An autosomal dominant disease characterized by a SYNCOPAL EPISODE and/or aborted sudden death, a structurally normal heart, and a characteristic ELECTROCARDIOGRAM. The electrocardiogram shows ST segment elevation in V1 to V3, with a morphology of the QRS complex resembling a right bundle branch block. The episodes of syncope and sudden death are caused by fast polymorphic ventricular tachycardias (TACHYCARDIA, VENTRICULAR) or VENTRICULAR FIBRILLATION which appear without warning. Several mutations linked to this syndrome affect the cardiac SODIUM CHANNEL gene SCN5A which codes for the alpha subunit of type V sodium channel.