During recent years, the actions of multiple cytokines, such as IL-1, IL-5, IL-6, IL-10, IL-12, IL-13, IL-16, IL-17, IL-18, IL-21, IL-22, IL-23, IL-27, IL-33, IL-35, and IL-37, have been reported in the progression of IBD complications. This evidence concerns the gene IL23A and inflammatory bowel disease.