Second, a possible associated dominant gain-of-function effect of the p.(Pro209Leu) missense variant has been reported,43 and third, this variant is located in one of the isoleucine–proline–valine motifs binding other NMD-causing proteins (like HSPB1 and HSPB5/αB-crystallin),54 which are generally spared in BAG3-DCM, and, taken together these factors could account for the differences in phenotype. This evidence concerns the gene HSPB1 and familial dilated cardiomyopathy.