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Qi M, Ma S, Liu J, Liu X, Wei J, Lu WJ, Zhang S, Chang Y, Zhang Y, Zhong K, Yan Y, Zhu M, Song Y, Chen Y, Hao G, Wang J, Wang L, Lee AS, Chen X, Wang Y, Lan F. In Vivo Base Editing of Scn5a Rescues Type 3 Long QT Syndrome in Mice. Circulation 2024; 149:317-329. [PMID: 37965733 DOI: 10.1161/circulationaha.123.065624] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 10/17/2023] [Indexed: 11/16/2023]
Abstract
BACKGROUND Pathogenic variants in SCN5A can result in long QT syndrome type 3, a life-threatening genetic disease. Adenine base editors can convert targeted A T base pairs to G C base pairs, offering a promising tool to correct pathogenic variants. METHODS We generated a long QT syndrome type 3 mouse model by introducing the T1307M pathogenic variant into the Scn5a gene. The adenine base editor was split into 2 smaller parts and delivered into the heart by adeno-associated virus serotype 9 (AAV9-ABEmax) to correct the T1307M pathogenic variant. RESULTS Both homozygous and heterozygous T1307M mice showed significant QT prolongation. Carbachol administration induced Torsades de Pointes or ventricular tachycardia for homozygous T1307M mice (20%) but not for heterozygous or wild-type mice. A single intraperitoneal injection of AAV9-ABEmax at postnatal day 14 resulted in up to 99.20% Scn5a transcripts corrected in T1307M mice. Scn5a mRNA correction rate >60% eliminated QT prolongation; Scn5a mRNA correction rate <60% alleviated QT prolongation. Partial Scn5a correction resulted in cardiomyocytes heterogeneity, which did not induce severe arrhythmias. We did not detect off-target DNA or RNA editing events in ABEmax-treated mouse hearts. CONCLUSIONS These findings show that in vivo AAV9-ABEmax editing can correct the variant Scn5a allele, effectively ameliorating arrhythmia phenotypes. Our results offer a proof of concept for the treatment of hereditary arrhythmias.
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Affiliation(s)
- Man Qi
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
- Chinese PLA General Hospital, College of Pulmonary & Critical Care Medicine, Beijing Key Laboratory of OTIR, Beijing, China (M.Q.)
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China (M.Q., Y. Chen)
| | - Shuhong Ma
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Jingtong Liu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China (J.L., Y.W.)
| | - Xujie Liu
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
- National Health Commission Key Laboratory of Cardiovascular Regenerative Medicine, Fuwai Central-China Hospital, Central-China Branch of National Center for Cardiovascular Diseases, Zhengzhou, China (X.L., F.L.)
| | - Jingjing Wei
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Wen-Jing Lu
- Beijing Laboratory for Cardiovascular Precision Medicine, The Key Laboratory of Biomedical Engineering for Cardiovascular Disease Research, Ministry of Education, Beijing Anzhen Hospital, Capital Medical University, Beijing, China (W.-J.L., S.Z., F.L.)
| | - Siyao Zhang
- Beijing Laboratory for Cardiovascular Precision Medicine, The Key Laboratory of Biomedical Engineering for Cardiovascular Disease Research, Ministry of Education, Beijing Anzhen Hospital, Capital Medical University, Beijing, China (W.-J.L., S.Z., F.L.)
| | - Yun Chang
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Yongshuai Zhang
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Kejia Zhong
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Yuting Yan
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Min Zhu
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Yabing Song
- School of Life Sciences, Tsinghua University, Beijing, China (Y.S., J. Wang)
| | - Yundai Chen
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China (M.Q., Y. Chen)
| | - Guoliang Hao
- Henan Academy of Innovations in Medical Science, Zhengzhou, China (G.H.)
| | - Jianbin Wang
- School of Life Sciences, Tsinghua University, Beijing, China (Y.S., J. Wang)
| | - Li Wang
- Shenzhen Key Laboratory of Cardiovascular Disease, Chinese Academy of Medical Sciences, Fuwai Hospital, Shenzhen, China (M.Q., S.M., X.L., Y. Chang, Y.Z., Y.Y., M.Z., L.W.)
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
| | - Andrew S Lee
- Institute for Cancer Research, Shenzhen Bay Laboratory, Shenzhen, China (A.S.L.)
| | - Xiangbo Chen
- Hangzhou Rongze Biotechnology Group Co, Ltd, Hangzhou, China (X.C.)
| | - Yongming Wang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China (J.L., Y.W.)
| | - Feng Lan
- Key Laboratory of Pluripotent Stem Cells in Cardiac Repair and Regeneration, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China (M.Q., S.M., X.L., J. Wei, Y. Chang, Y.Z., K.Z., Y.Y., M.Z., L.W., F.L.)
- National Health Commission Key Laboratory of Cardiovascular Regenerative Medicine, Fuwai Central-China Hospital, Central-China Branch of National Center for Cardiovascular Diseases, Zhengzhou, China (X.L., F.L.)
- Beijing Laboratory for Cardiovascular Precision Medicine, The Key Laboratory of Biomedical Engineering for Cardiovascular Disease Research, Ministry of Education, Beijing Anzhen Hospital, Capital Medical University, Beijing, China (W.-J.L., S.Z., F.L.)
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Najafi K, Mehrjoo Z, Ardalani F, Ghaderi-Sohi S, Kariminejad A, Kariminejad R, Najmabadi H. Identifying the causes of recurrent pregnancy loss in consanguineous couples using whole exome sequencing on the products of miscarriage with no chromosomal abnormalities. Sci Rep 2021; 11:6952. [PMID: 33772059 PMCID: PMC7997959 DOI: 10.1038/s41598-021-86309-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 03/08/2021] [Indexed: 12/26/2022] Open
Abstract
Recurrent miscarriages occur in about 5% of couples trying to conceive. In the past decade, the products of miscarriage have been studied using array comparative genomic hybridization (a-CGH). Within the last decade, an association has been proposed between miscarriages and single or multigenic changes, introducing the possibility of detecting other underlying genetic factors by whole exome sequencing (WES). We performed a-CGH on the products of miscarriage from 1625 Iranian women in consanguineous or non-consanguineous marriages. WES was carried out on DNA extracted from the products of miscarriage from 20 Iranian women in consanguineous marriages and with earlier normal genetic testing. Using a-CGH, a statistically significant difference was detected between the frequency of imbalances in related vs. unrelated couples (P < 0.001). WES positively identified relevant alterations in 11 genes in 65% of cases. In 45% of cases, we were able to classify these variants as pathogenic or likely pathogenic, according to the American College of Medical Genetics and Genomics guidelines, while in the remainder, the variants were classified as of unknown significance. To the best of our knowledge, our study is the first to employ WES on the products of miscarriage in consanguineous families with recurrent miscarriages regardless of the presence of fetal abnormalities. We propose that WES can be helpful in making a diagnosis of lethal disorders in consanguineous couples after prior genetic testing.
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Affiliation(s)
- Kimia Najafi
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Zohreh Mehrjoo
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
| | - Fariba Ardalani
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
| | - Siavash Ghaderi-Sohi
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Ariana Kariminejad
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Roxana Kariminejad
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Hossein Najmabadi
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran.
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran.
