Previous pharmacogenomic studies have proposed that the β1-adrenergic receptor (ADRB1) Arg389 > Gly [9] and G-protein receptor kinase 5 (GRK5) Gln41 > Leu [10] polymorphisms, both of which are over-represented in African Americans, may play roles in determining individual clinical responses to β-blockade treatment with HF. Here, ADRB1 is linked to hydrops fetalis.