Immune dysfunction is accompanied by aberrant levels of a broad spectrum of cytokines tightly linked to IBD pathogenesis, including IL-1β, IL-18, IL-33, IL-6, IL-10, IL-17 (and their isoforms), TNF-α, tumor growth factor beta (TGF-β), along with chemokines IL-8, chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α and 1β, MCP-3, MIP-3α, CXCL5, CXCL8, CXCL10, and RANTES 40. This evidence concerns the gene IL17A and irritable bowel syndrome.