Cluster M-2 bore hallmark genes of lipid-associated macrophages (LAMs), which have been reported in fat and other tissues and play a key role in obesity and lipid scavenging: Trem2, Cd9, Cd63, Lpl and Lgals3 (28, 29, 30, 31, 32, 33, 34) (Fig. 3G). The gene discussed is TREM2; the disease is obesity due to melanocortin 4 receptor deficiency.