MAPT and Alzheimer disease: The brains of both human subjects and mouse models of AD exhibit clusters of MHCII presenting reactive microglia in regions of high phospho-tau pathology (McGeer et al., 1988; Perlmutter et al., 1992; Yoshiyama et al., 2007; Romero-Molina et al., 2018, review: Das and Chinnathambi, 2019).