Along with GRK2, β-arrestin1 is known to desensitize and downregulate adrenal α-2 adrenergic receptors (α2Ars), resulting in the chronic escalation of CA secretion, which elevates epinephrine and nor-epinephrine levels, thereby aggravating chronic HF [64,65,66,67]. The gene discussed is GRK2; the disease is hydrops fetalis.