Taken together, the data obtained in this study indicate that expressions of CTSA, LNPEP, and MAS1 in the renin-angiotensin system in the left atrial myocardium of MR patients substantially differed from those in aortic valve disease patients, even after adjustment for plasma angiotensin II concentration and left atrial size. The gene discussed is CTSA; the disease is aortic valve disorder.