TREM2 and Alzheimer disease: It is worthy of note that a recent pathway analysis of AD susceptibility factors indicates that APOE, INPP5D, TREM2, ABCA7, CR1, PICALM, and BIN1 are jointly involved in three functional categories – immune responses, movement of phagocytes and myeloid cells, and engulfment of extracellular material – i.e., in the fundamental innate immune processes that mediate tissue homeostasis, wound clearance, and tissue repair [73].