These studies suggest that a complex intercellular mechanism underlies AD pathology.[17] In particular, the discovery and characterization of variants associated with the triggering receptor expressed on myeloid cells 2 (TREM2)[21, 22, 23, 24, 25] have emphasized the critical role of microglia[26, 27, 28, 29] in AD pathogenesis. This evidence concerns the gene TREM2 and Alzheimer disease.