To investigate whether the methylation level of master transcription factors (TBX21, GATA3, RORγt and FOXP3) and inflammatory factors (IFN-γ, IL-4, IL-17A and TGF-β) in CD4+T cells is associated with BD, we determined the promoter methylation level in active BD patients and healthy individuals. The gene discussed is IL17A; the disease is Behcet disease.