1
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Wu X, Li Y, Hong L. Effects of Mexiletine on a Race-specific Mutation in Nav1.5 Associated With Long QT Syndrome. Front Physiol 2022; 13:904664. [PMID: 35864896 PMCID: PMC9294368 DOI: 10.3389/fphys.2022.904664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.5 plays an essential role in the generation and propagation of action potential in cardiomyocytes. Mutations in Nav1.5 have been associated with LQT syndrome, Brugada syndrome, and sudden arrhythmia death syndrome. Genetic studies showed that Nav1.5 mutations vary across race-ethnic groups. Here we investigated an Asian-specific mutation Nav1.5-P1090L associated with LQT syndrome. We found that Nav1.5-P1090L mutation perturbed the sodium channel function. It altered the gating process of the channel and exhibited an enhanced window current. Treatment with mexiletine reversed the depolarization shift of the steady-state inactivation produced by P1090L. Mexiletine also modified the recovery from steady-state inactivation and the development of inactivation of P1090L. It rescued the dysfunctional inactivation of P1090L and reduced the P1090L channel’s availability.
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Affiliation(s)
- Xin Wu
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Yawei Li
- Department of Preventive Medicine, Northwestern University, Chicago, IL, United States
| | - Liang Hong
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- *Correspondence: Liang Hong,
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2
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Lee MJ, Monteil DC, Spooner MT. Peripartum management of patient with long QT3 after successful implantable cardioverter defibrillator device discharge resulting in device failure: a case report. Eur Heart J Case Rep 2021; 5:ytab487. [PMID: 34926986 PMCID: PMC8672658 DOI: 10.1093/ehjcr/ytab487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/17/2021] [Accepted: 11/24/2021] [Indexed: 11/18/2022]
Abstract
Background Long QT3 syndrome type 3 (LQT3) is a gain of function mutation of the SCN5A gene that is inherited in an autosomal dominant fashion. Long QT3 syndrome type 3 results in an increase in arrhythmic events during rest, sleep, and bradycardia by extending the QT interval and inducing Torsades de pointes and sudden cardiac death. Attempting to block the sodium channel with Class I anti-arrhythmics or blocking adrenergic tone with beta-blockers especially in women has shown to be beneficial. There have been few large-scale studies on treating patients with LQT3 due to its lethality and underreported number of cases. Specifically, the safety and efficacy of pharmacologic treatment in pregnant LQT3 patients are unknown. Case summary This case demonstrates the safe use of Mexiletine and Propranolol in a 3rd-trimester pregnant LQT3 patient after a presumed ventricular arrhythmia and device-lead electrical short from therapy rendered her implantable cardioverter defibrillator inoperable in a VVI mode (venticular demand pacing). With appropriate medications, the patient was safely monitored through the remainder of her pregnancy and safely delivered at 36 weeks of pregnancy a healthy baby girl. The daughter, heterozygous for LQT3, showed no evidence of intrauterine growth restriction or other side effects from the medications. Discussion There are many variants of the SCN5A gene mutations that can lead to different phenotypes and not all mutations are responsive to the same medications. In this case, Mexiletine and Propranolol, both of which have only recently shown to benefit certain variants or LQT3 respectively, were safely started during the 3rd trimester of pregnancy without harming the foetus.
