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Cui S, Hayashi K, Kobayashi I, Hosomichi K, Nomura A, Teramoto R, Usuda K, Okada H, Deng Y, Kobayashi-Sun J, Nishikawa T, Furusho H, Saito T, Hirase H, Ohta K, Fujimoto M, Horita Y, Kusayama T, Tsuda T, Tada H, Kato T, Usui S, Sakata K, Fujino N, Tajima A, Yamagishi M, Takamura M. The utility of zebrafish cardiac arrhythmia model to predict the pathogenicity of KCNQ1 variants. J Mol Cell Cardiol 2023; 177:50-61. [PMID: 36898499 DOI: 10.1016/j.yjmcc.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023]
Abstract
Genetic testing for inherited arrhythmias and discriminating pathogenic or benign variants from variants of unknown significance (VUS) is essential for gene-based medicine. KCNQ1 is a causative gene of type 1 long QT syndrome (LQTS), and approximately 30% of the variants found in type 1 LQTS are classified as VUS. We studied the role of zebrafish cardiac arrhythmia model in determining the clinical significance of KCNQ1 variants. We generated homozygous kcnq1 deletion zebrafish (kcnq1del/del) using the CRISPR/Cas9 and expressed human Kv7.1/MinK channels in kcnq1del/del embryos. We dissected the hearts from the thorax at 48 h post-fertilization and measured the transmembrane potential of the ventricle in the zebrafish heart. Action potential duration was calculated as the time interval between peak maximum upstroke velocity and 90% repolarization (APD90). The APD90 of kcnq1del/del embryos was 280 ± 47 ms, which was significantly shortened by injecting KCNQ1 wild-type (WT) cRNA and KCNE1 cRNA (168 ± 26 ms, P < 0.01 vs. kcnq1del/del). A study of two pathogenic variants (S277L and T587M) and one VUS (R451Q) associated with clinically definite LQTS showed that the APD90 of kcnq1del/del embryos with these mutant Kv7.1/MinK channels was significantly longer than that of Kv7.1 WT/MinK channels. Given the functional results of the zebrafish model, R451Q could be reevaluated physiologically from VUS to likely pathogenic. In conclusion, functional analysis using in vivo zebrafish cardiac arrhythmia model can be useful for determining the pathogenicity of loss-of-function variants in patients with LQTS.
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Affiliation(s)
- Shihe Cui
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenshi Hayashi
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
| | - Isao Kobayashi
- Faculty of Biological Science and Technology, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
| | - Kazuyoshi Hosomichi
- Laboratory of Computational Genomics, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Akihiro Nomura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Ryota Teramoto
- Laboratory for Comprehensive Genomic Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Keisuke Usuda
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hirofumi Okada
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Yaowen Deng
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Jingjing Kobayashi-Sun
- Faculty of Biological Science and Technology, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan; Department of Clinical Engineering, Faculty of Health Sciences, Komatsu University, Komatsu, Japan
| | - Tetsuo Nishikawa
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hiroshi Furusho
- Department of Cardiology, Ishikawa Prefectural Central Hospital, Kanazawa, Japan
| | - Takekatsu Saito
- Department of Pediatrics, Minamigaoka Hospital, Kanazawa, Japan
| | - Hiroaki Hirase
- Department of Cardiology, Takaoka Minami Heart Center, Takaoka, Japan
| | - Kunio Ohta
- Department of Pediatrics, School of Medicine, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan; Medical Education Research Center, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Manabu Fujimoto
- Department of Cardiology, Kouseiren Takaoka Hospital, Takaoka, Japan
| | - Yuki Horita
- Department of Cardiology, Kanazawa Cardiovascular Hospital, Kanazawa, Japan
| | - Takashi Kusayama
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Toyonobu Tsuda
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hayato Tada
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Takeshi Kato
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Soichiro Usui
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenji Sakata
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Noboru Fujino
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Atsushi Tajima
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa, Japan
| | | | - Masayuki Takamura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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Schwartz PJ, Moreno C, Kotta MC, Pedrazzini M, Crotti L, Dagradi F, Castelletti S, Haugaa KH, Denjoy I, Shkolnikova MA, Brink PA, Heradien MJ, Seyen SRM, Spätjens RLHMG, Spazzolini C, Volders PGA. Mutation location and IKs regulation in the arrhythmic risk of long QT syndrome type 1: the importance of the KCNQ1 S6 region. Eur Heart J 2021; 42:4743-4755. [PMID: 34505893 DOI: 10.1093/eurheartj/ehab582] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/02/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
