Compared to the general population, individuals heterozygous for APOE4 have a ∼3-fold higher risk of developing AD, and homozygous APOE4 individuals have a ∼15-fold increased risk (Chartier-Harlin et al., 1994; Farrer et al., 1997; Kloske and Wilcock, 2020). This evidence concerns the gene APOE and Alzheimer disease.