TREM2 and Alzheimer disease: Recent evidence demonstrates reduced myeloid cell accumulation around amyloid plaques in TREM2 hemizygous [222, 258, 286], and TREM2- [145, 162, 222, 258, 287] and DAP12-deficient [258] AD mouse models, as well as in postmortem AD human brain tissue from individuals harboring the TREM2 R47H variant [60].