CD33 and Alzheimer disease: More recent research in genome-wide association studies (GWAS) has implicated that single-nucleotide polymorphisms (SNPs) among 11 genes appear to affect the risk of AD, encompassing the PICALM, MS4A6E, MS4A4E, MS4A4A, EPHA1, CR1, CLU, CD33, CD2AP, BIN1, APOE, and ABCA7 gene (7–11).