Approximately 30–50% of patients with ulcerative colitis and around 15% of those with Crohn’s disease are treated with 5-aminosalicylate (5-ASA), while anti-Tumor Necrosis Factor α (TNF-α) is prescribed to roughly 20–40% of IBD patients, especially those with moderate to severe disease. The gene discussed is TNF; the disease is Crohn disease.