Fatal effects of these mutations as well as other DCM-related mutations in the hotspot of RBM20 is likely due to loss of recognition of the RSRSP stretch by protein kinase(s) that phosphorylate the serine residues or by a partner protein that specifically binds to RBM20 only after phosphorylation of the RSRSP stretch. Here, RBM20 is linked to familial dilated cardiomyopathy.