Clinical variables reported to be associated with anti-TNF response include age, disease duration, body mass index [BMI], smoking, C-reactive protein [CRP] levels, faecal calprotectin levels, serum drug concentrations, and anti-drug antibody concentrations.7,9–13 In the Personalised Anti-TNF Therapy in Crohn’s Disease [PANTS] study, the largest study of infliximab and adalimumab response in CD patients to date [enrolment n = 1610], baseline obesity, smoking, and greater disease activity were associated with low serum drug concentration after induction. The gene discussed is CRP; the disease is Crohn disease.