Congenital long QT syndrome (LQTS) is a disease characterized by prolongation of ventricle repolarization and by the occurrence, usually during emotional or physical stress, of life-threatening arrhythmias that lead to sudden death in most symptomatic and untreated patients. Two variants have been initially identified:the original Jervell and Lange-Nielsen syndrome of congenital deafness and autosomal recessive inheritance, and the more frequent Romano-Ward syndrome of autosomal dominant inheritance. Evidence also shows that approximately 25 to 30% of the cases are sporadic with syncope and a prolonged QT interval but without showing evidence for familial involvement. Familial and sporadic cases have been grouped under the definition of congenital long QT syndrome. We experienced a case of congenital long QT syndrome in a 13-year-old female girl. She had episodes of recurrent syncope and QT interval prolongation(QTc=0.46sec) in electrocardiogram(ECG). The ECG of her mother showed QT interval prologation(QTc=0.46sec). After applying atenolol, the QT interval returned to normal range and syncope has not occurred. We report a case of congenital long QT syndrome with a brief review of related literatures.
Adolescent ; Arrhythmias, Cardiac ; Atenolol ; Deafness ; Death, Sudden ; Electrocardiography ; Female ; Humans ; Jervell-Lange Nielsen Syndrome ; Long QT Syndrome* ; Mothers ; Reference Values ; Romano-Ward Syndrome ; Syncope* ; Wills

OBJECTIVETo investigate the molecular pathology in families with long QT syndrome (LQTS) including Jervell-Longe-Nielsen syndrome (JLNS) and Romano-ward syndrome (RWS) and Brugada syndrome (BS) in Chinese population.

METHODSPolymerase chain reaction and DNA sequencing were used to screen for KCNQ1, KCNH2, KCNE1, and SCN5A mutation.

RESULTSWe identified a novel mutation N1774S in the SCN5A gene of the BS family, a novel mutation G314S in a RWS family which had also been found in Europe, North America, and Japan, and a single nucleotide polymorphisms (SNPs) G643S in the KCNQ1 of the JLNS family. In this JLNS family, another heterozygous novel mutation in exon 2a was found in KCNQ1 of the patients.

CONCLUSIONNew mutations were found in our experiment, which expand the spectrum of KCNQ1 and SCN5A mutations that cause LQTS and BS.

Adolescent ; Adult ; Base Sequence ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Female ; Humans ; Jervell-Lange Nielsen Syndrome ; genetics ; KCNQ1 Potassium Channel ; genetics ; Long QT Syndrome ; congenital ; genetics ; Male ; Middle Aged ; Molecular Sequence Data ; Muscle Proteins ; genetics ; Mutation ; NAV1.5 Voltage-Gated Sodium Channel ; Pedigree ; Potassium Channels, Voltage-Gated ; genetics ; Romano-Ward Syndrome ; genetics ; Sodium Channels ; genetics

Congenital long QT syndrome (LQTS) is an inherited disease characterized by prolonged QT intervals and polymorphic ventricular tachycardia. The clinical manifestations vary from sudden cardiac death by ventricular arrhythmia to asymptom throughout life. In 1957, Jervell and Lange-Nielsen reported a syndrome of congen-ital sensory deafness associated with a prolonged QT interval in four children. The affected children had multiple syncopal episodes, and three died suddenly. The mode of inheritance is autosomal recessive. Affected persons are susceptible to recurrent syncope, and they have a high incidence of sudden death and short life expectancy. We report a case and review the literature on long QT syndrome diagnosed in a 30-year-old female with a history of convulsion and loss of consciousness during delivery.
Adult ; Arrhythmias, Cardiac ; Child ; Deafness* ; Death, Sudden ; Death, Sudden, Cardiac ; Female ; Humans ; Incidence ; Jervell-Lange Nielsen Syndrome ; Life Expectancy ; Long QT Syndrome* ; Seizures ; Syncope* ; Tachycardia, Ventricular ; Unconsciousness ; Wills

OBJECTIVEJervell and Lange-Nielsen syndrome (JLNS) is a severe cardioauditory syndrome manifested as QT interval prolongation, abnormal T waves, and relative bradycardia ventricular tachyarrhythmias. In this report, we screened a nonconsanguineous families with JLNS for mutations in KCNQ1.

