Humans ; Mutation, Missense ; KCNQ1 Potassium Channel/genetics* ; Long QT Syndrome/genetics* ; Phenotype ; Mutation ; Pedigree

Humans ; Mutation, Missense ; KCNQ1 Potassium Channel/genetics* ; Long QT Syndrome/genetics* ; Phenotype ; Mutation ; Pedigree

Long QT syndrome (LQTS) is a genetically heterogeneous disorder associated with sequence variations in more than 10 genes; in some cases, it is caused by large deletions or duplications among the main, known LQTS-associated genes. Here, we describe a 14-month-old Korean boy with congenital hearing loss and prolonged QT interval whose condition was clinically diagnosed as Jervell and Lange-Nielsen syndrome (JLNS), a recessive form of LQTS. Genetic analyses using sequence analysis and multiplex ligation-dependent probe amplification (MLPA) assay revealed a large deletion spanning exons 7-10 as well as a frameshift mutation (c.1893dup; p.Arg632Glnfs*20). To our knowledge, this is the first report of a large deletion in KCNQ1 identified in JLNS patients. This case indicates that a method such as MLPA, which can identify large deletions or duplications needs to be considered in addition to sequence analysis to diagnose JLNS.
Adolescent ; Alleles ; Base Sequence ; Electrocardiography ; Exons ; Frameshift Mutation ; Heterozygote ; Humans ; Jervell-Lange Nielsen Syndrome/diagnosis/*genetics ; KCNQ1 Potassium Channel/*genetics ; Male ; Nucleic Acid Amplification Techniques ; Pedigree ; Sequence Analysis, DNA ; Sequence Deletion

BACKGROUNDCongenital 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.

METHODSCongenital 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.

RESULTSThree 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).

CONCLUSIONSAlthough 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.

Adolescent ; Adult ; Aged ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Female ; Genotype ; Humans ; KCNQ1 Potassium Channel ; genetics ; Long QT Syndrome ; genetics ; pathology ; Male ; Middle Aged ; Mutation ; NAV1.5 Voltage-Gated Sodium Channel ; genetics ; Polymorphism, Single Nucleotide ; genetics ; Potassium Channels, Voltage-Gated ; genetics ; Young Adult

PURPOSE: Patients with gestational diabetes mellitus (GDM) have been reported to exhibit the same genetic susceptibility as that observed in those with type 2 diabetes mellitus (T2DM). Recent polymorphism studies have shown that several genes are related to T2DM and GDM. The aim of this study was to examine whether certain candidate genes, previously shown to be associated with T2DM, also offer a specific genetic predisposition to GDM. MATERIALS AND METHODS: The current study was conducted in 136 Korean pregnant women, who gave birth at Gil Hospital, from October 2008 to May 2011. These study subjects included 95 subjects with GDM and 41 non-diabetic controls. We selected the specific genes of PPARgamma2, IGF2BP2, and KCNQ1 for study and amplified them using the polymerase chain reaction. This was followed by genotyping for single nucleotide polymorphisms. We then compared the genotype frequencies between patients with GDM and non-diabetic controls using the chi2 test. We obtained and analyzed clinical information using Student's t-test, and statistical analyses were conducted using logistic regression with SPSS Statistics software, version 19.0. RESULTS: Significant differences were observed in maternal age, body mass index, weight gain and weight at time of delivery between the groups compared. Among pregnant women, polymorphisms in PPARgamma2 and IGF2BP2 were shown to be highly correlated with GDM occurrence, whereas no correlation was found for KCNQ1 polymorphisms. CONCLUSION: Our results indicated that genetic polymorphisms could also be of value in predicting the occurrence and diagnosis of GDM.
Diabetes, Gestational/*genetics ; Female ; Genetic Association Studies ; Genetic Predisposition to Disease ; Genotype ; Humans ; KCNQ1 Potassium Channel/*genetics ; Logistic Models ; PPAR gamma/*genetics ; Polymorphism, Single Nucleotide ; Pregnancy ; RNA-Binding Proteins/*genetics ; Republic of Korea

OBJECTIVETo study the association of polymorphisms in the potassium voltage-gated channel, KQT-like subfamily,member 1(KCNQ1) gene with type 2 diabetes in Chinese population from Jiangsu province.

METHODSSubjects consisting of 2925 cases and 3281 controls were enrolled from a community based cohort study of type 2 diabetes in Wuxi in 2007 and a community based cross-sectional survey on chronic non-communicable disease in Nantong in 2009. Epidemiological questionnaire survey and physical examinations were conducted and 10 h overnight fasting blood samples of 5 ml were drawn for all subjects.Genotypes were determined by TaqMan OpenArray Genotyping System and i-PLEX Sequenom MassARRAY platform. The relationship between KCNQ1 gene polymorphism and risk of type 2 diabetes after adjustment for age,sex and body mass index (BMI) was analyzed.

