Implications of critical PPARγ2, ADIPOQ and FTO gene polymorphisms in type 2 diabetes and obesity-mediated susceptibility to type 2 diabetes in an Indian population

Peroxisome proliferator-activated receptors (PPARγ), adiponectin (ADIPOQ) and fat mass and obesity-associated gene (FTO) have been reported as a key candidate genes for obesity, type 2 diabetes (T2D) susceptibility and insulin resistance, and we hypothesize that in the background of obesity, the effect of PPARγ2 (rs1801282), ADIPOQ (rs16861194) and FTO (rs9939609) variant could potentially influence T2D susceptibility. To decipher a more accurate estimation toward its population-specific impact of these variants toward susceptibility to T2D, a case-control study, systematic review and a meta-analysis was performed in a South Asian population. A case-control analysis of 518 T2D cases and 518 controls of Karnataka origin were performed to analyze the association of PPARγ2 (rs1801282), ADIPOQ (rs16861194) and FTO (rs9939609) on the risk of T2D. In addition, a systematic review and meta-analysis for PPARγ2 (rs1801282) and FTO (rs9939609) was elucidated from Asian population. Our investigation showed that PPARγ2 (rs1801282) and FTO (rs9939609) are associated with T2D susceptibility. When T2D cohort was further stratified according to the obesity status, PPARγ2 (rs1801282) and FTO (rs9939609) showed association with T2D only in the obese diabetic group and ADIPOQ (rs16861194) showed no difference in risk of susceptibility to the disease. The meta-analysis of PPARγ2 (rs1801282) showed population-specific association for T2D susceptibility as opposed to FTO (rs9939609) which showed no difference in population effect toward T2D susceptibility. In conclusion, our study showed that PPARγ2 (rs1801282) and FTO (rs9939609) variants are associated with T2D susceptibility when associated with adiposity in Indian population.