Maternally inherited deafness associated with a T1095C mutation in the mDNA

Hearing loss is a relatively frequent defect in children with a genetic or predisposition basis in about 50% of cases. Mitochondrial DNA (mtDNA)-assoc iated disorder often present with sensorineural hearing loss (SNHL) either in isolation or as a part of a multisystem disorder in adults but the frequ ency in pediatric cases is unknown. We analysed deafness-related mtDNA muta tions in 80 deaf children to assess the relative frequency of alterations i n childhood-onset SNHL. In 16 patients in whom maternal inheritance was pos sible, we screened for new mutations likely to affect mitochondrial protein synthesis. In one child we detected a novel mutation (T1095C) in the 125 r RNA gene. This mutation fulfils the suggested criteria for definition of a disease-related nucleotide variant. No mutations were found in other patien ts. Although we cannot exclude the presence of still undefined new mtDNA mu tations, our data suggest that mtDNA defect are not common in childhood-ons et SNHL.