Since then, a large number of GWAS for AD have been carried out and many novel risk loci for AD have been identified, such as BIN1, TREM2, CD33, SORL1, CD2AP, ABCA7 and EPHA1 [10].These loci have also been shown to be involved in multiple biological pathways in vivo, including immune actions, amyloid and tau protein processing, lipid metabolism, etc [8, 11–13]. Here, TREM2 is linked to Alzheimer disease.