AIMS Mutation type, location, dominant-negative IKs reduction, and possibly loss of cyclic adenosine monophosphate (cAMP)-dependent IKs stimulation via protein kinase A (PKA) influence the clinical severity of long QT syndrome type 1 (LQT1). Given the malignancy of KCNQ1-p.A341V, we assessed whether mutations neighbouring p.A341V in the S6 channel segment could also increase arrhythmic risk. METHODS AND RESULTS Clinical and genetic data were obtained from 1316 LQT1 patients [450 families, 166 unique KCNQ1 mutations, including 277 p.A341V-positive subjects, 139 patients with p.A341-neighbouring mutations (91 missense, 48 non-missense), and 900 other LQT1 subjects]. A first cardiac event represented the primary endpoint. S6 segment missense variant characteristics, particularly cAMP stimulation responses, were analysed by cellular electrophysiology. p.A341-neighbouring mutation carriers had a QTc shorter than p.A341V carriers (477 ± 33 vs. 490 ± 44 ms) but longer than the remaining LQT1 patient population (467 ± 41 ms) (P < 0.05 for both). Similarly, the frequency of symptomatic subjects in the p.A341-neighbouring subgroup was intermediate between the other two groups (43% vs. 73% vs. 20%; P < 0.001). These differences in clinical severity can be explained, for p.A341V vs. p.A341-neighbouring mutations, by the p.A341V-specific impairment of IKs regulation. The differences between the p.A341-neighbouring subgroup and the rest of LQT1 mutations may be explained by the functional importance of the S6 segment for channel activation. CONCLUSION KCNQ1 S6 segment mutations surrounding p.A341 increase arrhythmic risk. p.A341V-specific loss of PKA-dependent IKs enhancement correlates with its phenotypic severity. Cellular studies providing further insights into IKs-channel regulation and knowledge of structure-function relationships could improve risk stratification. These findings impact on clinical management.
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Affiliation(s)
- Peter J Schwartz
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy.,Istituto Auxologico Italiano, IRCCS, Laboratory of Cardiovascular Genetics, via Zucchi 18, 20095 Cusano Milanino, MI, Italy
| | - Cristina Moreno
- Department of Cardiology, CARIM, Maastricht University Medical Center, PO Box 5800, 6202 Maastricht, The Netherlands.,Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Dr., Bethesda, MD 20892-3701, USA
| | - Maria-Christina Kotta
- Istituto Auxologico Italiano, IRCCS, Laboratory of Cardiovascular Genetics, via Zucchi 18, 20095 Cusano Milanino, MI, Italy
| | - Matteo Pedrazzini
- Istituto Auxologico Italiano, IRCCS, Laboratory of Cardiovascular Genetics, via Zucchi 18, 20095 Cusano Milanino, MI, Italy
| | - Lia Crotti
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy.,Istituto Auxologico Italiano, IRCCS, Laboratory of Cardiovascular Genetics, via Zucchi 18, 20095 Cusano Milanino, MI, Italy.,Department of Cardiovascular, Neural and Metabolic Sciences, Istituto Auxologico Italiano, IRCCS, San Luca Hospital, Piazzale Brescia 20, 20149 Milan, Italy.,Department of Medicine and Surgery, University of Milano-Bicocca, Piazza dell'Ateneo Nuovo, 1, 20126 Milano, Italy
| | - Federica Dagradi
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy
| | - Silvia Castelletti
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy
| | - Kristina H Haugaa
- ProCardio center for innovation, Department of Cardiology, Oslo University Hospital, Postboks 4950 Nydalen, 0424 Oslo, Norway.,University of Oslo, Postboks 1171, Blindern 0318 Oslo, Norway
| | - Isabelle Denjoy
- Centre de Référence Maladies Cardiaques Héréditaires, Filière Cardiogen, Département de Rythmologie, Groupe Hospitalier Bichat-Claude Bernard, 46 Rue Henri -Huchard, 75877 PARIS Cedex 18, France
| | - Maria A Shkolnikova
- Pirogov Russian National Research Medical University, Research and Clinical Institute for Pediatrics named after Academician Yuri Veltischev, Centre for Cardiac Arrhythmia, Taldomskaya 2, 125412 Moscow, Russian Federation
| | - Paul A Brink
- Department of Internal Medicine, Stellenbosch University, Tygerberg 7505, South Africa
| | - Marshall J Heradien
- Department of Internal Medicine, Stellenbosch University, Tygerberg 7505, South Africa
| | - Sandrine R M Seyen
- Department of Cardiology, CARIM, Maastricht University Medical Center, PO Box 5800, 6202 Maastricht, The Netherlands
| | - Roel L H M G Spätjens
- Department of Cardiology, CARIM, Maastricht University Medical Center, PO Box 5800, 6202 Maastricht, The Netherlands
| | - Carla Spazzolini
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy
| | - Paul G A Volders
- Department of Cardiology, CARIM, Maastricht University Medical Center, PO Box 5800, 6202 Maastricht, The Netherlands
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3
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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4
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Williams N, Manderski E, Stewart S, Bao R, Tang Y. Lessons learned from testing cardiac channelopathy and cardiomyopathy genes in individuals who died suddenly: A two‐year prospective study in a large medical examiner’s office with an in‐house molecular genetics laboratory and genetic counseling services. J Genet Couns 2020; 29:293-302. [DOI: 10.1002/jgc4.1157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/16/2019] [Accepted: 07/10/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Nori Williams
- Molecular Genetics Laboratory The City of New York Office of Chief Medical Examiner New York NY USA
