SCN5A and familial long QT syndrome: Mutations in SCN5A lead to various arrhythmogenic diseases, e.g. long QT syndrome (LQTS; subform LQT-3), Brugada syndrome (BrS; BrS-1), cardiac conduction disease (CCD, also known as Lev-Lenègre syndrome), but also idiopathic atrial fibrillation, sinus node dysfunction, atrial standstill, and even dilated cardiomyopathy (DCM) [9], [10], [11], [12], [13], [14], [15], [16], [17].