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3
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Keywan C, Holm IA, Poduri A, Brownstein CA, Alexandrescu S, Chen J, Geffre C, Goldstein RD. A de novo BRPF1 variant in a case of Sudden Unexplained Death in Childhood. Eur J Med Genet 2020; 63:104002. [PMID: 32652122 DOI: 10.1016/j.ejmg.2020.104002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/02/2020] [Accepted: 07/04/2020] [Indexed: 10/23/2022]
Abstract
Sudden Unexplained Death in Childhood (SUDC), the death of a child that remains unexplained after a complete autopsy and investigation, is a rare and poorly understood entity. This case report describes a 3-year-old boy with history of language delay and ptosis, who died suddenly in his sleep without known cause. A pathogenic de novo frameshift mutation in BRPF1, a gene which has been associated with the syndrome of Intellectual Developmental Disorder with Dysmorphic Facies and Ptosis (IDDDFP), was identified during a post-mortem evaluation. The finding of a pathogenic variant in BRPF1, which has not previously been associated with sudden death, in an SUDC case has implications for this child's family and contributes to the broader field of SUDC research. This case demonstrates the utility of post-mortem genetic testing in SUDC.
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Affiliation(s)
- Christine Keywan
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA
| | - Ingrid A Holm
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA; Division of Genetics and Genomics and Manton Center for Orphan Diseases Research, Boston Children's Hospital, USA; Department of Pediatrics, Harvard Medical School, USA
| | - Annapurna Poduri
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA; Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Harvard Medical School, USA
| | - Catherine A Brownstein
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA; Division of Genetics and Genomics and Manton Center for Orphan Diseases Research, Boston Children's Hospital, USA; Department of Pediatrics, Harvard Medical School, USA
| | - Sanda Alexandrescu
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA; Department of Pathology at Boston Children's Hospital, Harvard Medical School, USA
| | - Jennifer Chen
- Pima County Office of the Medical Examiner, Tucson, AZ, USA
| | | | - Richard D Goldstein
- Robert's Program for Sudden Unexpected Death in Pediatrics, Boston Children's Hospital, USA; Department of Pediatrics, Harvard Medical School, USA; Division of General Pediatrics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.
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4
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Identification novel LQT syndrome-associated variants in Polish population and genotype-phenotype correlations in eight families. J Appl Genet 2018; 59:463-469. [PMID: 30244407 DOI: 10.1007/s13353-018-0464-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 10/28/2022]
Abstract
Congenital long QT syndrome (LQTS) is a primary cardiac channelopathy. Genetic testing has not only diagnostic but also prognostic and therapeutic implications. At present, 15 genes have been associated with the disease, with most mutations located in 3 major LQTS-susceptibility genes. During a routine genetic screening for KCNQ1, KCNH2 and SCN5A genes in index cases with LQTS, seven novel variants in KCNH2 and SCN5A genes were found. Genotype-phenotype correlations were analysed in these patients and their families. An open reading frame and splice site analysis of the exons was conducted using next-generation sequencing. In novel variants, phenotypes of carriers and their affected relatives were analysed. In 39 unrelated patients, 40 pathogenic/putative pathogenic mutations were found. Thirty-three of them, predominantly missense, were reported previously: 11 were in the KCNQ, 17 in the KCNH2 and 5 in the SCN5A gene. Seven novel missense variants were found in eight families. Among them, four variants were in typical for LQTS location. Two variants in the KCNH2 gene (p.D803Y and p.D46F) and one in the SCN5A gene (G1391R) were in amino acid (AA) position which up to present has not been reported in LQTS. Phenotype analysis showed the life-threatening course of the disease in index cases with a history of sudden cardiac death in six families. Mutation carriers presented with ECG abnormalities and some of them received beta-blocker therapy. We report three novel variants (KCNQ1 p.46, KCNH2 p.D803Y, SCN5A p.G1391R) which have never been reported for this AA location in LQTS; the phenotype-genotype correlation suggests their pathogenicity.
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5
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Reuter CM, Brimble E, DeFilippo C, Dries AM, Enns GM, Ashley EA, Bernstein JA, Fisher PG, Wheeler MT. A New Approach to Rare Diseases of Children: The Undiagnosed Diseases Network. J Pediatr 2018; 196:291-297.e2. [PMID: 29331327 PMCID: PMC5924635 DOI: 10.1016/j.jpeds.2017.12.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/09/2017] [Accepted: 12/14/2017] [Indexed: 10/18/2022]
Affiliation(s)
- Chloe M. Reuter
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elise Brimble
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Colette DeFilippo
- Department of Pediatrics, Division of Medical Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA,Stanford Children’s Health, Palo Alto, CA, 94304, USA
| | - Annika M. Dries
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Gregory M. Enns
- Department of Pediatrics, Division of Medical Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Euan A. Ashley
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA,Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Jonathan A. Bernstein
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Department of Pediatrics, Division of Medical Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA,Stanford Children’s Health, Palo Alto, CA, 94304, USA
| | - Paul Graham Fisher
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA,Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Matthew T. Wheeler
- Stanford Center for Undiagnosed Diseases, Stanford University School of Medicine, Stanford, CA, 94305, USA,Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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Turker I, Makiyama T, Vatta M, Itoh H, Ueyama T, Shimizu A, Ai T, Horie M. A Novel SCN5A Mutation Associated with Drug Induced Brugada Type ECG. PLoS One 2016; 11:e0161872. [PMID: 27560382 PMCID: PMC4999187 DOI: 10.1371/journal.pone.0161872] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/12/2016] [Indexed: 11/19/2022] Open
Abstract
Background Class IC antiarrhythmic agents may induce acquired forms of Brugada Syndrome. We have identified a novel mutation in SCN5A, the gene that encodes the α-subunit of the human cardiac sodium channel (hNav1.5), in a patient who exhibited Brugada- type ECG changes during pharmacotherapy of atrial arrhythmias. Objective To assess whether the novel mutation p.V1328M can cause drug induced Brugada Syndrome. Methods Administration of pilsicainide, a class IC antiarrhythmic agent, caused Brugada- type ST elevation in a 66-year-old Japanese male who presented with paroxysmal atrial fibrillation (PAF), type I atrial flutter and inducible ventricular fibrillation (VF) during electrophysiological study. Genetic screening using direct sequencing identified a novel SCN5A variant, p.V1328M. Electrophysiological parameters of WT and p.V1328M and their effects on drug pharmacokinetics were studied using the patch-clamp method. Results Whole-cell sodium current densities were similar for WT and p.V1328M channels. While p.V1328M mutation did not affect the voltage-dependence of the activation kinetics, it caused a positive shift of voltage-dependent steady-state inactivation by 7 mV. The tonic block in the presence of pilsicainide was similar in WT and p.V1328M, when sodium currents were induced by a low frequency pulse protocol (q15s). On the contrary, p.V1328M mutation enhanced pilsicainide induced use-dependent block at 2 Hz. (Ki: WT, 35.8 μM; V1328M, 19.3 μM). Conclusion Our study suggests that a subclinical SCN5A mutation, p.V1328M, might predispose individuals harboring it to drug-induced Brugada Syndrome.