METHODSMutation analysis was performed by using purified PCR products to direct sequence analysis on an ABI-3730XL automated DNA sequencer. The whole sequence of proband' KCNQ1 was screened firstly, then screened the mutation exon sequences of others of the family and 50 unrelated normal persons.

RESULTSA heterogeneous mutation was identified in the patients of the JLNS family, a missense mutation (G-->T) at nucleotide 917 encoded in exon 6 of KCNQ1. This substitution leads to a change from glycine to Valine at codon 306(G306V) corresponding to the S5 transmembrane segment of KCNQ1. The other normal members of the family and 50 unrelated normal persons were not identified this mutation.

CONCLUSIONThe result suggested that not only homozygous mutations or compound heterozygous mutations in KCNQ1 could cause Jervell-Lange-Nielsen syndrome, the single heterozygous mutation may also cause Jervell-Lange-Nielsen syndrome.

Adolescent ; Adult ; Aged ; Child ; Female ; Genotype ; Humans ; Jervell-Lange Nielsen Syndrome ; genetics ; KCNQ1 Potassium Channel ; genetics ; Long QT Syndrome ; genetics ; Male ; Middle Aged ; Mutation, Missense ; Pedigree ; Young Adult

No abstract available.
Atrioventricular Block* ; Long QT Syndrome*

Electrocardiography ; Humans ; Long QT Syndrome

No abstract available.
Electrocardiography ; Humans ; Long QT Syndrome ; Pulmonary Embolism

Taxifolin glycoside is a new drug candidate for the treatment of atopic dermatitis (AD). Many drugs cause side effects such as long QT syndrome by blocking the human ether-a-go-go related gene (hERG) K+ channels. To determine whether taxifolin glycoside would block hERG K+ channels, we recorded hERG K+ currents using a whole-cell patch clamp technique. We found that taxifolin glycoside directly blocked hERG K+ current in a concentration-dependent manner (EC50=9.6+/-0.7 microM). The activation curve of hERG K+ channels was negatively shifted by taxifolin glycoside. In addition, taxifolin glycoside accelerated the activation time constant and reduced the onset of the inactivation time constant. These results suggest that taxifolin glycoside blocks hERG K+ channels that function by facilitating activation and inactivation process.
Dermatitis, Atopic ; Humans ; Long QT Syndrome ; Quercetin

In order to assess the clinical manifestations and electrocardiogram (ECG) characteristics of Chinese long QT syndrome (LQTS) patients and describe the phenotype-genotype correlation, the subjects from 5 congenital LQTS families underwent clinical detailed examination including resting body surface ECG. QT interval and transmural dispersion of repolarization (TDR) were manually measured. Five families were genotyped by linkage analysis (polymerase chain reacting-short tandem repeat, PCR-STR). The phenotype-genotype correlation was analyzed. Four families were LQT2, 1 family was LQT3. Twenty-eight gene carriers were (14 males and 14 females) identified from 5 families. The mean QTc and TDRc were 0.56 +/- 0.04 s (range 0.42 to 0.63) and 0.16 +/- 0.04 s (range 0.09 to 0.24) respectively. 35.7% (10/28) had normal to borderline QTc (< or = 0.460 s). There was significant difference in QTc and TDRc between the patients with symptomatic LQTS and those with asymptomatic LQTS, and there was significant difference in TDRc between the asymptomatic patients and normal people also. A history of cardiac events was present in 50% (14/28), including 9 with syncope, 2 with sudden death (SD) and occurred in the absence of beta-blocker. Three SDs occurred prior to the diagnosis of LQTS and had no ECG record. Two out of 5 SDs (40%) occurred as the first symptom. Typical LQT2 T wave pattern were found in 40% (6/15) of all affected members. The appearing-normal T wave was found in one LQT3 family. Low penetrance of QTc and symptoms resulted in diagnostic challenge. ECG patterns and repolarization parameters may be used to predict the genotype in most families. Genetic test is very important for identification of gene carriers.
Arrhythmia/etiology ; Arrhythmia/genetics ; Asian Continental Ancestry Group ; Electrocardiography ; Genotype ; Long QT Syndrome/complications ; Long QT Syndrome/congenital ; Long QT Syndrome/*genetics ; Pedigree ; *Phenotype

No abstract available.
Humans ; Long QT Syndrome ; Postoperative Period ; Torsades de Pointes