Obesity-induced inflammatory cytokines have been closely related to IR, as many cytokines and inflammatory mediators, namely, tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1), C-reactive protein (CRP), and interleukins, have been demonstrated to be significantly upregulated in the course of IR. The gene discussed is CCL2; the disease is obesity due to melanocortin 4 receptor deficiency.