We performed a survey among multiple paediatric IBD centres for patients where a clinical diagnosis of IL2RA duplication was made and searched genetically characterised IBD cohorts in the UK [Oxford and London], screened an IBD cohort using parental samples as controls [Toronto], and searched the DECIPHER database and the 100 000 Genomes Project for further patients. The gene discussed is IL2RA; the disease is inflammatory bowel disease.