Although many patients respond to conventional and biologic therapies, the National Institute for Health Research (NIHR) portfolio cohort trial, Personalised Anti-TNF Therapy in Crohn’s disease (PANTS) (UKCRN 14175 & 17,747) of 1610 CD patients commencing anti-TNF therapy reports primary non-response at week 14 in 23·8% (95% CI 21·4–26·2) and non remission at week 54 in 63·1%, (60·3–65·8) [4]. The gene discussed is TNF; the disease is Crohn disease.