Mutations in mitochondrial 12S rRNA gene are one of the most important causes of aminoglycoside-induced and nonsyndromic hearing loss. Here we report the characterization of one Han Chinese pedigree with aminoglycosid...Mutations in mitochondrial 12S rRNA gene are one of the most important causes of aminoglycoside-induced and nonsyndromic hearing loss. Here we report the characterization of one Han Chinese pedigree with aminoglycoside-induced and nonsyndromic hearing loss. This Chinese family carrying the 12S rRNA A1555G mutation exhibited high penetrance and expressivity of heating impairment. In particular, penetrances of hearing loss in this family pedigree were 43.8% and 25%, respectively, when aminoglycoside-induced heating loss was included or excluded. Mutational analysis of entire mitochondrial genomes in this family showed the homoplasmic A1555G mutation and a set of variants belonging to haplogroup Y2. Of these, the A14693G variant occurred at the extremely conserved nucleotide （conventional position 54） of the TψC-loop of tRNA^Clu and was absent in 156 Chinese controls. Nucleotides at position 54 of tRNAs are often modified, thereby contributing to the structural formation and stabilization of functional tRNAs. Thus, the structural alteration of tRNA by the A14693G variant may lead to a failure in tRNA metabolism and impair mitochondrial protein synthesis, thereby worsening mitochondrial dysfunctions altered by the A1555G mutation. Therefore, the tRNA^Glu A14693G variant may have a potential modifier role in increasing the penetrance and expressivity of the deafness-associated A1555G mutation in this Chinese pedigree.展开更多
基金supported by the Public Health Service grants (No. RO1DC05230 and RO1DC07696) from the National Institute on Deafness and Other Communication Disordersgrants from the National Basic Research Priorities Program of China (No. 2004CCA02200)the Ministry of Science and Technology of Zhejiang Province (No. 2007G50G2090026)
文摘Mutations in mitochondrial 12S rRNA gene are one of the most important causes of aminoglycoside-induced and nonsyndromic hearing loss. Here we report the characterization of one Han Chinese pedigree with aminoglycoside-induced and nonsyndromic hearing loss. This Chinese family carrying the 12S rRNA A1555G mutation exhibited high penetrance and expressivity of heating impairment. In particular, penetrances of hearing loss in this family pedigree were 43.8% and 25%, respectively, when aminoglycoside-induced heating loss was included or excluded. Mutational analysis of entire mitochondrial genomes in this family showed the homoplasmic A1555G mutation and a set of variants belonging to haplogroup Y2. Of these, the A14693G variant occurred at the extremely conserved nucleotide （conventional position 54） of the TψC-loop of tRNA^Clu and was absent in 156 Chinese controls. Nucleotides at position 54 of tRNAs are often modified, thereby contributing to the structural formation and stabilization of functional tRNAs. Thus, the structural alteration of tRNA by the A14693G variant may lead to a failure in tRNA metabolism and impair mitochondrial protein synthesis, thereby worsening mitochondrial dysfunctions altered by the A1555G mutation. Therefore, the tRNA^Glu A14693G variant may have a potential modifier role in increasing the penetrance and expressivity of the deafness-associated A1555G mutation in this Chinese pedigree.
