APOE Polymorphism And Susceptibility To Dementia Of The Alzheimer's Type In The Indian Population

Objective: The study aimed at the estimation of the prevalence of APOE polymorphism among Indians suffering from dementia of the Alzheimer's type and its association with disease risk as compared to the non-demented individuals. Another aim was to generate baseline data for future studies, as no study is available for those from Indian race/ethnicity. Methods: The APOE genotypes of 100 patients with Alzheimer's Disease (AD) and 36 age-matched controls were determined by isotyping the polymorphic region from genomic DNA. PCR amplified APOE DNA fragment of 244 bp was digested with HhaI and fragments were analyzed on 15% PAGE. Results: The allele and genotype frequencies were found to be significantly higher in AD patients as compared to the controls and the E4 allele was found to affect the risk of the disease in a dose-dependent manner. The frequency of the E4 allele was significantly increased in the patient group (0.47) as compared to age-matched controls (0.13). More pronounced effects were observed in genotype comparison. Conclusions: The effect of APOE E4 was dosage dependent and the risk of AD in individuals with the E4E4 genotype was 20-fold greater than in individuals with the E3E4 genotype (10-fold), as compared to the E3E3 genotype. The risk was higher even after adjusting for age and sex. The E4 allele is an allele for developing AD in Indians.