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Affiliation(s)
- Isik Turker
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, United States of America
| | - Takeru Makiyama
- Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Matteo Vatta
- Department of Cardiovascular Genetics, Indiana University, Indianapolis, IN, United States of America
| | - Hideki Itoh
- Cardiovascular and Respiratory Medicine, Shiga Univ. School of Medicine, Otsu, Japan
| | - Takeshi Ueyama
- Cardiology, Yamaguchi University School of Medicine, Yamaguchi, Japan
| | - Akihiko Shimizu
- Cardiology, Yamaguchi University School of Medicine, Yamaguchi, Japan
| | - Tomohiko Ai
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, United States of America
- Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- * E-mail: (MH); (TA)
| | - Minoru Horie
- Cardiovascular and Respiratory Medicine, Shiga Univ. School of Medicine, Otsu, Japan
- * E-mail: (MH); (TA)
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7
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Chang YS, Yang YW, Lin YN, Lin KH, Chang KC, Chang JG. Mutation Analysis of KCNQ1, KCNH2 and SCN5A Genes in Taiwanese Long QT Syndrome Patients. Int Heart J 2015; 56:450-3. [PMID: 26118593 DOI: 10.1536/ihj.14-428] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Ya-Sian Chang
- Epigenome Research Center, China Medical University Hospital
- Department of Laboratory Medicine, China Medical University Hospital
| | - Yi-Wen Yang
- Department of Laboratory Medicine, China Medical University Hospital
| | - Yen-Nien Lin
- Division of Cardiology, Department of Internal Medicine, China Medical University Hospital
| | - Kuo-Hung Lin
- Division of Cardiology, Department of Internal Medicine, China Medical University Hospital
| | - Kuan-Cheng Chang
- Division of Cardiology, Department of Internal Medicine, China Medical University Hospital
- School of Medicine, China Medical University
| | - Jan-Gowth Chang
- Epigenome Research Center, China Medical University Hospital
- Department of Laboratory Medicine, China Medical University Hospital
- School of Medicine, China Medical University
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8
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Kim G, Kyung YC, Kang IS, Song J, Huh J, On YK. A pediatric case of Brugada syndrome diagnosed by fever-provoked ventricular tachycardia. KOREAN JOURNAL OF PEDIATRICS 2014; 57:374-8. [PMID: 25210526 PMCID: PMC4155183 DOI: 10.3345/kjp.2014.57.8.374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 09/09/2013] [Accepted: 10/13/2013] [Indexed: 12/01/2022]
Abstract
Brugada syndrome is a rare channelopathy associated with the SCN5A gene that causes fatal ventricular arrhythmias. This case of Brugada syndrome, in which ventricular tachycardia (VT) was provoked by high fever, is the first report in a Korean child. The boy had retinoblastoma of his left eye diagnosed at 16 months of age. After chemotherapy, he contracted a catheter-related infection with a high fever up to 41℃ leading to monomorphic VT. This was characterized as having right bundle branch block morphology, superior axis deviation, and a heart rate of 212/min. Direct current cardioversion recovered the VT to sinus rhythm after a lack of response to amiodarone and lidocaine. A second attack of VT that was not controlled by cardioversion, however, responded to lidocaine. The baseline electrocardiogram showed a long PR interval and QRS duration, and the patient's grandfather had a history of Brugada syndrome. A mutation in SCN5A was identified in this patient, his father, and his grandfather. The patient was treated with quinidine and followed up for 1 year.
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Affiliation(s)
- Geena Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Ye-Chan Kyung
- Division of Cardiology, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - I-Seok Kang
- Division of Cardiology, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jinyoung Song
- Division of Cardiology, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - June Huh
- Division of Cardiology, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Young Keun On
- Department of Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea
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Beyder A, Mazzone A, Strege PR, Tester DJ, Saito YA, Bernard CE, Enders FT, Ek WE, Schmidt PT, Dlugosz A, Lindberg G, Karling P, Ohlsson B, Gazouli M, Nardone G, Cuomo R, Usai-Satta P, Galeazzi F, Neri M, Portincasa P, Bellini M, Barbara G, Camilleri M, Locke GR, Talley NJ, D'Amato M, Ackerman MJ, Farrugia G. Loss-of-function of the voltage-gated sodium channel NaV1.5 (channelopathies) in patients with irritable bowel syndrome. Gastroenterology 2014; 146:1659-1668. [PMID: 24613995 PMCID: PMC4096335 DOI: 10.1053/j.gastro.2014.02.054] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 02/06/2014] [Accepted: 02/26/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS SCN5A encodes the α-subunit of the voltage-gated sodium channel NaV1.5. Many patients with cardiac arrhythmias caused by mutations in SCN5A also have symptoms of irritable bowel syndrome (IBS). We investigated whether patients with IBS have SCN5A variants that affect the function of NaV1.5. METHODS We performed genotype analysis of SCN5A in 584 persons with IBS and 1380 without IBS (controls). Mutant forms of SCN5A were expressed in human embryonic kidney-293 cells, and functions were assessed by voltage clamp analysis. A genome-wide association study was analyzed for an association signal for the SCN5A gene, and replicated in 1745 patients in 4 independent cohorts of IBS patients and controls. RESULTS Missense mutations were found in SCN5A in 13 of 584 patients (2.2%, probands). Diarrhea-predominant IBS was the most prevalent form of IBS in the overall study population (25%). However, a greater percentage of individuals with SCN5A mutations had constipation-predominant IBS (31%) than diarrhea-predominant IBS (10%; P < .05). Electrophysiologic analysis showed that 10 of 13 detected mutations disrupted NaV1.5 function (9 loss-of-function and 1 gain-of-function function). The p. A997T-NaV1.5 had the greatest effect in reducing NaV1.5 function. Incubation of cells that expressed this variant with mexiletine restored their sodium current and administration of mexiletine to 1 carrier of this mutation (who had constipation-predominant IBS) normalized their bowel habits. In the genome-wide association study and 4 replicated studies, the SCN5A locus was strongly associated with IBS. CONCLUSIONS About 2% of patients with IBS carry mutations in SCN5A. Most of these are loss-of-function mutations that disrupt NaV1.5 channel function. These findings provide a new pathogenic mechanism for IBS and possible treatment options.
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Affiliation(s)
- Arthur Beyder
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Amelia Mazzone
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Peter R. Strege
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David J. Tester
- Departments of Medicine (Cardiovascular Diseases), Pediatrics (Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics and the Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Yuri A. Saito
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Cheryl E. Bernard
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Felicity T. Enders
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Weronica E Ek
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
| | - Peter T Schmidt
- Department of Gastroenterology and Hepatology, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Aldona Dlugosz
- Department of Gastroenterology and Hepatology, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Greger Lindberg
- Department of Gastroenterology and Hepatology, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | | | - Bodil Ohlsson
- Department of Clinical Sciences, Skånes University Hospital, Malmoe, Sweden
| | - Maria Gazouli
- Laboratory of Biology, School of Medicine, University of Athens, Athens, Greece
| | - Gerardo Nardone
- Gastroenterology Unit, Department of Clinical Medicine and Surgery, University Federico II, Naples, Italy
| | - Rosario Cuomo
- Digestive Motility Diseases, Department of Clinical Medicine and Surgery, Federico II University Hospital , Naples, Italy
| | - Paolo Usai-Satta
- S.C. Gastroenterologia, Azienda Ospedaliera G. Brotzu, Cagliari, Italy
| | | | - Matteo Neri
- Department of Medicine and Aging Sciences and CESI, G. D'Annunzio University & Foundation, Chieti, Italy
| | - Piero Portincasa
- Department of Biomedical Sciences and Human Oncology (DIMO), Clinica Medica ‘A. Murri', University of Bari Medical School, Bari, Italy
| | - Massimo Bellini
- Gastroenterology Unit, Department of Gastroenterology, University of Pisa, Pisa, Italy
| | - Giovanni Barbara
- Department of Medical and Surgical Sciences, University of Bologna, St. Orsola - Malpighi Hospital, Bologna, Italy
| | - Michael Camilleri
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - G. Richard Locke
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Nicholas J. Talley
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Mauro D'Amato
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
| | - Michael J. Ackerman
- Departments of Medicine (Cardiovascular Diseases), Pediatrics (Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics and the Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota;,Corresponding authors: Gianrico Farrugia, MD and Michael J. Ackerman MD, PhD Mayo Clinic 200 First Street SW, Rochester, Minnesota 55905 Phone: 507-284-4695. Fax: 507-284-0266.
| | - Gianrico Farrugia
- Enteric Neuroscience Program, Division of Gastroenterology &Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Corresponding authors: Gianrico Farrugia, MD and Michael J. Ackerman MD, PhD Mayo Clinic 200 First Street SW, Rochester, Minnesota 55905 Phone: 507-284-4695. Fax: 507-284-0266.
