These findings suggest that the presence of multiple, simultaneous alterations in critical PLN functional parameters may contribute towards development of a more severe spectrum of disease (i.e., DCM) in PLN-Arg9Cys and PLN-Arg14del, while a milder phenotype (i.e., HCM) is associated with PLN-Arg25Cys. Here, PLN is linked to familial dilated cardiomyopathy.