It is also well acknowledged that activation of intrarenal renin–angiotensin system (RAS) plays a pivotal role in the pathogenesis of chronic kidney disease (CKD), and the antagonists of RAS, such as angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), are widely used in the treatment of CKD [15, 16]. The gene discussed is REN; the disease is chronic kidney disease.