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Weeke P, Denny JC, Basterache L, Shaffer C, Bowton E, Ingram C, Darbar D, Roden DM. Examining rare and low-frequency genetic variants previously associated with lone or familial forms of atrial fibrillation in an electronic medical record system: a cautionary note. ACTA ACUST UNITED AC 2014; 8:58-63. [PMID: 25410959 DOI: 10.1161/circgenetics.114.000718] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Studies in individuals or small kindreds have implicated rare variants in 25 different genes in lone and familial atrial fibrillation (AF) using linkage and segregation analysis, functional characterization, and rarity in public databases. Here, we used a cohort of 20 204 patients of European or African ancestry with electronic medical records and exome chip data to compare the frequency of AF among carriers and noncarriers of these rare variants. METHODS AND RESULTS The exome chip included 19 of 115 rare variants, in 9 genes, previously associated with lone or familial AF. Using validated algorithms querying a combination of clinical notes, structured billing codes, ECG reports, and procedure codes, we identified 1056 AF cases (>18 years) and 19 148 non-AF controls (>50 years) with available genotype data on the Illumina HumanExome BeadChip v.1.0 in the Vanderbilt electronic medical record-linked DNA repository, BioVU. Known correlations between AF and common variants at 4q25 were replicated. None of the 19 variants previously associated with AF were over-represented among AF cases (P>0.1 for all), and the frequency of variant carriers among non-AF controls was >0.1% for 14 of 19. Repeat analyses using non-AF controls aged >60 (n=14 904), >70 (n=9670), and >80 (n=4729) years did not influence these findings. CONCLUSIONS Rare variants previously implicated in lone or familial forms of AF present on the exome chip are detected at low frequencies in a general population but are not associated with AF. These findings emphasize the need for caution when ascribing variants as pathogenic or causative.
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Affiliation(s)
- Peter Weeke
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Joshua C Denny
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Lisa Basterache
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Christian Shaffer
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Erica Bowton
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Christie Ingram
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Dawood Darbar
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Dan M Roden
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.).
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Disease-targeted sequencing of ion channel genes identifies de novo mutations in patients with non-familial Brugada syndrome. Sci Rep 2014; 4:6733. [PMID: 25339316 PMCID: PMC4206841 DOI: 10.1038/srep06733] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/02/2014] [Indexed: 01/30/2023] Open
Abstract
Brugada syndrome (BrS) is one of the ion channelopathies associated with sudden cardiac death (SCD). The most common BrS-associated gene (SCN5A) only accounts for approximately 20–25% of BrS patients. This study aims to identify novel mutations across human ion channels in non-familial BrS patients without SCN5A variants through disease-targeted sequencing. We performed disease-targeted multi-gene sequencing across 133 human ion channel genes and 12 reported BrS-associated genes in 15 unrelated, non-familial BrS patients without SCN5A variants. Candidate variants were validated by mass spectrometry and Sanger sequencing. Five de novo mutations were identified in four genes (SCNN1A, KCNJ16, KCNB2, and KCNT1) in three BrS patients (20%). Two of the three patients presented SCD and one had syncope. Interestingly, the two patients presented with SCD had compound mutations (SCNN1A:Arg350Gln and KCNB2:Glu522Lys; SCNN1A:Arg597* and KCNJ16:Ser261Gly). Importantly, two SCNN1A mutations were identified from different families. The KCNT1:Arg1106Gln mutation was identified in a patient with syncope. Bioinformatics algorithms predicted severe functional interruptions in these four mutation loci, suggesting their pivotal roles in BrS. This study identified four novel BrS-associated genes and indicated the effectiveness of this disease-targeted sequencing across ion channel genes for non-familial BrS patients without SCN5A variants.
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Mahida S, Sacher F, Berte B, Yamashita S, Lim H, Derval N, Denis A, Shah A, Amraoui S, Hocini M, Jais P, Haissaguerre M. Evaluation Of Patients With Early Repolarization Syndrome. J Atr Fibrillation 2014; 7:1083. [PMID: 27957112 PMCID: PMC4956281 DOI: 10.4022/jafib.1083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 09/11/2014] [Accepted: 09/13/2014] [Indexed: 12/18/2022]
Abstract
In recent years, the early repolarization pattern has emerged as a risk factor for malignant ventricular arrhythmias and sudden cardiac death. The identification of the subset of patients who are at high risk of sudden death represents a significant challenge to the clinician. Multiple clinical and ECG features have been associated with an increased risk of sudden deathin however the majority of risk factors confer a small increase in absolute risk. The present article reviews current evidence and potential management strategies in patients with early repolarization.
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Affiliation(s)
- Saagar Mahida
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Frederic Sacher
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Benjamin Berte
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Seigo Yamashita
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Han Lim
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Nicolas Derval
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Arnaud Denis
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Ashok Shah
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Sana Amraoui
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Meleze Hocini
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Pierre Jais
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
| | - Michel Haissaguerre
- HôpitalCardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France
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104
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Perrin MJ, Adler A, Green S, Al-Zoughool F, Doroshenko P, Orr N, Uppal S, Healey JS, Birnie D, Sanatani S, Gardner M, Champagne J, Simpson C, Ahmad K, van den Berg MP, Chauhan V, Backx PH, van Tintelen JP, Krahn AD, Gollob MH. Evaluation of genes encoding for the transient outward current (Ito) identifies the KCND2 gene as a cause of J-wave syndrome associated with sudden cardiac death. ACTA ACUST UNITED AC 2014; 7:782-9. [PMID: 25214526 DOI: 10.1161/circgenetics.114.000623] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND J-wave ECG patterns are associated with an increased risk of sudden arrhythmic death, and experimental evidence supports a transient outward current (I(to))-mediated mechanism of J-wave formation. This study aimed to determine the frequency of genetic mutations in genes encoding the I(to) in patients with J waves on ECG. METHODS AND RESULTS Comprehensive mutational analysis was performed on I(to)-encoding KCNA4, KCND2, and KCND3 genes, as well as the previously described J-wave-associated KCNJ8 gene, in 51 unrelated patients with ECG evidence defining a J-wave syndrome. Only patients with a resuscitated cardiac arrest or type 1 Brugada ECG pattern were included for analysis. A rare genetic mutation of the KCND2 gene, p.D612N, was identified in a single patient. Co-expression of mutant and wild-type KCND2 with KChIP2 in HEK293 cells demonstrated a gain-of-function phenotype, including an increase in peak I(to) density of 48% (P<0.05) in the heterozygous state. Using computer modeling, this increase in Ito resulted in loss of the epicardial action potential dome, predicting an increased ventricular transmural Ito gradient. The previously described KCNJ8-S422L mutation was not identified in this cohort of patients with ECG evidence of J-wave syndrome. CONCLUSIONS These findings are the first to implicate the KCND2 gene as a novel cause of J-wave syndrome associated with sudden cardiac arrest. However, genetic defects in I(to)-encoding genes seem to be an uncommon cause of sudden cardiac arrest in patients with apparent J-wave syndromes.
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Affiliation(s)
- Mark J Perrin
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Arnon Adler
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Sharon Green
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Foad Al-Zoughool
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Petro Doroshenko
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Nathan Orr
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Shaheen Uppal
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Jeff S Healey
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - David Birnie
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Shubhayan Sanatani
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Martin Gardner
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Jean Champagne
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Chris Simpson
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Kamran Ahmad
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Maarten P van den Berg
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Vijay Chauhan
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Peter H Backx
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - J Peter van Tintelen
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Andrew D Krahn
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.)
| | - Michael H Gollob
- From the Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa (M.J.P., A.A., S.G., F.A.-Z., P.D., N.O., S.U., D.B.); Population Health Research Institute, McMaster University, Hamilton, ON (J.S.H.); Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC (S.S., A.D.K.); Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, NS (M.G.); Division of Cardiology, Department of Medicine, Laval University, Québec, QC (J.C.); Division of Cardiology, Department of Medicine, Queens University, Kingston (C.S.); Division of Cardiology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada (K.A.); Department of Genetics, University of Groningen, University Medical Center, Groningen, the Netherlands (M.P.v.d.B., J.P.v.T.); Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada (V.C., P.H.B., M.H.G.).
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105
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Tinker A, Aziz Q, Thomas A. The role of ATP-sensitive potassium channels in cellular function and protection in the cardiovascular system. Br J Pharmacol 2014; 171:12-23. [PMID: 24102106 DOI: 10.1111/bph.12407] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/30/2013] [Accepted: 08/26/2013] [Indexed: 12/14/2022] Open
Abstract
ATP-sensitive potassium channels (K(ATP)) are widely distributed and present in a number of tissues including muscle, pancreatic beta cells and the brain. Their activity is regulated by adenine nucleotides, characteristically being activated by falling ATP and rising ADP levels. Thus, they link cellular metabolism with membrane excitability. Recent studies using genetically modified mice and genomic studies in patients have implicated K(ATP) channels in a number of physiological and pathological processes. In this review, we focus on their role in cellular function and protection particularly in the cardiovascular system.
