful tool for better understanding and managing syndromic hearing impairments, such as MTS, before they become full-blown.

To analyze the clinical characteristics of patients with unilateral auditory neuropathy (UAN), and to provide guidance for future clinical diagnosis and research. Patients who were clinically diagnosed with UAN from 2004 to 2019 were included. Clinical characteristics, audiological features, imaging findings, genetic test results and management effect were summarized and followed. A total of 44 patients [mean age, 4.35 ± 4.39 years; 22 (50.00%) males and 22 (50.00%) females] were enrolled for analyses. Among the 38 patients who were tested by pure-tone or behavioral audiometry, the degree of hearing loss of the affected ear was characterized as mild in 2 ears (5.26%), moderate in 5 (13.16%), severe in 9 (23.68%) and profound in 22 (57.89%). For the 44 contralateral ears, 33 (75.00%) showed normal hearing and 11 (25.00%) presented with sensorineural hearing loss. Auditory brainstem responses were absent or abnormal in all 44 affected ears, while otoacoustic emissions and/or cochlear microphonics were present. Among the 18 patients who underwent magnetic resonance imaging (MRI), 7 (38.89%) presented cochlear nerve deficiency (CND). Nineteen candidate variants were found in 12 patients among the 15 UAN patients who were conducted targeted gene capture and next generation sequencing. Thirty patients were followed up by telephone to investigate their management effect. Our study demonstrates comprehensive audiological features of patients with UAN to improve the clinical understanding and diagnosis. Some patients with UAN could show ipsilateral CND and MRI is essential to evaluate if the nerve is deficient. No pathogenic variants that directly related to the pathogenesis of UAN have been found in this study currently.

Hearing is one of the most vital sensory functions in human beings and a crucial means of perceiving and acquiring information from the natural environment. The advancement of human society is closely linked to the development of language, with hearing serving as the foundation for verbal communication. As individuals age, the deterioration of the auditory system becomes a significant factor contributing to sensory impairments in the elderly. In addition to hearing loss, the aging of the auditory system is also associated with cognitive decline and psychosocial disorders, which severely impact the quality of life for older adults. Currently, there are no effective treatments or interventions available for addressing the aging of the auditory system. Therefore, identifying biomarkers of the auditory system aging is of great significance. The Aging Biomarker Consortium of China has conducted a comprehensive evaluation of aging biomarkers in the auditory system, focusing on three dimensions: morphological, functional, and humoral biomarkers. This initiative aims to establish a foundation for assessing the degree of aging in the auditory system and to promote the management of auditory health in an aging society, ultimately enhancing the auditory health of the elderly population both in China and globally.