AD possesses several key genetic risk factors, namely APP, PSEN1, and PSEN2 [68], but meta-analyses of genome-wide association studies have also shown that ApoE, ABCA7, Clu, Bin1, Cd33, Cd2ap, Epha1, Ms4a6A-E, Picalm, Sorl1, Ptk2b, NME8, FERMT2, CASS4, Inpp5d, Dsg2, Mef2c and Cr1 are strongly associated with late-onset AD [69–71]. Here, CD33 is linked to Alzheimer disease.