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Affiliation(s)
- Andrew Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, London, UK
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106
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Sethi KK, Sethi K, Chutani SK. Early repolarisation and J wave syndromes. Indian Heart J 2014; 66:443-52. [PMID: 25173204 PMCID: PMC4150048 DOI: 10.1016/j.ihj.2014.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/16/2014] [Indexed: 12/21/2022] Open
Abstract
J wave syndrome has emerged as a significant cause of Idiopathic ventricular fibrillation (IVF) responsible for sudden cardiac death. A large body of data is now available on genesis, genetics and ionic mechanisms of J wave syndromes. Two of these viz., Early repolarization syndrome (ER) and Brugada syndrome (BrS) are fairly well characterized enabling correct diagnosis in most patients. The first part of repolarization of ventricular myocardium is governed by Ito current i.e., rapid outward potassium current. The proposed mechanism of ventricular fibrillation (VF) and ventricular tachycardia (VT) storms is the faster Ito current in the epicardium than in the endocardium results in electrical gradient that forms the substrate for phase 2 reentry. Prevention of Ito current with quinidine supports this mechanism. Majority of ER patterns in young patients are benign. The key issue is to identify those at increased risk of sudden cardiac death. Association of both ER syndrome and Brugada syndrome with other disease states like coronary artery disease has also been reported. Individuals resuscitated from VF definitely need an implantable cardiac defibrillator (ICD) but in others there is no consensus regarding therapy. Role of electrophysiology study to provoke ventricular tachycardia or fibrillation is not yet well defined. Radiofrequency ablation of epicardial substrate in right ventricle in Brugada syndrome is also under critical evaluation. In this review we shall discuss historical features, epidemiology, electrocardiographic features, ionic pathogenesis, clinical features and current status of proposed treatment of ER and BrS.
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Affiliation(s)
- Kamal K Sethi
- Director of Cardiology, Division of Cardiology and Cardiac Electrophysiology, Delhi Heart & Lung Institute, 3 MM II, Panchkuian Road, New Delhi 110 055, India.
| | - Kabir Sethi
- Division of Cardiology and Cardiac Electrophysiology, Delhi Heart & Lung Institute, 3 MM II, Panchkuian Road, New Delhi 110 055, India
| | - Surendra K Chutani
- Division of Cardiology and Cardiac Electrophysiology, Delhi Heart & Lung Institute, 3 MM II, Panchkuian Road, New Delhi 110 055, India
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107
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Junttila MJ, Tikkanen JT, Kenttä T, Anttonen O, Aro AL, Porthan K, Kerola T, Rissanen HA, Knekt P, Huikuri HV. Early repolarization as a predictor of arrhythmic and nonarrhythmic cardiac events in middle-aged subjects. Heart Rhythm 2014; 11:1701-6. [PMID: 24858812 DOI: 10.1016/j.hrthm.2014.05.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Indexed: 01/22/2023]
Abstract
BACKGROUND Early repolarization (ER) in the inferior/lateral leads predicts mortality, but whether ER is a specific sign of increased risk for arrhythmic events is not known. OBJECTIVE The purpose of this study was to study the association of ER and arrhythmic events and nonarrhythmic morbidity and mortality. METHODS We assessed the prognostic significance of ER in a community-based general population of 10,846 middle-aged subjects (mean age 44 ± 8 years). The end-points were sustained ventricular tachycardia or resuscitated ventricular fibrillation (VT-VF), arrhythmic death, nonarrhythmic cardiac death, new-onset atrial fibrillation (AF), hospitalization for congestive heart failure, or coronary artery disease during mean follow-up of 30 ± 11 years. ER was defined as ≥0.1-mV elevation of J point in either inferior or lateral leads. RESULTS After including all risk factors of cardiac mortality and morbidity in Cox regression analysis, inferior ER (prevalence 3.5%) predicted VF-VT events (n = 108 [1.0%]) with a hazard ratio (HR) of 2.2 (95% confidence interval [CI] 1.1-4.5, P = .03) but not nonarrhythmic cardiac death (n = 1235 [12.2%]), AF (n = 1659 [15.2%]), congestive heart failure (n = 1752 [16.1%]), or coronary artery disease (n = 3592 [32.9%]) (P = NS for all). Inferior ER predicted arrhythmic death in cases without other QRS complex abnormalities (multivariate HR 1.68, 95 % CI 1.10-2.58, P = .02) but not in those with ER and other coexisting abnormalities in QRS morphology (HR 1.30, 95% CI 0.86-1.96, P = .22). CONCLUSION ER in the inferior leads, especially in cases without other QRS complex abnormalities, predicts the occurrence of VT-VF but not nonarrhythmic cardiac events, suggesting that ER is a specific sign of increased vulnerability to ventricular tachyarrhythmias.
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Affiliation(s)
- M Juhani Junttila
- Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland.
| | - Jani T Tikkanen
- Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland
| | - Tuomas Kenttä
- Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland
| | - Olli Anttonen
- Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland
| | - Aapo L Aro
- Division of Cardiology Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland
| | - Kimmo Porthan
- Division of Cardiology Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland
| | - Tuomas Kerola
- Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland
| | | | - Paul Knekt
- National Institute for Health and Welfare, Helsinki, Finland
| | - Heikki V Huikuri
- Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland
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108
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Cooper PE, Reutter H, Woelfle J, Engels H, Grange DK, van Haaften G, van Bon BW, Hoischen A, Nichols CG. Cantú syndrome resulting from activating mutation in the KCNJ8 gene. Hum Mutat 2014; 35:809-13. [PMID: 24700710 DOI: 10.1002/humu.22555] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 03/21/2014] [Indexed: 12/21/2022]
Abstract
ATP-sensitive potassium (KATP ) channels, composed of inward-rectifying potassium channel subunits (Kir6.1 and Kir6.2, encoded by KCNJ8 and KCNJ11, respectively) and regulatory sulfonylurea receptor (SUR1 and SUR2, encoded by ABCC8 and ABCC9, respectively), couple metabolism to excitability in multiple tissues. Mutations in ABCC9 cause Cantú syndrome (CS), a distinct multiorgan disease, potentially via enhanced KATP channel activity. We screened KCNJ8 in an ABCC9 mutation-negative patient who also exhibited clinical hallmarks of CS (hypertrichosis, macrosomia, macrocephaly, coarse facial appearance, cardiomegaly, and skeletal abnormalities). We identified a de novo missense mutation encoding Kir6.1[p.Cys176Ser] in the patient. Kir6.1[p.Cys176Ser] channels exhibited markedly higher activity than wild-type channels, as a result of reduced ATP sensitivity, whether coexpressed with SUR1 or SUR2A subunits. Our results identify a novel causal gene in CS, but also demonstrate that the cardinal features of the disease result from gain of KATP channel function, not from a Kir6-independent SUR2 function.
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Affiliation(s)
- Paige E Cooper
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri
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109
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Andreasen L, Nielsen JB, Darkner S, Christophersen IE, Jabbari J, Refsgaard L, Thiis JJ, Sajadieh A, Tveit A, Haunsø S, Svendsen JH, Schmitt N, Olesen MS. Brugada syndrome risk loci seem protective against atrial fibrillation. Eur J Hum Genet 2014; 22:1357-61. [PMID: 24667784 DOI: 10.1038/ejhg.2014.46] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 12/12/2013] [Accepted: 12/26/2013] [Indexed: 12/19/2022] Open
Abstract
Several studies have shown an overlap between genes involved in the pathophysiological mechanisms of atrial fibrillation (AF) and Brugada Syndrome (BrS). We investigated whether three single-nucleotide polymorphisms (SNPs) (rs11708996; G>C located intronic to SCN5A, rs10428132; T>G located in SCN10A, and rs9388451; T>C located downstream to HEY2) at loci associated with BrS in a recent genome-wide association study (GWAS) also were associated with AF. A total of 657 patients diagnosed with AF and a control group comprising 741 individuals free of AF were included. The three SNPs were genotyped using TaqMan assays. The frequencies of risk alleles in the AF population and the control population were compared in two-by-two models. One variant, rs10428132 at SCN10A, was associated with a statistically significant decreased risk of AF (odds ratio (OR)=0.77, P=0.001). A meta-analysis was performed by enriching the control population with allele frequencies from controls in the recently published BrS GWAS (2230 alleles). In this meta-analysis, both rs10428132 at SCN10A (OR=0.73, P=5.7 × 10(-6)) and rs11708996 at SCN5A (OR=0.80, P=0.02) showed a statistically significant decreased risk of AF. When assessing the additive effect of the three loci, we found that the risk of AF decreased in a dose-responsive manner with increasing numbers of risk alleles (OR=0.50, P=0.001 for individuals carrying ≥4 risk alleles vs ≤1 allele). In conclusion, the prevalence of three risk alleles previously associated with BrS was lower in AF patients than in patients free of AF, suggesting a protective role of these loci in developing AF.
