As many of the pro-inflammatory cytokines elevated in ulcerative colitis (e.g., IL-6, IL-13, IL-15, IL-23 and IFNγ) and Crohn’s disease (e.g., IL-13, IL15, IL-22, IL-24 and IL-27) rely on the Janus kinase (JAK) family of tyrosine kinases for signal transduction [15, 16], it has been proposed that JAK inhibition may be beneficial in the treatment of ulcerative colitis and Crohn’s disease. This evidence concerns the gene IL27 and Crohn disease.