Furthermore, prior work shows that APOE4 isoforms are recognised and engulfed by TREM2 at different rates than other APOE isoforms 59; this differential binding of TREM2 to APOE4 may result in an impaired switch of homeostatic microglia to disease associated microglia in AD 18,20,21. This evidence concerns the gene TREM2 and Alzheimer disease.