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Affiliation(s)
- Laura Andreasen
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark [3] The Ion Channel Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas B Nielsen
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stine Darkner
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ingrid E Christophersen
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark [3] Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Rud, Norway
| | - Javad Jabbari
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lena Refsgaard
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Thiis
- Departments of Cardiothoracic Surgery and Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ahmad Sajadieh
- Department of Cardiology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Arnljot Tveit
- Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Rud, Norway
| | - Stig Haunsø
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark [3] Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Jesper H Svendsen
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark [3] Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Nicole Schmitt
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] The Ion Channel Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten S Olesen
- 1] Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark [2] Laboratory for Molecular Cardiology, Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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110
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Dorantes M, Marrero R, Méndez A, Castro J, Vázquez A. [Family history of sudden death due to idiopathic ventricular fibrillation]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2014; 84:57-9. [PMID: 24631049 DOI: 10.1016/j.acmx.2013.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 10/25/2022] Open
Affiliation(s)
- Margarita Dorantes
- Servicio de Arritmias y Estimulación Cardiaca, Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba.
| | - Roberto Marrero
- Servicio de Arritmias y Estimulación Cardiaca, Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba
| | - Annerys Méndez
- Servicio de Arritmias y Marcapasos, Hospital Hermanos Ameijeiras, La Habana, Cuba
| | - Jesús Castro
- Servicio de Arritmias y Estimulación Cardiaca, Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba
| | - Alfredo Vázquez
- Servicio de Arritmias y Estimulación Cardiaca, Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba
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111
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Olesen MS, Nielsen MW, Haunsø S, Svendsen JH. Atrial fibrillation: the role of common and rare genetic variants. Eur J Hum Genet 2014; 22:297-306. [PMID: 23838598 PMCID: PMC3925267 DOI: 10.1038/ejhg.2013.139] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 04/28/2013] [Accepted: 05/27/2013] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting 1-2% of the general population. A number of studies have demonstrated that AF, and in particular lone AF, has a substantial genetic component. Monogenic mutations in lone and familial AF, although rare, have been recognized for many years. Presently, mutations in 25 genes have been associated with AF. However, the complexity of monogenic AF is illustrated by the recent finding that both gain- and loss-of-function mutations in the same gene can cause AF. Genome-wide association studies (GWAS) have indicated that common single-nucleotide polymorphisms (SNPs) have a role in the development of AF. Following the first GWAS discovering the association between PITX2 and AF, several new GWAS reports have identified SNPs associated with susceptibility of AF. To date, nine SNPs have been associated with AF. The exact biological pathways involving these SNPs and the development of AF are now starting to be elucidated. Since the first GWAS, the number of papers concerning the genetic basis of AF has increased drastically and the majority of these papers are for the first time included in a review. In this review, we discuss the genetic basis of AF and the role of both common and rare genetic variants in the susceptibility of developing AF. Furthermore, all rare variants reported to be associated with AF were systematically searched for in the Exome Sequencing Project Exome Variant Server.
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Affiliation(s)
- Morten S Olesen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Morten W Nielsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper H Svendsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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112
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Mustroph J, Maier LS, Wagner S. CaMKII regulation of cardiac K channels. Front Pharmacol 2014; 5:20. [PMID: 24600393 PMCID: PMC3930912 DOI: 10.3389/fphar.2014.00020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 01/31/2014] [Indexed: 11/23/2022] Open
Abstract
Cardiac K channels are critical determinants of cardiac excitability. In hypertrophied and failing myocardium, alterations in the expression and activity of voltage-gated K channels are frequently observed and contribute to the increased propensity for life-threatening arrhythmias. Thus, understanding the mechanisms of disturbed K channel regulation in heart failure (HF) is of critical importance. Amongst others, Ca/calmodulin-dependent protein kinase II (CaMKII) has been identified as an important regulator of K channel activity. In human HF but also various animal models, increased CaMKII expression and activity has been linked to deteriorated contractile function and arrhythmias. This review will discuss the current knowledge about CaMKII regulation of several K channels, its influence on action potential properties, dispersion of repolarization, and arrhythmias with special focus on HF.
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Affiliation(s)
- Julian Mustroph
- Department of Cardiology, University Medical Center Göttingen Göttingen, Germany
| | - Lars S Maier
- Department of Cardiology, University Medical Center Göttingen Göttingen, Germany
| | - Stefan Wagner
- Department of Cardiology, University Medical Center Göttingen Göttingen, Germany
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113
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Mizusawa Y, Bezzina CR. Early repolarization pattern: its ECG characteristics, arrhythmogeneity and heritability. J Interv Card Electrophysiol 2014; 39:185-92. [PMID: 24532112 DOI: 10.1007/s10840-013-9870-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 12/30/2013] [Indexed: 12/19/2022]
Abstract
Early repolarization (ER) has been accepted as a benign ECG variant for decades. Two seminal studies challenged this notion and have demonstrated that ER pattern is associated with an increased risk of arrhythmic and cardiac mortality in patients with idiopathic ventricular fibrillation (IVF) and in the general population. Recent clinical studies demonstrate its varying impact as an arrhythmogenic substrate on different diseases. For example, in ER syndrome, a primary electrical disease, ER appears as a major arrhythmogenic substrate for development of VF whereas in patients with coronary artery disease, an ER pattern may exist as a silent substrate, increasing the risk of VF during episodes of cardiac ischaemia. Due to the high prevalence of an ER pattern in the general population and a low VF event rate, it remains challenging to differentiate a malignant ER pattern from a benign form. Recent research suggests that a J-wave amplitude of more than 0.1 mV combined with a descending/horizontal ST segment may constitute a malignant ER pattern. Further studies are however necessary to evaluate its prognostic value for cardiac and arrhythmic death in the general population as well as in cases with a malignant ER pattern. While genetic testing has revealed putative causal DNA variants in sporadic cases, the lack of co-segregation with the disease in affected families suggests that ER syndrome is not monogenic but is likely a complex disorder influenced by multiple genetic as well as environmental factors.
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Affiliation(s)
- Yuka Mizusawa
- AMC Heart Centre, Department of Clinical and Experimental Cardiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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114
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HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. J Arrhythm 2014. [DOI: 10.1016/j.joa.2013.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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115
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Liu C, Tester DJ, Hou Y, Wang W, Lv G, Ackerman MJ, Makielski JC, Cheng J. Is sudden unexplained nocturnal death syndrome in Southern China a cardiac sodium channel dysfunction disorder? Forensic Sci Int 2014; 236:38-45. [PMID: 24529773 DOI: 10.1016/j.forsciint.2013.12.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 11/27/2013] [Accepted: 12/27/2013] [Indexed: 11/15/2022]
Abstract
Sudden unexplained nocturnal death syndrome (SUNDS) remains an enigma to both forensic pathologists and physicians. Previous epidemiological, clinical, and pilot genetic studies have implicated that SUNDS is most likely a disease allelic to Brugada syndrome (BrS). We have performed postmortem genetic testing to address the spectrum and role of genetic abnormalities in the SCN5A-encoded cardiac sodium channel and its several associated proteins in SUNDS victims from Southern China. Genomic DNA extracted from the blood samples of 123 medico-legal autopsy-negative SUNDS cases and 104 sex-, age- and ethnic-matched controls from Southern China underwent comprehensive amino acid coding region mutational analysis for the BrS associated genes SCN5A, SCN1B, SCN2B, SCN3B, SCN4B, MOG1, and GPD1-L using PCR and direct sequencing. We identified a total of 7 unique (4 novel) putative pathogenic mutations (all in SCN5A; V95I, R121Q [2 cases], R367H, R513H, D870H, V1764D, and S1937F) in 8/123 (6.5%) SUNDS cases. Three SCN5A mutations (V95I, R121Q, and R367H) have been previously implicated in BrS. An additional 8 cases hosted rare variants of uncertain clinical significance (SCN5A: V1098L, V1202M, R1512W; SCN1B: V138I [3 cases], T189M [2 cases]; SCN3B: A195T). There were no non-synonymous mutations found in SCN2B, SCN4B, MOG1, or GPD1-L. This first comprehensive genotyping for SCN5A and related genes in the Chinese Han population with SUNDS discovered 13 mutations, 4 of them novel, in 16 cases, which suggests cardiac sodium channel dysfunction might account for the pathogenesis of 7-13% of SUNDS in Southern China.
