New findings are that both Th17 and Tc17 cells contribute significantly to the IL-17A response in the inflamed small intestinal mucosa of patients with active CD and that IL-17A mRNA levels in the mucosa correlate with the mRNA levels of IFN-γ and Foxp3 mRNAs but not with the level of IL-10 mRNA. The gene discussed is IL17A; the disease is Cowden disease.