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The Ever Changing Moods of Calmodulin: How Structural Plasticity Entails Transductional Adaptability. J Mol Biol 2014; 426:2717-35. [DOI: 10.1016/j.jmb.2014.05.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 11/20/2022]
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252
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Yin G, Hassan F, Haroun AR, Murphy LL, Crotti L, Schwartz PJ, George AL, Satin J. Arrhythmogenic calmodulin mutations disrupt intracellular cardiomyocyte Ca2+ regulation by distinct mechanisms. J Am Heart Assoc 2014; 3:e000996. [PMID: 24958779 PMCID: PMC4309107 DOI: 10.1161/jaha.114.000996] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Background Calmodulin (CaM) mutations have been identified recently in subjects with congenital long QT syndrome (LQTS) or catecholaminergic polymorphic ventricular tachycardia (CPVT), but the mechanisms responsible for these divergent arrhythmia‐susceptibility syndromes in this context are unknown. We tested the hypothesis that LQTS‐associated CaM mutants disrupt Ca2+ homeostasis in developing cardiomyocytes possibly by affecting either late Na current or Ca2+‐dependent inactivation of L‐type Ca2+ current. Methods and Results We coexpressed CaM mutants with the human cardiac Na channel (NaV1.5) in tsA201 cells, and we used mammalian fetal ventricular cardiomyocytes to investigate LQTS‐ and CPVT‐associated CaM mutations (LQTS‐ and CPVT‐CaM). LQTS‐CaM mutants do not consistently affect L‐type Na current in heterologous cells or native cardiomyocytes, suggesting that the Na channel does not contribute to LQTS pathogenesis in the context of CaM mutations. LQTS‐CaM mutants (D96V, D130G, F142L) impaired Ca2+‐dependent inactivation, whereas the CPVT‐CaM mutant N54I had no effect on Ca2+‐dependent inactivation. LQTS‐CaM mutants led to loss of Ca2+‐transient entrainment with the rank order from greatest to least effect: CaM‐D130G~CaM‐D96V>>CaM‐F142L. This rank order follows measured Ca2+‐CaM affinities for wild‐type and mutant CaM. