A Meta-Analysis of the Associations Between the ATP-Binding Cassette Transporter ABCA1 R219K (rs2230806) Polymorphism and the Risk of Type 2 Diabetes in Asians

Asians have relatively low insulin secretion capacity and readily develop type 2 diabetes mellitus (T2DM) when insulin resistant. For that reason, insufficient insulin secretion is critical factor for Asians at the early stage of T2DM. ATP-binding cassette transporter1 (ABCA1) is a membrane protein responsible for cholesterol efflux and its function is also important for secreting insulin in pancreatic β-cells. Given the importance of its role, different polymorphisms of ABCA1 gene might contribute differently to the development of T2DM. Here, we analyzed the association between a variant form of ABCA1 gene called rs2230806 and the prevalence of T2DM in a large sample size by pooling all of the case-control studies published. Relevant case-control studies were identified by searching PubMed, EMBASE, Cochrane Library, Korean scientific database, Chinese medical databases, and the Indian medical database. The association was evaluated using five genetic models such as the allelic (AG), recessive (RG), dominant (DG), homozygous (HMG), and heterozygous (HTG) genetic models. Heterogeneity of each genetic model was determined by the I test. A total of eight studies (7 published studies and one data set from the Korean Genetic Epidemiology Study) were eligible, satisfying Hardy-Weinberg equilibrium and included 2755 T2DM patients (case) and 16 635 nondiabetic subjects (control). All subjects in the studies were Asians. Each genetic model exhibited heterogeneity. In all genetic models, rs2230806 had a significant association with prevalence of T2DM: AG (OR=0.78, 95% CI: 0.61-0.98), RG (OR=0.72, 95% CI: 0.51-1.03), DG (OR=0.73, 95% CI: 0.55-0.97), HMG (OR=0.62, 95% CI: 0.41-0.96), and HTG (OR=0.78, 95% CI: 0.61-0.99). There was no single study that changed the overall effects in allelic genetic model with random effects. No publication bias existed in any models except the RG model. In conclusion, middle-aged and elderly adults with the minor allele of rs2230806 will have a lower risk of T2DM. This is the first meta-analysis to evaluate the association in Asians.