Interestingly, majority of BAG3 mutations identified so far, namely Pro209Leu (causing myofibrillar myopathy), Arg218Trp (causing dilated cardiomyopathy) as well as one of four novel mutations associated with fulminant dilated cardiomyopathy in Polish patient (a large deletion of 17,990 bp removing BAG3 exons 3–4) are located within the exon 3 indicating importance of this region for the protein activity (Arimura et al. 2011; Selcen et al. 2009; Franaszczyk et al. 2014). The gene discussed is BAG3; the disease is myofibrillar myopathy.