title: Molecular and clinical characterization of the variable phenotype in Korean families with hearing loss associated with the mitochondrial A1555G mutation.
abstract: Hearing loss, which is genetically heterogeneous, can be caused by mutations in the mitochondrial DNA (mtDNA). The A1555G mutation of the 12S ribosomal RNA (rRNA) gene in the mtDNA has been associated with both aminoglycoside-induced and non-syndromic hearing loss in many ethnic populations. Here, we report for the first time the clinical and genetic characterization of nine Korean pedigrees with aminoglycoside-induced and non-syndromic hearing loss. These Korean families carry in the A1555G mutation of 12S rRNA gene and exhibit variable penetrance and expressivity of hearing loss. Specifically, the penetrance of hearing loss in these families ranged between 28.6% and 75%, with an average of 60.8%. These results were higher than the 29.8% penetrance that was previously reported in a Chinese population but similar to the 65.4% and 54.1% penetrance observed in a large Arab-Israeli population and nineteen Spanish pedigrees, respectively. The mutational analysis of the complete mtDNA genome in these families showed that the haplogroups of the Korean population, which belongs to the eastern Asian population, were similar to those of the Chinese population but different from the Spanish population, which belongs to the European-Caucasian population. The mtDNA variants that may act as modifier factors were also found to be similar to the Chinese population. Although the mtDNA haplogroups and variants were similar to the eastern Asian population, we did find some differing phenotypes, although some subjects had the same variants. This result suggests that both the ethnic background and environmental factors lead to a variable phenotype of the A1555G mutation.
authors.affiliation: Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.
authors.forename: Jae Woong
authors.initials: JW
authors.lastname: Bae
authors.forename: Dong-Bin
authors.initials: DB
authors.lastname: Kim
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Hong-Joon
authors.initials: HJ
authors.lastname: Park
authors.forename: Jong Dae
authors.initials: JD
authors.lastname: Lee
authors.forename: Dong Gu
authors.initials: DG
authors.lastname: Hur
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Bae
authors.forename: Da Jung
authors.initials: DJ
authors.lastname: Jung
authors.forename: Sang Heun
authors.initials: SH
authors.lastname: Lee
authors.forename: Un-Kyung
authors.initials: UK
authors.lastname: Kim
authors.forename: Kyu Yup
authors.initials: KY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001483:Base Sequence; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease; D054629:Genome, Mitochondrial / Q000235:genetics; D006239:Haplotypes / Q000235:genetics; D034381:Hearing Loss / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D012335:RNA, Ribosomal / Q000235:genetics*; D056910:Republic of Korea; D012359:tRNA Methyltransferases / Q000235:genetics
chemical_list: D017630:Connexins; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S; D000072259:Connexin 26; D012359:tRNA Methyltransferases; C496706:TRMU protein, human