In obesity, excess adipose tissue leads to hyperleptinemia and leptin resistance as well as increased production of pro-inflammatory cytokines (Maffei et al., 1995; Marsh et al., 1999; Schwartz et al., 2000; Fantuzzi, 2005) resulting in decreases in whole body insulin sensitivity and disruption in appetite control and regulation of food intake (Hellstrom, 2013). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.