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Badura K, Buławska D, Dąbek B, Witkowska A, Lisińska W, Radzioch E, Skwira S, Młynarska E, Rysz J, Franczyk B. Primary Electrical Heart Disease-Principles of Pathophysiology and Genetics. Int J Mol Sci 2024; 25:1826. [PMID: 38339103 PMCID: PMC10855675 DOI: 10.3390/ijms25031826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/27/2024] [Accepted: 01/28/2024] [Indexed: 02/12/2024] Open
Abstract
Primary electrical heart diseases, often considered channelopathies, are inherited genetic abnormalities of cardiomyocyte electrical behavior carrying the risk of malignant arrhythmias leading to sudden cardiac death (SCD). Approximately 54% of sudden, unexpected deaths in individuals under the age of 35 do not exhibit signs of structural heart disease during autopsy, suggesting the potential significance of channelopathies in this group of age. Channelopathies constitute a highly heterogenous group comprising various diseases such as long QT syndrome (LQTS), short QT syndrome (SQTS), idiopathic ventricular fibrillation (IVF), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndromes (ERS). Although new advances in the diagnostic process of channelopathies have been made, the link between a disease and sudden cardiac death remains not fully explained. Evolving data in electrophysiology and genetic testing suggest previously described diseases as complex with multiple underlying genes and a high variety of factors associated with SCD in channelopathies. This review summarizes available, well-established information about channelopathy pathogenesis, genetic basics, and molecular aspects relative to principles of the pathophysiology of arrhythmia. In addition, general information about diagnostic approaches and management is presented. Analyzing principles of channelopathies and their underlying causes improves the understanding of genetic and molecular basics that may assist general research and improve SCD prevention.
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Affiliation(s)
- Krzysztof Badura
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Dominika Buławska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Bartłomiej Dąbek
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Alicja Witkowska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Wiktoria Lisińska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Ewa Radzioch
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Sylwia Skwira
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Ewelina Młynarska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Beata Franczyk
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
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Zhou X, Ren L, Huang J, Zhang Y, Cai Y, Pu J. Novel SCN5A frame‑shift mutation underlying in patient with idiopathic ventricular fibrillation manifested with J wave in inferior lead and prolonged S‑wave in precordial lead. Exp Ther Med 2023; 25:287. [PMID: 37206574 PMCID: PMC10189605 DOI: 10.3892/etm.2023.11986] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 02/01/2023] [Indexed: 05/21/2023] Open
Abstract
Mutations in the SCN5A gene has been recognized as resulting in a series of life-threatening arrhythmias. However, it also causes idiopathic ventricular fibrillation (IVF) with J wave in inferior leads and prolonged S-wave upstroke in precordial leads, which has not been previously reported. The present study aimed to study the mechanisms of a patient with IVF manifested with J wave in inferior leads and prolonged S-wave upstroke in precordial leads. The electrocardiograms (ECG) of the proband were recorded and genetic testing was conducted. Patch-clamp and immunocytochemical studies were performed in heterologously transfected 293 cells. The VF attacks was documented in a 55-year-old male proband with syncope episodes. 12-lead ECG shown the transient J wave in the inferior leads and prolonged S-wave upstroke in precordial V1-V3 leads in the same timeframe. Genetic analysis revealed a novel 1 base deletion (G) at position 839 in exon 2 in SCN5A gene (C280S*fs61), which causes a severe truncation of the sodium channel. The functional study revealed that in 293 cells transfected with mutant channel, no sodium current could be recorded even though the immunocytochemical experiment confirmed the truncated sodium channel existed in cytosol. The kinetics of the wild-type (WT) channel were not altered when co-transfected with C280S*fs61 mutant which suggested a haploinsufficiency effect of sodium channel in the cells. The present study identified a novel C280Sfs*61 mutation that caused the 'loss of function' of the sodium channel by haploinsufficiency mechanism. The reduced sodium channel function in the heart may cause conduction delay that may underlie the manifestation of J wave and prolonged S-wave upstroke associated with IVF.
