It was shown that microglia uniformly downregulate their homeostatic signature genes, such as Sall1, Pu.1, Tmem119, Cx3cr1, and P2ry12/13 and upregulate risk genes for AD, such as Apoe and Trem2, in mouse models for aging, AD (5XFAD and APP-PS1), and amyotrophic lateral sclerosis (ALS) (SOD1) (34–36). Here, APOE is linked to Alzheimer disease.