BD is characterized by endothelial dysfunction, neutrophil hyperfunction, and the overproduction of reactive oxygen species (ROS).[8] Endothelin-1 (ET-1) is a vasoconstrictor peptide that is released from vascular endothelial and synovial cells.[22] In the present study, there were significant increases in plasma ET-1 concentrations in active BD patients compared to those in the controls, whereas there were no significant differences between ET-1 concentrations in the inactive BD patients and the controls. This evidence concerns the gene EDN1 and endothelial dysfunction.