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Chen J, Li H, Guo S, Yang Z, Sun S, Zeng J, Gou H, Chen Y, Wang F, Lin Y, Huang K, Yue H, Ma Y, Lin Y. Whole exome sequencing in Brugada and long QT syndromes revealed novel rare and potential pathogenic mutations related to the dysfunction of the cardiac sodium channel. Orphanet J Rare Dis 2022; 17:394. [PMID: 36303204 PMCID: PMC9615250 DOI: 10.1186/s13023-022-02542-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/04/2022] [Indexed: 11/21/2022] Open
Abstract
Background Brugada syndrome (Brs) and long QT syndrome (LQTs) are the most observed “inherited primary arrhythmia syndromes” and “channelopathies”, which lead to sudden cardiac death. Methods Detailed clinical information of Brs and LQTs patients was collected. Genomic DNA samples of peripheral blood were conducted for whole-exome sequencing on the Illumina HiSeq 2000 platform. Then, we performed bioinformatics analysis for 200 genes susceptible to arrhythmias and cardiomyopathies. Protein interaction and transcriptomic co-expression were analyzed using the online website and GTEx database.
Results All sixteen cases of Brs and six cases of LQTs were enrolled in the current study. Four Brs carried known pathogenic or likely pathogenic of single-point mutations, including SCN5A p.R661W, SCN5A p.R965C, and KCNH2 p.R692Q. One Brs carried the heterozygous compound mutations of DSG2 p.F531C and SCN5A p.A1374S. Two Brs carried the novel heterozygous truncated mutations (MAF < 0.001) of NEBL (p.R882X) and NPPA (p.R107X), respectively. Except for the indirect interaction between NEBL and SCN5A, NPPA directly interacts with SCN5A. These gene expressions had a specific and significant positive correlation in myocardial tissue, with high degrees of co-expression and synergy. Two Brs carried MYH7 p.E1902Q and MYH6 p.R1820Q, which were predicted as "damaging/possibly damaging" and "damaging/damaging" by Polyphen and SIFT algorithm. Two LQTs elicited the pathogenic single splicing mutation of KCNQ1 (c.922-1G > C). Three LQTs carried a single pathogenic mutation of SCN5A p.R1880H, KCNH2 p.D161N, and KCNQ1 p.R243S, respectively. One patient of LQTs carried a frameshift mutation of KCNH2 p. A188Gfs*143. Conclusions The truncated mutations of NEBL (p.R882X) and NPPA (p.R107X) may induce Brugada syndrome by abnormally affecting cardiac sodium channel. SCN5A (p.R661W, p.R965C and p.A1374S) and KCNH2 (p.R692Q) may cause Brugada syndrome, while SCN5A (p.R1880H), KCNQ1 (c.922-1G > C and p.R243S) and KCNH2 (p.D161N and p.A188Gfs*143) may lead to long QT syndrome.
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Affiliation(s)
- Jia Chen
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China.,The Second Department of Cardiology, Department of Obstetrics and Gynecology, The Second People's Hospital of Guangdong Province, Guangzhou, 510310, Guangdong Province, China
| | - Hong Li
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China.,The University of Hong Kong-Shenzhen Hospital, Shenzhen, 518048, Guangdong Province, China
| | - Sicheng Guo
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China.,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, Hunan Province, China
| | - Zhe Yang
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China.,Department of Endocrinology and Metabolism, Zhuhai Hospital Affiliated to Jinan University, Zhuhai, 519000, Guangdong Province, China
| | - Shaoping Sun
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China
| | - JunJie Zeng
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China
| | - Hongjuan Gou
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China
| | - Yechang Chen
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China
| | - Feng Wang
- Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangdong Cardiovascular Institute, Guangzhou, 510080, Guangdong Province, China
| | - Yanping Lin
- The Second Department of Cardiology, Department of Obstetrics and Gynecology, The Second People's Hospital of Guangdong Province, Guangzhou, 510310, Guangdong Province, China
| | - Kun Huang
- The Second Department of Cardiology, Department of Obstetrics and Gynecology, The Second People's Hospital of Guangdong Province, Guangzhou, 510310, Guangdong Province, China
| | - Hong Yue
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China.
| | - Yuting Ma
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China. .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Yubi Lin
- The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, 523710, Guangdong Province, China. .,Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangdong Cardiovascular Institute, Guangzhou, 510080, Guangdong Province, China.
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Kekenes-Huskey PM, Burgess DE, Sun B, Bartos DC, Rozmus ER, Anderson CL, January CT, Eckhardt LL, Delisle BP. Mutation-Specific Differences in Kv7.1 ( KCNQ1) and Kv11.1 ( KCNH2) Channel Dysfunction and Long QT Syndrome Phenotypes. Int J Mol Sci 2022; 23:7389. [PMID: 35806392 PMCID: PMC9266926 DOI: 10.3390/ijms23137389] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 06/22/2022] [Accepted: 06/24/2022] [Indexed: 11/16/2022] Open
Abstract
The electrocardiogram (ECG) empowered clinician scientists to measure the electrical activity of the heart noninvasively to identify arrhythmias and heart disease. Shortly after the standardization of the 12-lead ECG for the diagnosis of heart disease, several families with autosomal recessive (Jervell and Lange-Nielsen Syndrome) and dominant (Romano-Ward Syndrome) forms of long QT syndrome (LQTS) were identified. An abnormally long heart rate-corrected QT-interval was established as a biomarker for the risk of sudden cardiac death. Since then, the International LQTS Registry was established; a phenotypic scoring system to identify LQTS patients was developed; the major genes that associate with typical forms of LQTS were identified; and guidelines for the successful management of patients advanced. In this review, we discuss the molecular and cellular mechanisms for LQTS associated with missense variants in KCNQ1 (LQT1) and KCNH2 (LQT2). We move beyond the "benign" to a "pathogenic" binary classification scheme for different KCNQ1 and KCNH2 missense variants and discuss gene- and mutation-specific differences in K+ channel dysfunction, which can predispose people to distinct clinical phenotypes (e.g., concealed, pleiotropic, severe, etc.). We conclude by discussing the emerging computational structural modeling strategies that will distinguish between dysfunctional subtypes of KCNQ1 and KCNH2 variants, with the goal of realizing a layered precision medicine approach focused on individuals.
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Affiliation(s)
- Peter M. Kekenes-Huskey
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Don E. Burgess
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA; (D.E.B.); (E.R.R.)
| | - Bin Sun
- Department of Pharmacology, Harbin Medical University, Harbin 150081, China;
| | | | - Ezekiel R. Rozmus
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA; (D.E.B.); (E.R.R.)
| | - Corey L. Anderson
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; (C.L.A.); (C.T.J.); (L.L.E.)
| | - Craig T. January
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; (C.L.A.); (C.T.J.); (L.L.E.)
| | - Lee L. Eckhardt
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; (C.L.A.); (C.T.J.); (L.L.E.)
| | - Brian P. Delisle
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA; (D.E.B.); (E.R.R.)
