Diseases associated with SCN5A mutations include the long QT syndrome (LQTS), Brugada syndrome (BrS), isolated (progressive) conduction defect (Lev–Lenègre syndrome), atrial fibrillation, sick sinus syndrome, multifocal ectopic premature Purkinje-related complexes, and DCM. Here, SCN5A is linked to familial long QT syndrome.