During the development of obesity, the increased release of adipokines with pro-inflammatory activity (e.g., leptin) and the decrease of those with anti-inflammatory effects (e.g., adiponectin) establishes a chronic inflammatory state that predisposes an individual to the development of metabolic diseases (insulin resistance, type 2 diabetes and cardiovascular disorders) and cancer. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.