Introduction: The search of biochemical markers of endothelial dysfunction: lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1)—involved in atherosclerotic plaques formation—and endothelin-1 (ET-1)—potent vasoconstrictor-might help in detecting obstructive sleep apnea (OSA) patients at high risk of cardiovascular diseases. The gene discussed is EDN1; the disease is endothelial dysfunction.