A local focus of accumulation of the mitochondrial form of hearing loss in eveno-bytantaisky disctrict of yakutia

Previously, the m.1555A>G mutation in the MT-RNR1 gene associated with the mitochondrial form of hearing loss was detected in one patient from Eveno-Bytantaisky district of Yakutia. The aim of this work is to study the mitochondrial form of hearing loss in this region of Yakutia, which probably has a local focus of accumulation of the m.1555A>G mutation in the MT-RNR1 gene. In the work, a clinical-genealogical, clinical-audiological and molecular-genetic examination of 72 residents of Eveno-Bytantaisky district was carried out for the presence of the m.1555A>G mutation in the MT-RNR1 gene of mitochondrial DNA. As a result of molecular genetic analysis, among the examined individuals, the m.1555A>G mutation was found in 6 people. Clinical and genealogical analysis, carried out up to the fifth generation, revealed that these six individuals belong to three families (including 25 deaf people). In the examined individuals with the m.1555A>G mutation of the MT-RNR1 gene, clinical phenotype variability was revealed - from normal hearing to bilateral hearing loss of III degree, with a late debut (onset from 30 to 60 years). The revealed variability is probably due to incomplete penetrance and requires further extensive research aimed at searching for genes that modulate nuclear or mitochondrial genomes.