| | - Elizabeth Manderski
- Joan H. Marks Graduate Program in Human Genetics Sarah Lawrence College Bronxville NY USA
| | - Sarah Stewart
- Joan H. Marks Graduate Program in Human Genetics Sarah Lawrence College Bronxville NY USA
| | - Ruijun Bao
- Molecular Genetics Laboratory The City of New York Office of Chief Medical Examiner New York NY USA
| | - Yingying Tang
- Molecular Genetics Laboratory The City of New York Office of Chief Medical Examiner New York NY USA
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5
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Dong J, Williams N, Cerrone M, Borck C, Wang D, Zhou B, Eng LS, Subbotina E, Um SY, Lin Y, Ruiter K, Rojas L, Coetzee WA, Sampson BA, Tang Y. Molecular autopsy: using the discovery of a novel de novo pathogenic variant in the KCNH2 gene to inform healthcare of surviving family. Heliyon 2018; 4:e01015. [PMID: 30582040 PMCID: PMC6288419 DOI: 10.1016/j.heliyon.2018.e01015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/24/2018] [Accepted: 12/04/2018] [Indexed: 01/23/2023] Open
Abstract
Background Molecular testing of the deceased (Molecular Autopsy) is an overlooked area in the United States healthcare system and is not covered by medical insurance, leading to ineffective care for surviving families of thousands of sudden unexpected natural deaths each year. We demonstrated the precision management of surviving family members through the discovery of a novel de novo pathogenic variant in a decedent. Methods Forensic investigation and molecular autopsy were performed on an 18-year-old female who died suddenly and unexpectedly. Co-segregation family study of the first-degree relatives and functional characterization of the variant were conducted. Findings We identified a novel nonsense variant, NP_000229.1:p.Gln1068Ter, in the long QT syndrome type II gene KCNH2 in the decedent. This finding correlated with her ante-mortem electrocardiograms. Patch clamp functional studies using transfected COS-7 cells show that hERG-ΔQ1068 has a mixed phenotype, with both gain- (negative voltage shift of steady-state activation curve, the positive shift of the steady-state inactivation curve, and accelerated activation) and loss-of function (reduced current density, reduced surface expression and accelerated deactivation) hallmarks. Loss of cumulative activation during rapid pacing demonstrates that the loss-of-function phenotype predominates. The wild-type channel did not rescue the hERG-ΔQ1068 defects, demonstrating haploinsufficiency of the heterozygous state. Targeted variant testing in the family showed that the variant in KCNH2 arose de novo, which eliminated the need for exhaustive genome testing and annual cardiac follow-up for the parents and four siblings. Interpretation Molecular testing enables accurate determination of natural causes of death and precision care of the surviving family members in a time and cost-saving manner. We advocate for molecular autopsy being included under the healthcare coverage in US.
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Affiliation(s)
- Jingyun Dong
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Nori Williams
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Marina Cerrone
- Cardiovascular Genetics Program, Leon H Charney Division of Cardiology, NYU School of Medicine, NY, USA
| | - Christopher Borck
- Department of Pathology, New York City Office of Chief Medical Examiner, USA
| | - Dawei Wang
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Bo Zhou
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Lucy S Eng
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Ekaterina Subbotina
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Sung Yon Um
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Ying Lin
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Kevin Ruiter
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Lisa Rojas
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - William A Coetzee
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Barbara A Sampson
- Department of Pathology, New York City Office of Chief Medical Examiner, USA
| | - Yingying Tang
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
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6
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Tang Y, Williams N, Sampson BA. Genetic testing in sudden unexpected natural death in the young: New York City Office of Chief Medical Examiner's experience and perspective. Forensic Sci Med Pathol 2018; 15:481-484. [PMID: 30535908 DOI: 10.1007/s12024-018-0068-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2018] [Indexed: 12/23/2022]
Abstract
Postmortem genetic testing is a diagnostic tool that is becoming increasingly utilized. The benefits and limitations of genetic testing in cases of sudden, unexpected death in the young (≤ 40 years old) are reviewed from the perspective of the Office of Chief Medical Examiner of the City of New York, whose Molecular Genetics Laboratory, accredited by College of American Pathologists, has had 15 years of postmortem testing experience. Challenges to the interpretation and communication of testing results are highlighted, and opportunities for improving testing yield are discussed for age groups across the lifespan, from infancy to adulthood.
