The protein coding variant APOE ε4 (R112/R158; APOE4) allele increases AD risk while the APOE ε2 (C112/C158; APOE2) allele decreases AD risk when compared to the most common allele APOE ε3 (C112/R158; APOE3) [8, 9]. This evidence concerns the gene APOE and Alzheimer disease.