PTP1B have been linked to central leptin resistance in humans (Myers et al., 2010) as well as in a variety of animal models of obesity (Cheng et al., 2002; Zabolotny et al., 2002; White et al., 2009) and aging (Morrison et al., 2007). The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.