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Wuriyanghai Y, Makiyama T, Sasaki K, Kamakura T, Yamamoto Y, Hayano M, Harita T, Nishiuchi S, Chen J, Kohjitani H, Hirose S, Yokoi F, Gao J, Chonabayashi K, Watanabe K, Ohno S, Yoshida Y, Kimura T, Horie M. Complex aberrant splicing in the induced pluripotent stem cell–derived cardiomyocytes from a patient with long QT syndrome carrying KCNQ1-A344Aspl mutation. Heart Rhythm 2018; 15:1566-74. [DOI: 10.1016/j.hrthm.2018.05.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Indexed: 02/06/2023]
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Bhuiyan ZA. Mechanistic insight into an exonic splice defect mutation from native induced pluripotent stem cell-derived cardiomyocytes. Heart Rhythm 2018; 15:1575-1576. [PMID: 29890319 DOI: 10.1016/j.hrthm.2018.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Indexed: 11/26/2022]
Affiliation(s)
- Zahurul A Bhuiyan
- Laboratoire de Génétique, Service de Médecine Génétique, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
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Wei H, Wu J, Liu Z. Studying KCNQ1 Mutation and Drug Response in Type 1 Long QT Syndrome Using Patient-Specific Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Methods Mol Biol 2018; 1684:7-28. [PMID: 29058180 DOI: 10.1007/978-1-4939-7362-0_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Patient-specific human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) are becoming a valuable model for studying inherited cardiac arrhythmias. Type 1 long-QT syndrome is associated with the genetic variants of KCNQ1 gene that encodes Kv7.1, the α-subunit of the voltage-gated potassium channel QKT subfamily member 1 that channels the slow component of the outwardly rectifying K+ channel current in cardiac myocytes. Patient- or disease-specific hiPSC-CM model could facilitate the characterization of the genotype-phenotype relationships and testing of individualized drug responses.Here, we describe the methods in the generation of hiPSC-CMs, molecular and electrophysiological characterizations of their cellular phenotypes associated with KCNQ1/Kv7.1 defects, and evaluation of the effects of K+ channel-specific drugs.
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Affiliation(s)
- Heming Wei
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Republic of Singapore.
| | - Jianjun Wu
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Republic of Singapore
| | - Zhenfeng Liu
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Republic of Singapore
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7
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Kapplinger JD, Erickson A, Asuri S, Tester DJ, McIntosh S, Kerr CR, Morrison J, Tang A, Sanatani S, Arbour L, Ackerman MJ. KCNQ1 p.L353L affects splicing and modifies the phenotype in a founder population with long QT syndrome type 1. J Med Genet 2017; 54:390-398. [PMID: 28264985 PMCID: PMC5502312 DOI: 10.1136/jmedgenet-2016-104153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 11/30/2016] [Accepted: 12/19/2016] [Indexed: 12/23/2022]
Abstract
Background Variable expressivity and incomplete penetrance between individuals with identical long QT syndrome (LQTS) causative mutations largely remain unexplained. Founder populations provide a unique opportunity to explore modifying genetic effects. We examined the role of a novel synonymous KCNQ1 p.L353L variant on the splicing of exon 8 and on heart rate corrected QT interval (QTc) in a population known to have a pathogenic LQTS type 1 (LQTS1) causative mutation, p.V205M, in KCNQ1-encoded Kv7.1. Methods 419 adults were genotyped for p.V205M, p.L353L and a previously described QTc modifier (KCNH2-p.K897T). Adjusted linear regression determined the effect of each variant on QTc, alone and in combination. In addition, peripheral blood RNA was extracted from three controls and three p.L353L-positive individuals. The mutant transcript levels were assessed via qPCR and normalised to overall KCNQ1 transcript levels to assess the effect on splicing. Results For women and men, respectively, p.L353L alone conferred a 10.0 (p=0.064) ms and 14.0 (p=0.014) ms increase in QTc and in men only a significant interaction effect in combination with the p.V205M (34.6 ms, p=0.003) resulting in a QTc of ∼500 ms. The mechanism of p.L353L's effect was attributed to approximately threefold increase in exon 8 exclusion resulting in ∼25% mutant transcripts of the total KCNQ1 transcript levels. Conclusions Our results provide the first evidence that synonymous variants outside the canonical splice sites in KCNQ1 can alter splicing and clinically impact phenotype. Through this mechanism, we identified that p.L353L can precipitate QT prolongation by itself and produce a clinically relevant interactive effect in conjunction with other LQTS variants.
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Affiliation(s)
- Jamie D Kapplinger
- Mayo Medical School, Mayo Clinic, Rochester, Minnesota, USA.,Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Anders Erickson
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Sirisha Asuri
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - David J Tester
- Division of Heart Rhythm Services, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Sarah McIntosh
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Charles R Kerr
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Julie Morrison
- Gitxsan Health Society, Hazelton, British Columbia, Canada
| | - Anthony Tang
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Shubhayan Sanatani
- Division of Cardiology, Department of Pediatrics, University of British Columbia, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Laura Arbour
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael J Ackerman
- Mayo Medical School, Mayo Clinic, Rochester, Minnesota, USA.,Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA.,Division of Heart Rhythm Services, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Mayo Clinic, Rochester, Minnesota, USA
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Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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Abstract
A number of different ion channel types are involved in cell signaling networks, and homeostatic regulatory mechanisms contribute to the control of ion channel expression. Profiling of global gene expression using microarray technology has recently provided novel insights into the molecular mechanisms underlying the homeostatic and pathological control of ion channel expression. It has demonstrated that the dysregulation of ion channel expression is associated with the pathogenesis of neural, cardiovascular, and immune diseases as well as cancers. In addition to the transcriptional, translational, and post-translational regulation of ion channels, potentially important evidence on the mechanisms controlling ion channel expression has recently been accumulated. The regulation of alternative pre-mRNA splicing is therefore a novel therapeutic strategy for the treatment of dominant-negative splicing disorders. Epigenetic modification plays a key role in various pathological conditions through the regulation of pluripotency genes. Inhibitors of pre-mRNA splicing and histone deacetyalase/methyltransferase have potential as potent therapeutic drugs for cancers and autoimmune and inflammatory diseases. Moreover, membrane-anchoring proteins, lysosomal and proteasomal degradation-related molecules, auxiliary subunits, and pharmacological agents alter the protein folding, membrane trafficking, and post-translational modifications of ion channels, and are linked to expression-defect channelopathies. In this review, we focused on recent insights into the transcriptional, spliceosomal, epigenetic, and proteasomal regulation of ion channel expression: Ca(2+) channels (TRPC/TRPV/TRPM/TRPA/Orai), K(+) channels (voltage-gated, KV/Ca(2+)-activated, KCa/two-pore domain, K2P/inward-rectifier, Kir), and Ca(2+)-activated Cl(-) channels (TMEM16A/TMEM16B). Furthermore, this review highlights expression of these ion channels in expression-defect channelopathies.
