Numerous SNPs and rare coding variants in immune-related genes thought to be involved in microglial function have been identified as risk factors for AD in whole-genome sequencing and GWAS analyses, including TREM2, CR1, SHIP1, BIN1, CD33, PICALM, CLU, and the MS4A gene cluster (Gibson, 2010; Rosenberg et al., 2016; Bis et al., 2018). Here, TREM2 is linked to Alzheimer disease.