To determine the effects of MR and HF on the gene expression profiles of the renin-angiotensin system, gene expression profiles of the renin-angiotensin system in the left atrium were compared in left atrial tissues from MR patients with HF (n = 10), aortic valve disease patients with HF (n = 8), and normal controls (n = 6). The gene discussed is REN; the disease is hydrops fetalis.