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Affiliation(s)
- Susumu Ohya
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
| | - Hiroaki Kito
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Noriyuki Hatano
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan
| | - Katsuhiko Muraki
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan.
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Yang KC, Nerbonne JM. Mechanisms contributing to myocardial potassium channel diversity, regulation and remodeling. Trends Cardiovasc Med 2015; 26:209-18. [PMID: 26391345 DOI: 10.1016/j.tcm.2015.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/11/2015] [Accepted: 07/12/2015] [Indexed: 01/19/2023]
Abstract
In the mammalian heart, multiple types of K(+) channels contribute to the control of cardiac electrical and mechanical functioning through the regulation of resting membrane potentials, action potential waveforms and refractoriness. There are similarly vast arrays of K(+) channel pore-forming and accessory subunits that contribute to the generation of functional myocardial K(+) channel diversity. Maladaptive remodeling of K(+) channels associated with cardiac and systemic diseases results in impaired repolarization and increased propensity for arrhythmias. Here, we review the diverse transcriptional, post-transcriptional, post-translational, and epigenetic mechanisms contributing to regulating the expression, distribution, and remodeling of cardiac K(+) channels under physiological and pathological conditions.
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Affiliation(s)
- Kai-Chien Yang
- Department of Pharmacology, National Taiwan University, Taipei, Taiwan; Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jeanne M Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO; Internal Medicine, Washington University School of Medicine, St. Louis, MO; Cardiovascular Division, Washington University School of Medicine, St. Louis, MO.
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Ma D, Wei H, Lu J, Huang D, Liu Z, Loh LJ, Islam O, Liew R, Shim W, Cook SA. Characterization of a novel KCNQ1 mutation for type 1 long QT syndrome and assessment of the therapeutic potential of a novel IKs activator using patient-specific induced pluripotent stem cell-derived cardiomyocytes. Stem Cell Res Ther 2015; 6:39. [PMID: 25889101 PMCID: PMC4396080 DOI: 10.1186/s13287-015-0027-z] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 02/27/2015] [Accepted: 02/27/2015] [Indexed: 12/14/2022] Open
Abstract
Introduction Type 1 long QT syndrome (LQT1) is a common type of cardiac channelopathy associated with loss-of-function mutations of KCNQ1. Currently there is a lack of drugs that target the defected slowly activating delayed rectifier potassium channel (IKs). With LQT1 patient-specific human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs), we tested the effects of a selective IKs activator ML277 on reversing the disease phenotypes. Methods A LQT1 family with a novel heterozygous exon 7 deletion in the KCNQ1 gene was identified. Dermal fibroblasts from the proband and her healthy father were reprogrammed to hiPSCs and subsequently differentiated into hiPSC-CMs. Results Compared with the control, LQT1 patient hiPSC-CMs showed reduced levels of wild type KCNQ1 mRNA accompanied by multiple exon skipping mRNAs and a ~50% reduction of the full length Kv7.1 protein. Patient hiPSC-CMs showed reduced IKs current (tail current density at 30 mV: 0.33 ± 0.02 vs. 0.92 ± 0.21, P < 0.05) and prolonged action potential duration (APD) (APD 50 and APD90: 603.9 ± 39.2 vs. 319.3 ± 13.8 ms, P < 0.005; and 671.0 ± 41.1 vs. 372.9 ± 14.2 ms, P < 0.005). ML277, a small molecule recently identified to selectively activate KV7.1, reversed the decreased IKs and partially restored APDs in patient hiPSC-CMs. Conclusions From a LQT1 patient carrying a novel heterozygous exon7 deletion mutation of KCNQ1, we generated hiPSC-CMs that faithfully recapitulated the LQT1 phenotypes that are likely associated with haploinsufficiency and trafficking defect of KCNQ1/Kv7.1. The small molecule ML277 restored IKs function in hiPSC-CMs and could have therapeutic value for LQT1 patients. Electronic supplementary material The online version of this article (doi:10.1186/s13287-015-0027-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dongrui Ma
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Heming Wei
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. .,Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore.
| | - Jun Lu
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Dou Huang
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Zhenfeng Liu
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Li Jun Loh
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Omedul Islam
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore.
| | - Reginald Liew
- Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore.
| | - Winston Shim
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. .,Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore.
| | - Stuart A Cook
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. .,Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore. .,National Heart and Lung Institute, Imperial College, South Kensington Campus, London, SW7 2AZ, UK.
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Itoh H, Dochi K, Shimizu W, Denjoy I, Ohno S, Aiba T, Kimura H, Kato K, Fukuyama M, Hasagawa K, Schulze-Bahr E, Guicheney P, Horie M. A Common Mutation of Long QT Syndrome Type 1 in Japan. Circ J 2015; 79:2026-30. [DOI: 10.1253/circj.cj-15-0342] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
- Sorbonne Universités, Institut de Recherche sur les Maladies Cardiovasculaires, du Métabolisme et de la Nutrition
- Institute of Cardiometabolism and Nutrition (ICAN)
| | - Kenichi Dochi
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, Nippon Medical School
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Isabelle Denjoy
- AP-HP, Hôpital Bichat, Service de Cardiologie, Centre de Référence des Maladies Cardiaques Héréditaires, Université Denis Diderot
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Takeshi Aiba
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Hiromi Kimura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Koichi Kato
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Megumi Fukuyama
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Kanae Hasagawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster
- Interdisciplinary Centre for Clinical Research (IZKF) of the University of Münster
| | - Pascale Guicheney
- Sorbonne Universités, Institut de Recherche sur les Maladies Cardiovasculaires, du Métabolisme et de la Nutrition
- Institute of Cardiometabolism and Nutrition (ICAN)
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
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Imai M, Nakajima T, Kaneko Y, Niwamae N, Irie T, Ota M, Iijima T, Tange S, Kurabayashi M. A novel KCNQ1 splicing mutation in patients with forme fruste LQT1 aggravated by hypokalemia. J Cardiol 2014; 64:121-6. [DOI: 10.1016/j.jjcc.2013.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/10/2013] [Accepted: 11/20/2013] [Indexed: 10/25/2022]
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Christiansen M, Hedley PL, Theilade J, Stoevring B, Leren TP, Eschen O, Sørensen KM, Tybjærg-Hansen A, Ousager LB, Pedersen LN, Frikke-Schmidt R, Aidt FH, Hansen MG, Hansen J, Bloch Thomsen PE, Toft E, Henriksen FL, Bundgaard H, Jensen HK, Kanters JK. Mutations in Danish patients with long QT syndrome and the identification of a large founder family with p.F29L in KCNH2. BMC Med Genet 2014; 15:31. [PMID: 24606995 PMCID: PMC4007532 DOI: 10.1186/1471-2350-15-31] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 02/18/2014] [Indexed: 01/08/2023]
Abstract
Background Long QT syndrome (LQTS) is a cardiac ion channelopathy which presents clinically with palpitations, syncope or sudden death. More than 700 LQTS-causing mutations have been identified in 13 genes, all of which encode proteins involved in the execution of the cardiac action potential. The most frequently affected genes, covering > 90% of cases, are KCNQ1, KCNH2 and SCN5A. Methods We describe 64 different mutations in 70 unrelated Danish families using a routine five-gene screen, comprising KCNQ1, KCNH2 and SCN5A as well as KCNE1 and KCNE2. Results Twenty-two mutations were found in KCNQ1, 28 in KCNH2, 9 in SCN5A, 3 in KCNE1 and 2 in KCNE2. Twenty-six of these have only been described in the Danish population and 18 are novel. One double heterozygote (1.4% of families) was found. A founder mutation, p.F29L in KCNH2, was identified in 5 “unrelated” families. Disease association, in 31.2% of cases, was based on the type of mutation identified (nonsense, insertion/deletion, frameshift or splice-site). Functional data was available for 22.7% of the missense mutations. None of the mutations were found in 364 Danish alleles and only three, all functionally characterised, were recorded in the Exome Variation Server, albeit at a frequency of < 1:1000. Conclusion The genetic etiology of LQTS in Denmark is similar to that found in other populations. A large founder family with p.F29L in KCNH2 was identified. In 48.4% of the mutations disease causation was based on mutation type or functional analysis.
