Disruption of adrenergic receptor kinase Adrbk1 in mice causes embryonic lethality due to heart failure in homozygous mutants between E9.0 and E15.5 caused by hypoplasia of the ventricular septum and all cardiac chambers, resulting in poor ejection fraction and heart failure (Jaber et al., 1996). The gene discussed is GRK2; the disease is heart failure.