Ghrelin regulates growth hormone secretion and feeding, and the blood level of ghrelin is negatively correlated with the body mass index in healthy individuals and uncomplicated type 2 diabetes mellitus patients; it has been reported to be lower in obese patients and higher in lean patients with cancer, chronic heart failure, and anorexia nervosa (Ueno et al., 2007). The gene discussed is GHRL; the disease is type 2 diabetes mellitus.