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Affiliation(s)
- Melissa J Lee
- Department of Internal Medicine, Naval Medical Center Portsmouth, 620 John Paul Jones Cir, Portsmouth, VA 23708, USA
| | - Danielle C Monteil
- Department of Neurodevelopmental Pediatrics, Naval Medical Center Portsmouth, 620 John Paul Jones Cir, Portsmouth, VA 23708, USA
| | - Michael T Spooner
- Department of Cardiology, Naval Medical Center Portsmouth, 620 John Paul Jones Cir, Portsmouth, VA 23708, USA
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3
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Cano J, Zorio E, Mazzanti A, Arnau MÁ, Trenor B, Priori SG, Saiz J, Romero L. Ranolazine as an Alternative Therapy to Flecainide for SCN5A V411M Long QT Syndrome Type 3 Patients. Front Pharmacol 2020; 11:580481. [PMID: 33519442 PMCID: PMC7845660 DOI: 10.3389/fphar.2020.580481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/16/2020] [Indexed: 12/14/2022] Open
Abstract
The prolongation of the QT interval represents the main feature of the long QT syndrome (LQTS), a life-threatening genetic disease. The heterozygous SCN5A V411M mutation of the human sodium channel leads to a LQTS type 3 with severe proarrhythmic effects due to an increase in the late component of the sodium current (INaL). The two sodium blockers flecainide and ranolazine are equally recommended by the current 2015 ESC guidelines to treat patients with LQTS type 3 and persistently prolonged QT intervals. However, awareness of pro-arrhythmic effects of flecainide in LQTS type 3 patients arose upon the study of the SCN5A E1784K mutation. Regarding SCN5A V411M individuals, flecainide showed good results albeit in a reduced number of patients and no evidence supporting the use of ranolazine has ever been released. Therefore, we ought to compare the effect of ranolazine and flecainide in a SCN5A V411M model using an in-silico modeling and simulation approach. We collected clinical data of four patients. Then, we fitted four Markovian models of the human sodium current (INa) to experimental and clinical data. Two of them correspond to the wild type and the heterozygous SCN5A V411M scenarios, and the other two mimic the effects of flecainide and ranolazine on INa. Next, we inserted them into three isolated cell action potential (AP) models for endocardial, midmyocardial and epicardial cells and in a one-dimensional tissue model. The SCN5A V411M mutation produced a 15.9% APD90 prolongation in the isolated endocardial cell model, which corresponded to a 14.3% of the QT interval prolongation in a one-dimensional strand model, in keeping with clinical observations. Although with different underlying mechanisms, flecainide and ranolazine partially countered this prolongation at the isolated endocardial model by reducing the APD90 by 8.7 and 4.3%, and the QT interval by 7.2 and 3.2%, respectively. While flecainide specifically targeted the mutation-induced increase in peak INaL, ranolazine reduced it during the entire AP. Our simulations also suggest that ranolazine could prevent early afterdepolarizations triggered by the SCN5A V411M mutation during bradycardia, as flecainide. We conclude that ranolazine could be used to treat SCN5A V411M patients, specifically when flecainide is contraindicated.
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Affiliation(s)
- Jordi Cano
- Centro de Investigación e Innovación en Bioingeniería (CI2B), Universitat Politècnica de València, Valencia, España
| | - Esther Zorio
- Unidad de Cardiopatías Familiares y Muerte Súbita, Servicio de Cardiología, Hospital Universitario y Politécnico La Fe, Valencia, España.,Center for Biomedical Network Research on Cardiovascular Diseases (CIBERCV), Madrid, Spain
| | - Andrea Mazzanti
- Molecular Cardiology, IRCCS, Istituti Clinici Scientifici Maugeri, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Miguel Ángel Arnau
- Unidad de Cardiopatías Familiares y Muerte Súbita, Servicio de Cardiología, Hospital Universitario y Politécnico La Fe, Valencia, España
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería (CI2B), Universitat Politècnica de València, Valencia, España
| | - Silvia G Priori
- Molecular Cardiology, IRCCS, Istituti Clinici Scientifici Maugeri, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Javier Saiz