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Lopes LR, Zekavati A, Syrris P, Hubank M, Giambartolomei C, Dalageorgou C, Jenkins S, McKenna W, Plagnol V, Elliott PM. Genetic complexity in hypertrophic cardiomyopathy revealed by high-throughput sequencing. J Med Genet 2013; 50:228-39. [PMID: 23396983 PMCID: PMC3607113 DOI: 10.1136/jmedgenet-2012-101270] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Background Clinical interpretation of the large number of rare variants identified by high throughput sequencing (HTS) technologies is challenging. The aim of this study was to explore the clinical implications of a HTS strategy for patients with hypertrophic cardiomyopathy (HCM) using a targeted HTS methodology and workflow developed for patients with a range of inherited cardiovascular diseases. By comparing the sequencing results with published findings and with sequence data from a large-scale exome sequencing screen of UK individuals, we sought to quantify the strength of the evidence supporting causality for detected candidate variants. Methods and results 223 unrelated patients with HCM (46±15 years at diagnosis, 74% males) were studied. In order to analyse coding, intronic and regulatory regions of 41 cardiovascular genes, we used solution-based sequence capture followed by massive parallel resequencing on Illumina GAIIx. Average read-depth in the 2.1 Mb target region was 120. Rare (frequency<0.5%) non-synonymous, loss-of-function and splice-site variants were defined as candidates. Excluding titin, we identified 152 distinct candidate variants in sarcomeric or associated genes (89 novel) in 143 patients (64%). Four sarcomeric genes (MYH7, MYBPC3, TNNI3, TNNT2) showed an excess of rare single non-synonymous single-nucleotide polymorphisms (nsSNPs) in cases compared to controls. The estimated probability that a nsSNP in these genes is pathogenic varied between 57% and near certainty depending on the location. We detected an additional 94 candidate variants (73 novel) in desmosomal, and ion-channel genes in 96 patients (43%). Conclusions This study provides the first large-scale quantitative analysis of the prevalence of sarcomere protein gene variants in patients with HCM using HTS technology. Inclusion of other genes implicated in inherited cardiac disease identifies a large number of non-synonymous rare variants of unknown clinical significance.
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Affiliation(s)
- Luis R Lopes
- The Heart Hospital, 16-18 Westmoreland Street, London W1G 8PH, UK.
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Mitchell JL, Cuneo BF, Etheridge SP, Horigome H, Weng HY, Benson DW. Fetal Heart Rate Predictors of Long QT Syndrome. Circulation 2012; 126:2688-95. [DOI: 10.1161/circulationaha.112.114132] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background—
Fetal long QT syndrome (LQTS) is associated with complex arrhythmias including torsades de pointes and 2° atrioventricular block. Sinus bradycardia has also been associated with fetal LQTS, but little is known of this rhythm manifestation. Our purpose was to characterize the fetal heart rate (FHR)/gestational age (GA) profile of fetal LQTS.
Methods and Results—
We ascertained fetal LQTS subjects by family history (Group 1) or fetal arrhythmia referral (Group 2). We compared FHR in LQTS subjects versus normal fetuses. To identify FHR predictors of LQTS, we calculated a bradycardia index as % of LQTS FHR recordings either ≤110 beats per minute (obstetric standard) or ≤3
rd
percentile for GA. Among 42 LQTS subjects, 26 were in Group 1 and 16 in Group 2. There were 536 normal fetuses. The bradycardia index was only 15% for FHR ≤110 beats per minute, but 66% for FHR ≤3rd percentile for GA. Ten fetuses with complex arrhythmias also had severe and sustained sinus bradycardia throughout gestation. Identifying a fetal proband in Group 2 resulted in LQTS diagnosis in 9 unsuspected members of 6 families.
Conclusions—
FHR varies by GA in both normal and LQTS fetuses. Postnatal evaluation of neonates with FHR ≤3
rd
percentile for GA may improve ascertainment of LQTS in fetuses, neonates, and undiagnosed family members.
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Affiliation(s)
- Jason L. Mitchell
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Bettina F. Cuneo
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Susan P. Etheridge
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Hitoshi Horigome
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Hsin-Yi Weng
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - D. Woodrow Benson
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
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Park HS, Kim YN, Lee YS, Jung BC, Lee SH, Shin DG, Cho Y, Bae MH, Han SM, Lee MH. Genetic Analysis of SCN5A in Korean Patients Associated with Atrioventricular Conduction Block. Genomics Inform 2012; 10:110-6. [PMID: 23105938 PMCID: PMC3480677 DOI: 10.5808/gi.2012.10.2.110] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 05/30/2012] [Accepted: 06/03/2012] [Indexed: 01/08/2023] Open
Abstract
Recent several studies have shown that the genetic variation of SCN5A is related with atrioventricular conduction block (AVB); no study has yet been published in Koreans. Therefore, to determine the AVB-associated genetic variation in Korean patients, we investigated the genetic variation of SCN5A in Korean patients with AVB and compared with normal control subjects. We enrolled 113 patients with AVB and 80 normal controls with no cardiac symptoms. DNA was isolated from the peripheral blood, and all exons (exon 2-exon 28) except the untranslated region and exon-intron boundaries of the SCN5A gene were amplified by multiplex PCR and directly sequenced using an ABI PRISM 3100 Genetic Analyzer. When a variation was discovered in genomic DNA from AVB patients, we confirmed whether the same variation existed in the control genomic DNA. In the present study, a total of 7 genetic variations were detected in 113 AVB patients. Of the 7 variations, 5 (G87A-A29A, intervening sequence 9-3C>A, A1673G-H558R, G3578A-R1193Q, and T5457C-D1819D) have been reported in previous studies, and 2 (C48G-F16L and G3048A-T1016T) were novel variations that have not been reported. The 2 newly discovered variations were not found in the 80 normal controls. In addition, G298S, G514C, P1008S, G1406R, and D1595N, identified in other ethnic populations, were not detected in this study. We found 2 novel genetic variations in the SCN5A gene in Korean patients with AVB. However, further functional study might be needed.
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Affiliation(s)
- Hyoung Seob Park
- Division of Cardiology, Department of Internal Medicine, Keimyung University School of Medicine, Daegu 700-712, Korea
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Hedley PL, Jørgensen P, Schlamowitz S, Wangari R, Moolman-Smook J, Brink PA, Kanters JK, Corfield VA, Christiansen M. The genetic basis of long QT and short QT syndromes: A mutation update. Hum Mutat 2009; 30:1486-511. [DOI: 10.1002/humu.21106] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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14
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SCN5A channelopathies--an update on mutations and mechanisms. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:120-36. [PMID: 19027780 DOI: 10.1016/j.pbiomolbio.2008.10.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated Na+ channels mediate the rapid upstroke of the action potential in excitable tissues. Na(v)1.5, encoded by the SCN5A gene, is the predominant isoform in the heart. Mutations in SCN5A are associated with distinct cardiac excitation disorders often resulting in life-threatening arrhythmias. This review outlines the currently known SCN5A mutations linked to three distinct cardiac rhythm disorders: long QT syndrome subtype 3 (LQT3), Brugada syndrome (BS), and cardiac conduction disease (CCD). Electrophysiological properties of the mutant channels are summarized and discussed in terms of Na+ channel structure-function relationships and regarding molecular mechanisms underlying the respective cardiac dysfunction. Possible reasons for less convincing genotype-phenotype correlations are suggested.
