Association analysis of ApoE gene polymorphisms among Egyptian patients with Alzheimer's disease

Background: Alzheimer disease (AD) is one of the leading causes of dementia among elderly. It is a progressive brain disorder associated with unusual behaviors, personality changes, and irreversible decline in thinking ability. Epsilon 4 allele of apolipoprotein E (ApoE) is considered as a major risk factor for AD in several populations. Aim: We investigated APOE polymorphisms in a group of Egyptian patients with Alzheimer's disease. Subjects and methods: We analyzed APOE polymorphisms in 53 Alzheimer patients who were 60 years or older and the study included a control group of 100 individuals. For APOE genotyping, we used conventional PCRs followed by Restriction Fragment Length Polymorphism (RFLP) analysis. Additionally, we performed Real time PCR analysis to confirm the results of RFLP and apply a more accurate method that is fast, simple, and costeffective. Results: We observed that E4 allele was associated with 28.3% of Alzheimer patients as E3/E4 genotype (22.6%) and E4/E4 (17.0%), while we detected it in only 4% of the control group as E3/E4 genotype (8%). E3 allele has been shown in 69.8% of Alzheimer patients and in 93.5% of the control subjects. We have detected E2 allele in 18.9% of the cases and in 25% of the control group. RT-PCR analysis showed the exact patterns of genotype as determined by RFLP. Conclusion: There is a significant association between ApoE4 isomer and Alzheimer dementia in the Egyptian patients. We recommend conducting further studies to screen larger number of patients and confirm that ApoE4 could be considered as a reliable molecular marker for late onset Alzheimer disease (LOAD) among Egyptian elderly.