- Centro de Investigación e Innovación en Bioingeniería (CI2B), Universitat Politècnica de València, Valencia, España
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería (CI2B), Universitat Politècnica de València, Valencia, España
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4
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Yokoyama Y, Aiba T, Ueda N, Nakajima K, Kamakura T, Wada M, Yamagata K, Ishibashi K, Inoue Y, Miyamoto K, Nagase S, Noda T, Yasuda S, Shimizu W, Kusano K. Subcutaneous and transvenous implantable cardioverter defibrillator in high-risk long-QT syndrome type 3 associated with Val411Met mutation in SCN5A. J Cardiol Cases 2020; 22:238-241. [DOI: 10.1016/j.jccase.2020.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/20/2020] [Accepted: 06/25/2020] [Indexed: 10/23/2022] Open
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Blich M, Khoury A, Suleiman M, Lorber A, Gepstein L, Boulous M. Specific Therapy Based on the Genotype in a Malignant Form of Long QT3, Carrying the V411M Mutation. Int Heart J 2019; 60:979-982. [PMID: 31257342 DOI: 10.1536/ihj.18-705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Congenital long QT syndrome (LQTS) is a cardiac channelopathy that leads to the prolongation of the QT interval. This prolongation can lead to ventricular tachyarrhythmia, syncope, and sudden cardiac death. There are various types of LQTS. Treatment of LQT1 and LQT2 is mainly based on antiadrenergic therapy. LQT3, on the other hand, is a result of a mutation of the SCN5A gene, which encodes the sodium channels. In this type, patients are sensitive to vagal stimuli and episodes tend to occur at rest. Sodium channel blocking compounds, such as ranolazine, mexiletine, and flecainide, have been found to be effective in selective mutations.In this case report, we report the case of a child with congenital LQT3 (V411M) who presented first with sudden cardiac death and three weeks later with an implantable cardioverter defibrillator storm. Knowing the specific mutation and understanding the mechanism at the molecular level through an in vitro study yielded a clinically meaningful result. The patient's arrhythmia burden was totally eliminated following successful treatment with flecainide.
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Affiliation(s)
- Miry Blich
- Inherited Arrhythmia Clinic.,Division of Pacing and Electrophysiology, Rambam Health Care Campus, Technion Medical School
| | - Asaad Khoury
- Department of Pediatric Cardiology, Rambam Health Care Campus and Bruce Rappaport Faculty of Medicine
| | - Mahmoud Suleiman
- Division of Pacing and Electrophysiology, Rambam Health Care Campus, Technion Medical School
| | - Avraham Lorber
- Department of Pediatric Cardiology, Rambam Health Care Campus and Bruce Rappaport Faculty of Medicine
| | - Lior Gepstein
- Division of Pacing and Electrophysiology, Rambam Health Care Campus, Technion Medical School
| | - Monther Boulous
- Division of Pacing and Electrophysiology, Rambam Health Care Campus, Technion Medical School
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6
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Pérez-Riera AR, Barbosa-Barros R, Daminello Raimundo R, da Costa de Rezende Barbosa MP, Esposito Sorpreso IC, de Abreu LC. The congenital long QT syndrome Type 3: An update. Indian Pacing Electrophysiol J 2018; 18:25-35. [PMID: 29101013 PMCID: PMC5840852 DOI: 10.1016/j.ipej.2017.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 01/28/2023] Open
Abstract
Congenital long QT syndrome type 3 (LQT3) is the third in frequency compared to the 15 forms known currently of congenital long QT syndrome (LQTS). Cardiac events are less frequent in LQT3 when compared with LQT1 and LQT2, but more likely to be lethal; the likelihood of dying during a cardiac event is 20% in families with an LQT3 mutation and 4% with either an LQT1 or an LQT2 mutation. LQT3 is consequence of mutation of gene SCN5A which codes for the Nav1.5 Na+ channel α-subunit and electrocardiographically characterized by a tendency to bradycardia related to age, prolonged QT/QTc interval (mean QTc value 478 ± 52 ms), accentuated QT dispersion consequence of prolonged ST segment, late onset of T wave and frequent prominent U wave because of longer repolarization of the M cell across left ventricular wall.
