Contrary to the long-held view that most humans harbour only identical mitochondrial genomes, deep resequencing has uncovered unanticipated extreme genetic variation within mitochondrial DNA (mtDNA). Most, if not all, humans contain multiple mtDNA genotypes (heteroplasmy); specific patterns of variants accumulate in different tissues, including cancers, over time; and some variants are preferentially passed down or suppressed in the maternal germ line. These findings cast light on the origin and spread of mtDNA mutations at multiple scales, from the organelle to the human population, and challenge the conventional view that high percentages of a mutation are required before a new variant has functional consequences.

与大多数人只拥有相同的线粒体基因组的长期观点相反，深度重测序揭示了线粒体 DNA (mtDNA) 内意想不到的极端遗传变异。大多数（如果不是全部）人类包含多种 mtDNA 基因型（异质性）；随着时间的推移，特定的变异模式会在不同的组织中积累，包括癌症；并且一些变体优先在母系种系中传递或抑制。这些发现揭示了 mtDNA 突变在多个尺度上的起源和传播，从细胞器到人群，并挑战了传统观点，即在新变体产生功能性后果之前需要高百分比的突变。