Middle-aged microglia in both clusters expressed relatively high levels of interferon responses genes (including Gbp2, Ifitm3, Ifi27l2a, and Isg15) (Figure 10, A and B), as well as genes that are expressed at high levels in microglia located at the rims of slowly expanding lesions in people with PMS (C1qa, C1qb, C1qc, Cstb, Fth1, Ftl1, and a panel of ribosomal proteins) (Supplemental Figure 4). Here, ISG15 is linked to premenstrual tension.