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Affiliation(s)
- Andrés Ricardo Pérez-Riera
- Metodologia da Pesquisa e Escrita Científica da Faculdade de Medicina do ABC, Santo André, São Paulo, Brazil.
| | - Raimundo Barbosa-Barros
- Centro Coronariano do Hospital de Messejana Dr. Carlos Alberto Studart Gomes, Fortaleza, Ceará, Brazil
| | - Rodrigo Daminello Raimundo
- Metodologia da Pesquisa e Escrita Científica da Faculdade de Medicina do ABC, Santo André, São Paulo, Brazil
| | | | | | - Luiz Carlos de Abreu
- Program in Molecular and Integrative Physiological Sciences (MIPS), Department of Environmental Health, Harvard T.H. Chan School of Public Health, USA
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7
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Sato D, Clancy CE, Bers DM. Dynamics of sodium current mediated early afterdepolarizations. Heliyon 2017; 3:e00388. [PMID: 28924617 PMCID: PMC5591396 DOI: 10.1016/j.heliyon.2017.e00388] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 06/05/2017] [Accepted: 08/15/2017] [Indexed: 12/19/2022] Open
Abstract
Early afterdepolarizations (EADs) have been attributed to two primary mechanisms: 1) recovery from inactivation of the L-type calcium (Ca) channel and/or 2) spontaneous Ca release, which depolarizes the membrane potential through the electrogenic sodium-calcium exchanger (NCX). The sodium (Na) current (INa), especially the late component of the Na current, has been recognized as an important player to set up the conditions for EADs by reducing repolarization reserve and increasing intracellular Na concentration, which leads to Ca overload. However, INa itself has not been considered as a direct initiator of EADs. A recent experimental study by Horvath et al. has shown that the amplitude of the late component of the Na current is as large as potassium (K) and Ca currents (∼1 pA/pF). This result suggests that INa by itself can exceeds the sum of outward currents and depolarize the membrane potential. In this study, we show that INa can also directly initiate EADs. Mathematical analysis reveals a fundamental dynamical origin of EADs arising directly from the Na channel reactivation. This system has three fixed points. The dynamics of the INa mediated EAD oscillation is different from that of the membrane voltage oscillation of the pacemaker cell, which has only one fixed point.
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Affiliation(s)
- Daisuke Sato
- Corresponding author at: Department of Pharmacology, Genome Building (GBSF), University of California, Davis, CA 95616-8636, United States.
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Chadda KR, Jeevaratnam K, Lei M, Huang CLH. Sodium channel biophysics, late sodium current and genetic arrhythmic syndromes. Pflugers Arch 2017; 469:629-641. [PMID: 28265756 PMCID: PMC5438422 DOI: 10.1007/s00424-017-1959-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 02/14/2017] [Indexed: 12/11/2022]
Abstract
Arrhythmias arise from breakdown of orderly action potential (AP) activation, propagation and recovery driven by interactive opening and closing of successive voltage-gated ion channels, in which one or more Na+ current components play critical parts. Early peak, Na+ currents (INa) reflecting channel activation drive the AP upstroke central to cellular activation and its propagation. Sustained late Na+ currents (INa-L) include contributions from a component with a delayed inactivation timecourse influencing AP duration (APD) and refractoriness, potentially causing pro-arrhythmic phenotypes. The magnitude of INa-L can be analysed through overlaps or otherwise in the overall voltage dependences of the steady-state properties and kinetics of activation and inactivation of the Na+ conductance. This was useful in analysing repetitive firing associated with paramyotonia congenita in skeletal muscle. Similarly, genetic cardiac Na+ channel abnormalities increasing INa-L are implicated in triggering phenomena of automaticity, early and delayed afterdepolarisations and arrhythmic substrate. This review illustrates a wide range of situations that may accentuate INa-L. These include (1) overlaps between steady-state activation and inactivation increasing window current, (2) kinetic deficiencies in Na+ channel inactivation leading to bursting phenomena associated with repetitive channel openings and (3) non-equilibrium gating processes causing channel re-opening due to more rapid recoveries from inactivation. All these biophysical possibilities were identified in a selection of abnormal human SCN5A genotypes. The latter presented as a broad range of clinical arrhythmic phenotypes, for which effective therapeutic intervention would require specific identification and targeting of the diverse electrophysiological abnormalities underlying their increased INa-L.
