These dynamic functions could also be tested in transplanted human microglia that express variants or lack the expression of AD susceptibility genes, for example CD33 and BIN1 (Bridging INtegrator-1), as similarly shown for TREM2 (Hasselmann et al., 2019; McQuade et al., 2020; Claes et al., 2021). This evidence concerns the gene TREM2 and Alzheimer disease.