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15
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Ellinor PT, Nam EG, Shea MA, Milan DJ, Ruskin JN, MacRae CA. Cardiac sodium channel mutation in atrial fibrillation. Heart Rhythm 2007; 5:99-105. [PMID: 18088563 DOI: 10.1016/j.hrthm.2007.09.015] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 09/13/2007] [Indexed: 12/18/2022]
Abstract
BACKGROUND Mutations in the sodium channel SCN5A have been implicated in many cardiac disorders, including the long QT syndrome, Brugada syndrome, conduction system disease, and dilated cardiomyopathy with atrial arrhythmias. OBJECTIVE In view of the pleiotropic effects of SCN5A mutations, the purpose of this study was to examine a cohort of patients with familial atrial fibrillation (AF) for mutations in the SCN5A gene. METHODS Probands with AF were enrolled in the study between June 1, 2001 and February 10, 2004. Each patient underwent a standardized evaluation, which included an interview, physical examination, ECG, echocardiogram, and blood sample for genetic analysis. Direct sequencing of the coding region of SCN5A was used to screen for mutations in genomic DNA. RESULTS One hundred eighty-nine patients with AF were enrolled during the study period. From this cohort, a subset of 57 probands with a family history of AF in at least one first-degree relative was studied. Forty-seven subjects were men (82%); 45 had paroxysmal AF (79%). Echocardiography revealed ejection fraction 62% +/- 6.4 % and left atrial dimension 40 +/- 6.9 mm. A single mutation (N1986K) was observed in one family but was not present in more than 600 control chromosomes. Expression of the N1986K mutant in Xenopus oocytes revealed a hyperpolarizing shift in channel steady-state inactivation. CONCLUSION In a cohort with familial AF, a single SCN5A mutation causing the arrhythmia in one kindred was identified. These data extend the range of phenotypes observed with SCN5A mutations and suggest that variation in the SCN5A gene is not a major cause of familial AF.
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Affiliation(s)
- Patrick T Ellinor
- Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Wang DW, Desai RR, Crotti L, Arnestad M, Insolia R, Pedrazzini M, Ferrandi C, Vege A, Rognum T, Schwartz PJ, George AL. Cardiac Sodium Channel Dysfunction in Sudden Infant Death Syndrome. Circulation 2007; 115:368-76. [PMID: 17210841 DOI: 10.1161/circulationaha.106.646513] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations in genes responsible for the congenital long-QT syndrome, especially SCN5A, have been identified in some cases of sudden infant death syndrome. In a large-scale collaborative genetic screen, several SCN5A variants were identified in a Norwegian sudden infant death syndrome cohort (n=201). We present functional characterization of 7 missense variants (S216L, R680H, T1304M, F1486L, V1951L, F2004L, and P2006A) and 1 in-frame deletion allele (delAL586-587) identified by these efforts. METHODS AND RESULTS Whole-cell sodium currents were measured in tsA201 cells transiently transfected with recombinant wild-type or mutant SCN5A cDNA (hH1) coexpressed with the human beta1 subunit. All variants exhibited defects in the kinetics and voltage dependence of inactivation. Five variants (S216L, T1304M, F1486L, F2004L, and P2006A) exhibited significantly increased persistent sodium currents (range, 0.5% to 1.7% of peak current) typical of SCN5A mutations associated with long-QT syndrome. These same 5 variants also displayed significant depolarizing shifts in voltage dependence of inactivation (range, 5 to 14 mV) and faster recovery from inactivation, but F1486L uniquely exhibits a depolarizing shift in the conductance-voltage relationship. Three alleles (delAL586-587, R680H, and V1951L) exhibited increased persistent current only under conditions of internal acidosis (R680H) or when expressed in the context of a common splice variant (delQ1077), indicating that they have a latent dysfunctional phenotype. CONCLUSIONS Our present results greatly expand the spectrum of functionally characterized SCN5A variants associated with sudden infant death syndrome and provide further biophysical correlates of arrhythmia susceptibility in this syndrome.
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Affiliation(s)
- Dao W Wang
- Departments of Pharmacology, Vanderbilt University, Nashville, Tenn, USA
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18
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Arnestad M, Crotti L, Rognum TO, Insolia R, Pedrazzini M, Ferrandi C, Vege A, Wang DW, Rhodes TE, George AL, Schwartz PJ. Prevalence of long-QT syndrome gene variants in sudden infant death syndrome. Circulation 2007; 115:361-7. [PMID: 17210839 DOI: 10.1161/circulationaha.106.658021] [Citation(s) in RCA: 331] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The hypothesis that some cases of sudden infant death syndrome (SIDS) could be caused by long-QT syndrome (LQTS) has been supported by molecular studies. However, there are inadequate data regarding the true prevalence of mutations in arrhythmia-susceptibility genes among SIDS cases. Given the importance and potential implications of these observations, we performed a study to more accurately quantify the contribution to SIDS of LQTS gene mutations and rare variants. METHODS AND RESULTS Molecular screening of 7 genes (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, KCNJ2, CAV3) associated with LQTS was performed with denaturing high-performance liquid chromatography and nucleotide sequencing of genomic DNA from 201 cases diagnosed as SIDS according to the Nordic Criteria, and from 182 infant and adult controls. All SIDS and control cases originated from the same regions in Norway. Genetic analysis was blinded to diagnosis. Mutations and rare variants were found in 26 of 201 cases (12.9%). On the basis of their functional effect, however, we considered 8 mutations and 7 rare variants found in 19 of 201 cases as likely contributors to sudden death (9.5%; 95% CI, 5.8 to 14.4%). CONCLUSIONS We demonstrated that 9.5% of cases diagnosed as SIDS carry functionally significant genetic variants in LQTS genes. The present study demonstrates that sudden arrhythmic death is an important contributor to SIDS. As these variants likely modify ventricular repolarization and QT interval duration, our results support the debated concept that an ECG would probably identify most infants at risk for sudden death due to LQTS either in infancy or later on in life.
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De Bruin ML, van Puijenbroek EP, Bracke M, Hoes AW, Leufkens HGM. Pharmacogenetics of drug-induced arrhythmias: a feasibility study using spontaneous adverse drug reactions reporting data. Pharmacoepidemiol Drug Saf 2006; 15:99-105. [PMID: 16329159 DOI: 10.1002/pds.1194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE The bottleneck in pharmacogenetic research on rare adverse drug reactions (ADR) is retrieval of patients. Spontaneous reports of ADRs may form a useful source of patients. We investigated the feasibility of a pharmacogenetic study, in which cases were selected from the database of a spontaneous reporting system for ADRs, using drug-induced arrhythmias as an example. METHODS Reports of drug-induced arrhythmias to proarrhythmic drugs were selected from the database of the Netherlands Pharmacovigilance Centre (1996-2003). Information on the patient's general practitioner (GP) was obtained from the original report, or from another health care provider who reported the event. GPs were contacted and asked to recruit the patient as well as two age, gender and drug matched controls. Patients were asked to fill a questionnaire and provide a buccal swab DNA sample through the mail. DNA samples were screened for 10 missense mutations in 5 genes associated with the congenital long-QT (LQT) syndrome (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2). RESULTS We identified 45 eligible cases, 29 GPs could be contacted of which seven were willing to participate. Four cases and five matched controls could be included in the study, giving an overall participation rate of 9% (4/45). The main reason for GPs not being willing to participate was lack of time. Variants were identified in KCNH2, SCN5A and KCNE1. CONCLUSIONS Spontaneous reporting systems for ADRs may be used for pharmacogenetic research. The methods described, however, need to be improved to increase participation and international collaboration may be required.
