CD33 and Alzheimer disease: In this sense, candidate single nucleotide polymorphisms (SNPs) were selected for being previously associated with AD occurrence and progression in different GWAs studies, including genetic variants in APOE, CLU, ABCA7, PICALM, BIN1, SORL1, PTK2B, EPHA1, CD33, CD2AP, MS4A6A, HLA-DRB5/HLA-DRB1, TREM1, TREM2, and TREML2 genes (Lambert, 2013; Replogle et al., 2015) which are assumed to be associated with AD through different pathways (Replogle et al., 2015; Giri et al., 2016).