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Affiliation(s)
- Michael Christiansen
- Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institut, Ørestads Boulevard 5, 2300S, Copenhagen, Denmark.
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Fukuyama M, Ohno S, Wang Q, Shirayama T, Itoh H, Horie M. Nonsense-mediated mRNA decay due to a CACNA1C splicing mutation in a patient with Brugada syndrome. Heart Rhythm 2013; 11:629-34. [PMID: 24321233 DOI: 10.1016/j.hrthm.2013.12.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Brugada syndrome (BrS) is an inherited cardiac arrhythmia associated with sudden death due to ventricular fibrillation. Mutations in genes related to the cardiac L-type calcium channel have been reported to be causative of BrS. Generally, the messenger RNA (mRNA) that contains a nonsense mutation is rapidly degraded via its decay pathway, which is known as nonsense-mediated mRNA decay (NMD). Previously, we reported a male patient with BrS who carried c.1896G>A (the first nucleotide of CACNA1C exon 14), which caused a synonymous mutation, p.R632R. OBJECTIVE To examine how the synonymous CACNA1C mutation p.R632R produces the phenotype of BrS, with a special emphasis on the splicing error and NMD processes. METHODS We extracted mRNA from leukocytes of the proband and his 2 children and performed reverse transcription polymerase chain reaction. Complementary DNAs were checked by using direct sequencing and quantitative analysis. RESULTS The subsequent sequence electropherogram of the complementary DNAs did not show the substitution of the nucleotide identified in the genomic DNA of the proband. In the mRNA quantification analysis, we confirmed that reduction in the CACNA1C expression level was suspected to be caused by NMD. CONCLUSIONS Mutant mRNA with a c.1896G>A substitution may be diminished by NMD, and the resultant decrease in CACNA1C message leads to a novel mechanism for inducing BrS that is distinct from that reported previously.
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Affiliation(s)
- Megumi Fukuyama
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Qi Wang
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Takeshi Shirayama
- Division of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan.
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Lara-Pezzi E, Gómez-Salinero J, Gatto A, García-Pavía P. The alternative heart: impact of alternative splicing in heart disease. J Cardiovasc Transl Res 2013; 6:945-55. [PMID: 23775418 DOI: 10.1007/s12265-013-9482-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/04/2013] [Indexed: 01/16/2023]
Abstract
Alternative splicing is the main driver of protein diversity and allows the production of different proteins from each gene in the genome. Changes in exon exclusion, intron retention or the use of alternative splice sites can alter protein structure, localisation, regulation and function. In the heart, alternative splicing of sarcomeric genes, ion channels and cell signalling proteins can lead to cardiomyopathies, arrhythmias and other pathologies. Also, a number of inherited conditions and heart-related diseases develop as a result of mutations affecting splicing. Here, we review the impact that changes in alternative splicing have on individual genes and on whole biological processes associated with heart disease. We also discuss promising therapeutic tools based on the manipulation of alternative splicing.
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Gao Y, Li C, Liu W, Wu R, Qiu X, Liang R, Li L, Zhang L, Hu D. Genotype-phenotype analysis of three Chinese families with Jervell and Lange-Nielsen syndrome. J Cardiovasc Dis Res 2012; 3:67-75. [PMID: 22629021 PMCID: PMC3354473 DOI: 10.4103/0975-3583.95357] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Long QT syndrome (LQTS) is characterized by QT prolongation, syncope and sudden death. This study aims to explore the causes, clinical manifestations and therapeutic outcomes of Jervell and Lange-Nielsen syndrome (JLNS), a rare form of LQTS with congenital sensorineural deafness, in Chinese individuals. MATERIALS AND METHODS Three JLNS kindreds from the Chinese National LQTS Registry were investigated. Mutational screening of KCNQ1 and KCNE1 genes was performed by polymerase chain reaction and direct DNA sequence analysis. LQTS phenotype and therapeutic outcomes were evaluated for all probands and family members. RESULTS We identified 7 KCNQ1 mutations. c.1032_1117dup (p.Ser373TrpfsX10) and c.1319delT (p.Val440AlafsX26) were novel, causing JLNS in a 16-year-old boy with a QTc (QT interval corrected for heart rate) of 620 ms and recurrent syncope. c.605-2A>G and c.815G>A (p.Gly272Asp) caused JLNS in a 12-year-old girl and her 5-year-old brother, showing QTc of 590 to 600 ms and recurrent syncope. The fourth JLNS case, a 46-year-old man carrying c.1032G>A (p.Ala344Alasp) and c.569G>A (p.Arg190Gln) and with QTc of 460 ms, has been syncope-free since age 30. His 16-year-old daughter carries novel missense mutation c.574C>T (p.Arg192Cys) and c.1032G>A(p.Ala344Alasp) and displayed a severe phenotype of Romano-Ward syndrome (RWS) characterized by a QTc of 530 ms and recurrent syncope with normal hearing. Both the father and daughter also carried c.253G>A (p.Asp85Asn; rs1805128), a rare single nucleotide polymorphism (SNP) on KCNE1. Bizarre T waves were seen in 3/4 JLNS patients. Symptoms were improved and T wave abnormalities became less abnormal after appropriate treatment. CONCLUSION This study broadens the mutation and phenotype spectrums of JLNS. Compound heterozygous KCNQ1 mutations can result in both JLNS and severe forms of RWS in Chinese individuals.