RESULTSThe C allele of rs2237897, rs2237892 and rs2237895 at KCNQ1 increased the risk of type 2 diabetes with adjusted OR (95%CI) value being 1.41(1.30-1.54), 1.35(1.24-1.47), 1.22(1.12-1.33) respectively (all P value < 0.05) under the additive genetic model after adjusted by age,sex and BMI. Stratification analyses in additive genetic model showed that the C allele of rs2237897 increased the risk of type 2 diabetes in subgroups stratified by age ( ≤ 56 years and > 56 years), sex (females and males), BMI (< 24 kg/m(2) and ≥ 24 kg/m(2)) with OR (95%CI) value being 1.39(1.22-1.59), 1.43(1.28-1.60), 1.40(1.26-1.55), 1.44(1.26-1.66), 1.48(1.33-1.66), 1.34(1.17-1.53) respectively (all P value< 0.05).

CONCLUSIONPolymorphisms of rs2237897, rs2237892 and rs2237895 in the KCNQ1 gene were associated with occurrence of type 2 diabetes among Jiangsu province population.

Aged ; Asian Continental Ancestry Group ; genetics ; China ; epidemiology ; Cohort Studies ; Cross-Sectional Studies ; Diabetes Mellitus, Type 2 ; epidemiology ; genetics ; Female ; Genotype ; Humans ; KCNQ1 Potassium Channel ; genetics ; Male ; Middle Aged ; Polymorphism, Single Nucleotide

Mutation or common intronic variants in cardiac ion channel genes have been suggested to be associated with sudden cardiac death caused by idiopathic ventricular tachyarrhythmia. This study aimed to find mutations in cardiac ion channel genes of Korean sudden cardiac arrest patients with structurally normal heart and to verify association between common genetic variation in cardiac ion channel and sudden cardiac arrest by idiopathic ventricular tachyarrhythmia in Koreans. Study participants were Korean survivors of sudden cardiac arrest caused by idiopathic ventricular tachycardia or fibrillation. All coding exons of the SCN5A, KCNQ1, and KCNH2 genes were analyzed by Sanger sequencing. Fifteen survivors of sudden cardiac arrest were included. Three male patients had mutations in SCN5A gene and none in KCNQ1 and KCNH2 genes. Intronic variant (rs2283222) in KCNQ1 gene showed significant association with sudden cardiac arrest (OR 4.05). Four male sudden cardiac arrest survivors had intronic variant (rs11720524) in SCN5A gene. None of female survivors of sudden cardiac arrest had SCN5A gene mutations despite similar frequencies of intronic variants between males and females in 55 normal controls. Common intronic variant in KCNQ1 gene is associated with sudden cardiac arrest caused by idiopathic ventricular tachyarrhythmia in Koreans.
Adolescent ; Adult ; Aged ; Arrhythmias, Cardiac/genetics ; *Death, Sudden, Cardiac ; Ether-A-Go-Go Potassium Channels/genetics ; Female ; Genetic Markers ; Genetic Predisposition to Disease ; Genetic Variation ; Heart/physiology ; Heart Conduction System/abnormalities ; Humans ; KCNQ1 Potassium Channel/*genetics ; Male ; Middle Aged ; NAV1.5 Voltage-Gated Sodium Channel/*genetics ; Republic of Korea ; Tachycardia, Ventricular/*genetics ; Ventricular Fibrillation/*genetics ; Young Adult

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 > or = 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.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Asian Continental Ancestry Group/genetics ; Calcium Channels/genetics ; Child ; Child, Preschool ; Electrocardiography ; Heart Arrest/genetics/pathology ; Humans ; Infant ; KCNQ1 Potassium Channel/genetics ; KCNQ2 Potassium Channel/genetics ; Long QT Syndrome/*diagnosis/*genetics ; Middle Aged ; Mutation/*genetics ; NAV1.5 Voltage-Gated Sodium Channel/genetics ; Penetrance ; Potassium Channels, Inwardly Rectifying/genetics ; Republic of Korea ; Risk Factors ; Seizures/genetics/pathology ; Young Adult

Diabetes Mellitus, Type 2 ; ethnology ; genetics ; Female ; Humans ; KCNQ1 Potassium Channel ; genetics ; Male

OBJECTIVE: To investigate KCNQ1, KCNH2, KCNE1 and KCNE2 gene variants in the cases of sudden manhood death syndrome (SMDS). METHODS: One hundred and sixteen sporadic cases of SMDS and one hundred and twenty-five healthy controlled samples were enrolled. Genomic DNA was extracted from blood samples. Gene variants of KCNQ1, KCNH2, KCNE1 and KCNE2 were screened by direct sequencing. RESULTS: A total of 14 mutations and 14 SNP were detected. Two non-synonymous mutations of them were newfound. There was no non-synonymous mutation found in the control group. CONCLUSION There are KCNQ1, KCNH2, KCNE1 and KCNE2 gene variants found in Chinese SMDS cases. KCNQ1, KCNH2, KCNE1 and KCNE2 gene mutation may correlate partly with the occurrence of some cases of the SMDS in China.
Base Sequence ; Case-Control Studies ; China ; DNA Mutational Analysis ; Death, Sudden/ethnology* ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels/genetics* ; Humans ; KCNQ1 Potassium Channel/genetics* ; Long QT Syndrome ; Mutation ; Polymorphism, Single Nucleotide ; Potassium Channels ; Potassium Channels, Voltage-Gated/genetics*