Quantitative assessment of the influence of PPARG P12A polymorphism on gestational diabetes mellitus risk

The peroxisome proliferator-activated receptor-γ (PPARG) is a member of the nuclear hormone receptor superfamily that has attracted considerable attention as a candidate gene for gestational diabetes mellitus (GDM) based on its function as a key factor involved in the regulation of adipocyte differentiation as well as lipid and glucose metabolism and insulin sensitivity. Many studies have examined the association between P12A polymorphism (rs1801282) in the PPARG gene and risk of GDM, but the results have been inconsistent. To derive a more precise estimation of the relationship, a meta-analysis of 2,858 GDM patients and 6,890 controls from nine published case-control studies was performed. An overall random effects odds ratio of 0.89 (95 % confidence interval [CI]: 0.77-1.04, P = 0.15) was found for 12A allele. In the subgroup analysis by ethnicity, significantly decreased risks were found in East Asians, while no significant associations were detected among Caucasian and Middle Eastern populations. Similar results were also observed using dominant genetic model. This meta-analysis suggested an overall weak association between the P12A polymorphism and GDM risk among East Asians. However, additional very large-scale studies are warranted to provide conclusive evidence on the effects of the PPARG gene on risk of GDM.