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Affiliation(s)
- Yuanfeng Gao
- Heart Center, Peking University People's Hospital, Beijing - 100 044, P. R. China
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Tsuji-Wakisaka K, Akao M, Ishii TM, Ashihara T, Makiyama T, Ohno S, Toyoda F, Dochi K, Matsuura H, Horie M. Identification and functional characterization of KCNQ1 mutations around the exon 7-intron 7 junction affecting the splicing process. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1452-9. [PMID: 21810471 DOI: 10.1016/j.bbadis.2011.07.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/28/2011] [Accepted: 07/18/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND KCNQ1 gene encodes the delayed rectifier K(+) channel in cardiac muscle, and its mutations cause long QT syndrome type 1 (LQT1). Especially exercise-related cardiac events predominate in LQT1. We previously reported that a KCNQ1 splicing mutation displays LQT1 phenotypes. METHODS AND RESULTS We identified novel mutation at the third base of intron 7 (IVS7 +3A>G) in exercise-induced LQT1 patients. Minigene assay in COS7 cells and RT-PCR analysis of patients' lymphocytes demonstrated the presence of exon 7-deficient mRNA in IVS7 +3A>G, as well as c.1032G>A, but not in c.1022C>T. Real-time RT-PCR demonstrated that both IVS7 +3A>G and c.1032G>A carrier expressed significant amounts of exon-skipping mRNAs (18.8% and 44.8% of total KCNQ1 mRNA). Current recordings from Xenopus oocytes injected cRNA by simulating its ratios of exon skipping displayed a significant reduction in currents to 64.8 ± 4.5% for IVS7 +3A>G and to 41.4 ± 9.5% for c.1032G>A carrier, respectively, compared to the condition without splicing error. Computer simulation incorporating these quantitative results revealed the pronounced QT prolongation under beta-adrenergic stimulation in IVS7 +3A>G carrier model. CONCLUSION Here we report a novel splicing mutation IVS7 +3A>G, identified in a family with mild form LQT1 phenotypes, and examined functional outcome in comparison with three other variants around the exon 7-intron 7 junction. In addition to c.1032G>A mutation, IVS7 +3A>G generates exon-skipping mRNAs, and thereby causing LQT1 phenotype. The severity of clinical phenotypes appeared to differ between the two splicing-related mutations and to result from the amount of resultant mRNAs and their functional consequences.
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Affiliation(s)
- Keiko Tsuji-Wakisaka
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
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Hedley PL, Jørgensen P, Schlamowitz S, Wangari R, Moolman-Smook J, Brink PA, Kanters JK, Corfield VA, Christiansen M. The genetic basis of long QT and short QT syndromes: A mutation update. Hum Mutat 2009; 30:1486-511. [DOI: 10.1002/humu.21106] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Kapplinger JD, Tester DJ, Alders M, Benito B, Berthet M, Brugada J, Brugada P, Fressart V, Guerchicoff A, Harris-Kerr C, Kamakura S, Kyndt F, Koopmann TT, Miyamoto Y, Pfeiffer R, Pollevick GD, Probst V, Zumhagen S, Vatta M, Towbin JA, Shimizu W, Schulze-Bahr E, Antzelevitch C, Salisbury BA, Guicheney P, Wilde AAM, Brugada R, Schott JJ, Ackerman MJ. An international compendium of mutations in the SCN5A-encoded cardiac sodium channel in patients referred for Brugada syndrome genetic testing. Heart Rhythm 2009; 7:33-46. [PMID: 20129283 DOI: 10.1016/j.hrthm.2009.09.069] [Citation(s) in RCA: 516] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 09/25/2009] [Indexed: 01/08/2023]
Abstract
BACKGROUND Brugada syndrome (BrS) is a common heritable channelopathy. Mutations in the SCN5A-encoded sodium channel (BrS1) culminate in the most common genotype. OBJECTIVE This study sought to perform a retrospective analysis of BrS databases from 9 centers that have each genotyped >100 unrelated cases of suspected BrS. METHODS Mutational analysis of all 27 translated exons in SCN5A was performed. Mutation frequency, type, and localization were compared among cases and 1,300 ostensibly healthy volunteers including 649 white subjects and 651 nonwhite subjects (blacks, Asians, Hispanics, and others) that were genotyped previously. RESULTS A total of 2,111 unrelated patients (78% male, mean age 39 +/- 15 years) were referred for BrS genetic testing. Rare mutations/variants were more common among BrS cases than control subjects (438/2,111, 21% vs. 11/649, 1.7% white subjects and 31/651, 4.8% nonwhite subjects, respectively, P <10(-53)). The yield of BrS1 genetic testing ranged from 11% to 28% (P = .0017). Overall, 293 distinct mutations were identified in SCN5A: 193 missense, 32 nonsense, 38 frameshift, 21 splice-site, and 9 in-frame deletions/insertions. The 4 most frequent BrS1-associated mutations were E1784K (14x), F861WfsX90 (11x), D356N (8x), and G1408R (7x). Most mutations localized to the transmembrane-spanning regions. CONCLUSION This international consortium of BrS genetic testing centers has added 200 new BrS1-associated mutations to the public domain. Overall, 21% of BrS probands have mutations in SCN5A compared to the 2% to 5% background rate of rare variants reported in healthy control subjects. Additional studies drawing on the data presented here may help further distinguish pathogenic mutations from similarly rare but otherwise innocuous ones found in cases.
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Affiliation(s)
- Jamie D Kapplinger
- Department of Medicine, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA
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21
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Kapplinger JD, Tester DJ, Salisbury BA, Carr JL, Harris-Kerr C, Pollevick GD, Wilde AAM, Ackerman MJ. Spectrum and prevalence of mutations from the first 2,500 consecutive unrelated patients referred for the FAMILION long QT syndrome genetic test. Heart Rhythm 2009; 6:1297-303. [PMID: 19716085 DOI: 10.1016/j.hrthm.2009.05.021] [Citation(s) in RCA: 329] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 05/23/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Long QT syndrome (LQTS) is a potentially lethal, highly treatable cardiac channelopathy for which genetic testing has matured from discovery to translation and now clinical implementation. OBJECTIVES Here we examine the spectrum and prevalence of mutations found in the first 2,500 unrelated cases referred for the FAMILION LQTS clinical genetic test. METHODS Retrospective analysis of the first 2,500 cases (1,515 female patients, average age at testing 23 +/- 17 years, range 0 to 90 years) scanned for mutations in 5 of the LQTS-susceptibility genes: KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNE1 (LQT5), and KCNE2 (LQT6). RESULTS Overall, 903 referral cases (36%) hosted a possible LQTS-causing mutation that was absent in >2,600 reference alleles; 821 (91%) of the mutation-positive cases had single genotypes, whereas the remaining 82 patients (9%) had >1 mutation in > or =1 gene, including 52 cases that were compound heterozygous with mutations in >1 gene. Of the 562 distinct mutations, 394 (70%) were missense, 428 (76%) were seen once, and 336 (60%) are novel, including 92 of 199 in KCNQ1, 159 of 226 in KCNH2, and 70 of 110 in SCN5A. CONCLUSION This cohort increases the publicly available compendium of putative LQTS-associated mutations by >50%, and approximately one-third of the most recently detected mutations continue to be novel. Although control population data suggest that the great majority of these mutations are pathogenic, expert interpretation of genetic test results will remain critical for effective clinical use of LQTS genetic test results.
