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[Non-syndromic familial hearing impairment transmitted by mitochondrial inheritance]
C Morales Angulo1, I Del Castillo, M Sarduy
1Servicio de ORL, Hospital Sierrallana, Torrelavega (Santander).
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.