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Affiliation(s)
- Karan R Chadda
- Faculty of Health and Medical Sciences, University of Surrey, VSM Building, Guildford, GU2 7AL, UK
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, VSM Building, Guildford, GU2 7AL, UK
- School of Medicine, Perdana University-Royal College of Surgeons Ireland, 43400, Serdang, Selangor Darul Ehsan, Malaysia
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
- Department of Biochemistry, University of Cambridge, Hopkins Building, Cambridge, CB2 1QW, UK.
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9
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Loussouarn G, Sternberg D, Nicole S, Marionneau C, Le Bouffant F, Toumaniantz G, Barc J, Malak OA, Fressart V, Péréon Y, Baró I, Charpentier F. Physiological and Pathophysiological Insights of Nav1.4 and Nav1.5 Comparison. Front Pharmacol 2016; 6:314. [PMID: 26834636 PMCID: PMC4712308 DOI: 10.3389/fphar.2015.00314] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/21/2015] [Indexed: 12/19/2022] Open
Abstract
Mutations in Nav1.4 and Nav1.5 α-subunits have been associated with muscular and cardiac channelopathies, respectively. Despite intense research on the structure and function of these channels, a lot of information is still missing to delineate the various physiological and pathophysiological processes underlying their activity at the molecular level. Nav1.4 and Nav1.5 sequences are similar, suggesting structural and functional homologies between the two orthologous channels. This also suggests that any characteristics described for one channel subunit may shed light on the properties of the counterpart channel subunit. In this review article, after a brief clinical description of the muscular and cardiac channelopathies related to Nav1.4 and Nav1.5 mutations, respectively, we compare the knowledge accumulated in different aspects of the expression and function of Nav1.4 and Nav1.5 α-subunits: the regulation of the two encoding genes (SCN4A and SCN5A), the associated/regulatory proteins and at last, the functional effect of the same missense mutations detected in Nav1.4 and Nav1.5. First, it appears that more is known on Nav1.5 expression and accessory proteins. Because of the high homologies of Nav1.5 binding sites and equivalent Nav1.4 sites, Nav1.5-related results may guide future investigations on Nav1.4. Second, the analysis of the same missense mutations in Nav1.4 and Nav1.5 revealed intriguing similarities regarding their effects on membrane excitability and alteration in channel biophysics. We believe that such comparison may bring new cues to the physiopathology of cardiac and muscular diseases.
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Affiliation(s)
- Gildas Loussouarn
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Damien Sternberg
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-EstParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et MyogénétiqueParis, France
| | - Sophie Nicole
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France
| | - Céline Marionneau
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Francoise Le Bouffant
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Gilles Toumaniantz
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Julien Barc
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Olfat A Malak
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Véronique Fressart
- Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et Myogénétique Paris, France
| | - Yann Péréon
- Centre Hospitalier Universitaire de Nantes, Centre de Référence Maladies Neuromusculaires Nantes-AngersNantes, France; Atlantic Gene Therapies - Biotherapy Institute for Rare DiseasesNantes, France
| | - Isabelle Baró
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Flavien Charpentier
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France; Centre Hospitalier Universitaire de Nantes, l'Institut du ThoraxNantes, France
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The genetic basis for inherited forms of sinoatrial dysfunction and atrioventricular node dysfunction. J Interv Card Electrophysiol 2015; 43:121-34. [PMID: 25863800 PMCID: PMC4486151 DOI: 10.1007/s10840-015-9998-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/13/2015] [Indexed: 01/01/2023]
Abstract
The sinoatrial node (SAN) and the atrioventricular node (AVN) are the anatomical and functional regions of the heart which play critical roles in the generation and conduction of the electrical impulse. Their functions are ensured by peculiar structural cytological properties and specific collections of ion channels. Impairment of SAN and AVN activity is generally acquired,but in some cases familial inheritance has been established and therefore a genetic cause is involved. In recent years, combined efforts of clinical practice and experimental basic science studies have identified and characterized several causative gene mutations associated with the nodal syndromes. Channelopathies, i.e., diseases associated with defective ion channels, remain the major cause of genetically determined nodal arrhythmias; however, it is becoming increasingly evident that mutations in other classes of regulatory and structural proteins also have profound pathophysiological roles. In this review, we will present some aspects of the genetic identification of the molecular mechanism underlying both SAN and AVN dysfunctions with a particular focus on mutations of the Na, pacemaker (HCN), and Ca channels. Genetic defects in regulatory proteins and calcium-handling proteins will be also considered. In conclusion, the identification of the genetic defects associated with familial nodal dysfunction is an essential step for implementing an appropriate therapeutic treatment.
