CTSS and Alzheimer disease: In particular, for AD, 19 microglial genes overlapped between PIGs [52] (plague-induced genes), DAM [22], and reversed genes, including Apoe, Fcer1g, C1qa, Frcls, C1qb, Itm2b, C1qc, Man2b1, Cd9, Olfml3, Cst3, Trem2, Ctsl, Ctsb, Ctss, Gusb, Ctsz, Hexa, and Cx3cr1 (Fig. 4d).