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Affiliation(s)
- Yingying Tang
- Molecular Genetics Laboratory, Office of Chief Medical Examiner, 421 East 26th Street, New York, NY, 10016, USA.
| | - Nori Williams
- Molecular Genetics Laboratory, Office of Chief Medical Examiner, 421 East 26th Street, New York, NY, 10016, USA
| | - Barbara A Sampson
- Forensic Pathology Department, Office of Chief Medical Examiner, New York, NY, USA
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7
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A challenge for mutation specific risk stratification in long QT syndrome type 1. J Cardiol 2018; 72:56-65. [DOI: 10.1016/j.jjcc.2017.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/05/2017] [Accepted: 12/20/2017] [Indexed: 01/31/2023]
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8
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Liu Z, Zheng R, Grushko MJ, Uversky VN, McDonald TV. Functionally Aberrant Mutant KCNQ1 With Intermediate Heterozygous and Homozygous Phenotypes. Can J Cardiol 2018; 34:1174-1184. [PMID: 30170673 DOI: 10.1016/j.cjca.2018.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 06/19/2018] [Accepted: 06/26/2018] [Indexed: 10/28/2022] Open
Abstract
BACKGROUND Deleterious mutations in KCNQ1 may lead to an autosomal dominant form of long QT syndrome (LQTS) (Romano-Ward) or autosomal recessive form (Jervell and Lange-Nielsen). Both are associated with severe ventricular tachyarrhythmias due to the reduction of the slowly activating delayed rectifier K+ current (IKs). Our objective was to investigate the functional consequences of KCNQ1-R562S mutation in an atypical form of KCNQ1-linked LQTS. METHODS Mutant KCNQ1-R562S was analyzed via confocal imaging, surface biotinylation assays, co-immunoprecipitation, phosphatidylinositol-4,5-bisphosphate pulldown test, whole-cell patch clamp, and computational intrinsic disorder analyses. RESULTS Protein expression, assembly with KCNE1, and trafficking to the surface membrane of KCNQ1-R562S were comparable with wild-type channels. The most significant functional effect of the R562S mutation was a depolarizing shift in the voltage dependence of activation that was dependent on association with KCNE1. The biophysical abnormality was only partially dominant over coexpressed wild-type channels. R562S mutation impaired C-terminal association with membrane phosphatidylinositol-4,5-bisphosphate. These changes led to compromised rate-related accumulation of repolarizing current that is an important property of normal IKs. CONCLUSIONS KCNQ1-R562S mutation reduces effective IKs due to channel gating alteration with a mild clinical expression in the heterozygous state due to minimal dominant phenotype. In the homozygous state, it is exhibited with a moderately severe LQTS phenotype due to the incomplete absence of IKs.
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Affiliation(s)
- Zhenning Liu
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Renjian Zheng
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
| | | | - Vladimir N Uversky
- Department of Molecular Medicine, and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Thomas V McDonald
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Cardiovascular Sciences, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA.
