MYPN and familial dilated cardiomyopathy: Since MKO mice show a relatively mild form of slowly progressive DCM under basal conditions and MYPN-Q526X knockin mice were only studied until 12 weeks of age, it is likely that the phenotype was missed and that homozygous MYPN-Q526X knockin mice, like MKO mice, would develop cardiac systolic dysfunction with age or in response to stress.