TEMPORAL BONE ANALYSIS OF PATIENTS WITH PRESBYCUSIS REVEALS HIGH-FREQUENCY OF MITOCHONDRIAL MUTATIONS

Presbycusis is a histologically and genetically heterogenous group of disorders, which lead to progressive, primarily sensorineural hearing loss with aging. Acquired mitochondrial DNA defects have been proposed as important determinants of aging, particularly in neuro-muscular ti ssues. The spiral ganglion and membranous labyrinth from archival temp oral bones of 5 patients with presbycusis were examined for mutations within the mitochondrially-encoded cytochrome oxidase II gene. When co mpared to controls, results indicate that mitochondrial mutations in t he peripheral auditory system occur commonly with age-related hearing loss, that there is great individual variability in both quantity and location of mutation accumulation, and that at least a proportion of p resbycusis patients have a highly significant load of mutations in aud itory tissue. This work supports the hypothesis that acquired mitochon drial mutations are a determinant of hearing loss in a subgroup of pre sbycusis patients.