A dominant variant in apoptosis-related gene XKR8 is relevant to hereditary auditory neuropathy

Abstract

AbstractBackgroundAuditory neuropathy is an unusual type of hearing loss. At least 40% of patients with this disease have underlying genetic causes. However, in many hereditary auditory neuropathy cases, etiology remains undetermined.MethodsWe collected data and blood samples from a four-generation Chinese family. After excluding relevant variants in known deafness-related genes, exome sequencing was conducted. Candidate genes were verified by pedigree segregation, transcript/protein expression in the mouse cochlea, and plasmid expression studies in HEK 293T cells. Moreover, a mutant mouse model was generated and underwent hearing evaluations; protein localization in the inner ear was also assessed.ResultsThe clinical features of the family were diagnosed as auditory neuropathy. A novel variant c.710G > A (p.W237X) in apoptosis-related geneXKR8was identified. Genotyping of 16 family members confirmed the segregation of this variant with the deafness phenotype. BothXKR8mRNA and XKR8 protein were expressed in the mouse inner ear, predominantly in regions of spiral ganglion neurons; Moreover, this nonsense variant impaired the surface localization of XKR8 in cells. Transgenic mutant mice exhibited late-onset auditory neuropathy, and their altered XKR8 protein localization in the inner ear confirmed the damaging effects of this variant.ConclusionsWe identified a variant in theXKR8gene that is relevant to auditory neuropathy. The essential role ofXKR8in inner ear development and neural homeostasis should be explored.