Mitochondrial DNA coding and control region variants as genetic risk factors for type 2 diabetes.

Both the coding and control regions of mitochondrial DNA (mtDNA) play roles in the generation of diabetes; however, no studies have thoroughly reported on the combined diabetogenic effects of variants in the two regions. We determined the mitochondrial haplogroup and the mtDNA sequence of the control region in 859 subjects with diabetes and 1,151 normoglycemic control subjects. Full-length mtDNA sequences were conducted in 40 subjects harboring specific diabetes-related haplogroups. Multivariate logistic regression analysis with adjustment for age, sex, and BMI revealed that subjects harboring the mitochondrial haplogroup B4 have significant association with diabetes (DM) (odds ratio [OR], 1.54 [95% CI 1.18-2.02]; P < 0.001), whereas subjects harboring D4 have borderline resistance against DM generation (0.68 [0.49-0.94]; P = 0.02). Upon further study, we identified an mtDNA composite group susceptible to DM generation consisting of a 10398A allele at the coding region and a polycytosine variant at nucleotide pair 16184-16193 of the control region, as well as a resistant group consisting of C5178A, A10398G, and T152C variants. The OR for susceptible group is 1.31 (95% CI 1.04-1.67; P = 0.024) and for the resistant group is 0.48 (0.31-0.75; P = 0.001). Our study found that mtDNA variants in the coding and control regions can have combined effects influencing diabetes generation.