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Affiliation(s)
- Jamie D Kapplinger
- Department of Medicine, Divisions of Cardiovascular Diseases and Pediatric Cardiology, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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Ryan AW, Hughes DA, Tang K, Kelleher DP, Ryan T, McManus R, Stoneking M. Natural selection and the molecular basis of electrophoretic variation at the coagulation F13B locus. Eur J Hum Genet 2009; 17:219-27. [PMID: 18716611 DOI: 10.1038/ejhg.2008.137] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Electrophoretic analysis of protein variation at the coagulation F13B locus has previously revealed three alleles, with alleles 1, 2, and 3 each being at high frequency in European, African, and Asian populations, respectively. To determine if this unusual pattern of interpopulation differentiation reflects local natural selection or neutral genetic drift, we re-sequenced 4.6 kb of the gene, encompassing all exons, splice junctions, and 1.4 kb of the promoter, in African, European, and Asian samples. These analyses revealed three major lineages, which correspond to the common protein alleles and differ from each other at a non-synonymous substitution in exon 3 and a novel splice acceptor in intron K. There is previous evidence that these lineages are not functionally equivalent; we therefore carried out case-control analyses and confirmed that variability at F13B modulates susceptibility and/or survivorship in coronary artery disease (P<0.05) and type II diabetes within the coronary artery disease cohort (P<0.01). Tajima's D and Fu and Li's tests did not indicate significant departures from neutral expectations. However, publicly available data from SeattleSNPs and HapMap do indicate highly unusual levels of population differentiation (P=0.003) and an excess of allele-specific, extended haplotype homozygosity within the African population (P=0.0125). Possible causes of this putative signal of selection include hematophagous organisms, infection by pathogens that cause disseminated intravascular coagulation, and metabolic or dietary factors.
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Gong Q, Zhang L, Moss AJ, Vincent GM, Ackerman MJ, Robinson JC, Jones MA, Tester DJ, Zhou Z. A splice site mutation in hERG leads to cryptic splicing in human long QT syndrome. J Mol Cell Cardiol 2008; 44:502-9. [PMID: 18272172 DOI: 10.1016/j.yjmcc.2008.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/09/2008] [Accepted: 01/10/2008] [Indexed: 10/22/2022]
Abstract
Mutations in the human ether-a-go-go-related gene (hERG) cause type 2 long QT syndrome. In this study, we investigated the pathogenic mechanism of the hERG splice site mutation 2398+1G>C and the genotype-phenotype relationship of mutation carriers in three unrelated kindreds with long QT syndrome. The effect of 2398+1G>C on mRNA splicing was studied by analysis of RNA isolated from lymphocytes of index patients and using minigenes expressed in HEK293 cells and neonatal rat ventricular myocytes. RT-PCR analysis revealed that the 2398+1G>C mutation disrupted the normal splicing and activated a cryptic splice donor site in intron 9, leading to the inclusion of 54 nt of the intron 9 sequence in hERG mRNA. The cryptic splicing resulted in an in-frame insertion of 18 amino acids in the middle of the cyclic nucleotide binding domain. In patch clamp experiments the splice mutant did not generate hERG current. Western blot and immunostaining studies showed that the mutant expressed an immature form of hERG protein that failed to reach the plasma membrane. Coexpression of the mutant and wild-type channels led to a dominant negative suppression of wild-type channel function by intracellular retention of heteromeric channels. Our results demonstrate that 2398+1G>C activates a cryptic site and generates a full-length hERG protein with an insertion of 18 amino acids, which leads to a trafficking defect of the mutant channel.
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Affiliation(s)
- Qiuming Gong
- Division of Cardiovascular Medicine, Oregon Health and Science University, Portland, OR , USA
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Tsuji K, Akao M, Ishii TM, Ohno S, Makiyama T, Takenaka K, Doi T, Haruna Y, Yoshida H, Nakashima T, Kita T, Horie M. Mechanistic basis for the pathogenesis of long QT syndrome associated with a common splicing mutation in KCNQ1 gene. J Mol Cell Cardiol 2007; 42:662-9. [PMID: 17292394 DOI: 10.1016/j.yjmcc.2006.12.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 12/15/2006] [Accepted: 12/28/2006] [Indexed: 01/06/2023]
Abstract
Mutations in KCNQ1, the gene encoding the delayed rectifier K(+) channel in cardiac muscle, cause long QT syndrome (LQTS). We studied 3 families with LQTS, in whom a guanine to adenine change in the last base of exon 7 (c.1032G>A), previously reported as a common splice-site mutation, was identified. We performed quantitative measurements of exon-skipping KCNQ1 mRNAs caused by this mutation using real-time reverse transcription polymerase chain reaction. Compared with normal individuals who have minor fractions of splicing variants (Delta7-8: 0.1%, Delta8: 6.9%, of total KCNQ1 transcripts), the affected individuals showed remarkable increases of exon-skipping mRNAs (Delta7: 23.5%, Delta7-8: 16.8%, Delta8: 4.5%). Current recordings from Xenopus laevis oocytes heterologously expressing channels of wild-type (WT) or exon-skipping KCNQ1 (Delta7, Delta7-8, or Delta8) revealed that none of the mutants produced any measurable currents, and moreover they displayed mutant-specific degree of dominant-negative effects on WT currents, when co-expressed with WT. Confocal microscopy analysis showed that fluorescent protein-tagged WT was predominantly expressed on the plasma membrane, whereas the mutants showed intracellular distribution. When WT was co-expressed with mutants, the majority of WT co-localized with the mutants in the intracellular space. Finally, we provide evidence showing direct protein-protein interactions between WT and the mutants, by using fluorescence resonance energy transfer. Thus, the mutants may exert their dominant-negative effects by trapping WT intracellularly and thereby interfering its translocation to the plasma membrane. In conclusion, our data provide a mechanistic basis for the pathogenesis of LQTS caused by a splicing mutation in KCNQ1.