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Affiliation(s)
- Xiaoqian Zhou
- Department of Cardiology, Shanghai East Hospital, Tongji University, Shanghai 100123, P.R. China
| | - Lan Ren
- Department of Cardiology, Beijing Jishuitan Hospital, Beijing 100035, P.R. China
- Department of Cardiology, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, P.R. China
| | - Jian Huang
- Department of Cardiology, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, P.R. China
| | - Yinhui Zhang
- Department of Cardiology, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, P.R. China
| | - Ying Cai
- Department of Cardiology, Shanghai East Hospital, Tongji University, Shanghai 100123, P.R. China
- Correspondence to: Professor Jielin Pu and Professor Ying Cai, Department of Cardiology, Shanghai East Hospital, Tongji University, 1800 Yuntai Road, Pudong, Shanghai 100123, P.R. China
| | - Jielin Pu
- Department of Cardiology, Shanghai East Hospital, Tongji University, Shanghai 100123, P.R. China
- Department of Cardiology, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, P.R. China
- Correspondence to: Professor Jielin Pu and Professor Ying Cai, Department of Cardiology, Shanghai East Hospital, Tongji University, 1800 Yuntai Road, Pudong, Shanghai 100123, P.R. China
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Crespo-García T, Cámara-Checa A, Dago M, Rubio-Alarcón M, Rapún J, Tamargo J, Delpón E, Caballero R. Regulation of cardiac ion channels by transcription factors: Looking for new opportunities of druggable targets for the treatment of arrhythmias. Biochem Pharmacol 2022; 204:115206. [PMID: 35963339 DOI: 10.1016/j.bcp.2022.115206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 11/29/2022]
Abstract
Cardiac electrical activity is governed by different ion channels that generate action potentials. Acquired or inherited abnormalities in the expression and/or function of ion channels usually result in electrophysiological changes that can cause cardiac arrhythmias. Transcription factors (TFs) control gene transcription by binding to specific DNA sequences adjacent to target genes. Linkage analysis, candidate-gene screening within families, and genome-wide association studies have linked rare and common genetic variants in the genes encoding TFs with genetically-determined cardiac arrhythmias. Besides its critical role in cardiac development, recent data demonstrated that they control cardiac electrical activity through the direct regulation of the expression and function of cardiac ion channels in adult hearts. This narrative review summarizes some studies showing functional data on regulation of the main human atrial and ventricular Na+, Ca2+, and K+ channels by cardiac TFs such as Pitx2c, Tbx20, Tbx5, Zfhx3, among others. The results have improved our understanding of the mechanisms regulating cardiac electrical activity and may open new avenues for therapeutic interventions in cardiac acquired or inherited arrhythmias through the identification of TFs as potential drug targets. Even though TFs have for a long time been considered as 'undruggable' targets, advances in structural biology have led to the identification of unique pockets in TFs amenable to be targeted with small-molecule drugs or peptides that are emerging as novel therapeutic drugs.
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Affiliation(s)
- T Crespo-García
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - A Cámara-Checa
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - M Dago
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - M Rubio-Alarcón
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - J Rapún
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - J Tamargo
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - E Delpón
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain.
| | - R Caballero
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
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- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
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Yao H, Fan J, Cheng YJ, Chen XM, Ji CC, Liu LJ, Zheng ZH, Wu SH. SCN1Bβ mutations that affect their association with Kv4.3 underlie early repolarization syndrome. J Cell Mol Med 2018; 22:5639-5647. [PMID: 30160358 PMCID: PMC6201368 DOI: 10.1111/jcmm.13839] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/13/2018] [Indexed: 12/12/2022] Open
Abstract
Background Abnormal cardiac ion channels current, including transient outward potassium current (Ito), is associated with early repolarization syndrome (ERS). Previous studies showed that mutations in SCN1Bβ both to increase the Ito current and to decrease the sodium current. Yet its role in ERS remains unknown. Objective To determine the role of mutations in the SCN1Bβ subunits in ERS. Methods We screened for mutations in the SCN1B genes from four families with ERS. Wild‐type and mutant SCN1Bβ genes were co‐expressed with wild‐type KCND3 in human embryonic kidney cells (HEK293). Whole‐cell patch‐clamp technique and co‐immunoprecipitation were used to study the electrophysiological properties and explore the underlying mechanisms. Results S248R and R250T mutations in SCN1Bβ were detected in 4 families’ probands. Neither S248R nor R250T mutation had significant influence on the sodium channel current density (INa) when co‐expressed with SCN5A/WT. Co‐expression of KCND3/WT and SCN1Bβ/S248R or SCN1Bβ/R250T increased the transient outward potassium current Ito by 27.44% and 199.89%, respectively (P < 0.05 and P < 0.01, respectively) when compared with SCN1Bβ/WT. Electrophysiological properties showed that S248R and R250T mutations decreased the steady‐state inactivation and recovery from inactivation of Ito channel. Co‐immunoprecipitation study demonstrated an increased association between SCN1Bβ mutations and Kv4.3 compared with SCN1Bβ/WT (P < 0.05 and P < 0.01, respectively). Conclusion The S248R and R250T mutations of SCN1Bβ gene caused gain‐of‐function of Ito by associated with Kv4.3, which maybe underlie the ERS phenotype of the probands.
