APOE and Alzheimer disease: For example, APOE e4 allele frequency varies across ethnicities, [e.g., 37% (14%) for AD cases (controls) in Caucasian, 32% (19%) for AD cases (controls) in African Americans, 19% (11%) for AD cases (controls) in Hispanic, and 28% (9%) for AD cases (controls) in Japanese] (Farrer et al., 1997).