Abstract
CONTEXT: Mitochondrial ATP production is important in the regulation of glucose-stimulated insulin secretion. Genetic factors may modulate the capacity of the β-cells to secrete insulin and thereby contribute to the risk of type 2 diabetes. OBJECTIVE: The aim of this study was to identify genetic loci in or adjacent to nuclear-encoded genes of the oxidative phosphorylation (OXPHOS) pathway that are associated with insulin secretion in vivo. DESIGN AND METHODS: To find polymorphisms associated with glucose-stimulated insulin secretion, data from a genome-wide association study (GWAS) of 1467 non-diabetic individuals, including the Diabetes Genetic Initiative (DGI), was examined. A total of 413 single nucleotide polymorphisms with a minor allele frequency ≥0.05 located in or adjacent to 76 OXPHOS genes were included in the DGI GWAS. A more extensive population-based study of 4323 non-diabetics, the PPP-Botnia, was used as a replication cohort. Insulinogenic index during an oral glucose tolerance test was used as a surrogate marker of glucose-stimulated insulin secretion. Multivariate linear regression analyses were used to test genotype-phenotype associations. RESULTS: Two common variants were identified in the DGI, where the major C-allele of rs606164, adjacent to NADH dehydrogenase (ubiquinone) 1 subunit C2 (NDUFC2), and the minor G-allele of rs1323070, adjacent to cytochrome c oxidase subunit VIIa polypeptide 2 (COX7A2), showed nominal associations with decreased glucose-stimulated insulin secretion (P=0.0009, respective P=0.003). These associations were replicated in PPP-Botnia (P=0.002 and P=0.05). CONCLUSION: Our study shows that genetic variation near genes involved in OXPHOS may influence glucose-stimulated insulin secretion in vivo.