Its absence in the agouti-related protein (AgRP) expressing neurons leads to increased adiposity attributable to a reduced tendency for voluntary exercise [112], while its deficit in other hypothalamic neurons (Sim1 neurons within the paraventricular nucleus) manifests in obesity, hyperphagia, and glucose intolerance [113]. The gene discussed is AGRP; the disease is obesity due to melanocortin 4 receptor deficiency.