Association Studies Between PPARγ2Prol2Ala/C161T Polymorphism And Obesity In The Hubei Han Chinese Population

BackgroundObesity has turned up as one of the major health concerns in the21st century and is one of the leading causes of preventable death. Although the recent increases in obesity are largely caused by dietary and lifestyle factors, a number of studies have indicated that some of the genes involved in pathways regulating energy expenditure and food intake play a role in the predisposition to obesity. Amongst these genes, sequence variations in the peroxisome proliferator-activated receptor (PPARγ2) genes are of particular relevance.ObjectivesThe purpose of the present study was to investigate the association of Pro12Ala and C161T polymorphisms in the PPAR-γ2gene with obesity in the Hubei Han Chinese population and to conduct a meta-analysis of all available published evidence.Materials and MethodsStudy subjects consist of642obese patients and499healthy controls. Clinical parameters measured included weight, height, waist, hip circumference, fasting blood Glucose,2hours’ postprandial blood glucose, systolic blood pressure and diastolic blood pressure, total cholesterol, triacylglycerol, HDL-cholesterol, LDL-cholesterol, and fasting insulin. A meta-analysis included twenty-four studies of the Pro12Ala polymorphism and five studies of C161T polymorphism with obesity.The C161T and Pro12Ala polymorphisms of the PPARγ2gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. The differences of genotype and allelic frequencies between obese patients and control groups were compared by Chi-square analysis. Logistic regression analysis was performed to evaluate the influence of the genotype and other variables on the risk of obesity. The differences of clinical characteristics between obese patients and control groups were compared by t-test. P<0.05was considered statistically significant. All statistical analyses were performed using SPSS11.5software for windows. In meta-analysis:Stata10.0software was used to evaluate the heterogeneity between studies. Pooled ORs were calculated using a random or fixed effects model according to the presence or absence of heterogeneity between studies, respectively. ResultsThere is no difference in A allele frequency between the cases (6.7%) and controls (5.1%) in Hubei Han Chinese population; however, in male subgroup, A allele frequencies in the cases (11%) is significantly higher than in controls (4%), For the PPARy2Pro12Ala polymorphism, twenty-four association studies of the Pro12Ala polymorphism with obesity were identified, In meta-analysis, the overall OR for the A allele was1.754(95%CI1.077-2.858, P=0.024) in Chinese populations,1.489(95%CI1.045-2.121, P=0.028) in East Asian populations, and1.301(95%CI1.109-1.527, P=0.001) in all populations. The frequencies of CC genotype and C allele in obese patients were significantly higher than those of controls group (CC:59.2%vs.48.3%, P=0.008; C:76.5%vs.69%, P=0.006) in our population. For the PPARy2C161T polymorphism, five association studies of the C161T polymorphism with obesity were identified, In meta-analysis, significant association was observed for CC+CT (OR=1.713,95%CI1.111-2.642, P=0.015), not for the C allele (OR=1.194,95%CI0.924-1.543, P=0.176).ConclusionsThe present study shows that the PPARy2C161T variant is significantly associated with obesity in the Hubei Han Chinese population. Meta-analysis demonstrated that PPAR y2C161T and Pro12Ala polymorphisms were reproducibly associated with obesity in the global populations.