Associations between CD33 rs3865444 and ABCA7 rs3764650 polymorphisms and susceptibility to Alzheimer's disease

Several studies have evaluated the association of Siglec-3(CD33) rs3865444 polymorphism and ATP-binding cassette transporter A7(ABCA7) rs3764650 polymorphism with susceptibility to Alzheimer's disease. However, these studies have yielded contradictory results. Therefore, to resolve this issue, a meta-analysis was undertaken to examine 12 previously published studies. The pooled effect of CD33 rs3865444 showed no significant relationship with susceptibility to Alzheimer's disease under various genetic models. The pooled effect of ABCA7 rs3764650 also lacked association with susceptibility to Alzheimer's disease in the allele model (p = 0.06, OR = 1.06, 95% CI, 1.00-1.13), while significant associations were revealed for the dominant model (p < 0.0001 OR = 1.20, 95% CI, 1.10-1.31), recessive model (p = 0.01, OR = 1.59, 95% CI, 1.12-2.28), and additive model (p = 0.003, OR = 1.44, 95% CI, 1.13-1.83). A subsequent meta-analysis revealed significant association of these models for Caucasians (dominant: p < 0.00001, OR = 1.28, 95% CI, 1.16-1.41; recessive: p = 0.002, OR = 1.96, 95% CI, 1.27-3.04; additive: p = 0.001, OR = 1.96, 95% CI, 1.30-2.94), contrary to what was demonstrated for Asians. Results of the present meta-analysis indicate that ABCA7 rs3764650 might increase the risk of Alzheimer's disease, particularly for older Caucasians.