Two additional clusters (designated DAM1 and DAM2) expressed signature genes consistent with so-called damage-associated microglia (DAM) transcriptional state previously described in models of Alzheimer’s disease and MS (18, 45, 48), including Apoe, Trem2, Cd9, Ctsd, and Ctsb (Figure 5B, Table 1). Here, CD9 is linked to Alzheimer disease.