Fig. 7: Model for mtDNA dynamics in somatic lineages over a lifetime.

a, Schematic diagram illustrating the origin and dynamics of mtDNA alterations across a lifetime. Heteroplasmic variants in the fertilized egg and somatically acquired postzygotic mutations undergo drift in somatic lineages. Mutation and turnover rates (mitotic and homeostatic turnover rates) are shown at the top right. Stars indicate PZ_simple mutations. Bars on the left, middle and right depict clone-VAF distribution within the cell at different time points. b, A contour plot representing how an mtDNA population changes with continuous mitotic turnover from simulation studies assuming a baseline mtDNA copy number of 750. The x axis shows the mitotic turnover count and the y axis shows the frequency of the most prevalent mtDNA, regardless of mutations. c, A contour plot representing how clone-VAF of PZ_simple mtDNA mutations changes with continuous mitotic turnover from simulation studies assuming a baseline copy number of 750 and absolute mutation rate of 5.0 × 10⁻⁸ per bp replication. The x axis shows the mitotic turnover count and the y axis shows the top heteroplasmy level of postzygotic mutation.