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Zhang J, Chen Y, Yang J, Xu B, Wen Y, Xiang G, Wei G, Zhu C, Xing Y, Li Y. Electrophysiological and trafficking defects of the SCN5A T353I mutation in Brugada syndrome are rescued by alpha-allocryptopine. Eur J Pharmacol 2014; 746:333-43. [PMID: 25261036 DOI: 10.1016/j.ejphar.2014.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 09/04/2014] [Accepted: 09/08/2014] [Indexed: 10/24/2022]
Abstract
Brugada syndrome (BrS), which causes arrhythmias that lead to sudden cardiac death, is linked to loss-of-function mutations that affect sodium channels. Here, we investigate the rescue effect of alpha-allocryptopine (All) from Chinese herbal medicine in a T353I mutation of SCN5A, which combines trafficking abnormalities with Brugada syndrome. SCN5A-T353I expressed in HEK293 cells showed a small peak current (I(peak)) of only 59.6% of WT and an observably sustained current (I(sus)). We found that All strongly enhanced the I(peak) of the T353I channel by enhancing the plasma membrane (PM) expression of Nav1.5 and rescued defective trafficking after co-incubation with HEK293 cells that carry mutation channel 24 h. It is also beneficial to increase the I(peak) of the T353I mutation by All by prolonging the closed-state inactivation (CSI) process and shortening the recovery from inactivation of the T353I mutation. Interestingly, the I(sus) of T353I was significantly inhibited by All, which reduces the occurrence of LQT syndrome 3 (LQT3). We provide evidence that All can rescue the trafficking deficiencies and restore the cellular electrophysiological characteristics of SCN5A-T353I. This feature of All may benefit patients with the BrS-associated Nav1.5 channel and might have other potential therapeutic effects.
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Affiliation(s)
- Jiancheng Zhang
- Provincial Clinical Medicine College of Fujian Medical University, Fuzhou 350001, Fujian, PR China
| | - Yu Chen
- Guang׳anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, PR China
| | - Jie Yang
- Department of Cardiology, General Hospital of People׳s Liberation Army, Beijing 100853, PR China
| | - Bin Xu
- Department of Cardiology, General Hospital of People׳s Liberation Army, Beijing 100853, PR China
| | - Yi Wen
- Department of Cardiology, General Hospital of People׳s Liberation Army, Beijing 100853, PR China
| | - Guojian Xiang
- Provincial Clinical Medicine College of Fujian Medical University, Fuzhou 350001, Fujian, PR China
| | - Guoliang Wei
- Provincial Clinical Medicine College of Fujian Medical University, Fuzhou 350001, Fujian, PR China
| | - Chao Zhu
- Department of Cardiology, General Hospital of People׳s Liberation Army, Beijing 100853, PR China
| | - Yanwei Xing
- Guang׳anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, PR China.
| | - Yang Li
- Department of Cardiology, General Hospital of People׳s Liberation Army, Beijing 100853, PR China.
