TREM2 and obesity due to melanocortin 4 receptor deficiency: We identified 17 genes upregulated by obesity in all data sets, including genes involved in inflammatory responses [secreted phosphoprotein 1 (Spp1), regulator of G protein signaling 1 (Rgs1), dehydrogenase/reductase 9 (Dhrs9), C-C motif chemokine ligand 2 (Ccl2), macrophage scavenger receptor 1 (Msr1), interleukin 1 receptor antagonist (Il1rn), Cd84] and markers of lipid-associated macrophages (triggering receptor expressed on myeloid cells 2 (Trem2), neutral cholesterol ester hydrolase 1 (Nceh1))3,4 (Fig. 1B).