NAMPT and obesity due to melanocortin 4 receptor deficiency: Following the recent isolation and characterization of visfatin, or pre-B-cell colony-enhancing factor (PBEF)/nicotinamide phosphoribosyltransferase (Nampt), as a novel adipocytokine, there has been a rapidly growing interest in this protein, its potential properties and subsequent role in the development of T2DM and obesity.