Here, we capitalize on a real-world bioresource from a large multicenter cohort study, Biomarkers of Systemic Treatment Outcomes in Psoriasis (BSTOP), within the UK pharmacovigilance registry British Association of Dermatologists Biologic Interventions Registry (BADBIR), to investigate the clinical utility of therapeutic drug monitoring as applied to the exemplar TNF inhibitor adalimumab. The gene discussed is TNF; the disease is psoriasis.