Elevated serum levels of ET-1 and other biochemical markers of endothelial function in the aqueous humor of glaucoma patients suggest that endothelial dysfunction is associated with disease pathology (Sugiyama et al., 1995; Noske et al., 1997; Resch et al., 2009a; Ghanem et al., 2011; Cellini et al., 2012; Li et al., 2016). The gene discussed is EDN1; the disease is glaucoma.