A family of hereditary long QT syndrome caused by Q738X HERG mutation

We report a family of type 2 long QT syndrome caused by a novel single nucleotide HERG mutation (c.C2212T, p.Q738X). A female complained of syncope and ECG showed long QT, flat T wave, lack of QT shortening during sinus tachycardia and subsequent Torsade de Pointes. After implantation of ICD, she has experienced no syncope. Her father exhibited advanced atrioventricular block and persistent atrial flutter, and her daughter showed long QT with broad-based, sharp T wave. A possible cause to show wide variety of ECG phenotypes under the same mutation in this family is discussed.