Functional polymorphism of hOGG1 gene is associated with type 2 diabetes mellitus in Chinese population.

hOGG1 protein excises the 8-hydroxy-2'-deoxyguanine (8-OHdG) which is associated with type 2 diabetes mellitus (T2DM). Our aim of this work is to explore whether the polymorphisms of hOGG1 gene are associated with T2DM. We screened the polymorphisms in the 5'-UTR (c.-18G>T, c.-23A>G, c.-45G>A and c.-53G>C) and c.977C>G (Ser326Cys) in exon 7 of hOGG1 gene. A case-control study indicated that c.-23A/G heterozygote was markedly associated with diabetes (P=0.004, OR=2.648, 95%CI=1.355-5.176) and with an increased level of C-peptide (705.00 versus 545.91 pmol/L, P=0.044). Furthermore, a significantly increased risk of T2DM was observed in the subjects carrying heterozygous variant of c.-23A>G and homozygous mutation of Ser326Cys (OR=3.684, 95%CI=1.400-9.697). The promoter activity of the variant allele c.-23G decreased 30-40% in Hela and HEK293 cell lines. In conclusion, the variant c.-23A>G of hOGG1 gene could decrease the gene promoter activity and was a risk factor for T2DM.