IBD patients on anti-TNF therapy (median 3410 AU/mL (IQR 1843–6617 AU/mL); p = 0.030) or azathioprine (5903 AU/mL (989–5903 AU/mL); p = 0.031) showed significantly decreased anti-S-IgG levels compared with patients on therapy with ustekinumab (20,928 AU/mL (7882–23,558 AU/mL)). The gene discussed is TNF; the disease is inflammatory bowel disease.