TREM2 and Alzheimer disease: By sorting brain immune cells and carrying out massively parallel RNA sequencing (RNA seq) on these cells over the course of disease progression in the 5X FAD mouse model of human AD Keren-Shaul et al. (2017), demonstrated the TREM2-independent (“Stage 1”) and subsequent TREM2-dependent (“Stage 2”) emergence of “disease-associated microglia,” or DAM, during clinical and pathological progression (TREM = “triggering receptor expressed on myeloid cells”).