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 PCRRFLP
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.