Aminoglycoside-induced hearing loss in a patient with the 961 mutation in mitochondrial DNA.

The A1555G mutation in the mitochondrial 12S ribosomal RNA gene is often found in patients with hearing loss after aminoglycoside exposure. A second pathogenic mutation in this gene, deletion of thymidine at position 961 with varying numbers of cytosines inserted (delT961Cn), has recently been found to predispose patients to aminoglycoside-induced deafness. We report on a Japanese patient bearing the delT961Cn who had streptomycin-induced deafness. Our report suggests that the delT961Cn plays an important secondary role in the pathogenesis of deafness caused by aminoglycosides. The combination of taking family histories and molecular screening at the 1555 and 961 positions is thought to reduce the frequency of tragic irreversible deafness due to aminoglycosides.