APOE and Alzheimer disease: The best proxy genotyped for the APOE ε4 AD-risk allele, rs2075650, located on chromosome 19 in the TOMM40 gene and 13kb upstream of APOE, was identified as a strong risk factor for PCA (OR 2.03, [95% CI = 1.68–2.46], P = 6 × 10−14, PGC = 3 × 10−13; Fig. 1 and Fig. 2A).