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Priest JR, Ceresnak SR, Dewey FE, Malloy-Walton LE, Dunn K, Grove ME, Perez MV, Maeda K, Dubin AM, Ashley EA. Molecular diagnosis of long QT syndrome at 10 days of life by rapid whole genome sequencing. Heart Rhythm 2014; 11:1707-13. [PMID: 24973560 DOI: 10.1016/j.hrthm.2014.06.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND The advent of clinical next generation sequencing is rapidly changing the landscape of rare disease medicine. Molecular diagnosis of long QT syndrome (LQTS) can affect clinical management, including risk stratification and selection of pharmacotherapy on the basis of the type of ion channel affected, but results from the current gene panel testing requires 4-16 weeks before return to clinicians. OBJECTIVE A term female infant presented with 2:1 atrioventricular block and ventricular arrhythmias consistent with perinatal LQTS, requiring aggressive treatment including epicardial pacemaker and cardioverter-defibrillator implantation and sympathectomy on day of life 2. We sought to provide a rapid molecular diagnosis for the optimization of treatment strategies. METHODS We performed Clinical Laboratory Improvement Amendments-certified rapid whole genome sequencing (WGS) with a speed-optimized bioinformatics platform to achieve molecular diagnosis at 10 days of life. RESULTS We detected a known pathogenic variant in KCNH2 that was demonstrated to be paternally inherited by follow-up genotyping. The unbiased assessment of the entire catalog of human genes provided by WGS revealed a maternally inherited variant of unknown significance in a novel gene. CONCLUSION Rapid clinical WGS provides faster and more comprehensive diagnostic information at 10 days of life than does standard gene panel testing. In selected clinical scenarios such as perinatal LQTS, rapid WGS can provide more timely and clinically actionable information than can a standard commercial test.
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Affiliation(s)
- James R Priest
- Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford University, Stanford, California; Child Health Research Institute; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Scott R Ceresnak
- Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford University, Stanford, California; Child Health Research Institute; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Frederick E Dewey
- Division of Cardiovascular Medicine; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Lindsey E Malloy-Walton
- Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford University, Stanford, California; Child Health Research Institute; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Kyla Dunn
- Children's Heart Center, Lucile Packard Children's Hospital at Stanford, Palo Alto, California; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Megan E Grove
- Division of Cardiovascular Medicine; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Marco V Perez
- Division of Cardiovascular Medicine; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Katsuhide Maeda
- Division of Cardiothoracic Surgery; Child Health Research Institute; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Anne M Dubin
- Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford University, Stanford, California; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Euan A Ashley
- Division of Cardiovascular Medicine; Child Health Research Institute; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California.
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Song W, Shou W. Cardiac sodium channel Nav1.5 mutations and cardiac arrhythmia. Pediatr Cardiol 2012; 33:943-9. [PMID: 22460359 PMCID: PMC3393812 DOI: 10.1007/s00246-012-0303-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 03/09/2012] [Indexed: 12/19/2022]
Abstract
As a major cardiac voltage-gated sodium channel isoform in the heart, the Nav1.5 channel is essential for cardiac action potential initiation and subsequent propagation throughout the heart. Mutations of Nav1.5 have been linked to a variety of cardiac diseases such as long QT syndrome (LQTs), Brugada syndrome, cardiac conduction defect, atrial fibrillation, and dilated cardiomyopathy. The mutagenesis approach and heterologous expression systems are most frequently used to study the function of this channel. This review focuses primarily on recent findings of Nav1.5 mutations associated with type 3 long QT syndrome (LQT3) in particular. Understanding the functional changes of the Nav1.5 mutation may offer critical insight into the mechanism of long QT3 syndrome. In addition, this review provides the updated information on the current progress of using various experimental model systems to study primarily the long QT3 syndrome.
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Affiliation(s)
- Weihua Song
- Department of Pediatrics, Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 West Walnut Street, Indianapolis, IN 46202, USA
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Carrasco JI, Izquierdo I, Medina P, Arnau MÁ, Salvador A, Zorio E. Flecainide, a therapeutic option in a patient with long QT syndrome type 3 caused by the heterozygous V411M mutation in the SCN5A gene. Rev Esp Cardiol 2012; 65:1058-9. [PMID: 22721569 DOI: 10.1016/j.recesp.2012.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 03/10/2012] [Indexed: 10/28/2022]
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