In the single common variant association test, four COL4A1 variants were nominally associated with AD risk after the adjustment of age, gender, and APOE ε4 status, including rs874203 (p = 1.80 × 10−2), rs874204 (p = 1.84 × 10−2), rs16975492 (p = 2.34 × 10−2), and rs1373744 (p = 3.05 × 10−2) (Table 2). This evidence concerns the gene APOE and Alzheimer disease.