Mitochondrial COX2 G7598A Mutation May Have a Modifying Role in the Phenotypic Manifestation of Aminoglycoside Antibiotic-Induced Deafness Associated with 12S rRNA A1555G Mutation in a Han Chinese Pedigree

Recent studies suggest that certain mitochondrial haplogroup markers and some specific variants in mitochondrial haplogroup may also influence the phenotypic expression of particular mitochondrial disorders. In this report, the clinical, genetic, and molecular characterization were identified in a Chinese pedigree with the aminoglycoside antibiotic (AmAn)-induced deafness and nonsyndromic hearing loss (NSHL). The pathogenic gene responsible for this hereditary NSHL pedigree was determined by Microarray chip, which possessed the nine NSHL hot-spot mutations, including GJB2 (35delG, 176dell6bp, 235de1C, and 299delAT), GJB3 (538C>T), SLC26A4 (IVS7-2A>G and 2168A>G), and mitochondrial DNA (mtDNA) 12S rRNA (C1494T and A1555G). Only the homoplasmic A1555G mutation was detected, which was confirmed by direct sequencing. Also, real-time amplification refractory mutation system quantitative polymerase chain reaction methodology was performed to calculate the A1555G mutation load. The proband's complete mtDNA genom...