LEP and obesity due to melanocortin 4 receptor deficiency: All the activated pathways were involved in essential biological systems: cardiovascular system (Nitric Oxide Signaling in the Cardiovascular System and Cardiac B- adrenergic Signaling), nervous system (Glioma Signaling), immune system (NF-kB Signaling), hepatic system (HGF Signaling and Leptin Signaling in Obesity), and circulatory system (eNOS Signaling).