This bidirectional interaction is a characteristic of what is commonly known as the “cardiorenal syndrome.” They often share common pathophysiological mechanisms, such as oxidative stress and inflammatory responses, activation of renin-angiotensin system, abnormal signaling pathways (such as the Wnt/β-catenin signaling pathway and the TGF-β1/Smad signaling pathway), endothelial dysfunction, and vascular calcification (33). The gene discussed is REN; the disease is endothelial dysfunction.