TOPICAL GENTAMICIN-INDUCED HEARING-LOSS - A MITOCHONDRIAL RIBOSOMAL-RNA STUDY OF GENETIC SUSCEPTIBILITY

Mitochondrial ribosomal RNA mutation has been shown to predispose affe cted individuals to aminoglycoside-induced hearing loss (AIHL). An A-t o-G nucleotide substitution at the 1555 position within the 12S riboso mal RNA gene has been identified with a maternally inherited pattern i n affected Asian pedigrees. The aim of this study was to identify the frequency of this DNA polymorphism in subjects who appear to show hype rsensitivity to topical (middle ear) application of aminoglycoside. In this pilot study, 10 subjects with AIHL were recruited. Eight underwe nt vestibular ablative therapy with middle ear instillation of gentami cin for disabling vertigo, and two were treated with topical antibioti c drops for otitis media in the presence of a tympanic perforation. DN A samples were extracted and polymerase chain reaction (PCR) technique was used for gene amplification and purification, searching for 1555 A-to-G substitution in the 12S ribosomal RNA gene. None of the subject s demonstrated this specific mutation.