Th17 cells, which have been linked to the pathogenesis of several inflammatory and autoimmune diseases, including CHS,13 require in the mouse TGF-β, interleukin (IL)-1β, IL-6 and the transcription factor RORγt for their differentiation.14,15 Furthermore, TGF-β is a strong chemoattractant for leucocytes and modulates the expression of adhesion molecules.8 The analysis of the role of TGF-β in the immune system is complicated by the fact that most tissues produce TGF-β and express receptors for TGF-β. The gene discussed is TGFB1; the disease is autoimmune disease.