Long and short QT syndrome.

: In the past decade molecular genetic analysis has greatly expanded our knowledge about inherited arrhythmogenic syndromes. The congenital long QT syndrome (LQTS) and the recently described short QT syndrome (SQTS), with the defining characteristic of abnormal prolongation or shortening of the QTc interval on the surface electrocardiogram, are caused by cardiac ion channel dysfunctions. These "channelopathies" show a high degree of genetic heterogeneity of the molecular pathways in terms of the relationships between genetic defects and phenotypic expression. In this brief review we summarize the current understanding of the molecular basis of long and short QT syndrome with focus on the impact of molecular genetics on the clinical management of these diseases.