CD9 and early-onset autosomal dominant Alzheimer disease: 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).