SOD1 deficiency leads to the accumulation of ROS; decreases the activity of catalytic enzymes such as glutathione peroxidase (GPx), glutathione (GSH), and catalase (CAT); exacerbates oxidative stress; and disrupts the intestinal epithelial barrier (such as decreased expression of E-cadherin), worsening colitis. The gene discussed is CAT; the disease is colitis.