Association of adiponectin gene (ADIPOQ) rs2241766 polymorphism with obesity in adults: a meta-analysis

Abstract

Background: Adiponectin plays an important role in regulating glucose levels and fatty acid oxidation. Multiple studies have assessed the association between rs2241766 polymorphism in the adiponectin (ADIPOQ) gene and obesity susceptibility. However, the results are inconsistent and inconclusive. The aim of this meta-analysis was to investigate this association in adults.

Method: Several electronic databases were searched for relevant literature published up to November 2013. Statistical analyses were performed using software Review Manager (Version 5.02) and STATA (Version 10.0). The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with a random-effects model or a fixed-effect model depending on heterogeneity among studies. Q tests and Egger's tests were performed to assess heterogeneity and publication bias. Sensitivity analysis was conducted to confirm the reliability and stability of the meta-analysis.

Results: A total of 2,819 obese and 3,024 controls in 18 case-control studies were included in the meta-analysis. The results indicated that compared with TT genotype, the ADIPOQ-rs2241766 GG genotype was associated with an increased risk for obesity (OR = 1.39, 95% CI: 1.11-1.73, P for heterogeneity = 0.520, I2 = 0%) in overall studies. Whereas, GT genotype was associated with a borderland increased risk for obesity (OR = 1.13, 95% CI: 0.94-1.36, P for heterogeneity = 0.006, I2 = 51%). The susceptibility of obesity was increased based on genotypes of TT<GT<GG (P for trend = 0.011). Subgroup analysis of different regions revealed that the ADIPOQ-rs2241766 GG genotype increased obesity risk in the Chinese studies (OR = 1.54, 95% CI: 1.19-2.00) but not in the non-Chinese studies (OR = 1.02, 95% CI: 0.66-1.58). Similar results were observed in allelic, recessive, and dominant genetic models. There was no significant evidence of publication bias in the overall, Chinese, and non-Chinese studies (P = 0.426, P = 0.935, and P = 0.390, respectively).

Conclusion: The results of this meta-analysis suggest that the ADIPOQ-rs2241766 G/T polymorphism might be associated with obesity in Chinese studies but not in non-Chinese studies in adults. Better-designed studies that consider confounding factors and assess larger sample sizes with a focus on ADIPOQ-rs2241766G/T polymorphisms and obesity are required in the future.

Figure 1. Flow diagram of eligible study selection.

Figure 2. Forest plots regarding the association of ADIPOQ-rs2241766 G/T polymorphism with obesity (GG vs. TT).

(A) in all studies; (B) in Chinese studies; (C) in non-Chinese studies. Studies are listed individually. The OR is presented graphically by a square box to indicate the point estimate and the lines on each side indicate the 95% CI. Box sizes are proportional to inverse-variance weights. This graph is centered by OR = 1 (equivalent to a finding without effect), Points at the right and left of the center line indicate OR>1 and OR<1, respectively.

Figure 3. Egger’s funnel plot analyses to detect publication bias (GG vs. TT of ADIPOQ-rs2241766 G/T polymorphism).

(A) All studies, (B) Chinese studies, and (C) non-Chinese studies. Each point represents a separate study included in this meta-analysis. s.e: standardized effect.