Genetic and clinical features of sensorineural hearing loss associated with the 1555 mitochondrial mutation

Abstract

Mitochondrial mutations are known to be one of the causes of non-syndromic sensorineural hearing loss (SNHL). Of these mutations, a 1555A→G mutation has been reported to cause susceptibility to aminoglycoside antibiotics. The pedigrees shown in this study revealed maternal inheritance exclusively of the hearing impairment, consistent with the hypothesis of a mitochondrial inheritance. Although the hearing loss found in these patients sharing the 1555 mutation exhibited individual variation, there were some common features. Many subjects who harbor this mitochondrial mutation exhibited mild, high frequency, progressive hearing loss even without aminoglycoside injections. Regardless of aminoglycoside exposure, the hearing loss was usually associated with permanent tinnitus. Most of our patients had no history of vestibular dysfunction, such as dizziness and/or vertigo. The results presented here support the hypothesis that the A1555G mutation may play a more general role in causing hearing loss. This indicates the necessity for widespread screening of this mutation in the general population.