We, therefore, limited our testing to SNPs within the interval between TOMM40 and APOC1 (which includes the APOE coding region, promoter, and 3’-UTR), whose allelic frequencies vary progressively by at least 5% across EastAs, EuroAs, and AAs and may modulate (and are most likely responsible for ethnic differences in) the effect of ε4 on AD risk. This evidence concerns the gene APOE and Alzheimer disease.