Complete mtDNA genomes reveal similar penetrances of maternally inherited type 2 diabetes in two Chinese families.

Previous work suggests that mitochondrial DNA (mtDNA) derived from the maternal genome has a close affinity with type 2 diabetes. This would support a familial pattern for type 2 diabetes. Thereby, we analyzed complete mtDNA genomes from two families, A and B, from Southwest China that demonstrated maternally inherited type 2 diabetes. Our data support that mtDNA lineages from families A and B belong to haplogroups A4 and D4h1, respectively. This suggests that maternally inherited type 2 diabetes with similar penetrances can arise in Chinese individuals with strikingly different maternal genetic backgrounds. Two private coding region mutations (G13759A in MT-ND5 and G15930A in tRNA-Thr) were identified in family B. Further evolutionary and phylogenetic analyses suggest that both these mutations have multiple origins and are unlikely to be disease causing.