MYBPC3 and hydrops fetalis: To test the phosphorylation status of cMyBP-C in human HF, immunohistochemistry (IHC) was performed using cardiac tissue sections from normal healthy donors, as well as hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) patients (N = 4 patients per group, Fig. 2A).