On the other hand, the DC enzyme indoleamine 2,3-dioxygenase 1 (IDO1) was found to be lower in patients with ITP, which would hamper the transition of CD4+ T cells to Tregs and therefore contribute to a Treg deficiency which may stimulate the onset of disease [116]. The gene discussed is IDO1; the disease is autoimmune thrombocytopenic purpura.