SCN5A and Ventricular arrhythmia: Variants of SCN5A have been demonstrated to contribute to various kinds of ventricular arrhythmias including long QT syndrome (LQTS) type 3; Brugada syndrome (BrS) and idiopathic ventricular fibrillation (IVF), which greatly increase the risk of sudden death in young individuals with a structurally normal heart.