Microglia seem to have an active and biphasic role on the AD pathology, promoting at early stages the clearance of Abeta deposits (Condello et al., 2015) and, at late stages, mediating the loss of synapses (Wu et al., 2015; Spangenberg and Green, 2017), the exacerbation of the Abeta and tau pathologies (Xiang et al., 2016; Leyns and Holtzman, 2017) and the secretion of reactive oxygen species and inflammatory cytokines (Colonna and Butovsky, 2017). The gene discussed is MAPT; the disease is Alzheimer disease.