Meanwhile, a large number of genes involved in physiopathologic processes including cholesterol metabolism (APOE, CLU, ABCA7 and SORL1), immune response (CR1, CD33, MS4A, CLU, ABCA7 and EPHA1), endocytosis (BIN1, PICALM, CD2AP, EPHA1 and SORL1) have been proven to be associated with the risk of AD (Ikram and Decarli, 2012; Karch and Goate, 2015). Here, CD33 is linked to Alzheimer disease.