There are two main types of macrophages involved in the inflammatory response: firstly, the so-called M1- macrophages or F4/80 + CD11c +, characterized by high expression of TNF-α and inducible nitric oxide synthase (iNOS), also found in animal models, primarily expressed in the visceral adipose tissue (cc Adipose tissue macrophages: going off track during obesity), and secondly, the M2 phenotype, identified as F4/80 + CD 206 + CD301 + CD11c-- macrophages, mainly prevalent in lean adipose tissue, which express genes encoding anti-inflammatory cytokines like IL-10 [11]. The gene discussed is ITGAX; the disease is obesity due to melanocortin 4 receptor deficiency.