IL-6, secreted by a wide variety of cells (e.g., adipocytes, endothelial cells, β-pancreatic cells, macrophages, and monocytes), regulates energy homeostasis and inflammation, influencing the transition from acute to chronic inflammatory disease, such as obesity and insulin resistance [14], by promoting the synthesis of pro-inflammatory cytokines and by negatively regulating inflammatory targets. The gene discussed is IL6; the disease is obesity due to melanocortin 4 receptor deficiency.