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Affiliation(s)
- Marie L De Bruin
- Utrecht Institute for Pharmaceutical Sciences (UIPS), Department of Pharmacoepidemiology and Pharmacotherapy, Utrecht, The Netherlands.
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Head CE, Balasubramaniam R, Thomas G, Goddard CA, Lei M, Colledge WH, Grace AA, Huang CLH. Paced electrogram fractionation analysis of arrhythmogenic tendency in DeltaKPQ Scn5a mice. J Cardiovasc Electrophysiol 2006; 16:1329-40. [PMID: 16403066 DOI: 10.1111/j.1540-8167.2005.00200.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Gain-of-function mutations within Scn5a, including the DeltaKPQ 1505-1507 deletion in the inactivation domain compromising myocardial repolarization, are implicated in human long QT 3 syndrome (LQT3), associated with ventricular arrhythmogenesis and sudden death. METHODS AND RESULTS Patch clamp studies on isolated ventricular Scn5a+/Delta myocytes from DeltaKPQ mice produced by homologous recombination in embryonic stem (ES) cells confirmed such altered electrophysiological properties of the mutant channel. Programmed electrical stimulation (PES) with decremental pacing from the basal right ventricular epicardial surface and paced electrogram fractionation analysis (PEFA) of electrograms recorded from the basal left ventricular epicardial surface of Langendorff-perfused whole heart preparations demonstrated ventricular tachycardia (VT) in 8 of 9 Scn5a+/Delta mutant (but no Scn5a+/+ (wild-type (WT)) controls; n = 17), with increased electrogram durations (EGD) and more dispersed conduction curves. Isoproterenol (100 nM) was without effect on tachycardic Scn5a+/Delta hearts (n = 9) yet propranolol (1 microM) prevented VT in all isoproterenol-infused WT control (n = 4) but no Scn5a+/Delta hearts (n = 4). Furthermore propranolol itself increased EGD and dispersion in Scn5a+/Delta hearts. In contrast, mexiletine (10 microM) suppressed VTs in 4 of 5 Scn5a+/Delta hearts without altering EGD or dispersion. CONCLUSION Beta-adrenoreceptor blockade does not confer an antiarrhythmic effect and may even enhance arrhythmogenesis by increasing reentrant substrate in Scn5a+/Delta hearts while mexiletine protects against VT without modifying conduction characteristics. Together these findings permit a scheme where VT in LQT3 is initiated by triggered mechanisms but propagated by reentry.
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Affiliation(s)
- Catherine E Head
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, UK
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HEAD CATHERINEE, BALASUBRAMANIAM RICHARD, THOMAS GLYN, GODDARD CATHARINEA, LEI MING, COLLEDGE WILLIAMH, GRACE ANDREWA, HUANG CHRISTOPHERLH. Paced Electrogram Fractionation Analysis of Arrhythmogenic Tendency in DeltaKPQ Scn5a Mice. J Cardiovasc Electrophysiol 2005. [DOI: 10.1111/j.1540-8167.2005.50086.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Cardiac rhythm problems result in high levels of morbidity and mortality, with sudden arrhythmic death claiming approximately 300,000 lives in the United States each year. Investigations into the genetic contributions to rhythm and conduction disorders have found genes or loci associated with primary rhythm/conduction disorders such as familial atrial fibrillation and atrio-ventricular block, underscoring the importance of collecting a thorough family history. Combinations of single or multiple genes and environmental risk factors may place only certain family members at risk. Some cardiac muscle problems, such as cardiomyopathy, predispose to arrhythmia and have documented genetic components. Primary health care providers need current knowledge of genetic contributions to rhythm/conduction problems so that family members at risk can be identified early and cared for appropriately. This article provides an overview of the genetic contributions to cardiac rhythm and conduction problems.
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Affiliation(s)
- Theresa Terry Beery
- Institute for Nursing Research, University of Cincinnati, College of Nursing, PO Box 210038, Cincinnati, OH 45221-0038, USA.
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Shin DJ, Jang Y, Park HY, Lee JE, Yang K, Kim E, Bae Y, Kim J, Kim J, Kim SS, Lee MH, Chahine M, Yoon SK. Genetic analysis of the cardiac sodium channel gene SCN5A in Koreans with Brugada syndrome. J Hum Genet 2004; 49:573-578. [PMID: 15338453 DOI: 10.1007/s10038-004-0182-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 06/24/2004] [Indexed: 01/10/2023]
Abstract
The SCN5A gene encodes the alpha subunit of the human cardiac voltage-gated sodium channel. Mutations in SCN5A are responsible for Brugada syndrome, an inherited cardiac disease that leads to idiopathic ventricular fibrillation (IVF) and sudden death. In this study, we screened nine individuals from a single family and 12 sporadic patients who were clinically diagnosed with Brugada syndrome. Using PCR-SSCP, DHPLC, and DNA sequencing analysis, we identified a novel single missense mutation associated with Brugada syndrome in the family and detected a C5607T polymorphism in Korean subjects. A single nucleotide substitution of G to A at nucleotide position 3934 changed the coding sense of exon 21 of the SCN5A from glycine to serine (G1262S) in segment 2 of domain III (DIII-S2). Four individuals in the family carried the identical mutation in the SCN5A gene, but none of the 12 sporadic patients did. This mutation was not found in 150 unrelated normal individuals. This finding is the first report of a novel mutation in SCN5A associated with Brugada syndrome in Koreans.
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Affiliation(s)
- Dong-Jik Shin
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Yangsoo Jang
- Cardiovascular Genome Center, Yonsei University Medical Center, Seoul, South Korea
| | - Hyun-Young Park
- Cardiovascular Genome Center, Yonsei University Medical Center, Seoul, South Korea
| | | | - Keumjin Yang
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Eunmin Kim
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Yoonjung Bae
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Jongmin Kim
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Jeongki Kim
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea
| | - Sung Soon Kim
- Department of Cardiology, Yonsei Cardiovascular Center, Seoul, South Korea
| | - Moon Hyoung Lee
- Department of Cardiology, Yonsei Cardiovascular Center, Seoul, South Korea
| | - Mohamed Chahine
- Laval Hospital Research Centre and Department of Medicine, Laval University, Sainte-Foy, Quebec, Canada
| | - Sungjoo Kim Yoon
- Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Sciences, Seoul, 137-040, South Korea.
