Abstract
Genetic variants, many of which are in mitochondrial DNA (mtDNA), contribute to hearing loss. Screening for these variants facilitates the identification of potential carriers, as many people with these mutations do not show hearing loss at birth but show late-onset hearing loss. We conducted a population-based cohort study involving 180,458 neonates born in Beijing, China. Hearing screening was performed through detailed counseling and systematic health assessment. The patient's peripheral blood was collected, and the variants was screened by next generation sequencing. An investigation of 142 probands and their matrilineal family members indicated a homoplasmic or heteroplasmic mtDNA mutation (adenine-to-guanine mutation at position 1555 in mtDNA 12S rRNA [A1555G] or cytosine-to-thymine mutation at position 1494 in mtDNA 12S rRNA) incidence of 0.227% (409 individuals). In total, 71.8% of the probands carried the homoplasmic A1555G mutation, 21.1% had the heteroplasmic A1555G mutation, and the remaining 7.1% had the homoplasmic cytosine-to-thymine mutation at position 1494 in mtDNA 12S rRNA mutation. A mtDNA haplotype analysis showed that 50.8% of the cases belonged to haplogroup D, the predominant haplotype in this Chinese population. Individuals with haplogroups B and M, which accounted for 10.7% and 9.0% of all cases, respectively, tended to have lower hearing thresholds at higher frequencies. We found no significant difference in the rate of hearing loss between vaccinated and unvaccinated individuals with mtDNA mutations, suggesting that the amounts of aminoglycoside antibiotics contained in vaccines were insufficient to induce hearing loss. This study reveals the incidence of mtDNA variants in the largest population studied to date and establishes that carriers of mtDNA variants can safely receive vaccines with no or low aminoglycoside antibiotic levels. This study provides a paradigm for studying the impact of these mtDNA variants on disease pathogenesis and the effects of mediation strategies.