Referenced in: none

Automatically associated channels: Kv11.1

Title: Heterogeneous Phenotype of Long QT Syndrome Caused by the KCNH2-H562R Mutation: Importance of Familial Genetic Testing.

Authors: Carmen Muñoz-Esparza, Esperanza García-Molina, Mariela Salar-Alcaraz, Pablo Peñafiel-Verdú, Juan J Sánchez-Muñoz, Juan Martínez Sánchez, Valentín Cabañas-Perianes, Mariano Valdés Chávarri, Arcadio García Alberola, Juan R Gimeno-Blanes

Journal, date & volume: Rev Esp Cardiol (Engl Ed), 2015 Mar 25 , ,

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25819988

Abstract
Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel.We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography.The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment.Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment.