The results of the meta-analysis of AD genotype showed that ApoE ε2/ε4 (OR 1.521, 95% CI [1.270–1.823], P < 0.001), ε3/ε4 (OR 2.491, 95% CI [2.267–2.738], P < 0.001) and ε4/ε4 (OR 5.481, 95% CI [4.801–6.257], P < 0.001) allele genotype frequencies were higher than those of the healthy controls. This evidence concerns the gene APOE and Alzheimer disease.