Currently, vedolizumab, a humanized anti-α4β7 integrin monoclonal antibody (mAb) is effectively used to ameliorate IBD symptoms and reduce associated damage by blocking gut homing of inflammatory cells by antagonizing α4β7 integrin binding to its cognate ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) on intestinal endothelium (5). The gene discussed is MADCAM1; the disease is inflammatory bowel disease.