Long QT syndrome: Biophysical and pharmacologic mechanisms in LQT3

The congenital long QT syndromes (LQTSs) are a group of inherited cardiac d isorders that increase the risk of sudden death from ventricular arrhythmia s. Individuals with LQTS show abnormalities in cardiac repolarization, Muta tions that cause LQTSs are distributed throughout the human genome on chrom osomes 3, 4, 7, 11, and 21. Recent molecular genetic studies established th at LQT3 results from mutations in the cardiac sodium ion channel gene (SCN5 A), Research efforts are aimed at elucidating molecular mechanisms, determi ning the links between clinical phenotypes and the individual gene mutation s, and pharmacologic targeting of the phenotypes, This approach will ultima tely guide rational therapy. In addition, LQT3 serves as a model for inheri ted molecular-based disorders, as well as a paradigm for understanding the genesis and control of other cardiac arrhythmias.