Abstract
BACKGROUND: Hearing loss, characterized by significant genetic heterogeneity, is a widespread global disorder. Mutations in the OTOG and OTOGL genes have recently been implicated in non-syndromic sensorineural hearing loss. However, the mutation spectrum of OTOGL and its functional relevance remain incompletely understood. METHODS: We investigated a Chinese family with unexplained hearing loss using whole-exome sequencing. Compound heterozygous mutations in the OTOGL gene were identified and validated through Sanger sequencing. The proband's clinical features were assessed through audiological evaluations, and genotype-phenotype correlation analysis was conducted. Additionally, single-cell RNA sequencing analysis of the inner ear was performed to explore OTOGL's expression profile in auditory-related cell types. RESULTS: Two compound heterozygous mutations in the OTOGL gene (p.Ile34Val and p.Phe319del) were identified in the proband, a 6-year-old boy with moderate congenital hearing loss. These mutations are predicted to be pathogenic and may explain the observed phenotype. Single-cell RNA sequencing revealed specific OTOGL expression in key auditory-related cell types, providing insights into its developmental and functional roles in the inner ear. CONCLUSION: The findings have marked implications for molecular diagnosis and genetic counseling, potentially guiding more personalized treatment and intervention strategies in clinical practice.