We know that genetic variation in the IL2RA region is associated with susceptibility to type 1 diabetes [37–39], multiple sclerosis [40, 41], Graves’ disease [42], rheumatoid arthritis [43], Crohn’s disease [44], systemic lupus erythematosus [45] and juvenile idiopathic arthritis [46]. Here, IL2RA is linked to Crohn disease.