A novel mutation in the mitochondrial tRNA(Ser(UCN)) gene in a family withnon-syndromic sensorineural hearing impairment

We describe a family with non-syndromic sensorineural hearing impairment in herited in a manner consistent with maternal transmission. Affected members were found to have a novel heteroplasmic mtDNA mutation, T7510C, in the tR NA(Ser(UCN)) gene. This mutation was not found in 661 controls, is well con served between species, and disrupts base pairing in the acceptor stem of t he tRNA, making it the probable cause of hearing impairment in this family. Sequencing of the other mitochondrial tRNA genes did not show any other pa thogenic mutations. Four other mutations causing hearing impairment have be en reported in the tRNA(Ser(UCN)) gene, two having been shown to affect tRN A(Ser(UCN)) levels. With increasing numbers of reports of mtDNA mutations c ausing hearing impairment, screening for such mutations should be considere d in all cases unless mitochondrial inheritance can be excluded for certain .