Genetic background of people in the Dominican Republic with or without obese type 2 diabetes revealed by mitochondrial DNA polymorphism
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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.
KeywordsMitochondrial DNA D-loop region Sequence polymorphism Dominican Republic Population structure
We thank the doctors in Dominican Republic, Casimiro Velazco, Gloris Moquete, Aracelys German, Ruben Dario Pimentel, Ivan Brugal, Modesto Cruz, and Sakae Magoshi for assistance with specimen collection; doctor Enrique Perezmella for specimen shipment; and doctors at Oita University, Yoichiro Kusuda, and Tsutomu Yamashita for their help. We also thank Ms. Naoko Anaguchi for technical assistance. This work was supported by Grants-in-Aid for Scientific Research 10045072 and 13576024 (to TS), 15406035 (to HY), and 14571102 (to KH) from the Ministry of Education, Culture, Sports, Science and Technology (1998), and the Japan Society for the Promotion of Science (1999–2004), Japan, and also supported in part by Grants-in-Aid (to HS) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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