This document relates to methods and materials for using nucleic acid and amino acid sequence variants of ribonucleic acid binding motif protein 20 (RBM20). For example, methods and materials for using nucleic acid sequence variants and/or their corresponding amino acid variants of RBM20 that are associated with dilated cardiomyopathy to identify mammals (e.g., humans) at risk of having dilated cardiomyopathy that is likely to progress to heart failure are provided.