Sudden cardiac death and inherited arrhythmia syndromes.

Sudden cardiac death (SCD) at youth is rare and is often caused by inherited cardiac disorders. This review focuses on the genetic background of inherited primary electrical diseases, the so-called "channelopathies." Following a short clinical description of each syndrome, the recent findings in the genetics of long QT syndrome, short QT syndrome, isolated cardiac conduction defect, familial sick sinus syndrome, familial atrial fibrillation, cathecholaminergic polymorphic ventricular tachycardia, familial Wolff-Parkinson-White (WPW) syndrome, and Brugada syndrome are discussed. The currently proposed theoretical model of overlapping phenotypes in SCN5A sodium channel mutations is presented. The recent data indicate that advances in molecular genetics, experimental and clinical electrophysiology shed some light on the genetic background of primary electrical diseases. However, it is also becoming clear that the process from a mutation of a gene to the clinical presentation of a patient is currently only partially understood and extremely complex.