CD33 and Alzheimer disease: According to the possible role in the process of AD, these genes were classified as several groups: (1) Lipid metabolism: APOE CLU, ABCA7, SORL1; (2) Immune response: CR1, CD33, MS4A, EPHA1, CLU, ABCA7, HLA-DRB5/DRB1 and INPP5D; (3) Endocytosis: BIN1, PICALM, CD2AP, EPHA1, RIN3, SORL1, MEF2C and MADD [8,12–16].