TREM2 and Alzheimer disease: In the context of AD, microglia respond to amyloid pathology by transforming into DAM, downregulating genes such as Cx3cr1, Tmem119 and P2ry12 and upregulating genes such as Trem2, Apoe, and Ctsb have been observed (Keren-Shaul et al., 2017; Krasemann et al., 2017; Sala Frigerio et al., 2019).