Mutation of PRDM16 is known to cause cardiomyopathy associated with DCM and LVNC.4 More recently, truncating variants in PRDM16 have been identified by in silico analysis as one of three specific LVNC variant classes.8 These genetic observations and the Prdm16csp1/wt phenotype reinforce the case that heterozygous PRDM16 inactivation/truncation in humans is sufficient to cause cardiomyopathy. This evidence concerns the gene PRDM16 and familial dilated cardiomyopathy.