Of note, several inflammation-related genes expressed in macrophage/microglia, including TREM2, CD33, CR1, and ABCA7, have been shown to be related to the risk of late-onset AD and are generating great interests in the AD research community (Harold et al., 2009; Lambert et al., 2009; Hollingworth et al., 2011; Naj et al., 2011; Guerreiro et al., 2013). This evidence concerns the gene TREM2 and Alzheimer disease.