Association of apolipoprotein E polymorphism with plasma lipids and Alzheimer's disease in a Southern Brazilian population

Apolipoprotein E (protein: apo E; gene: APOE) plays an important role in th e multifactorial etiology of both Alzheimer's disease (AD) and lipid level concentrations. The polymerase chain reaction (PCR) was used to investigate the APOE gene polymorphism in 446 unrelated Caucasians, among them 23 AD p atients, and 100 Afro-Brazilians living in Porto Alegre, Brazil. The freque ncies of the APOE*2, APOE*3 and APOE*4 alleles were 0.075, 0.810 and 0.115 in Caucasians and 0.075, 0.700 and 0.225 in Afro-Brazilians, respectively ( chi(2) = 8.72, P = 0.013). A highly significant association was observed be tween the APOE*4 allele and AD in this population-based sample. The APOE*4 frequency in AD patients (39%) was about four times higher than in the gene ral Caucasian population (11.5%). The influence of each of the three common APOE alleles on lipid traits was evaluated by the use of the average exces s statistic. The E*2 allele is associated with lower levels of triglyceride s and of total and non-HDL cholesterol in both men and women. Conversely, t he E*4 allele is associated with higher levels of these traits in women onl y. The effect of APOE alleles was of greater magnitude in women.