SCN5A and long QT syndrome 3: Variants in the SCN5A gene have been associated with CCD, SSS, DCM, Brugada syndrome (BrS), long QT syndrome type 3 (LQT3), atrial and ventricular fibrillation, sudden death (adults and infants), arrhythmogenic right ventricular dysplasia, drug-induced arrhythmia, heart block, nodal rhythm defect, and early repolarization syndrome, among others.