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Affiliation(s)
- Chao Liu
- Guangzhou Institute of Forensic Science, Guangzhou 510030, China
| | - David J Tester
- Departments of Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, United States
| | - Yiding Hou
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Wen Wang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Guoli Lv
- Guangzhou Institute of Forensic Science, Guangzhou 510030, China
| | - Michael J Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, United States
| | - Jonathan C Makielski
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI 53792, United States
| | - Jianding Cheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China.
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Hu D, Barajas-Martínez H, Terzic A, Park S, Pfeiffer R, Burashnikov E, Wu Y, Borggrefe M, Veltmann C, Schimpf R, Cai JJ, Nam GB, Deshmukh P, Scheinman M, Preminger M, Steinberg J, López-Izquierdo A, Ponce-Balbuena D, Wolpert C, Haïssaguerre M, Sánchez-Chapula JA, Antzelevitch C. ABCC9 is a novel Brugada and early repolarization syndrome susceptibility gene. Int J Cardiol 2014; 171:431-42. [PMID: 24439875 DOI: 10.1016/j.ijcard.2013.12.084] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 12/17/2013] [Accepted: 12/21/2013] [Indexed: 12/26/2022]
Abstract
BACKGROUND Genetic defects in KCNJ8, encoding the Kir6.1 subunit of the ATP-sensitive K(+) channel (I(K-ATP)), have previously been associated with early repolarization (ERS) and Brugada (BrS) syndromes. Here we test the hypothesis that genetic variants in ABCC9, encoding the ATP-binding cassette transporter of IK-ATP (SUR2A), are also associated with both BrS and ERS. METHODS AND RESULTS Direct sequencing of all ERS/BrS susceptibility genes was performed on 150 probands and family members. Whole-cell and inside-out patch-clamp methods were used to characterize mutant channels expressed in TSA201-cells. Eight ABCC9 mutations were uncovered in 11 male BrS probands. Four probands, diagnosed with ERS, carried a highly-conserved mutation, V734I-ABCC9. Functional expression of the V734I variant yielded a Mg-ATP IC₅₀ that was 5-fold that of wild-type (WT). An 18-y/o male with global ERS inherited an SCN5A-E1784K mutation from his mother, who displayed long QT intervals, and S1402C-ABCC9 mutation from his father, who displayed an ER pattern. ABCC9-S1402C likewise caused a gain of function of IK-ATP with a shift of ATP IC₅₀ from 8.5 ± 2 mM to 13.4 ± 5 μM (p<0.05). The SCN5A mutation reduced peak INa to 39% of WT (p<0.01), shifted steady-state inactivation by -18.0 mV (p<0.01) and increased late I(Na) from 0.14% to 2.01% of peak I(Na) (p<0.01). CONCLUSION Our study is the first to identify ABCC9 as a susceptibility gene for ERS and BrS. Our findings also suggest that a gain-of-function in I(K-ATP) when coupled with a loss-of-function in SCN5A may underlie type 3 ERS, which is associated with a severe arrhythmic phenotype.
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Affiliation(s)
- Dan Hu
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA.
| | - Hector Barajas-Martínez
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA
| | - Andre Terzic
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sungjo Park
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Ryan Pfeiffer
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA
| | - Elena Burashnikov
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA
| | - Yuesheng Wu
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA
| | - Martin Borggrefe
- 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany
| | - Christian Veltmann
- 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany
| | - Rainer Schimpf
- 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany
| | | | - Gi-Byong Nam
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | | | - Melvin Scheinman
- Department of Medicine, University of California, San Francisco, CA, USA
| | | | - Jonathan Steinberg
- Arrhythmia Institute, Valley Health System, Columbia University College of Physicians & Surgeons, New York, NY, USA
| | - Angélica López-Izquierdo
- Unidad de Investigación, "Carlos Méndez" del Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Mexico
| | - Daniela Ponce-Balbuena
- Unidad de Investigación, "Carlos Méndez" del Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Mexico
| | - Christian Wolpert
- 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany
| | - Michel Haïssaguerre
- Hôspital Cardiologique du Haut Lévêque, Université Bordeaux II, Pessac cedex, France
| | - José Antonio Sánchez-Chapula
- Unidad de Investigación, "Carlos Méndez" del Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Mexico
| | - Charles Antzelevitch
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY, USA.
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Zhou L, Solhjoo S, Millare B, Plank G, Abraham MR, Cortassa S, Trayanova N, O'Rourke B. Effects of regional mitochondrial depolarization on electrical propagation: implications for arrhythmogenesis. Circ Arrhythm Electrophysiol 2014; 7:143-51. [PMID: 24382411 DOI: 10.1161/circep.113.000600] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Sudden cardiac death often involves arrhythmias triggered by metabolic stress. Loss of mitochondrial function is thought to contribute to the arrhythmogenic substrate, but how mitochondria contribute to uncoordinated electrical activity is poorly understood. It has been proposed that the formation of metabolic current sinks, caused by the nonuniform collapse of mitochondrial inner membrane potential (ΔΨm), contributes to re-entrant arrhythmias because ΔΨm depolarization is tightly coupled to the activation of sarcolemmal ATP-sensitive K(+) channels, hastening action potential repolarization and shortening the refractory period. METHODS AND RESULTS Here, we use computational and experimental methods to investigate how ΔΨm instability can induce re-entrant arrhythmias. We develop the first tissue-level model of cardiac electrical propagation incorporating cellular electrophysiology, excitation-contraction coupling, mitochondrial energetics, and reactive oxygen species balance. Simulations show that re-entry and fibrillation can be initiated by regional ΔΨm loss because of the disparity of refractory periods inside and outside the metabolic sink. Computational results are compared with the effects of a metabolic sink generated experimentally by local perfusion of a mitochondrial uncoupler in a monolayer of cardiac myocytes. CONCLUSIONS The results demonstrate that regional mitochondrial depolarization triggered by oxidative stress activates sarcolemmal ATP-sensitive K(+) currents to form a metabolic sink. Consequent shortening of the action potential inside, but not outside, the sink increases the propensity for re-entry. ΔΨm recovery during pacing can lead to novel mechanisms of ectopic activation. The findings highlight the importance of mitochondria as potential therapeutic targets for sudden death associated with cardiovascular disease.
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Koncz I, Gurabi Z, Patocskai B, Panama BK, Szél T, Hu D, Barajas-Martínez H, Antzelevitch C. Mechanisms underlying the development of the electrocardiographic and arrhythmic manifestations of early repolarization syndrome. J Mol Cell Cardiol 2013; 68:20-8. [PMID: 24378566 DOI: 10.1016/j.yjmcc.2013.12.012] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 10/25/2013] [Accepted: 12/13/2013] [Indexed: 12/14/2022]
Abstract
Early repolarization pattern in the ECG has been associated with increased risk for ventricular tachycardia/fibrillation (VT/VF), particularly when manifest in inferior leads. This study examines the mechanisms underlying VT/VF in early repolarization syndrome (ERS). Transmembrane action potentials (APs) were simultaneously recorded from 2 epicardial sites and 1 endocardial site of coronary-perfused canine left-ventricular (LV) wedge preparations, together with a pseudo-ECG. Transient outward current (Ito) was recorded from epicardial myocytes isolated from the inferior and lateral LV of the same heart. J wave area (pseudo-ECG), epicardial AP notch magnitude and index were larger in inferior vs. lateral wall preparations at baseline and after exposure to provocative agents (NS5806+verapamil+acetylcholine (ACh)). Ito density was greater in myocytes from inferior vs. lateral wall (18.4 ± 2.3pA/pF vs. 11.6 ± 2.0pA/pF; p<0.05). A combination of NS5806 (7 μM) and verapamil (3 μM) or pinacidil (4 μM), used to pharmacologically model the genetic defects responsible for ERS, resulted in prominent J-point and ST-segment elevation. ACh (3 μM), simulating increased vagal tone, precipitated phase-2-reentry-induced polymorphic VT/VF. Using identical protocols, inducibility of arrhythmias was 3-fold higher in inferior vs. lateral wedges. Quinidine (10 μM) or isoproterenol (1 μM) restored homogeneity and suppressed VT/VF. Our data support the hypothesis that 1) ERS is caused by a preferential accentuation of the AP notch in the LV epicardium; 2) this repolarization defect is accentuated by elevated vagal tone; 3) higher intrinsic levels of Ito account for the greater sensitivity of the inferior LV wall to development of VT/VF; and 4) quinidine and isoproterenol exert ameliorative effects by reversing the repolarization abnormality.
