Mutations in mitochondrial DNA (mtDNA), particularly those in the 12S rRNA gene, have been shown to be associated with sensorineural hearing loss. Recently, a systematic and extended mutation screening of the mitochondrial 12S rRNA gene has been initiated in the large clinical population of the Otology Clinic at the Chinese PLA General Hospital with the aim of identifying mtDNA mutations associated with hearing loss. Here we report the clinical and molecular characterization of a Chinese patient with auditory neuropathy. Sequence analysis of mtDNA in this patient identified a T-to-C transition at position 1095 (T1095C) in the 12S rRNA gene and other nucleotide changes. The T1095C mutation is expected to disrupt an evolutionarily conserved A-to-U base-pair, which is at the highly conserved P-site of 12S rRNA. The T1095C mutation has also been found to be associated with hearing loss in several unrelated families. Among other nucleotide changes, two novel variants: the I175V mutation in the CO2 and the V112M mutation in the ND6 localize at highly evolutionarily conserved residues from different organisms. Furthermore, the absence of mutation in the otoferlin related to auditory neuropathy showed that otoferlin may not be involved in the phenotypic expression of T1095C mutation in this subject. These data suggest that the T1095C mutation may be associated with auditory neuropathy in this subject, and two novel variants I175V and V112M may play a role in the phenotypic expression of the T1095C mutation.
(c) 2005 Wiley-Liss, Inc.