A meta-analysis was performed to evaluate the associations of uncoupling protein 2 (UCP2) gene polymorphisms (Ala55Val, 45-bp insertion/deletion, and -866G/A) with overweight and obesity. A total of 42 studies were included in our analysis. Pooled effect estimates and 95% confidential intervals of each polymorphism were calculated under different inherited models. Fixed or random effect model was selected based on the between-study heterogeneity evaluated with I(2) . Source of heterogeneity was explored by subgroup analysis and meta-regression analysis. Potential publication bias was assessed using funnel plot and Peters test. After excluding studies that deviated from the Hardy-Weinberg equilibrium, T allele of Ala55Val polymorphism was associated with an increased risk of overweight and obesity under recessive model in the overall (OR = 1.24, 95%CI = 1.06-1.45) and Asian (OR = 1.28, 95%CI = 1.06-1.55) populations; and A allele of -866G/A polymorphism had a protective effect on overweight and obesity, especially for European populations (dominant model: OR = 0.88, 95%CI = 0.81-0.96, co-dominant 1 model: OR = 0.89, 95%CI = 0.81-0.98, co-dominant 2 model: OR = 0.85, 95%CI = 0.74-0.94, additive model: OR = 0.88, 95%CI = 0.80-0.95, and allelic model: OR = 0.91, 95%CI = 0.86-0.97). No evidence was observed in the association of 45-bp insertion/deletion polymorphism with overweight and obesity susceptibility. We failed to fully explore the between-study heterogeneity regarding the association of Ala55Val polymorphism with overweight and obesity. Further studies are required to provide more convincing evidence.
Keywords: Adiposity; CI, confidence interval; FEM, fixed effect model; HWE, Hardy–Weinberg equilibrium; Meta-analysis; OR, odds ratio; Obesity; Polymorphism; REM, random effect model; UCP, uncoupling protein; Uncoupling protein.