Objectives: We investigated mitochondrial DNA 12S rRNA (MTRNR1) gene mutations as a cause of hearing loss in probands with or without a history of aminoglycoside use.
Patients and methods: The study included 70 patients (40 females, 30 males; age range 3 to 42 years) with nonsyndromic sensorineural hearing loss. Eleven probands had a history of aminoglycoside use before the onset of hearing loss. All cases were first screened and found to be negative for the GJB2 (connexin 26) gene mutations. The m.1555A>G mutation was screened using the PCR-RFLP technique. The entire 12S rRNA gene was later screened with the PCR-TTGE technique followed by direct sequencing.
Results: Of 11 patients with a history of aminoglycoside use, one patient was found to have the m.1555A>G mutation. Two probands with no history of aminoglycoside use exhibited the m.750A>G polymorphism. No pathogenic base substitutions were detected in the remaining patients.
Conclusion: Apart from the common aminoglycoside ototoxicity-related DNA change, m.1555A>G, we could not identify a common mitochondrial 12S rRNA mutation associated with hearing loss in Turkey. Screening of larger series may document rare alterations.