Fig. 2: Distribution of heteroplasmy.

A Distribution of heteroplasmy counts (MHC) in study participants (n = 10,986) across the double-stranded mitochondrial DNA (mtDNA) molecule, following quality control procedures (see Methods). Heteroplasmic variants were identified at 2264 unique sites across the mtDNA genome, with each site occurring in less than 1% of participants in the combined sample (Supplementary Data 3). Pink regions indicate the D-loop regions. Blue regions indicate the 13 protein-coding genes. B Distribution of MHC and mitochondrial local constraint score sum (MSS) score across the study participants. MHC represents the total number of heteroplasmic variants in an individual, while MSS reflects the predicted deleteriousness and functional impact of these variants. Approximately 32.4% of participants carried at least one heteroplasmic variant. Among all participants, 12.4% had MSS values between 0.01 and 0.25, 4.4% had values between 0.251 and 0.5, and 7.9% had MSS values greater than 0.5. C The distribution of MHC across age groups indicates a trend of increasing MHC levels with advancing age.