In clinical studies with HF patients, HR reduction without affecting BP was considered to be desirable, since the BP-reducing effect of well-established HF therapeutics such as BB, angiotensin-converting enzyme inhibitors (ACEis), angiotensin II type 1 receptor blockers (ARBs), or mineralocorticoid receptor antagonists (MRAs) can limit the achievement of the target doses. The gene discussed is ACE; the disease is hydrops fetalis.