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Affiliation(s)
- Hao Yao
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Jun Fan
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Yun-Jiu Cheng
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Xu-Miao Chen
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Cheng-Cheng Ji
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Li-Juan Liu
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Zi-Heng Zheng
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
| | - Su-Hua Wu
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, and Key Laboratory on Assisted Circulation, NHC, Guangzhou, China
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Han D, Tan H, Sun C, Li G. Dysfunctional Nav1.5 channels due to SCN5A mutations. Exp Biol Med (Maywood) 2018; 243:852-863. [PMID: 29806494 DOI: 10.1177/1535370218777972] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The voltage-gated sodium channel 1.5 (Nav1.5), encoded by the SCN5A gene, is responsible for the rising phase of the action potential of cardiomyocytes. The sodium current mediated by Nav1.5 consists of peak and late components (INa-P and INa-L). Mutant Nav1.5 causes alterations in the peak and late sodium current and is associated with an increasingly wide range of congenital arrhythmias. More than 400 mutations have been identified in the SCN5A gene. Although the mechanisms of SCN5A mutations leading to a variety of arrhythmias can be classified according to the alteration of INa-P and INa-L as gain-of-function, loss-of-function and both, few researchers have summarized the mechanisms in this way before. In this review article, we aim to review the mechanisms underlying dysfunctional Nav1.5 due to SCN5A mutations and to provide some new insights into further approaches in the treatment of arrhythmias. Impact statement The field of ion channelopathy caused by dysfunctional Nav1.5 due to SCN5A mutations is rapidly evolving as novel technologies of electrophysiology are introduced and our understanding of the mechanisms of various arrhythmias develops. In this review, we focus on the dysfunctional Nav1.5 related to arrhythmias and the underlying mechanisms. We update SCN5A mutations in a precise way since 2013 and presents novel classifications of SCN5A mutations responsible for the dysfunction of the peak (INa-P) and late (INa-L) sodium channels based on their phenotypes, including loss-, gain-, and coexistence of gain- and loss-of function mutations in INa-P, INa-L, respectively. We hope this review will provide a new comprehensive way to better understand the electrophysiological mechanisms underlying arrhythmias from cell to bedside, promoting the management of various arrhythmias in practice.
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Affiliation(s)
- Dan Han
- 1 Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, P.R. China
| | - Hui Tan
- 2 Department of Respiratory Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, P.R. China
| | - Chaofeng Sun
- 1 Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, P.R. China
| | - Guoliang Li
- 1 Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, P.R. China
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Boddum K, Saljic A, Jespersen T, Christensen AH. A Novel SCN5A Variant Associated with Abnormal Repolarization, Atrial Fibrillation, and Reversible Cardiomyopathy. Cardiology 2018; 140:8-13. [PMID: 29635243 DOI: 10.1159/000487475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 02/07/2018] [Indexed: 01/17/2023]
Abstract
A variety of life-threating arrhythmias are caused by mutations in the cardiac voltage-gated sodium channel encoded by the SCN5A gene. In this study, we report a novel loss-of-function SCN5A variant, p.Ile1343Val (c.4027A>G), identified in a 42-year-old proband who presented with an unusual ECG with abnormal repolarization with biphasic T-waves in anteroseptal leads, persistent atrial fibrillation (AF), intermittent left bundle branch block (LBBB), and reversible cardiomyopathy. The patient did not meet the diagnostic criteria for Brugada syndrome, long QT syndrome, or any other known SCN5A-associated phenotype. Characterization of the biophysical properties of the variant by in vitro patch clamp experiments revealed a reduced Na+ current with no effect on the inactivation kinetics of the channel. This loss-of-function of Na+ current could explain the intermittent LBBB as well as the AF. In conclusion, we describe a unique combination of electrical and structural abnormalities associated with a novel SCN5A variant. Our findings broaden the spectrum of cardiac phenotypes associated with SCN5A channelopathy, underlining the complex clinical manifestations of genetic variations within this gene.
