NPPB and hydrops fetalis: The qPCR results showed that, 3-month-old MYH6-Cre-BDNF–/– hearts showed significantly higher expression of the HF markers atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in the left ventricle than WT hearts (Figures 5Ia,b; p < 0.05).