Objective: To characterise the hearing loss, and the frequency of the mitochondrial deoxyribonucleic acid 12S ribosomal ribonucleic acid A1555G mutation, in a large pedigree of aminoglycoside-induced deafness.
Design: Hearing loss was clinically assessed. Blood samples were collected from 27 family members (19 matrilinear and eight non-matrilinear) and leukocyte deoxyribonucleic acid was extracted. Mitochondrial deoxyribonucleic acid fragments, spanning the 1555 location, were amplified by polymerase chain reaction. Polymerase chain reaction products were analysed by restriction fragment length polymorphism and deoxyribonucleic acid sequencing.
Results: We detected the A1555G mutation in all 19 matrilinear relatives. Of these 19, two exhibited congenital deafness, four had no hearing deficits and the remaining 13 suffered mild to profound hearing loss.
Conclusion: We confirmed that the A1555G mutation is a 'hot spot' associated with non-syndromic, inherited hearing loss. This mutation may play a vital role in the pathogenesis of hearing impairment, and can result in various grades of deafness.