Obesity generates a state of chronic, low-grade inflammation in liver and adipose tissue accompanied by macrophage infiltration and the local secretion of inflammatory cytokines and chemokines that attenuate insulin action, resulting in insulin resistance and the subsequent development of Type 2 diabetes (Wellen and Hotamisligil, 2005; Hotamisligil, 2006; Lumeng et al., 2007; Shoelson et al., 2007). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.