The effect size of common MC4R polymorphism on obesity in children in this meta-analysis (OR = 1.26, 95%CI = 1.19–1.33) was similar with the initial observation in European children (OR = 1.30, 95%CI = 1.20–1.41) [7], but was significantly larger than that in adults in our study (OR = 1.15, 95%CI = 1.12–1.17) (since the 95%CIs of the former and latter ORs did not overlap). This evidence concerns the gene MC4R and obesity disorder.