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Affiliation(s)
- István Koncz
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Pharmacology & Pharmacotherapy, University of Szeged, H-6720 Szeged, Dóm tér 12, Hungary
| | - Zsolt Gurabi
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Pharmacology & Pharmacotherapy, University of Szeged, H-6720 Szeged, Dóm tér 12, Hungary
| | - Bence Patocskai
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Pharmacology & Pharmacotherapy, University of Szeged, H-6720 Szeged, Dóm tér 12, Hungary
| | - Brian K Panama
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA
| | - Tamás Szél
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Pharmacology & Pharmacotherapy, University of Szeged, H-6720 Szeged, Dóm tér 12, Hungary
| | - Dan Hu
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA
| | - Hector Barajas-Martínez
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA
| | - Charles Antzelevitch
- Department of Molecular Genetics, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA; Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA.
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Abstract
The sarcolemmal adenosine triphosphate (ATP)-sensitive K(+) (sarcKATP) channel in the heart is a hetero-octamer comprising the pore-forming subunit Kir6.2 and the regulatory subunit sulfonylurea receptor SUR2A. By functional analysis of genetically engineered mice lacking sarcKATP channels, the pathophysiological roles of the K(+) channel in the heart have been extensively evaluated. Although mitochondrial KATP (mitoKATP) channel is proposed to be an important effector for the protection of ischemic myocardium and the inhibition of ischemia/reperfusion-induced ventricular arrhythmias, the molecular identity of mitoKATP channel has not been established. Although selective sarcKATP-channel blockers can prevent ischemia/reperfusion-induced ventricular arrhythmias by inhibiting the action potential shortening in the acute phase, the drugs may aggravate the ischemic damages due to intracellular Ca(2+) overload. The sarcKATP channel is also mandatory for optimal adaptation to hemodynamic stress such as sympathetic activation. Dysfunction of mutated sarcKATP channels in atrial cells may lead to electrical instability and atrial fibrillation. Recently, it has been proposed that the gain-of-function mutation of cardiac Kir6.1 channel can be a pathogenic substrate for J wave syndromes, a cause of idiopathic ventricular fibrillation as early repolarization syndrome or Brugada syndrome, whereas loss of function of the channel mutations can underlie sudden infant death syndrome. However, precise role of Kir6.1 channels in cardiac cells remains to be defined and further study may be needed to clarify the role of Kir6.1 channel in the heart.
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Affiliation(s)
- Haruaki Nakaya
- 1Department of Pharmacology, Chiba University Graduate School of Medicine, Chiba, Japan
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120
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Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. Heart Rhythm 2013; 10:1932-63. [DOI: 10.1016/j.hrthm.2013.05.014] [Citation(s) in RCA: 1341] [Impact Index Per Article: 121.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 12/15/2022]
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121
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Abstract
An early repolarization (ER) pattern in the ECG, consisting of J point elevation, distinct J wave with or without ST segment elevation or slurring of the terminal part of the QRS, was long considered a benign electrocardiographic manifestation. Experimental studies a dozen years ago suggested that an ER is not always benign, but may be associated with malignant arrhythmias. Validation of this hypothesis derives from recent case-control and population-based studies showing that an ER pattern in inferior or infero-lateral leads is associated with increased risk for life-threatening arrhythmias, termed early repolarization syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BrS) and ERS, these syndromes have been grouped under the heading of J wave syndromes. BrS and ERS appear to share common ECG characteristics, clinical outcomes, risk factors as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. However, they differ with respect to the magnitude and lead location of abnormal J waves and can be considered to represent a continuous spectrum of phenotypic expression. Recent studies support the hypothesis that BrS and ERS are caused by a preferential accentuation of the AP notch in right or left ventricular epicardium, respectively, and that this repolarization defect is accentuated by cholinergic agonists. Quinidine, cilostazol and isoproterenol exert ameliorative effects by reversing these repolarization abnormalities. Identifying subjects truly at risk is the challenge ahead. Our goal here is to review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes.
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122
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Genetic screening of KCNJ8 in Japanese patients with J-wave syndromes or idiopathic ventricular fibrillation. J Arrhythm 2013. [DOI: 10.1016/j.joa.2013.01.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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123
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Tikkanen JT, Huikuri HV. Early repolarization ECG pattern in the Finnish general population. J Electrocardiol 2013; 46:439-41. [DOI: 10.1016/j.jelectrocard.2013.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Indexed: 01/25/2023]
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125
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Hoogendijk MG, Potse M, Coronel R. Critical appraisal of the mechanism underlying J waves. J Electrocardiol 2013; 46:390-4. [DOI: 10.1016/j.jelectrocard.2013.06.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Indexed: 11/26/2022]
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Abstract
More than 20 years have passed since the description of Brugada syndrome as a clinical entity. The original case series depicted patients who all had coved ST-segment elevation in the right precordial leads, associated with a high risk of sudden death and no apparent structural heart disease. As subsequent registry data were published, it became apparent that the spectrum of risk is wide, with the majority of patients classified as low risk. Two consensus documents have been published that will continue to be updated. Despite intense research efforts, many controversies still exist over its pathophysiology and the risk stratification for sudden death. Management continues to be challenging with a lack of drug therapy and high complication rates from implantable cardioverter defibrillators. In this review, we highlight the current state-of-the-art therapies and their controversies.
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Affiliation(s)
- Anthony Li
- Cardiovascular Sciences Research Centre, St George's University of London, Cranmer Terrace, London, SW17 0RE, UK
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127
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Li A, Knutsen RH, Zhang H, Osei-Owusu P, Moreno-Dominguez A, Harter TM, Uchida K, Remedi MS, Dietrich HH, Bernal-Mizrachi C, Blumer KJ, Mecham RP, Koster JC, Nichols CG. Hypotension due to Kir6.1 gain-of-function in vascular smooth muscle. J Am Heart Assoc 2013; 2:e000365. [PMID: 23974906 PMCID: PMC3828800 DOI: 10.1161/jaha.113.000365] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background KATP channels, assembled from pore‐forming (Kir6.1 or Kir6.2) and regulatory (SUR1 or SUR2) subunits, link metabolism to excitability. Loss of Kir6.2 results in hypoglycemia and hyperinsulinemia, whereas loss of Kir6.1 causes Prinzmetal angina–like symptoms in mice. Conversely, overactivity of Kir6.2 induces neonatal diabetes in mice and humans, but consequences of Kir6.1 overactivity are unknown. Methods and Results We generated transgenic mice expressing wild‐type (WT), ATP‐insensitive Kir6.1 [Gly343Asp] (GD), and ATP‐insensitive Kir6.1 [Gly343Asp,Gln53Arg] (GD‐QR) subunits, under Cre‐recombinase control. Expression was induced in smooth muscle cells by crossing with smooth muscle myosin heavy chain promoter–driven tamoxifen‐inducible Cre‐recombinase (SMMHC‐Cre‐ER) mice. Three weeks after tamoxifen induction, we assessed blood pressure in anesthetized and conscious animals, as well as contractility of mesenteric artery smooth muscle and KATP currents in isolated mesenteric artery myocytes. Both systolic and diastolic blood pressures were significantly reduced in GD and GD‐QR mice but normal in mice expressing the WT transgene and elevated in Kir6.1 knockout mice as well as in mice expressing dominant‐negative Kir6.1 [AAA] in smooth muscle. Contractile response of isolated GD‐QR mesenteric arteries was blunted relative to WT controls, but nitroprusside relaxation was unaffected. Basal KATP conductance and pinacidil‐activated conductance were elevated in GD but not in WT myocytes. Conclusions KATP overactivity in vascular muscle can lead directly to reduced vascular contractility and lower blood pressure. We predict that gain of vascular KATP function in humans would lead to a chronic vasodilatory phenotype, as indeed has recently been demonstrated in Cantu syndrome.
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Affiliation(s)
- Anlong Li
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO
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128
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Abstract
Proper generation and conduction of the cardiac electrical impulse is essential for the continuous coordinated contraction of the heart. Dysregulation of cardiac electrical function may lead to cardiac arrhythmias, which constitute a huge medical and social burden. Identifying the genetic factors underlying cardiac electrical activity serves the double purpose of allowing the early identification of individuals at risk for arrhythmia and discovering new potential therapeutic targets for prevention. The aim of this review is to provide an overview of the genes and genetic loci linked thus far to cardiac electrical function and arrhythmia. These genes and loci have been primarily uncovered through studies on the familial rhythm disorders and through genome-wide association studies on electrocardiographic parameters in large sets of the general population. An overview of all genes and loci with their respective effect is given.
