A meta-analysis of Alzheimer's disease's relationship with human ApoE gene variants

Purpose: To explore the association between Alzheimer's disease and apolipoprotein E (ApoE). Studies on this relationship are plentiful, but they mostly suffer from the disadvantage of inadequate sample size, so we conducted this meta-analysis to assess the association between ApoE polymorphisms and AD in humans. Method: The research literature centered on the association between Alzheimer's disease and ApoE polymorphisms was searched using databases including EMBASE, CQVIP, Medline, Web of knowledge, PubMed, Cochrane Library, CNKI, and Wanfang Data up to July 2020. The quality of the included literature was assessed using the NOS scale. We used RevMan 5.3 statistical software for the data extraction and meta-analysis. Results: A total of 569 studies were retrieved according to the search strategy and the inclusion criteria. After removing the duplicate studies and studies that did not match the topic, 155 studies were obtained. 39 publications were finally included according to the inclusion and exclusion criteria. Five of them were selected for the meta-analysis after a careful evaluation. Conclusion: Patients with Alzheimer's disease have a high positive rate of the epsilon 4 allele (OR = 2.19, 95% CI: 1.38-3.48) and a low positive rate of the epsilon 3 allele, but there is no significant association between the ApoE epsilon 2 allele and AD (OR = 0.71, 95% CI: 0.19-2.58). The positivity rates of the epsilon 4/epsilon 4 and epsilon 3/epsilon 4 genotypes were higher in the case group (OR = 3.82, 95% CI: 1.86-7.84; OR = 2.07, 95% CI: 1.40-3.06), but the positivity rates of the epsilon 2/epsilon 3 and epsilon 3/epsilon 3 genotypes were significantly lower in the case group than in the control group (OR = 0.62, 95% CI: 0.18-2.11; OR = 0.52, 95% CI: 0.36-0.75).