Apolipoprotein E ϵ4 Allele and Familial Aggregation of Alzheimer Disease

Abstract
APOLIPOPROTEIN E (apoE) genotype is a major risk factor for Alzheimer disease (AD). Numerous studies have reported an association between the apoE ϵ4 allele and late-1 and early-onset AD.2,3 A dose-related effect of the apoE ϵ4 allele has been suggested,4-8 but not in a limited number of series of patients who had early-onset AD or who were nonwhite.2,9-11 Results of Kaplan-Meier analyses suggested a decrease in age of onset of disease ranging from 8 to 16 years4,12,13 when the number of ϵ4 alleles increased from 0 to 2.