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Affiliation(s)
- Keiko Tsuji
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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Sarzani R, Pietrucci F, Francioni M, Salvi F, Letizia C, D'Erasmo E, Dessì Fulgheri P, Rappelli A. Expression of potassium channel isoforms mRNA in normal human adrenals and aldosterone-secreting adenomas. J Endocrinol Invest 2006; 29:147-53. [PMID: 16610241 DOI: 10.1007/bf03344088] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Increased aldosterone secretion has been found in a mouse lacking the KCNE1 gene which codes for a regulatory protein of the KCNQ1 gene product, forming the channel for the outward rectifying delayed K+ current. Abnormalities in proteins regulating the K+ fluxes across membranes may be responsible for aldosterone-secreting adenomas (aldosteronomas) also because K+ channels are involved in cell growth. Normal and adenomatous adrenal samples and NCI-H295 cell line were used to: a) evaluate KCNE1 and KCNQ1 gene expression, b) sequence the full length cDNAs of KCNE1 and both KCNQ1 isoforms. These differently spliced KCNE1 and KCNQ1 mRNAs were expressed in adrenal tissue. In contrast, KCNQ1 isoform 2 mRNA was not expressed in kidney control tissues and NCl-H295 cell line. NCI-H295 cell line also had a significantly lower expression of KCNQ1 isoform 1 mRNA than normal adrenals and aldosteronomas. We did not find any somatic mutations in the coding sequences of both genes. This different expression pattern of KCNQ1 isoforms in NCI-H295 cell line with the lack of the mRNA for the dominant-negative KCNQ1 isoform 2 supports the involvement of voltage-gated K+ channel in cell proliferation.
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Affiliation(s)
- R Sarzani
- Department of Internal Medicine, Polytechnical University of Marche, Ancona, University of Rome La Sapienza, Rome, Italy.
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Fodstad H, Bendahhou S, Rougier JS, Laitinen-Forsblom PJ, Barhanin J, Abriel H, Schild L, Kontula K, Swan H. Molecular characterization of two founder mutations causing long QT syndrome and identification of compound heterozygous patients. Ann Med 2006; 38:294-304. [PMID: 16754261 DOI: 10.1080/07853890600756065] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Mutations of at least six different genes have been found to cause long QT syndrome (LQTS), an inherited arrhythmic disorder characterized by a prolonged QT interval on the electrocardiogram (ECG), ventricular arrhythmias and risk of sudden death. AIM The aims were to define the yet undetermined phenotypic characteristics of two founder mutations and to study clinical features in compound heterozygotes identified during the course of the study. METHODS To maximize identification of the compound heterozygotes, we used an extended group of LQTS patients comprising 700 documented or suspected cases. Functional studies were carried out upon transient expression in COS-7 or HEK293 cells. RESULTS The KCNQ1 IVS7-2A>G (KCNQ1-FinB) mutation associated with a mean QTc interval of 464 ms and a complete loss-of-channel function. The HERG R176W (HERG-FinB) mutation caused a reduction in current density as well as slight acceleration of the deactivation kinetics in vitro, and its carriers had a mean QTc of 448 ms. The HERG R176W mutation was also present in 3 (0.9%) out of 317 blood donors. A total of six compound heterozygotes were identified who had the HERG R176W mutation in combination with a previously reported LQTS mutation (KCNQ1 G589D or IVS7-2A>G). When present simultaneously with an apparent LQTS-causing mutation, the HERG R176W mutation may exert an additional in vivo phenotypic effect. CONCLUSIONS The HERG R176W mutation represents a population-prevalent mutation predisposing to LQTS. Compound heterozygosity for mutant LQTS genes may modify the clinical picture in LQTS.
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Affiliation(s)
- Heidi Fodstad
- Biomedicum Helsinki and Department of Medicine, University of Helsinki, Finland, and Service of Cardiology, University Hospital, Lausanne, Switzerland.
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Zehelein J, Thomas D, Khalil M, Wimmer AB, Koenen M, Licka M, Wu K, Kiehn J, Brockmeier K, Kreye VAW, Karle CA, Katus HA, Ulmer HE, Schoels W. Identification and characterisation of a novel KCNQ1 mutation in a family with Romano–Ward syndrome. Biochim Biophys Acta Mol Basis Dis 2004; 1690:185-92. [PMID: 15511625 DOI: 10.1016/j.bbadis.2004.06.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Revised: 06/16/2004] [Accepted: 06/16/2004] [Indexed: 12/29/2022]
Abstract
Romano-Ward syndrome (RWS), the autosomal dominant form of the congenital long QT syndrome, is characterised by prolongation of the cardiac repolarisation process associated with ventricular tachyarrhythmias of the torsades de pointes type. Genetic studies have identified mutations in six ion channel genes, KCNQ1, KCNH2, SCN5A, KCNE1 and KCNE2 and the accessory protein Ankyrin-B gene, to be responsible for this disorder. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequence analysis have identified a KCNQ1 mutation in a family that were clinically conspicuous due to several syncopes and prolonged QTc intervals in the ECG. The mutant subunit was expressed and functionally characterised in the Xenopus oocyte expression system. A novel heterozygous missense mutation with a C to T transition at the first position of codon 343 (CCA) of the KCNQ1 gene was identified in three concerned family members (QTc intervals: 500, 510 and 530 ms, respectively). As a result, proline 343 localised within the highly conserved transmembrane segment S6 of the KCNQ1 channel is replaced by a serine. Co-expression of mutant (KCNQ1-P343S) and wild-type (KCNQ1) cRNA in Xenopus oocytes produced potassium currents reduced by approximately 92%, while IKs reconstitution experiments with a combination of KCNQ1 mutant, wild-type and KCNE1 subunits yielded currents reduced by approximately 60%. A novel mutation (P343S) identified in the KCNQ1 subunit gene of three members of a RWS family showed a dominant-negative effect on native IKs currents leading to prolongation of the heart repolarisation and possibly increases the risk of malign arrhythmias with sudden cardiac death.
