Since the loss of Treg function and induction of Th17-cells are observed in sarcoidosis, and because the pathogenic conversion of FoxP3 T cells into Th17-cells has been found in ARD, it would be worthwhile to investigate the plasticity of Tregs towards Th17-cells as well as the presence of IL-17-producing Tregs in sarcoidosis. The gene discussed is IL17A; the disease is sarcoidosis.