Mitochondriale A1555G-Mutation: Molekulargenetische Diagnostik bei sporadischen Fällen nichtsyndromaler Schwerhörigkeit

Background. The A1555G mutation in mitochondrial DNA is the cause of hearing impairment in about 50% of all carriers. The severity and onset of this impairment is predominantly affected by the use of aminoglycosides. Patients and Methods. A total of 391 patients displaying sporadic, non-syndromic, mild to severe hearing impairment were analyzed for the A1555G mutation using molecular genetic methods. Results. We analysed additional family members of the two patients (0.5% of the total) who had the mutation. All maternal relatives carried the mutation, but only three individuals from the two families displayed a variable sensorineural hearing loss. Conclusion. The A1555G mutation is infrequently involved as a genetic cause of sporadic, non-syndromic hearing impairment. Nevertheless, based on the variable clinical outcome of hearing impairment and the possibility of preventive steps, a genetic test in this patient subgroup is indicated.