Influence of four polymorphisms in ABCA1 and PTGS2 genes on risk of Alzheimer's disease: a meta-analysis

We preformed this meta-analysis to investigate the influence of ABCA1 (ATP-binding cassette sub-family A member 1) rs2422493 (C-477T), rs1800977 (C-14T), rs2066718 (V771M), and PTGS2 (Prostaglandin-endoperoxide synthase 2) rs20417 (G-765C) polymorphisms on the risk of Alzheimer's disease (AD). Seventeen eligible case-control studies were acquired from PubMed, Embase, Alzgene, Chinese National Knowledge Infrastructure and Wanfang databases. The pooled odds ratios (ORs) with 95 % confidence intervals (95 % CI) were calculated to evaluate the association under five genetic models. Combined data indicated that ABCA1 rs2422493 polymorphism was statistically significant associated with increasing AD risk in three genetic models (allelic T vs C: OR = 1.12, 95 % CI: 1.01-1.24; homozygous TT vs CC: OR = 1.26, 95 % CI: 1.03-1.55; and recessive TT vs TC + CC: OR = 1.33, 95 % CI: 1.12-1.58) while no association was found between two other ABCA1 polymorphisms and AD susceptibility. Nevertheless, a further risk-stratification analysis showed that ApoE-epsilon 4 carriers with any ABCA1 polymorphism suffered a much higher probability to be AD patients. Meanwhile, PTGS2 rs20417 polymorphism was linked to decreasing AD risk with a P < 0.0001 in five genetic models (e.g., allelic C vs G: OR = 0.59, 95 % CI: 0.50-0.70; homozygous CC vs GG: OR = 0.31, 95 % CI: 0.18-0.52; and heterozygous CG vs GG: OR = 0.64, 95 % CI: 0.52-0.78). In summary, our meta-analysis results showed that ABCA1 rs2422493 polymorphism was a risk factor for AD while PTGS2 rs20417 variant showed a protective effect on AD risk. In addition, ABCA1 rs2066718 and rs1800977 polymorphisms might not contribute to AD susceptibility in general population, but they should play a role on AD development when interacted with ApoE-epsilon 4.