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Chugh SS, Senashova O, Watts A, Tran PT, Zhou Z, Gong Q, Titus JL, Hayflick SJ. Postmortem molecular screening in unexplained sudden death. J Am Coll Cardiol 2004; 43:1625-9. [PMID: 15120823 DOI: 10.1016/j.jacc.2003.11.052] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Accepted: 11/06/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVES We examined the prevalence of defects in arrhythmia-related candidate genes among patients with unexplained sudden cardiac death (SCD). BACKGROUND Patients with unexplained sudden death may constitute up to 5% of overall SCD cases. For such patients, systematic postmortem genetic analysis of archived tissue, using a candidate gene approach, may identify etiologies of SCD. METHODS We performed analysis of KCNQ1 (KVLQT1), KCNH2 (HERG), SCN5A, KCNE1, and KCNE2 defects in a subgroup of 12 adult subjects with unexplained sudden death, derived from a 13-year, 270-patient autopsy series of SCD. Archived, paraffin-embedded myocardial tissue blocks obtained at the original postmortem examination were the source of deoxyribonucleic acid for genetic analysis. RESULTS Two patients were found to have the same HERG defect, a missense mutation in exon 7 (nucleotide change G1681A, coding effect A561T). The mutation was heterozygous in Patient 1, but Patient 2 appeared to be homozygous for the defect. Patch-clamp recordings showed that the A561T mutant channel expressed in human embryonic kidney cells failed to generate HERG current. Western blot analysis implicated a trafficking defect in the protein, resulting in loss of post-translational processing from the immature to the mature form of HERG. No mutations were detected among the remaining four candidate genes. CONCLUSIONS In this autopsy series, only 2 of 12 patients with unexplained sudden death were observed to have a defect in HERG among five candidate genes tested. It is likely that elucidation of SCD mechanisms in such patients will await the discovery of multiple, novel arrhythmia-causing gene defects.
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Affiliation(s)
- Sumeet S Chugh
- Division of Cardiology, Oregon Health and Science University, Portland, 97239, USA.
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Chen J, Xie X, Zhu J, Tao Q, Wang X. Single-nucleotide polymorphisms in SCN5A gene in Chinese Han population and their correlation with cardiac arrhythmias. Genet Med 2004; 6:159. [PMID: 15354335 DOI: 10.1097/00125817-200405000-00009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Abstract
Inherited disorders of ion-channels are associated with paroxysmal dysfunction of excitable tissues and manifest as diseases of the brain, heart and skeletal muscle. These so-called channelopathies have now been described for most of the major categories of voltage-dependent ion-channels including those selectively permeable to sodium. Sodium channelopathies affecting the heart and brain are reviewed in this essay. They show striking differences and similarities including, for example, their responsiveness to changes in body temperature and sleep state. They represent a paradigm for efforts to trace disturbed behaviour of physiological systems back to its molecular origins and understanding their molecular basis may provide clues to important health issues such as cardiac side effects of drugs and response to medication used to treat epilepsy.
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Affiliation(s)
- Cathy Head
- Department of Paediatric Cardiology, Guy's Hospital, London, UK.
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27
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Abstract
In the last few years, a very active line of research took place after the first identification of SCN5A mutations associated with an inherited form of cardiac arrhythmias and sudden death, the LQT3 variant of the long QT syndrome. Subsequently, two allelic diseases additional to LQT3 were shown to be due to mutations in the same gene, the Brugada syndrome (BrS) and the Lev-Lenegre syndrome (progressive cardiac conduction defect). Genotype-phenotype correlation and in vitro expression studies provide evidence that structure-function relationships of the SCN5A protein are much more complex than initially anticipated. The biophysical characterization of the sodium channel defects associated with different phenotypes and the genotype-phenotype correlation studies brought to the attention of the scientific community a plethora of mechanisms by which even a single amino acid substitution may remarkably affect cardiac excitability. Finally, the evidence of patients harboring an SCN5A mutation and overlapping clinical presentations creates a need for a revision of the traditional classification of the above mentioned diseases. It is now appropriate to consider the "sodium channel syndrome" as a unique clinical entity that may manifest itself with a spectrum of possible phenotypes.
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Affiliation(s)
- Carlo Napolitano
- Molecular Cardiology, Fondazione Salvatore Maugeri, IRCCS, Pavia, Italy.
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Ye B, Valdivia CR, Ackerman MJ, Makielski JC. A common human SCN5A polymorphism modifies expression of an arrhythmia causing mutation. Physiol Genomics 2003; 12:187-93. [PMID: 12454206 DOI: 10.1152/physiolgenomics.00117.2002] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
SCN5A encodes the alpha-subunit of the ion channel that carries Na current in human heart. From a human cardiac cDNA library we recloned SCN5A. The new clone hH1b differed from existing clones hH1 in four and from hH1a in three positions. The common polymorphism H558R was uniquely present in hH1b. Voltage clamp study showed minor but potentially important kinetic differences between hH1b and the other clones. More dramatically, when the LQT3 mutation M1766L was introduced into the different clones, Na current was markedly reduced in the hH1 and hH1a backgrounds, whereas in hH1b the Na current was not reduced. Immunocytochemistry experiments showed a trafficking defect for M1766L Na channels in hH1 and hH1a but not in hH1b. The double-mutation M1766L/H558R in the hH1a background restored normal trafficking and current including persistent late current, suggesting the disease phenotype was the result of a "double hit" that included the common polymorphism, H558R. These results show that the choice of background clone must be carefully considered in mutagenesis studies. This also represents an example of intragenic complementation, the first for such a large protein.
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Affiliation(s)
- Bin Ye
- Department of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53792, USA
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Groenewegen WA, Firouzi M, Bezzina CR, Vliex S, van Langen IM, Sandkuijl L, Smits JPP, Hulsbeek M, Rook MB, Jongsma HJ, Wilde AAM. A cardiac sodium channel mutation cosegregates with a rare connexin40 genotype in familial atrial standstill. Circ Res 2003; 92:14-22. [PMID: 12522116 DOI: 10.1161/01.res.0000050585.07097.d7] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Atrial standstill (AS) is a rare arrhythmia that occasionally appears to be genetically determined. This study investigates the genetic background of this arrhythmogenic disorder in a large family. Forty-four family members were clinically evaluated. One deceased and three living relatives were unambiguously affected by AS. All other relatives appeared unaffected. Candidate gene screening revealed a novel mutation in the cardiac sodium channel gene SCN5A (D1275N) in all three affected living relatives and in five unaffected relatives, and the deceased relative was an obligate carrier. In addition, two closely linked polymorphisms were detected within regulatory regions of the gene for the atrial-specific gap junction protein connexin40 (Cx40) at nucleotides -44 (G-->A) and +71 (A-->G). Eight relatives were homozygous for both polymorphisms, which occurred in only approximately 7% of control subjects, and three of these relatives were affected by AS. The three living AS patients exclusively coinherited both the rare Cx40 genotype and the SCN5A-D1275N mutation. SCN5A-D1275N channels showed a small depolarizing shift in activation compared with wild-type channels. Rare Cx40 genotype reporter gene analysis showed a reduction in reporter gene expression compared with the more common Cx40 genotype. In this study, familial AS was associated with the concurrence of a cardiac sodium channel mutation and rare polymorphisms in the atrial-specific Cx40 gene. We propose that, although the functional effect of each genetic change is relatively benign, the combined effect of genetic changes eventually progresses to total AS.
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Grant AO, Carboni MP, Neplioueva V, Starmer CF, Memmi M, Napolitano C, Priori S. Long QT syndrome, Brugada syndrome, and conduction system disease are linked to a single sodium channel mutation. J Clin Invest 2002; 110:1201-9. [PMID: 12393856 PMCID: PMC150793 DOI: 10.1172/jci15570] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The function of the 12 positive charges in the 53-residue III/IV interdomain linker of the cardiac Na(+) channel is unclear. We have identified a four-generation family, including 17 gene carriers with long QT syndrome, Brugada syndrome, and conduction system disease with deletion of lysine 1500 (DeltaK1500) within the linker. Three family members died suddenly. We have examined the functional consequences of this mutation by measuring whole-cell and single-channel currents in 293-EBNA cells expressing the wild-type and DeltaK1500 mutant channel. The mutation shifted V(1/2)h( infinity ) to more negative membrane potentials and increased k(h) consistent with a reduction of inactivation valence of 1. The shift in h( infinity ) was the result of an increase in closed-state inactivation rate (11-fold at -100 mV). V(1/2)m was shifted to more positive potentials, and k(m) was doubled in the DeltaK1500 mutant. To determine whether the positive charge deletion was the basis for the gating changes, we performed the mutations K1500Q and K1500E (change in charge, -1 and -2, respectively). For both mutations, V(1/2)h was shifted back toward control; however, V(1/2)m shifted progressively to more positive potentials. The late component of Na(+) current was increased in the DeltaK1500 mutant channel. These changes can account for the complex phenotype in this kindred and point to an important role of the III/IV linker in channel activation.
