Genetic background of people in the Dominican Republic with or without obese type 2 diabetes revealed by mitochondrial DNA polymorphism.

People in the Dominican Republic are considered to be genetically heterogeneous owing to the post-Colombian admixture of Native American, African, and European populations. To characterize their genetic background, nucleotide sequences of the D-loop region of human mitochondrial DNA (mtDNA) were examined in 33 healthy women and 50 gender-matched patients with obese type 2 diabetes (OD) from the Dominican Republic. Phylogenetic analysis of 198 mtDNA lineages including Native Americans, Africans, and Europeans enabled us to assess relative genetic contributions of the three ancestral fractions to the two groups in the Dominican Republic. In the OD group, the majority (64.0%) of the mtDNA lineages were from African ancestry, whereas the Native American fraction was predominant (51.5%) in the healthy group, with both showing smallest amounts (14.0% and 9.1%, respectively) of European contribution. This difference in maternal genetic background between the two groups was similarly demonstrated by phylogenetic analysis at the population level based on net nucleotide diversities between populations. These findings may imply ethnic-specific predisposition to OD, a possible association of an unidentified factor from African ancestry with OD in the Dominican Republic population.