Inhibitors of renin–angiotensin–aldosterone system (RAAS) constitute a cornerstone of therapy of HF and the efficacy of angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), and finally, mineralocorticoid receptor antagonists (MRAs) have been firmly established. The gene discussed is NR3C2; the disease is hydrops fetalis.