Besides skeletal muscle degeneration, dystrophin-deficiency in DMD also initiates severe cardiac complications. Among those, cardiac arrhythmias and the development of a dilated cardiomyopathy considerably contribute to the morbidity and mortality associated with the disease.5,6 Although the precise mechanisms causing these cardiac complications are largely unknown, there is evidence that impaired cardiac ion channel expression and function are involved. For example, dystrophin-deficient ventricular cardiomyocytes derived from mouse models for DMD express less cardiac Nav1.5 sodium channel protein than healthy myocytes.7,8 Dystrophic cardiomyocytes also show significantly reduced sodium current densities and altered sodium channel gating properties.7-9 Reduced sodium currents in murine dystrophic cardiomyocytes match with the impairments in cardiac impulse conduction observed in DMD patients (e.g.10). Since ion channels in cardiomyocytes do not function in isolation, but instead in an orchestrated fashion as part of complex protein networks,11,12 it is not surprising that dystrophin-deficiency impairs the properties of Nav1.5 channels. Nav1.5 is considered a member of the DAPC and as such a direct interaction partner of the dystrophin-binding protein syntrophin.7,13,14 The lack of dystrophin may therefore disturb regulatory interactions of Nav1.5 within the DAPC, which normally are a prerequisite for the proper expression and function of this channel. Accordingly, syntrophin mutations were linked with an abnormal sodium current through Nav1.5 channels.15