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

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

Animals ; Cochlea ; pathology ; Gene Deletion ; Hearing Loss ; etiology ; pathology ; KCNQ1 Potassium Channel ; genetics ; Mice

BACKGROUNDAtrial fibrillation is a common arrhythmia with multi-factorial pathogenesis. Recently, a single nucleotide polymorphism (G/T) at position 1057 in the KCNE4 gene, resulting in a glutamic acid (Glu, E)/aspartic acid (Asp, D) substitution at position 145 of the KCNE4 peptide, was found in our laboratory to be associated with idiopathic atrial fibrillation (atrial fibrillation more frequent with KCNE4 145D). However, the functional effect of the KCNE4 145E/D polymorphism is still unknown.

METHODSWe constructed KCNE4 (145E/D) expression plasmids and transiently co-transfected them with the KCNQ1 gene into Chinese hamster ovary-K1 cells and performed whole-cell patch-clamping recording to identify the possible functional consequences of the single nucleotide polymorphism. Quantitative data were analyzed by Student;s t test. Probability values less than 0.05 were considered statistically significant.

RESULTSA slowly activating, non-inactivating voltage-dependent current ((24.0 +/- 2.9) pA/pF, at +60 mV)) could be recorded in the cells transfected with KCNQ1 alone. Co-expression of wild type KCNE4 inhibited the KCNQ1 current ((7.3 +/- 1.1) pA/pF)). By contrast, co-expression of KCNE4 (145D) augment the KCNQ1 current ((42.9 +/- 7) pA/pF)). The V(1/2) of activation for the KCNQ1/KCNE4 (145D) current was shifted significantly towards the depolarizing potential compared to that for the KCNQ1 current ((-2.3 +/- 0.2) mv vs (-13.0 +/- 1.5) mv, P < 0.01)) without changing the slope factorkappa. Furthermore, KCNE4 (145D) also affected the activation and deactivation kinetics of KCNQ1 channels.

CONCLUSIONWe provide experimental evidence that the KCNE4 (145E/D) polymorphism exerts the effect of "gain of function" on the KCNQ1 channel. It may underlie the genetic mechanism of atrial fibrillation. Further studies on the functional association between I(Ks) and KCNE4 (145D) polymorphism in cardiac myocytes are suggested.

Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Humans ; KCNQ1 Potassium Channel ; physiology ; Polymorphism, Single Nucleotide ; Potassium Channels, Voltage-Gated ; analysis ; genetics ; physiology

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*

INTRODUCTIONType 2 diabetes (T2D) candidate gene: potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1) was suggested by conducting a genome wide association study (GWAS) in Japanese population. Association studies have been replicated among East Asian populations; however, the association between this gene and T2D in Southeast Asian populations still needs to be studied. This study aimed to investigate the association of KCNQ1 common variants with type 2 diabetes in Malaysian Malay subjects.

MATERIALS AND METHODSThe KCNQ1 single nucleotide polymorphisms (SNPs): rs2237892, rs2283228, and rs2237895 were genotyped in 234 T2D and 177 normal Malay subjects.

RESULTSThe risk allele of the rs2283228 (A) was strongly associated with T2D (OR = 1.7, P = 0.0006) while the rs2237892 (C) was moderately associated with T2D (OR = 1.45, P = 0.017). The recessive genetic models showed that rs2283228 was strongly associated with T2D (OR = 2.35, P = 0.00005) whereas rs2237892 showed a moderate association with T2D (OR = 1.69, P = 0.01). The haplotype block (TCA), which contained the protective allele, correlated with a protection from T2D (OR = 0.5, P = 0.003). Furthermore, the diplotype (CAA-TCA) that contained the protective haplotype was protected against T2D (OR = 0.46, P = 0.006).

CONCLUSIONThe KCNQ1 SNPs, haplotypes and diplotypes are associated with T2D in the Malaysian Malay subjects.

Adult ; Diabetes Mellitus, Type 2 ; ethnology ; genetics ; Female ; Genetics, Population ; Haplotypes ; genetics ; Humans ; KCNQ1 Potassium Channel ; genetics ; Malaysia ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; genetics ; Sequence Analysis, DNA

OBJECTIVERecent studies suggest that mutation of the slow delayed rectifier potassium channel [I(Ks)] contributes to familial atrial fibrillation (FAF). In the current study, we explored the potential association between KCNQ1 polymorphism with lone AF (LAF).

METHODSClinical data and blood samples were collected from 95 Han Chinese patients with LAF and matched healthy controls. Variants of the KCNQ1 gene were identified using single-strand conformational polymorphism (SSCP) analysis. A case-control association study in KCNQ1 identified four known single-nucleotide polymorphisms (SNPs) during SSCP screening of the 95 LAF patients and 190 healthy controls.

RESULTSThree new variations were identified in KCNQ1 from 95 sporadic LAF including 1 in 5'UTR(c.-22T > C), 1 in exon9 synonymous mutation (c.1008C > T) and 1 in intron region (c.1590 + 31A > T). These variations were heterozygous and not presented in 190 healthy controls. Highly significant difference was detected between LAF group and control groups in rs760419 polymorphism. Logistic regression revealed that rs760419 was independent risk factor for LAF(OR = 2.056, P = 0.001).

CONCLUSIONSKCNQ1 mutation is associated with LAF and rs760419 polymorphism is a susceptible marker for LAF.

Adult ; Asian Continental Ancestry Group ; genetics ; Atrial Fibrillation ; genetics ; Case-Control Studies ; Ethnic Groups ; genetics ; Female ; Genotype ; Humans ; KCNQ1 Potassium Channel ; genetics ; Male ; Middle Aged ; Polymorphism, Single Nucleotide

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

OBJECTIVETo search for the mutations of potassium voltage-gated channel, KQT-like subfamily member 1(KCNQ1) gene in 31 Chinese long QT syndrome(LQTS) families.

METHODSDue to the genetic heterogeneity, the genotype of patients was first predicted based on the spectrum of ST-T-wave patterns on ECG. Ten of 31 probands were considered as LQT1. Then the mutation of KCNQ1 gene was screened by the polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) technique combined with DNA sequencing in all members of these 10 families. To avoid omitting some LQT1 patients without typical characteristics and also to do methodological comparison, the mutations of KCNQ1 gene on 16 exons were screened by PCR and direct DNA sequencing in the rest 21 non-LQT1 probands only. Co-segregation analysis was carried out after the finding of an abnormal sequence. In case that the abnormality existed in patients only, the test of such exon was performed in 50 irrelevant normal individuals.

RESULTSTwo missense mutations and three single nucleotide polymorphisms (SNPs) were found in the LQT1 predicted families. The two mutations were S277L (1 family) and G306V (1 family) in exon 5 and were not reported previously. Three polymorphisms were 435C-->T (7 families), 1632C-->A (1 family), and IVS1+9 C-->G (3 families). Only a splice mutation IVS1+5G-->A (2 families) and a polymorphism IVS10+18C-->T (1 family) were found in the non-LQT1 predicted probands. All three mutations were localized within the functional domain of KCNQ1 and were co-segregated with the disease, and were not found in 50 normal individuals.

CONCLUSIONTwo novel missense mutations, 1 splice mutation and four SNPs on KCNQ1 gene were found in the 31 LQTS families. Combined with ECG-based genotype prediction, PCR-SSCP could find most mutations on KCNQ1 and be a simple and economic method for screening LQTS.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Infant ; KCNQ Potassium Channels ; KCNQ1 Potassium Channel ; Long QT Syndrome ; genetics ; Male ; Middle Aged ; Mutation ; Potassium Channels ; genetics ; Potassium Channels, Voltage-Gated