[Non-syndromic familial hearing impairment transmitted by mitochondrial inheritance].

OBJECTIVE

To determine the clinical features and mode of inheritance of hearing impairment observed in several members of a Spanish family with putative genetic susceptibility to ototoxicity induced by aminoglycoside antibiotics.

MATERIALS AND

METHODS

In 14 patients belonging to the same family, an interview, otological examination and audiometry were carried out. Three of these patients also underwent a study of brainstem auditory-evoked potentials. A genetic study was made of 11 patients and 9 unaffected relatives to determine the mode of inheritance of the hearing impairment and to detect associated mutations.

RESULTS

Most of the patients developed hearing loss before the age of 8 years, particularly for high frequencies. In almost all of them, there was no further evolution. Six patients had previous exposure to ototoxic drugs. Three patients had sudden hearing loss. In 2 of the 3 patients examined for brainstem auditory-evoked potentials, the hearing impairment was of cochlear origin. The genetic study detected A1555G mutation in the mitochondrial DNA of all the maternal relatives studied.

CONCLUSIONS

Mitochondrially-inherited sensorineural hearing loss should be suspected in families with a maternal transmission of the disorder and more than one relative with aminoglycoside-induced hearing loss.