RCT: randomized clinical trial; ADA: anti-drug antibody; CT-P13: biosimilar infliximab; IFX: infliximab; CD: Crohn’s disease; CDI: Clostridium difficile infection; TDM: therapeutic drug monitoring; RA: rheumatoid arthritis; UC: ulcerative colitis; IBD: inflammatory bowel disease; SC: subcutaneous; IV: intravenous; ATI:  antibodies to infliximab; TNFi: tumor necrosis factor-inhibiting. The gene discussed is TNF; the disease is clostridium difficile infection.