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Prevalence and Clinical Characteristics of Mitochondrial DNA Mutations in Korean Patients With Sensorineural Hearing
Sun Young Joo1,2, Seung Hyun Jang1,2, Jung Ah Kim1,2
1Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Korea.
Background:
Mutations in mitochondrial DNA (mtDNA) are associated with several genetic disorders, including sensorineural hearing loss. However, the prevalence of mtDNA mutations in a large cohort of Korean patients with hearing loss has not yet been investigated. Thus, this study aimed to investigate the frequency of mtDNA mutations in a cohort of with pre- or post-lingual hearing loss of varying severity.
Methods:
A total of 711 Korean families involving 1,099 individuals were evaluated. Six mitochondrial variants associated with deafness (MTRNR1 m.1555A>G, MTTL1 m.3243A>G, MTCO1 m.7444G>A and m.7445A>G, and MTTS1 m.7471dupC and m.7511T>C) were screened using restriction fragment length polymorphism. The prevalence of the six variants was also analyzed in a large control dataset using whole-genome sequencing data from 4,534 Korean individuals with unknown hearing phenotype.
Results:
Overall, 12 of the 711 (1.7%) patients with hearing loss had mtDNA variants, with 10 patients from independent families positive for the MTRNR1 m.1555A>G mutation and 2 patients positive for the MTCO1 m.7444G>A mutation. The clinical characteristics of patients with the mtDNA variants were characterized by post-lingual progressive hearing loss due to the m.1555A>G variant (9 of 472; 1.9%). In addition, 18/4,534 (0.4%) of the Korean population have mitochondrial variants associated with hearing loss, predominantly the m.1555A>G variant.
Conclusion:
A significant proportion of Korean patients with hearing loss is affected by the mtDNA variants, with the m.1555A>G variant being the most prevalent. These results clarify the genetic basis of hearing loss in the Korean population and emphasize the need for genetic testing for mtDNA variants.