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Affiliation(s)
- Kim Boddum
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arnela Saljic
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alex Hørby Christensen
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark
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Liu X, Shen Y, Xie J, Bao H, Cao Q, Wan R, Xu X, Zhou H, Huang L, Xu Z, Zhu W, Hu J, Cheng X, Hong K. A mutation in the CACNA1C gene leads to early repolarization syndrome with incomplete penetrance: A Chinese family study. PLoS One 2017; 12:e0177532. [PMID: 28493952 PMCID: PMC5426766 DOI: 10.1371/journal.pone.0177532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 04/28/2017] [Indexed: 01/06/2023] Open
Abstract
Background Early repolarization syndrome (ERS) may be a near-Mendelian or an oligogenic disease; however, no direct evidence has been provided to support this theory. Methods and results We described a large Chinese family with nocturnal sudden cardiac death induced by ERS in most of the young male adults. One missense mutation (p.Q1916R) was found in the major subunit of the L-type calcium channel gene CACNA1C by the direct sequencing of candidate genes. A concomitant gain-of-function variant in the sodium channel gene SCN5A (p.R1193Q) was found to rescue the phenotype of the female CACNA1C-Q1916R mutation carriers, which led to the incomplete penetrance. The functional studies, via the exogenous expression approach, revealed that the CACNA1C-Q1916R mutation led to a decreasing L-type calcium current and the protein expression defect. The decreased calcium current produced by the mutant channel was improved by isoproterenol but exacerbated by testosterone. The effects of CACNA1C-Q1916R mutation and testosterone on cellular electrophysiology were further confirmed by the human ventricular action potential simulation. Conclusions Our results demonstrated that the loss-of-function CACNA1C-Q1916R mutation contributed to ERS-related sudden cardiac death, and the phenotypic incomplete penetrance was modified by the SCN5A-R1193Q variant and sex. These findings suggest that phenotypes of ERS are modified by multiple genetic factors, which supports the theory that ERS may be an oligogenic disease.
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Affiliation(s)
- Xin Liu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yang Shen
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Jinyan Xie
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Huihui Bao
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qing Cao
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Rong Wan
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Xiaoming Xu
- Department of Forensic Medicine, Medical College of Nanchang University, Nanchang, China
| | - Hui Zhou
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Lin Huang
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhenyan Xu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Wengen Zhu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jinzhu Hu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Xiaoshu Cheng
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Kui Hong
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
- * E-mail:
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Guo Q, Ren L, Chen X, Hou C, Chu J, Pu J, Zhang S. A novel mutation in the SCN5A gene contributes to arrhythmogenic characteristics of early repolarization syndrome. Int J Mol Med 2016; 37:727-33. [PMID: 26820605 PMCID: PMC4771109 DOI: 10.3892/ijmm.2016.2468] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 01/13/2016] [Indexed: 12/17/2022] Open
Abstract
Several genetic variants have been associated with early repolarization syndrome (ERS). However, the lack of functional validations of the mutant effects has limited the interpretation of genetic tests. In the present study, we identified and characterized a novel sodium channel, voltage gated, type V alpha subunit (SCN5A) mutation that was associated with ERS. A 67-year-old male proband suffering from recurrent syncope underwent a documented electrocardiogram (ECG) for polymorphic ventricular tachycardia (VT). It was noted that baseline 12-lead ECG exhibited a predominantly elevated ST-segment which mimicked acute myocardial ischemia in lead V2-V6, and the ECG also demonstrated J waves in lead Ⅱ, Ⅲ, aVF and V2-V6. Using genetic analysis, we noted that the proband carried a novel heterozygous missense mutation of A1055G in the SCN5A gene. Whole-cell configuration of patch-clamp analysis revealed that the mutation significantly decreased peak sodium current (INa) density and shifted the steady-state inactivation curve of INa to a more negative potential. Confocal imaging suggested that in the mutant channel a defect of protein expression both on the cell membrane and in cytoplasm was present. The present study demonstrated that a novel heterozygous missense mutation of A1055G in SCN5A led to 'loss-of function' of the sodium channels, and we suggest that it accounts for the arrhythmogenic characteristics of ERS.
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Affiliation(s)
- Qi Guo
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Lan Ren
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Xuhua Chen
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Cuihong Hou
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Jianmin Chu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Jielin Pu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
| | - Shu Zhang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, P.R. China
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