Association Between ABCA1 R219K Variant and Alzheimer's Disease: An Updated Meta-Analysis and Systematic Review

Background: Over a dozen studies have investigated the effect of the R219K variant in the ATP-binding cassette transporter A1 (ABCA1) gene on the risk of Alzheimer's disease (AD), but the results are conflicting. Objective: We performed a systematic review and meta-analysis to comprehensively assess the association between the ABCA1 R219K variant and the risk of AD. Methods: Studies included in the meta-analysis were obtained by searching PubMed, Web of Science and AlzGene. Review Manager 5.4 was used for meta-analysis. Both the odds ratio (OR) and its 95% confidence interval (CI) were used to evaluate the effect of ABCA1 R219K polymorphism on AD susceptibility. Heterogeneity between the included studies was assessed using I2 statistics and Cochran Qtest. Funnel plots were used to assess publication bias. Results: A total of 14 eligible studies involving 10084 subjects were retrieved from PubMed, Web of Science and AlzGene. Meta-analysis results showed that R219K polymorphism was significantly associated with a decreased risk of AD in Chinese under a recessive model (OR = 0.67; 95% CI = 0.51- 0.88; P = 0.004). Conclusion: The present meta-analysis indicated that the KK genotype of R219K polymorphism may act as a protective factor for AD in the Chinese population. Additional studies with larger sample sizes are needed to further confirm this association.