Association between Apolipoprotein E Gene Polymorphism and Alzheimer's Disease in an Iranian Population: A Meta-Analysis

The development of Alzheimer's disease (AD) has been strongly linked to the apolipoprotein E (APOE) polymorphism. A number studies have reported that the APOE epsilon 4 allele is a genetic risk factor for developing AD, whereas the APOE epsilon 2 and APOE epsilon 3 alleles are considered to be neutral or even protective; however, there are conflicting data about these relationships in certain ethnic populations. Several meta-analyses have been performed to reduce the heterogeneity of results from different studies and estimate the real association in specific ethnicities. The aim of this study was to investigate the association between the APOE polymorphism and AD in an Iranian population. Our results showed a higher incidence of AD among individuals carrying the APOE epsilon 4 allele (OR = 4.81, 95% CI: 3.28-7.05), more notably in those with the APOE epsilon 4/e4 genotype (OR = 7.47, 95% CI: 2.35-23.73), while carrying the APOE epsilon 3 allele was demonstrated to have a protective effect (OR = 0.40, 95% CI: 0.30-0.54). The association between the APOE epsilon 2 allele and AD was not statically significant. However, further studies focusing on other parameters such as age, sex and environmental conditions are needed to reveal the true association between the APOE polymorphism and AD.