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Affiliation(s)
- Elisabeth M Lodder
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Tel.: +31 20 5665962; Fax: +31 20 6976177;
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129
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Current perspectives in genetic cardiovascular disorders: from basic to clinical aspects. Heart Vessels 2013; 29:129-41. [PMID: 23907713 DOI: 10.1007/s00380-013-0391-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 06/27/2013] [Indexed: 12/18/2022]
Abstract
We summarize recent advances in the clinical genetics of hypercholesterolemia, hypertrophic cardiomyopathy (HCM), and lethal arrhythmia, all of which are monogenic cardiovascular diseases being essential to understanding the heart and circulatory pathophysiology. Among the issues of hypercholesterolemia which play a pivotal role in development of vascular damages, familial hypercholesterolemia is the common genetic cardiovascular disease; in addition to identifying the gene mutation coding low-density lipoprotein receptor, lipid kinetics in autosomal recessive hypercholesterolemia as well as in proprotein convertase subtilisin/kexin 9 gene mutation were recently demonstrated. As for HCM, some gene mutations were identified to correlate with clinical manifestations. Additionally, a gene polymorphism of the renin-angiotensin system in development of heart failure was identified as a modifier gene. The lethal arrhythmias such as sudden death syndromes, QT prolongation, and Brugada syndrome were found to exhibit gene mutation coding potassium and/or sodium ion channels. Interestingly, functional analysis of these gene mutations helped to identify the role of each gene mutation in developing these cardiovascular disorders. We suggest considering the genetic mechanisms of cardiovascular diseases associated with hyperlipidemia, myocardial hypertrophy, or lethal arrhythmia in terms of not only clinical diagnosis but also understanding pathophysiology of each disease with therapeutic aspects.
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130
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Jalife J. And the beat goes on ... the beat goes on: organization and quasi-periodicity in ventricular fibrillation. Cardiovasc Res 2013; 99:375-7. [DOI: 10.1093/cvr/cvt162] [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: 11/14/2022] Open
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132
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Nielsen MW, Holst AG, Olesen SP, Olesen MS. The genetic component of Brugada syndrome. Front Physiol 2013; 4:179. [PMID: 23874304 PMCID: PMC3710955 DOI: 10.3389/fphys.2013.00179] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/24/2013] [Indexed: 12/12/2022] Open
Abstract
Brugada syndrome (BrS) is a clinical entity first described in 1992. BrS is characterized by ST-segment elevations in the right precordial leads and susceptibility to ventricular arrhythmias and sudden cardiac death. It affects young subjects, predominantly males, with structurally normal hearts. The prevalence varies with ethnicity ranging from 1:2,000 to 1:100,000 in different parts of the world. Today, hundreds of variants in 17 genes have been associated with BrS of which mutations in SCN5A, coding for the cardiac voltage-gated sodium channel, accounts for the vast majority. Despite this, approximately 70% of BrS cases cannot be explained genetically with the current knowledge. Moreover, the monogenic role of some of the variants previously described as being associated with BrS has been questioned by their occurrence in about 4% (1:23) of the general population as found in NHLBI GO Exome Sequencing Project (ESP) currently including approximately 6500 individuals. If we add the variants described in the five newest identified genes associated with BrS, they appear at an even higher prevalence in the ESP (1:21). The current standard treatment of BrS is an implantable cardioverter-defibrillator (ICD). The risk stratification and indications for ICD treatment are based on the ECG and on the clinical and family history. In this review we discuss the genetic basis of BrS.
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Affiliation(s)
- Morten W Nielsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia Copenhagen, Denmark ; Department of Cardiology, Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen Copenhagen, Denmark
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Brugada J, Blom N, Sarquella-Brugada G, Blomstrom-Lundqvist C, Deanfield J, Janousek J, Abrams D, Bauersfeld U, Brugada R, Drago F, de Groot N, Happonen JM, Hebe J, Yen Ho S, Marijon E, Paul T, Pfammatter JP, Rosenthal E. Pharmacological and non-pharmacological therapy for arrhythmias in the pediatric population: EHRA and AEPC-Arrhythmia Working Group joint consensus statement. ACTA ACUST UNITED AC 2013; 15:1337-82. [DOI: 10.1093/europace/eut082] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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LI NING, WANG RONGRONG, HOU CUIHONG, ZHANG YINHUI, TENG SIYONG, PU JIELIN. A heterozygous missense SCN5A mutation associated with early repolarization syndrome. Int J Mol Med 2013; 32:661-7. [PMID: 23799537 DOI: 10.3892/ijmm.2013.1422] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 09/10/2012] [Indexed: 11/06/2022] Open
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Genetic testing in heritable cardiac arrhythmia syndromes: differentiating pathogenic mutations from background genetic noise. Curr Opin Cardiol 2013; 28:63-71. [PMID: 23128497 DOI: 10.1097/hco.0b013e32835b0a41] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW In this review, we summarize the basic principles governing rare variant interpretation in the heritable cardiac arrhythmia syndromes, focusing on recent advances that have led to disease-specific approaches to the interpretation of positive genetic testing results. RECENT FINDINGS Elucidation of the genetic substrates underlying heritable cardiac arrhythmia syndromes has unearthed new arrhythmogenic mechanisms and given rise to a number of clinically meaningful genotype-phenotype correlations. As such, genetic testing for these disorders now carries important diagnostic, prognostic, and therapeutic implications. Recent large-scale systematic studies designed to explore the background genetic 'noise' rate associated with these genetic tests have provided important insights and enhanced how positive genetic testing results are interpreted for these potentially lethal, yet highly treatable, cardiovascular disorders. SUMMARY Clinically available genetic tests for heritable cardiac arrhythmia syndromes allow the identification of potentially at-risk family members and contribute to the risk-stratification and selection of therapeutic interventions in affected individuals. The systematic evaluation of the 'signal-to-noise' ratio associated with these genetic tests has proven critical and essential to assessing the probability that a given variant represents a rare pathogenic mutation or an equally rare, yet innocuous, genetic bystander.
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Abstract
ATP-sensitive potassium (KATP) channels were first discovered in the heart 30 years ago. Reconstitution of KATP channel activity by coexpression of members of the pore-forming inward rectifier gene family (Kir6.1, KCNJ8, and Kir6.2 KCNJ11) with sulfonylurea receptors (SUR1, ABCC8, and SUR2, ABCC9) of the ABCC protein subfamily has led to the elucidation of many details of channel gating and pore properties. In addition, the essential roles of Kir6.x and SURx subunits in generating cardiac and vascular KATP(2) and the detrimental consequences of genetic deletions or mutations in mice have been recognized. However, despite this extensive body of knowledge, there has been a paucity of defined roles of KATP subunits in human cardiovascular diseases, although there are reports of association of a single Kir6.1 variant with the J-wave syndrome in the ECG, and 2 isolated studies have reported association of loss of function mutations in SUR2 with atrial fibrillation and heart failure. Two new studies convincingly demonstrate that mutations in the SUR2 gene are associated with Cantu syndrome, a complex multi-organ disorder characterized by hypertrichosis, craniofacial dysmorphology, osteochondrodysplasia, patent ductus arteriosus, cardiomegaly, pericardial effusion, and lymphoedema. This realization of previously unconsidered consequences provides significant insight into the roles of the KATP channel in the cardiovascular system and suggests novel therapeutic possibilities.
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Affiliation(s)
- Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases and Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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The KCNJ8-S422L variant previously associated with J-wave syndromes is found at an increased frequency in Ashkenazi Jews. Eur J Hum Genet 2013; 22:94-8. [PMID: 23632791 DOI: 10.1038/ejhg.2013.78] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 01/11/2013] [Accepted: 03/27/2013] [Indexed: 02/03/2023] Open
Abstract
J-wave syndromes have been associated with increased risk of ventricular fibrillation and sudden cardiac death. Previous studies have identified the KCNJ8-S422L variant in heterozygous form in individuals with J-wave syndromes. Its absence in over 1500 controls, coupled with in vitro analysis, have led to the conclusion that S422L is pathogenic. We previously performed whole-genome sequencing in a family quartet of Ashkenazi Jewish decent with no history of J-wave syndrome. Re-examination of these data reveals that both parents are heterozygous for the S422L variant, while the 12-year old son carries two copies--thus representing the first reported case of a S422L homozygote. In order to examine whether the S422L mutation might segregate at appreciable frequencies in specific populations, we genotyped the variant in a panel consisting of 722 individuals from 22 European, Middle Eastern non-Jewish, Ashkenazi Jewish, and non-Ashkenazi Jewish populations. We found that the S422L allele was at a significantly higher frequency in Ashkenazi Jews (~4%) compared with other populations in our survey, which have frequencies <0.25%. We also performed ECGs in both male members of the family quartet. The homozygous boy demonstrated no clinically significant ECG abnormalities, while the heterozygous father presented with a subtle J-wave point elevation. Our results suggest that either (a) previous studies implicating S422L as pathogenic for J-wave syndromes failed to appropriately account for European population structure and the variant is likely benign, or (b) Ashkenazi Jews may be at significantly increased risk of J-wave syndromes and ultimately sudden cardiac death.
