['To report the clinical, auditory, and vestibular characteristics of a nonsyndromic otovestibular dysfunction in a large Belgian family caused by a missense mutation of the DFNA9 gene: COCH.', 'Retrospective study of the clinical, audiologic, and vestibular data of 60 genetically affected cases.', 'Tertiary referral center.', 'All members of a Belgian kindred who carry the genetic (P51S) defect linked to the inherited hearing and vestibular impairment.', 'Diagnostic otologic, audiometric, and vestibular analysis and imaging.', 'Pure tone audiometry, supraliminary audiometry. and vestibular investigation.', 'The autosomal dominant inherited impairment was characterized by peripheral degeneration of the inner ear, leading to total deafness and bilateral vestibular areflexia.'] Is hereditary otovestibular dysfunction and Ménière 's disease in a large Belgian family caused by a missense mutation in the COCH gene?