G6PC1 and obesity due to melanocortin 4 receptor deficiency: Moreover, glucose metabolism-associated genes, glucose-6-phosphatase (G6pc) and insulin-like growth factor binding protein 1 (Igfbp1), were down-regulated, accompanied with adrenoceptor β 3 (Adrb3) whose gene polymorphism is related to type 2 diabetes and obesity up-regulated (Figure 1C).