Gene expression levels of Nppa and Nppb, which are the biomarkers for heart failure, were assessed by quantitative PCR (qPCR), and both were significantly higher in the Rbm20S637A/S637A mice than in the WT and Rbm20KO/KO mice at 4 weeks of age (Fig. 3f), supporting the onset of functional phenotypes. Here, NPPB is linked to heart failure.