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Affiliation(s)
- J Zehelein
- Innere Medizin III, Universitätsklinik Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
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Zhang L, Vincent GM, Baralle M, Baralle FE, Anson BD, Benson DW, Whiting B, Timothy KW, Carlquist J, January CT, Keating MT, Splawski I. An intronic mutation causes long QT syndrome. J Am Coll Cardiol 2004; 44:1283-91. [PMID: 15364333 DOI: 10.1016/j.jacc.2004.06.045] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Revised: 06/03/2004] [Accepted: 06/07/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVES The purpose of this research was to determine whether an intronic variant (T1945+6C) in KCNH2 is a disease-causing mutation, and if expanded phenotyping criteria produce improved identification of long QT syndrome (LQTS) patients. BACKGROUND Long QT syndrome is usually caused by mutations in conserved coding regions or invariant splice sites, yet no mutation is found in 30% to 50% of families. In one such family, we identified an intronic variant in KCNH2. Long QT syndrome diagnosis is hindered by reduced penetrance, as the long QT phenotype is absent on baseline electrocardiogram (ECG) in about 30%. METHODS Fifty-two family members were phenotyped by baseline QTc, QTc maximum on serial ECGs (Ser QTc-max), and on exercise ECGs (Ex QTc-max) and by T-wave patterns. Linkage analysis tested association of the intronic change with phenotype. The consequences of T1945+6C on splicing was studied using a minigene system and on function by heterologous expression. RESULTS Expanded phenotype/pedigree criteria identified 23 affected and 29 unaffected. Affected versus unaffected had baseline QTc 484 +/- 48 ms versus 422 +/- 20 ms, Ser QTc-max 508 +/- 48 ms versus 448 +/- 10 ms, Ex QTc-max 513 +/- 54 ms versus 444 +/- 11 ms, and LQT2 T waves in 87% versus 0%. Linkage analysis demonstrated a logarithm of odds score of 10.22. Splicing assay showed T1945+6C caused downstream intron retention. Complementary deoxyribonucleic acid with retained intron 7 failed to produce functional channels. CONCLUSIONS T1945+6C is a disease-causing mutation. It alters KCNH2 splicing and cosegregates with the LQT2 phenotype. Expanded ECG criteria plus pedigree analysis provided accurate clinical diagnosis of all carriers including those with reduced penetrance. Intronic mutations may be responsible for LQTS in some families with otherwise negative mutation screening.
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Affiliation(s)
- Li Zhang
- LDS Hospital, Salt Lake City, Utah 84103, USA
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Abstract
KCNQ genes encode a growing family of six transmembrane domains, single pore-loop, K(+) channel alpha-subunits that have a wide range of physiological correlates. KCNQ1 (KvLTQ1) is co-assembled with the product of the KCNE1 (minimal K(+)-channel protein) gene in the heart to form a cardiac-delayed rectifier-like K(+) current. Mutations in this channel can cause one form of inherited long QT syndrome (LQT1), as well as being associated with a form of deafness. KCNQ1 can also co-assemble with KCNE3, and may be the molecular correlate of the cyclic AMP-regulated K(+) current present in colonic crypt cells. KCNQ2 and KCNQ3 heteromultimers are thought to underlie the M-current; mutations in these genes may cause an inherited form of juvenile epilepsy. The KCNQ4 gene is thought to encode the molecular correlate of the I(K,n) in outer hair cells of the cochlea and I(K,L) in Type I hair cells of the vestibular apparatus, mutations in which lead to a form of inherited deafness. The recently identified KCNQ5 gene is expressed in brain and skeletal muscle, and can co-assemble with KCNQ3, suggesting it may also play a role in the M-current heterogeneity. This review will set this family of K(+) channels amongst the other known families. It will highlight the genes, physiology, pharmacology, and pathophysiology of this recently discovered, but important, family of K(+) channels.
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Affiliation(s)
- J Robbins
- Sensory Function Group, Centre for Neuroscience Research, King's College, Guy's Campus, London SE1 1UL, UK.
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Piippo K, Swan H, Pasternack M, Chapman H, Paavonen K, Viitasalo M, Toivonen L, Kontula K. A founder mutation of the potassium channel KCNQ1 in long QT syndrome: implications for estimation of disease prevalence and molecular diagnostics. J Am Coll Cardiol 2001; 37:562-8. [PMID: 11216980 DOI: 10.1016/s0735-1097(00)01124-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES We took advantage of the genetic isolate of Finns to characterize a common long QT syndrome (LQTS) mutation, and to estimate the prevalence of LQTS. BACKGROUND The LQTS is caused by mutations in different ion channel genes, which vary in their molecular nature from family to family. METHODS The potassium channel gene KCNQ1 was sequenced in two unrelated Finnish patients with Jervell and Lange-Nielsen syndrome (JLNS), followed by genotyping of 114 LQTS probands and their available family members. The functional properties of the mutation were studied using a whole-cell patch-damp technique. RESULTS We identified a novel missense mutation (G589D or KCNQ1-Fin) in the C-terminus of the KCNQ1 subunit. The voltage threshold of activation for the KCNQ1-Fin channel was markedly increased compared to the wild-type channel. This mutation was present in homozygous form in two siblings with JLNS, and in heterozygous form in 34 of 114 probands with Romano-Ward syndrome (RWS) and 282 family members. The mean (+/- SD) rate-corrected QT intervals of the heterozygous subjects (n = 316) and noncarriers (n = 423) were 460 +/- 40 ms and 410 +/- 20 ms (p < 0.001), respectively. CONCLUSIONS A single missense mutation of the KCNQ1 gene accounts for 30% of Finnish cases with LQTS, and it may be associated with both the RWS and JLNS phenotypes of the syndrome. The relative enrichment of this mutation most likely represents a founder gene effect. These circumstances provide an excellent opportunity to examine how genetic and nongenetic factors modify the LQTS phenotype.
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Affiliation(s)
- K Piippo
- Department of Medicine, University of Helsinki, Finland
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Kotajima N, Hirakata T, Kanda T, Yokoyama T, Hoshino Y, Tanaka T, Tamura J, Nagai R, Kobayasii I. Prolongation of QT interval and ventricular septal hypertrophy. Jpn Heart J 2000; 41:463-9. [PMID: 11041097 DOI: 10.1536/jhj.41.463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Long QT syndrome (LQTS) is a prime example of interplay between molecular biology, cellular physiology, and organ physiology. Both the congenital and acquired forms of LQTS are due to intrinsic and/or acquired abnormalities of the ionic currents responsible for cardiac repolarization. We analyzed the QTc interval, QRS axes and interventricular septal thickness (IVST) in 41 patients who had a prolonged QT interval on routine electrocardiography (ECG) (5 females and 36 males, mean age 65+/-13 years). The QRS axis of patients in the LQTS group (27+/-49 degrees) was significantly lower (p < 0.05) than in the control group (46+/-26 degrees). However, the IVST in the LQTS group (10+/-2 mm) was significantly thicker than in the control group (9+/-1 mm) (p < 0.05), while the WTd was not significantly different. The QTc interval in patients with ventricular septal hypertrophy (IVST > or = 12 min, 478.8+/-7.9 msec) was significantly longer (p < 0.05) than in the normal group (IVST < 12 mm, 472.1+/-17.5 msec). In conclusion, the results of this preliminary study suggest that prolongation of the QT interval on ECG should prompt screening for electrocardiographic evidence of ventricular hypertrophy in patients with this disease.
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Affiliation(s)
- N Kotajima
- Department of Laboratory Medicine, Gunma University School of Medicine, Maebashi, Japan
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