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ROBERTS JASOND, GOLLOB MICHAELH. Early Repolarization: A Rare Primary Arrhythmic Syndrome and Common Modifier of Arrhythmic Risk. J Cardiovasc Electrophysiol 2013; 24:837-43. [DOI: 10.1111/jce.12156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 02/16/2013] [Accepted: 03/13/2013] [Indexed: 01/08/2023]
Affiliation(s)
- JASON D. ROBERTS
- Inherited Arrhythmia Clinic & Arrhythmia Research Laboratory; University of Ottawa; Heart Institute; Ottawa Ontario Canada
| | - MICHAEL H. GOLLOB
- Inherited Arrhythmia Clinic & Arrhythmia Research Laboratory; University of Ottawa; Heart Institute; Ottawa Ontario Canada
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Kawata H, Morita H, Yamada Y, Noda T, Satomi K, Aiba T, Isobe M, Nagase S, Nakamura K, Fukushima Kusano K, Ito H, Kamakura S, Shimizu W. Prognostic significance of early repolarization in inferolateral leads in Brugada patients with documented ventricular fibrillation: a novel risk factor for Brugada syndrome with ventricular fibrillation. Heart Rhythm 2013; 10:1161-8. [PMID: 23587501 DOI: 10.1016/j.hrthm.2013.04.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND Little is known about the clinical and prognostic impact of early repolarization (ER) on patients with Brugada syndrome (BrS), especially those with documented ventricular fibrillation (VF). OBJECTIVE To investigate the prevalence and prognostic significance of ER in inferolateral leads in patients with BrS and documented VF. METHODS We investigated 10 different 12-lead electrocardiograms (ECGs) recorded on different days to identify the presence of ER, which was defined as J-point elevation ≥0.1 mV in inferior (II, III, aVF) or lateral leads (I, aVL, V₄-V₆), in 49 individuals (46 men; age 46 ± 13 years) with a type 1 ECG of BrS and previous history of VF. RESULTS ER was observed persistently (in all ECGs) in 15 patients (31%; P group), intermittently (in at least one but not in all ECGs) in 16 patients (33%; I group), and not observed in 18 patients (37%; N group), yielding an overall ER incidence of 63% (31/49). During the follow-up period (7.7 years), recurrence of VF was documented in all 15 patients (100%) in the P group, and less in 12 patients (75%) in the I group and in 8 patients (44%) in the N group. The P group showed a worse prognosis than N group (P = .0001) by Kaplan-Meier analysis. Either persistent or intermittent ER in an inferolateral lead was an independent predictor of fatal arrhythmic events (hazard ratio 4.88, 95% confidence interval 2.02-12.7, P = .0004; and hazard ratio 2.50, 95% confidence interval 1.03-6.43, P = .043, respectively). CONCLUSION The prevalence of ER in inferolateral leads was high and an especially persistent form of ER was associated with a worse outcome in BrS patients with documented VF.
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Affiliation(s)
- Hiro Kawata
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
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Gourraud JB, Le Scouarnec S, Sacher F, Chatel S, Derval N, Portero V, Chavernac P, Sandoval JE, Mabo P, Redon R, Schott JJ, Le Marec H, Haïssaguerre M, Probst V. Identification of large families in early repolarization syndrome. J Am Coll Cardiol 2013; 61:164-72. [PMID: 23273290 DOI: 10.1016/j.jacc.2012.09.040] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 08/06/2012] [Accepted: 09/22/2012] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The aim of this study was to identify families affected by early repolarization syndrome (ERS) and to determine the mode of transmission of the disease. BACKGROUND Early repolarization (ER) has recently been linked to idiopathic ventricular fibrillation. Familial inheritance of the disease has been suggested but not demonstrated. METHODS We screened relatives of 4 families affected by ERS. ER was defined as a distinct J-wave in at least 2 consecutive leads and a 1-mm amplitude above baseline. The Valsalva maneuver was performed in affected and unaffected family members to decrease heart rate and thus increase or reveal an ER pattern. RESULTS Twenty-two sudden cardiac deaths occurred in the 4 families including 10 before 35 years of age. In the 4 families, the prevalence of ER was 56%, 34%, 61%, and 33% of, respectively, 30, 82, 29, and 30 screened relatives. In these families, transmission of an ER pattern is compatible with an autosomal dominant mode of inheritance. All probands were screened for genes identified in ERS, and no mutation was found. The Valsalva maneuver was performed in 80 relatives, resulting in increased J-wave amplitude for 17 of 20 affected patients and revealing an ER pattern in 17 relatives in whom 5 are obligate transmitters of an ER pattern. CONCLUSIONS ERS can be inherited through autosomal dominant transmission and should be considered a real inherited arrhythmia syndrome. Familial investigation can be facilitated by using the Valsalva maneuver to reveal the electrocardiographic pattern in family members. The prognosis value of this test remains to be assessed.
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Liu H, Chatel S, Simard C, Syam N, Salle L, Probst V, Morel J, Millat G, Lopez M, Abriel H, Schott JJ, Guinamard R, Bouvagnet P. Molecular genetics and functional anomalies in a series of 248 Brugada cases with 11 mutations in the TRPM4 channel. PLoS One 2013; 8:e54131. [PMID: 23382873 PMCID: PMC3559649 DOI: 10.1371/journal.pone.0054131] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/10/2012] [Indexed: 11/19/2022] Open
Abstract
Brugada syndrome (BrS) is a condition defined by ST-segment alteration in right precordial leads and a risk of sudden death. Because BrS is often associated with right bundle branch block and the TRPM4 gene is involved in conduction blocks, we screened TRPM4 for anomalies in BrS cases. The DNA of 248 BrS cases with no SCN5A mutations were screened for TRPM4 mutations. Among this cohort, 20 patients had 11 TRPM4 mutations. Two mutations were previously associated with cardiac conduction blocks and 9 were new mutations (5 absent from ∼14′000 control alleles and 4 statistically more prevalent in this BrS cohort than in control alleles). In addition to Brugada, three patients had a bifascicular block and 2 had a complete right bundle branch block. Functional and biochemical studies of 4 selected mutants revealed that these mutations resulted in either a decreased expression (p.Pro779Arg and p.Lys914X) or an increased expression (p.Thr873Ile and p.Leu1075Pro) of TRPM4 channel. TRPM4 mutations account for about 6% of BrS. Consequences of these mutations are diverse on channel electrophysiological and cellular expression. Because of its effect on the resting membrane potential, reduction or increase of TRPM4 channel function may both reduce the availability of sodium channel and thus lead to BrS.
