This article reports on a project in which Instances of point and length heteroplasmy in the mitochondrial DNA control region were compiled and analyzed from over 5,000 global human population samples.
These data represent observations from a large and broad population sample, representing nearly 20 global populations. As expected, length heteroplasmy was frequently observed in the HVI, HVII and HVIII C-stretches. Length heteroplasmy was also observed in the AC dinucleotide repeat region, as well as other locations. Point heteroplasmy was detected in approximately 6 percent of all samples, and although the vast majority of heteroplasmic samples comprised two molecules differing at a single position, samples that exhibited two and three mixed positions were also observed in this data set. In general, the sites at which heteroplasmy was most often observed correlated with reported control region mutational hotspots; however, for some sites, observations of heteroplasmy did not mirror established mutation rate data, suggesting the action of other mechanisms, both selective and neutral. Interestingly, these data indicate that the frequency of heteroplasmy differs between populations, perhaps reflecting variable mutation rates among different mtDNA lineages and/or artifacts of particular population groups. The results presented here contribute to a general understanding of mitochondrial DNA control region heteroplasmy and provide additional empirical information on the mechanisms contributing to mtDNA control region mutation and evolution. (publisher abstract modified)