Fig. 2: Characteristics of mtDNA heteroplasmic variants detected through the bulk analysis of 146 fibroblast cell lines and 141 derived iPSC lines.

a Distribution of the mean number of heteroplasmies defined in fibroblast and iPS cell lines. b Correlation of the mean number of heteroplasmies per fibroblast cell line with the donor’s age. Shaded regions show mean ± standard deviation (s.d.). c Correlation of the mean number of heteroplasmies per fibroblast cell line in each mtDNA region with the donor’s age. Shaded regions show mean ± s.d. d Distribution of the average heteroplasmy fraction (HF) in fibroblast and iPS cell lines. e Correlation of the average HF per fibroblast cell line with the donor’s age. Shaded regions show mean ± s.d. f Correlation of the average HF per fibroblast cell line in each mtDNA region with the donor’s age. Shaded regions show mean ± s.d. g Heteroplasmies defined in fibroblast (top) and iPS cell lines (bottom). HFs are shown on the left y axis. mtDNA regions covered by different colours. The depth of the shading represents the mutation rate of each mtDNA region (shown on the right side of y axis). Three fibroblast-specific mutations are highlighted in red rectangles. The regions were significantly enriched mutations than expected by chance were labelled by asterisks. h Frequency of specific mutations in fibroblast and iPS cell lines. i The fibroblast-specific mutation 414G was associated with the donor’s age. j Distribution of heteroplasmies defined in fibroblast and iPS cell lines. k Distribution of heteroplasmies defined in fibroblast and iPS cell lines, two iPSC lines derived from the same fibroblast cell line are shown separately. l Ratio of non-synonymous/synonymous variants (NS/SS) observed in fibroblasts, iPSCs and iPSC-specific variants. m Distribution of the mtDNA copy number in fibroblast and iPS cell lines. n Distribution of the heteroplasmy fraction in fibroblast and iPS cell lines. Red lines show the mean HFs within each dataset. a, d P values were calculated using two-sided Wilcoxon test. Source data are provided as a Source Data file. b, c, f P values were calculated using linear regression model. g P values were calculated using two-sided Fisher’s exact test.