These dark microglia are structurally different from ionized calcium-binding adapter molecule 1 (Iba1) expressed microglia, and they are increased at the site of microglial alteration and activation such as around amyloid plaques (APs), dystrophic neurons, triggering receptor expressed on myeloid cells 2 (TREM2), in stress, aging, and AD (Heneka et al., 2013; Zheng et al., 2017). The gene discussed is TREM2; the disease is Alzheimer disease.