APOE and Alzheimer disease: Besides APOE ε4 identification, GWAS studies have uncovered more than 20 genetic loci associated with AD risk involved in mainly three pathways, the inflammatory response (CR1, MS4A, CD33, TREM2), lipid metabolism (CLU, ABCA7, SORL1) and endocytosis (BIN1, CD2AP, PICALM) [25,26].