SPP1 and amyotrophic lateral sclerosis: The microgliosis we observed previously in C9-ALS-FTSD24 is supported here by the upregulation of CD163, a marker of macrophage activity, and the downregulation of P2RY12, a marker of microglial homeostasis.50,51 The 20 significantly differentially expressed genes clustered into two similarly sized groups, those that were upregulated in C9-ALS-FTSD (SERPINA3, S100A10, FKBP5, EMP1, CD163, SPP1, CP, CTSE, BAG3) and those that were downregulated (ARC, RALB, EGR1, JUN, COX5B, P2RY12, BDNF, SLC17A6, BAD, MFGE8, FOS) relative to control cases.