A mitochondrial mutation responsible for antibiotic-induced ototoxicity and also causing nonsyndromic deafness was described by Prezant et al. (1993) in a large Arab kindred.  Members of this kindred who had a homoplasmic A1555G transition in the 12S rRNA gene had phenotypes ranging from profound hearing loss to completely normal hearing.  The mutation occurs in a site implicated in aminoglycoside activity by analogy to the evolutionarily related bacterial ribosome.

Abu-Amero and Bosley (2006) studied the molecular and biological characteristics of mitochondria in patients with Leber hereditary optic neuropathy (LHON)-like optic neuropathies.  Thirty five patients (21 males and 14 females) and 159 matched controls from Saudi Arabia were included in this study.  Forty one non-synonymous mtDNA sequence variants were identified in LHON patients; 14 were pathogenic.  Of these variants, 21 were in complex I, seven in complex III, five in complex IV, six in complex V, one in tRNA glutamine, and one in 12S rRNA.  Similar to previous reports on mutation association with LHON, these mtDNA changes were transitions.  One nonpathogenic variant (G1393A) was found in the MT-RNR1 gene.