VIP and obesity due to melanocortin 4 receptor deficiency: This approach has been successfully applied to uncover many disease-related pathways, such as the IL12/IL23 pathway associated with Crohn’s disease[11], the Vasoactive Intestinal Peptide (VIP) pathway important for Obesity[12], as well as the WNT-signaling pathway in Type2 diabetes(T2D)[13].