In this case–control study, serum Cav-3 concentrations were higher in HF than in matched controls and showed the best discrimination when combined with NT-proBNP (AUC 0.878), exceeding either marker alone (NT-proBNP AUC 0.850; Cav-3 AUC 0.705). The gene discussed is CAV3; the disease is hydrops fetalis.