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Affiliation(s)
- Hui Liu
- Laboratoire Cardiogénétique, Hospices Civils de Lyon, Groupe Hospitalier Est, Bron, France
- Laboratoire Cardiogénétique, Equipe d’Accueil 4173, Université Lyon 1, Lyon, France
| | - Stéphanie Chatel
- Unité Mixte de Recherche 915, Institut National de la Santé Et de la Recherche Médicale, l’institut du thorax, Nantes, France
- Equipe de Recherche Labellisée 3147, Centre National de la Recherche Scientifique, l’institut du thorax, Nantes, France
- Université de Nantes, l’institut du thorax, Nantes, France
| | - Christophe Simard
- Groupe Signalisation, Electrophysiologie et Imagerie des lésions d’ischémie- reperfusion myocardique, Equipe d’Accueil 4650, Université de Caen, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Ninda Syam
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Laurent Salle
- Groupe Signalisation, Electrophysiologie et Imagerie des lésions d’ischémie- reperfusion myocardique, Equipe d’Accueil 4650, Université de Caen, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Vincent Probst
- Unité Mixte de Recherche 915, Institut National de la Santé Et de la Recherche Médicale, l’institut du thorax, Nantes, France
- Equipe de Recherche Labellisée 3147, Centre National de la Recherche Scientifique, l’institut du thorax, Nantes, France
- Université de Nantes, l’institut du thorax, Nantes, France
- Service de Cardiologie, CHU Nantes, l’institut du thorax, Nantes, France
| | - Julie Morel
- Groupe Signalisation, Electrophysiologie et Imagerie des lésions d’ischémie- reperfusion myocardique, Equipe d’Accueil 4650, Université de Caen, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Gilles Millat
- Laboratoire Cardiogénétique, Hospices Civils de Lyon, Groupe Hospitalier Est, Bron, France
- Laboratoire Neurocardiologie, EA 4612, Université Lyon 1, Lyon, France
| | - Michel Lopez
- Service de Cardiologie, Hôpital Saint Luc, Saint Joseph, Lyon, France
| | - Hugues Abriel
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Jean-Jacques Schott
- Unité Mixte de Recherche 915, Institut National de la Santé Et de la Recherche Médicale, l’institut du thorax, Nantes, France
- Equipe de Recherche Labellisée 3147, Centre National de la Recherche Scientifique, l’institut du thorax, Nantes, France
- Université de Nantes, l’institut du thorax, Nantes, France
- Service de Cardiologie, CHU Nantes, l’institut du thorax, Nantes, France
| | - Romain Guinamard
- Groupe Signalisation, Electrophysiologie et Imagerie des lésions d’ischémie- reperfusion myocardique, Equipe d’Accueil 4650, Université de Caen, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Patrice Bouvagnet
- Laboratoire Cardiogénétique, Hospices Civils de Lyon, Groupe Hospitalier Est, Bron, France
- Laboratoire Cardiogénétique, Equipe d’Accueil 4173, Université Lyon 1, Lyon, France
- Service de Cardiologie Pédiatrique, Hospices Civils de Lyon, Groupe Hospitalier Est, Bron, France
- * E-mail:
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Hsiao PY, Tien HC, Lo CP, Juang JMJ, Wang YH, Sung RJ. Gene mutations in cardiac arrhythmias: a review of recent evidence in ion channelopathies. APPLICATION OF CLINICAL GENETICS 2013; 6:1-13. [PMID: 23837003 PMCID: PMC3699290 DOI: 10.2147/tacg.s29676] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Over the past 15 years, molecular genetic studies have linked gene mutations to many inherited arrhythmogenic disorders, in particular, “ion channelopathies”, in which mutations in genes encode functional units of ion channels and/or their transporter-associated proteins in patients without primary cardiac structural abnormalities. These disorders are exemplified by congenital long QT syndrome (LQTS), short QT syndrome, Brugada syndrome (BrS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). Functional and pathophysiological studies have led to better understanding of the clinical spectrum, ion channel structures and cellular electrophysiology involving dynamics of intracellular calcium cycling in many subtypes of these disorders and more importantly, development of potentially more effective pharmacological agents and even curative gene therapy. In this review, we have summarized (1) the significance of unveiling mutations in genes encoding transporter-associated proteins as the cause of congenital LQTS, (2) the technique of catheter ablation applied at the right ventricular outflow tract may be curative for severely symptomatic BrS, (3) mutations with channel function modulated by protein Kinase A-dependent phosphorylation can be the culprit of CPVT mimicry in Andersen-Tawil syndrome (LQT7), (4) ablation of the ion channel anchoring protein may prevent arrhythmogenesis in Timothy syndrome (LQT8), (5) altered intracellular Ca2+ cycling can be the basis of effective targeted pharmacotherapy in CPVT, and (6) the technology of induced pluripotent stem cells is a promising diagnostic and research tool as it has become a new paradigm for pathophysiological study of patient- and disease-specific cells aimed at screening new drugs and eventual clinical application of gene therapy. Lastly, we have discussed (7) genotype-phenotype correlation in relation to risk stratification of patients with congenital LQTS in clinical practice.
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Affiliation(s)
- Pi-Yin Hsiao
- Institute of Life Sciences, National Central University, Taoyuan, Taiwan
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146
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Bébarová M. Arrhythmogenesis in Brugada syndrome: impact and constrains of current concepts. Int J Cardiol 2013; 167:1760-71. [PMID: 23295036 DOI: 10.1016/j.ijcard.2012.12.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/15/2012] [Accepted: 12/06/2012] [Indexed: 01/13/2023]
Abstract
Brugada syndrome (BrS), an inherited arrhythmogenic disease first described in 1992, is characterized by ST segment elevations on the electrocardiogram in the right precordium and by a high occurrence of arrhythmias including the life-threatening ventricular tachycardia/fibrillation. Knowledge of the underlying mechanisms of formation of arrhythmogenic substrate in BrS is essential, namely for the risk stratification of BrS patients and their therapy which is still restrained almost exclusively to the implantation of cardioverter/defibrillator. In spite of many crucial findings in this field published within recent years, the final consistent view has not been established so far. Hence, BrS described 20 years ago remains an actual topic of both clinical and experimental studies. This review presents an overview of the current knowledge related to the pathogenesis of BrS arrhythmogenic substrate, namely of the genetic basis of BrS, functional consequences of mutations related to BrS, and arrhythmogenic mechanisms in BrS.
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Affiliation(s)
- Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00 Brno, Bohunice, Czech Republic.
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Abstract
The abrupt cessation of effective cardiac function due to an aberrant heart rhythm can cause sudden and unexpected death at any age, a syndrome called sudden cardiac death (SCD). Annually, more than 300,000 cases of SCD occur in the United States alone, making this a major public health concern. Our current understanding of the mechanisms responsible for SCD has emerged from decades of basic science investigation into the normal electrophysiology of the heart, the molecular physiology of cardiac ion channels, fundamental cellular and tissue events associated with cardiac arrhythmias, and the molecular genetics of monogenic disorders of heart rhythm. This knowledge has helped shape the current diagnosis and treatment of inherited arrhythmia susceptibility syndromes associated with SCD and has provided a pathophysiological framework for understanding more complex conditions predisposing to this tragic event. This Review presents an overview of the molecular basis of SCD, with a focus on monogenic arrhythmia syndromes.
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Affiliation(s)
- Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232, USA.
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Krahn AD, Obeyesekere MN. Inheritance of Early Repolarization and Familial Malignant Forms. J Am Coll Cardiol 2013; 61:173-5. [DOI: 10.1016/j.jacc.2012.09.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 09/24/2012] [Accepted: 09/25/2012] [Indexed: 12/01/2022]
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Di Diego JM, Sicouri S, Myles RC, Burton FL, Smith GL, Antzelevitch C. Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations. J Mol Cell Cardiol 2012; 54:53-64. [PMID: 23142540 DOI: 10.1016/j.yjmcc.2012.10.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/22/2012] [Accepted: 10/29/2012] [Indexed: 01/06/2023]
Abstract
The electrophysiological heterogeneity that exists across the ventricular wall in the mammalian heart has long been recognized, but remains an area that is incompletely understood. Experimental studies of the mechanisms of arrhythmogenesis in the whole heart often examine the epicardial surface in isolation and thereby disregard transmural electrophysiology. Significant heterogeneity exists in the electrophysiological properties of cardiomyocytes isolated from different layers of the ventricular wall, and given that regional heterogeneities of membrane repolarization properties can influence the electrophysiological substrate for re-entry, the diversity of cell types and characteristics spanning the ventricular wall is important in the study of arrhythmogenesis. For these reasons, coronary-perfused left ventricular wedge preparations have been developed to permit the study of transmural electrophysiology in the intact ventricle. Since the first report by Yan and Antzelevitch in 1996, electrical recordings from the transmural surface of canine wedge preparations have provided a wealth of data regarding the cellular basis for the electrocardiogram, the role of transmural heterogeneity in arrhythmogenesis, and differences in the response of the different ventricular layers to drugs and neurohormones. Use of the wedge preparation has since been expanded to other species and more recently it has also been widely used in optical mapping studies. The isolated perfused wedge preparation has become an important tool in cardiac electrophysiology. In this review, we detail the methodology involved in recording both electrical and optical signals from the coronary-perfused wedge preparation and review the advances in cardiac electrophysiology achieved through study of the wedge.
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Affiliation(s)
- José M Di Diego
- Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA
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Ishikawa T, Sato A, Marcou CA, Tester DJ, Ackerman MJ, Crotti L, Schwartz PJ, On YK, Park JE, Nakamura K, Hiraoka M, Nakazawa K, Sakurada H, Arimura T, Makita N, Kimura A. A novel disease gene for Brugada syndrome: sarcolemmal membrane-associated protein gene mutations impair intracellular trafficking of hNav1.5. Circ Arrhythm Electrophysiol 2012; 5:1098-107. [PMID: 23064965 DOI: 10.1161/circep.111.969972] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations in genes including SCN5A encoding the α-subunit of the cardiac sodium channel (hNav1.5) cause Brugada syndrome via altered function of cardiac ion channels, but more than two-thirds of Brugada syndrome remains pathogenetically elusive. T-tubules and sarcoplasmic reticulum are essential in excitation of cardiomyocytes, and sarcolemmal membrane-associated protein (SLMAP) is a protein of unknown function localizing at T-tubules and sarcoplasmic reticulum. METHODS AND RESULTS We analyzed 190 unrelated Brugada syndrome patients for mutations in SLMAP. Two missense mutations, Val269Ile and Glu710Ala, were found in heterozygous state in 2 patients but were not found in healthy individuals. Membrane surface expression of hNav1.5 in the transfected cells was affected by the mutations, and silencing of mutant SLMAP by small interfering RNA rescued the surface expression of hNav1.5. Whole-cell patch-clamp recordings of hNav1.5-expressing cells transfected with mutant SLMAP confirmed the reduced hNav1.5 current. CONCLUSIONS The mutations in SLMAP may cause Brugada syndrome via modulating the intracellular trafficking of hNav1.5 channel.
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Affiliation(s)
- Taisuke Ishikawa
- Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
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