ADRB2 and hydrops fetalis: Genetic determinants of drug response: Polymorphisms in β-adrenergic receptors ((adrenoceptor beta 2 (ADRB1) and adrenoceptor beta 2 (ADRB2)), angiotensin-converting enzyme (ACE), and drug-metabolizing enzymes like cytochrome P450 family-2 subfamily D member 6 (CYP2D6) significantly affect the pharmacodynamics and pharmacokinetics in HF medications, including beta-blockers, ACE inhibitors, and angiotensin receptor blockers (ARBs).