In the case of inflammatory bowel disease, the expression of Duox2 is significantly increased in human colon biopsies, and in isolated intestinal epithelial cells, from patients with both Crohn’s disease and ulcerative colitis compared to expression levels in normal adjacent colonic mucosa, suggesting that an unchecked ROS response to pathogens could contribute to the tissue injury observed in these chronic inflammatory disorders (13). This evidence concerns the gene DUOX2 and Crohn disease.