IL21 and inflammatory bowel disease: Mutations in the IL21 gene, a critical regulator of STAT1, STAT3, and STAT5 signaling141 cause early‐onset IBD and common variable immunodeficiency‐like disease.31 In the context of IL‐21 deficiency, the IBD phenotype could be explained by the lack of anti‐inflammatory action of I‐L21 in inducing IL‐10 production through a STAT3‐mediated signaling axis.