EDN1 and Schnyder corneal dystrophy: Some plasma factors such as transforming growth factor β1 (TGFβ1) and endothelin-1 (ET-1) have also been shown to stimulate NADPH oxidase activity in neutrophils, monocytes and endothelial cells and many of these factors are present at higher levels in the plasma of SCD patients as a result of persistent inflammatory state associated with SCD (54).