MERTK and Alzheimer disease: Compared with all other microglial clusters, the FRM cluster also presented a distinct gene signature, with enrichment of key AD GWAS genes (Inpp5d, Bin1, Mef2c), microglial signaling genes (Tgfbr1, Mertk, Smad3), and autophagy/mitophagy genes (Atg5, Atg7, Prkn) (Fig. 5g).