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9
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Wang D, Shah KR, Um SY, Eng LS, Zhou B, Lin Y, Mitchell AA, Nicaj L, Prinz M, McDonald TV, Sampson BA, Tang Y. Cardiac channelopathy testing in 274 ethnically diverse sudden unexplained deaths. Forensic Sci Int 2014; 237:90-9. [DOI: 10.1016/j.forsciint.2014.01.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/23/2013] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
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10
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Tang Y, Stahl-Herz J, Sampson BA. Molecular diagnostics of cardiovascular diseases in sudden unexplained death. Cardiovasc Pathol 2014; 23:1-4. [DOI: 10.1016/j.carpath.2013.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/15/2013] [Accepted: 09/18/2013] [Indexed: 10/26/2022] Open
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11
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Li J, Seyler C, Wiedmann F, Schmidt C, Schweizer PA, Becker R, Katus HA, Thomas D. Anti-KCNQ1 K⁺ channel autoantibodies increase IKs current and are associated with QT interval shortening in dilated cardiomyopathy. Cardiovasc Res 2013; 98:496-503. [PMID: 23447643 DOI: 10.1093/cvr/cvt046] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Autoimmune-associated proarrhythmia in dilated cardiomyopathy (DCM) is poorly understood. Given the significance of KCNQ1 potassium channels in heart rhythm disorders, we hypothesized that circulating anti-KCNQ1 autoantibodies directly modulate cardiac electrophysiology in DCM patients. The purpose of this pilot study was to characterize ion channel autoantibodies in DCM targeting the cardiac repolarizing K(+) current, IKs, and the underlying KCNQ1 potassium channel. METHODS AND RESULTS One hundred and fifty DCM patients were screened for anti-KCNQ1 autoantibodies using an enzyme-linked immunosorbent assay. Autoantibodies targeting the extracellular pore domain of the KCNQ1 channel were detected in 6% of study patients. Seropositive individuals exhibited significantly shorter corrected QT intervals when compared with seronegative patients (371 ± 39.9 ms vs. 408 ± 47.9 ms; P = 0.036). There was no difference in clinical severity of heart failure between groups. The functional significance of anti-KCNQ1 antibodies was determined in human embryonic kidney 293 cells expressing KCNQ1/KCNE1 using the whole-cell patch clamp technique. IKs recordings demonstrated a 2.7-fold increase in mean current density on exposure to patients' sera containing anti-KCNQ1 antibodies in contrast to seronegative controls (8.74 ± 1.44 pA/pF vs. 3.26 ± 0.36 pA/pF; P = 0.003). IKs enhancement was not associated with increased KCNQ1 protein levels or altered cell surface expression of the channel. CONCLUSION Anti-KCNQ1 autoantibodies found in a subgroup of DCM patients are associated with QT interval shortening and increased IKs current.
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Affiliation(s)
- Jin Li
- Department of Cardiology, University Hospital of Heidelberg, Im Neuenheimer Feld 410, Heidelberg 69120, Germany
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12
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Roberts BN, Yang PC, Behrens SB, Moreno JD, Clancy CE. Computational approaches to understand cardiac electrophysiology and arrhythmias. Am J Physiol Heart Circ Physiol 2012; 303:H766-83. [PMID: 22886409 DOI: 10.1152/ajpheart.01081.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cardiac rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. These impulses spread throughout the cardiac muscle to manifest as electrical waves in the whole heart. Regularity of electrical waves is critically important since they signal the heart muscle to contract, driving the primary function of the heart to act as a pump and deliver blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. For more than 50 years, mathematically based models of cardiac electrical activity have been used to improve understanding of basic mechanisms of normal and abnormal cardiac electrical function. Computer-based modeling approaches to understand cardiac activity are uniquely helpful because they allow for distillation of complex emergent behaviors into the key contributing components underlying them. Here we review the latest advances and novel concepts in the field as they relate to understanding the complex interplay between electrical, mechanical, structural, and genetic mechanisms during arrhythmia development at the level of ion channels, cells, and tissues. We also discuss the latest computational approaches to guiding arrhythmia therapy.
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Affiliation(s)
- Byron N Roberts
- Tri-Institutional MD-PhD Program, Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College/The Rockefeller University/Sloan-Kettering Cancer Institute, Weill Medical College of Cornell University, New York, New York, USA
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Abstract
The coordinated generation and propagation of action potentials within cardiomyocytes creates the intrinsic electrical stimuli that are responsible for maintaining the electromechanical pump function of the human heart. The synchronous opening and closing of cardiac Na(+), Ca(2+), and K(+) channels corresponds with the activation and inactivation of inward depolarizing (Na(+) and Ca(2+)) and outward repolarizing (K(+)) currents that underlie the various phases of the cardiac action potential (resting, depolarization, plateau, and repolarization). Inherited mutations in pore-forming α subunits and accessory β subunits of cardiac K(+) channels can perturb the atrial and ventricular action potential and cause various cardiac arrhythmia syndromes, including long QT syndrome, short QT syndrome, Brugada syndrome, and familial atrial fibrillation. In this Review, we summarize the current understanding of the molecular and cellular mechanisms that underlie K(+)-channel-mediated arrhythmia syndromes. We also describe translational advances that have led to the emerging role of genetic testing and genotype-specific therapy in the diagnosis and clinical management of individuals who harbor pathogenic mutations in genes that encode α or β subunits of cardiac K(+) channels.
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