Microglial deficiencies in TREM2 are associated with increased AD risk in humans and result in diminished microglial responses to amyloidosis in 5xFAD mice (Guerreiro et al., 2013; Jonsson et al., 2013; Wang et al., 2015, 2016; Keren-Shaul et al., 2017; Kleinberger et al., 2017; Krasemann et al., 2017; Zhou et al., 2020). This evidence concerns the gene TREM2 and Alzheimer disease.