Obscurin mutants D4, D14 and D20 exhibited significantly lower levels of obscurin protein compared with the other DCM samples and controls (D4, 45±7%, p = <0.0001, n = 8, D14, 48±3%, p = <0.0001, n = 21 and D20, 72±6%, p = <0.014, n = 14). This evidence concerns the gene OBSCN and familial dilated cardiomyopathy.