Upadacitinib is a Janus kinase-1 (JAK-1) selective inhibitor, recently approved for the treatment of moderate-to-severe Crohn’s disease, with good efficacy and safety data in both induction (U-EXCEL and U-EXCEED studies) and the maintenance of remission (U-ENDURE study) [5]. This evidence concerns the gene JAK1 and Crohn disease.