Isoform-specific Dst-b mutant mice exhibited late-onset protein aggregate myopathy with cardiomyopathy, which could be termed ‘dystoninopathy.’ Protein aggregates observed in the striated muscles of Dst-b mutant mice were composed of desmin, αB-crystallin, plectin, and truncated Dst-b. The gene discussed is PLEC; the disease is cardiomyopathy.