Clinical characteristics of patients with congenital long QT syndrome and bigenic mutations
Journal
Chinese Medical Journal
Journal Volume
127
Journal Issue
8
Pages
1482-1486
Date Issued
2014
Author(s)
Chen C.-Y.
Lo L.-W.
Yeh S.-F.S.
Abstract
Background Congenital long QT syndrome (LQTS) is an ion channelopathy associated with genetic mutations. It is well known that most LQTS patients (91%) have a single mutation. The purpose of this study was to investigate the clinical characteristics of congenital LQTS patients with bigenic mutations in Taiwan, China. Methods Congenital LQTS patients were recruited consecutively at Taiwan University Hospital in Taiwan from 2003 to 2009. The diagnosis of LQTS was defined by an LQTS Schwartz score greater than 4. Mutation screening in KCNQ1, KCNH2, KCNE1, and SCN5A was performed using direct sequencing. Results Three of 16 LQTS patients (18.7%) were identified with bigenic mutations. One patient had missense mutations in KCNQ1 and KCNH2, the second in KCNQ1 and KCNE1, and the third in KCNH2 and SCN5A. The mean age at onset of LQTS for patients with bigenic mutations was (17±3) years, and all of these patients were female. Two of them experienced seizure and one presented with syncope, although one of them had a family history of syncope. The mean QTc interval was (515±17) ms, similar to those with single mutation or SNPs ((536±74) ms, P=0.63). Compared to those LQTS patients with single mutation or SNPs, a significantly higher percentage of LQTS patients with bigenic mutations presented with seizure and were younger at onset of the first index event (P=0.03 and 0.001, respectively), but lower percentage of them presented with sudden cardiac death (P=0.03). Conclusions Although the percentage of bigenic mutations in LQTS is less than 10% in Caucasian populations, we identified 3 of 16 LQTS patients (18.7%, 95% confidence interval: 0.04-0.46) with bigenic mutations in Taiwan. However, the severity of their clinical presentations was not higher than those patients with single mutation or SNPs.
SDGs
Other Subjects
adolescent; adult; aged; article; bigenic mutation; child; clinical article; clinical feature; controlled study; disease severity; faintness; female; gene; gene mutation; genetic analysis; human; KCNE1 gene; KCNH2 gene; KCNQ1 gene; long QT syndrome; male; middle aged; missense mutation; polymerase chain reaction; school child; scn5a gene; scoring system; seizure; single nucleotide polymorphism; sudden cardiac death; very elderly; young adult; genetics; genotype; long QT syndrome; mutation; pathology; ERG1 potassium channel; KCNE1 protein, human; KCNQ1 protein, human; potassium channel HERG; potassium channel KCNQ1; SCN5A protein, human; sodium channel Nav1.5; voltage gated potassium channel; Adolescent; Adult; Aged; Ether-A-Go-Go Potassium Channels; Female; Genotype; Humans; KCNQ1 Potassium Channel; Long QT Syndrome; Male; Middle Aged; Mutation; NAV1.5 Voltage-Gated Sodium Channel; Polymorphism, Single Nucleotide; Potassium Channels, Voltage-Gated; Young Adult
Publisher
Chinese Medical Association
Type
journal article