APOE and Alzheimer disease: Paradoxically, several studies suggest that apolipoprotein E ε4 allele (APOE4), considered the strongest genetic risk factor for late-onset AD, has a weaker effect in Blacks than in Whites [4, 5] or that the effect of APOE4 on AD risk is attenuated in African ancestry (AFR), especially when the APOE gene is on a local African ancestry [6–8].