AGRP and obesity due to melanocortin 4 receptor deficiency: As dysregulation of leptin signaling is tightly associated with human obesity and diabetes (10), our discovery of a dual action of TET3 (5hmC modification and recruitment of chromatin-modifiers) in the regulation of Agrp/AGRP expression in both human and mouse cells offers new opportunities for the future development of therapeutic interventions for metabolic disorders and related psychiatric conditions.