title: Long QT syndrome: a Korean single center study.
abstract: The long QT syndrome (LQTS) is a rare hereditary disorder in which affected individuals have a possibility of ventricular tachyarrhythmia and sudden cardiac death. We investigated 62 LQTS (QTc ≥ 0.47 sec) and 19 family members whose genetic study revealed mutation of LQT gene. In the proband group, the modes of presentation were ECG abnormality (38.7%), aborted cardiac arrest (24.2%), and syncope or seizure (19.4%). Median age of initial symptom development was 10.5 yr. Genetic studies were performed in 61; and mutations were found in 40 cases (KCNQ1 in 19, KCNH2 in 10, SCN5A in 7, KCNJ2 in 3, and CACNA1C in 1). In the family group, the penetrance of LQT gene mutation was 57.9%. QTc was longer as patients had the history of syncope (P = 0.001), ventricular tachycardia (P = 0.017) and aborted arrest (P = 0.010). QTc longer than 0.508 sec could be a cut-off value for major cardiac events (sensitivity 0.806, specificity 0.600). Beta-blocker was frequently applied for treatment and had significant effects on reducing QTc (P = 0.007). Implantable cardioverter defibrillators were applied in 6 patients. Congenital LQTS is a potentially lethal disease. It shows various genetic mutations with low penetrance in Korean patients.
authors.affiliation: Department of Pediatrics, Seoul National University Boramae Hospital, Seoul, Korea. ; Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yun-Sik
authors.initials: YS
authors.lastname: Lee
authors.forename: Bo-Sang
authors.initials: BS
authors.lastname: Kwon
authors.forename: Gi-Beom
authors.initials: GB
authors.lastname: Kim
authors.forename: Se-Il
authors.initials: SI
authors.lastname: Oh
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Bae
authors.forename: Sung-Sup
authors.initials: SS
authors.lastname: Park
authors.forename: Chung-Il
authors.initials: CI
authors.lastname: Noh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics; D015220:Calcium Channels / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D006323:Heart Arrest / Q000235:genetics / Q000473:pathology; D006801:Humans; D007223:Infant; D051657:KCNQ1 Potassium Channel / Q000235:genetics; D051658:KCNQ2 Potassium Channel / Q000235:genetics; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics; D019683:Penetrance; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D056910:Republic of Korea; D012307:Risk Factors; D012640:Seizures / Q000235:genetics / Q000473:pathology; D055815:Young Adult; D020864:Calcium Channels, N-Type
chemical_list: D015220:Calcium Channels; D051657:KCNQ1 Potassium Channel; D051658:KCNQ2 Potassium Channel; D062554:NAV1.5 Voltage-Gated Sodium Channel; D024661:Potassium Channels, Inwardly Rectifying; C105656:CACNA1A protein, human; D020864:Calcium Channels, N-Type; C489461:Kir2.1 channel; C568320:SCN5A protein, human
keywords: Heart Ventricles; Long QT Syndrome; Mutation; Tachycardia