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Affiliation(s)
- Augustus O Grant
- Duke University Medical Center, Box 3504, Durham, North Carolina 27710, USA.
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Grant AO, Carboni MP, Neplioueva V, Starmer CF, Memmi M, Napolitano C, Priori S. Long QT syndrome, Brugada syndrome, and conduction system disease are linked to a single sodium channel mutation. J Clin Invest 2002. [DOI: 10.1172/jci0215570] [Citation(s) in RCA: 171] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Rivolta I, Clancy CE, Tateyama M, Liu H, Priori SG, Kass RS. A novel SCN5A mutation associated with long QT-3: altered inactivation kinetics and channel dysfunction. Physiol Genomics 2002; 10:191-7. [PMID: 12209021 DOI: 10.1152/physiolgenomics.00039.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the gene (SCN5A) encoding the alpha-subunit of the cardiac Na+ channel cause congenital long QT syndrome (LQT-3). Here we describe a novel LQT-3 mutation I1768V (I1768V) located in the sixth transmembrane spanning segment of domain IV. This mutation is unusual in that it is located within a transmembrane spanning domain and does not promote the typically observed sustained inward current corresponding to a gain of channel function (bursting). Rather, I1768V increases the rate of recovery from inactivation and increases the channel availability, observed as a positive shift of the steady-state inactivation curve (+7.6 mV). Using a Markovian model of the cardiac Na+ channel, we simulated these changes in gating behavior and demonstrated that a small increase in the rate of recovery from inactivation is sufficient to explain all of the experimentally observed current changes. The effect of these alterations in channel gating results in an increase in window current that may act to disrupt cardiac repolarization.
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Affiliation(s)
- Ilaria Rivolta
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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Abstract
Cardiac sodium (Na) channels are dynamic molecules that undergo rapid structural changes in response to the changing electrical field in the myocardium. Inherited mutations in SCN5A, the gene encoding the cardiac Na channel, provoke life-threatening cardiac arrhythmias, often by modifying these voltage-dependent conformational changes. These disorders (i.e. the long QT syndrome and Brugada syndrome) may serve as valuable models for understanding the mechanistic linkages between Na channel dysfunction and cardiac arrhythmias in more common, acquired conditions such as cardiac ischemia. In addition, the balance between therapeutic and adverse effects from Na channel blockade by antiarrhythmic compounds may be shifted by subtle alterations in Na channel function. This review examines recent studies that tie key loci in the Na channel primary sequence to its dynamic function, while examining the emerging themes linking Na channel structure, function, and pharmacology to inherited and acquired disorders of cardiac excitability.
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Affiliation(s)
- J R Balser
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN 37232-6602, USA.
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Splawski I, Shen J, Timothy KW, Lehmann MH, Priori S, Robinson JL, Moss AJ, Schwartz PJ, Towbin JA, Vincent GM, Keating MT. Spectrum of mutations in long-QT syndrome genes. KVLQT1, HERG, SCN5A, KCNE1, and KCNE2. Circulation 2000; 102:1178-85. [PMID: 10973849 DOI: 10.1161/01.cir.102.10.1178] [Citation(s) in RCA: 807] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Long-QT Syndrome (LQTS) is a cardiovascular disorder characterized by prolongation of the QT interval on ECG and presence of syncope, seizures, and sudden death. Five genes have been implicated in Romano-Ward syndrome, the autosomal dominant form of LQTS: KVLQT1, HERG, SCN5A, KCNE1, and KCNE2. Mutations in KVLQT1 and KCNE1 also cause the Jervell and Lange-Nielsen syndrome, a form of LQTS associated with deafness, a phenotypic abnormality inherited in an autosomal recessive fashion. METHODS AND RESULTS We used mutational analyses to screen a pool of 262 unrelated individuals with LQTS for mutations in the 5 defined genes. We identified 134 mutations in addition to the 43 that we previously reported. Eighty of the mutations were novel. The total number of mutations in this population is now 177 (68% of individuals). CONCLUSIONS KVLQT1 (42%) and HERG (45%) accounted for 87% of identified mutations, and SCN5A (8%), KCNE1 (3%), and KCNE2 (2%) accounted for the other 13%. Missense mutations were most common (72%), followed by frameshift mutations (10%), in-frame deletions, and nonsense and splice-site mutations (5% to 7% each). Most mutations resided in intracellular (52%) and transmembrane (30%) domains; 12% were found in pore and 6% in extracellular segments. In most cases (78%), a mutation was found in a single family or an individual.
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Affiliation(s)
- I Splawski
- Department of Human Genetics, Howard Hughes Medical Institute, Division of Cardiology, Salt Lake City, Utah, USA.
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Abstract
It is becoming clear that mutations in the KVLQT1, human "ether-a-go-go" related gene, cardiac voltage-dependent sodium channel gene, minK and MiRP1 genes, respectively, are responsible for the LQT1, LQT2, LQT3, LQT5 and LQT6 variants of the Romano-Ward syndrome, characterized by autosomal dominant transmission and no deafness. The much rarer Jervell-Lange-Nielsen syndrome (with marked QT prolongation and sensorineural deafness) arises when a child inherits mutant KVLQT1 or minK alleles from both parents. In addition, some families are not linked to the known genetic loci. Cardiac voltage-dependent sodium channel gene encodes the cardiac sodium channel, and long QT syndrome (LQTS) mutations prolong action potentials by increasing inward plateau sodium current. The other mutations cause a decrease in net repolarizing current by reducing potassium currents through "dominant negative" or "loss of function" mechanisms. Polymorphic ventricular tachycardia (torsade de pointes) is thought to be initiated by early after-depolarizations in the Purkinje system and maintained by reentry in the myocardium. Clinical presentations vary with the specific gene affected and the specific mutation. Nevertheless, patients with identical mutations can also present differently, and some patients with LQTS mutations may have no manifest baseline phenotype. The question of whether the latter situation is one of high risk for administration of QT prolonging drugs or during myocardial ischemia is under active investigation. More generally, the identification of LQTS genes has provided tremendous new insights for our understanding of normal cardiac electrophysiology and its perturbation in a wide range of conditions associated with sudden death. It seems likely that the approach of applying information from the genetics of uncommon congenital syndromes to the study of common acquired diseases will be an increasingly important one in the next millennium.
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Affiliation(s)
- C E Chiang
- Department of Medicine, Taipei Veterans General Hospital and National Yang-Ming University School of Medicine, Taiwan.
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Escayg A, MacDonald BT, Meisler MH, Baulac S, Huberfeld G, An-Gourfinkel I, Brice A, LeGuern E, Moulard B, Chaigne D, Buresi C, Malafosse A. Mutations of SCN1A, encoding a neuronal sodium channel, in two families with GEFS+2. Nat Genet 2000; 24:343-5. [PMID: 10742094 DOI: 10.1038/74159] [Citation(s) in RCA: 659] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- A Escayg
- [1] Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
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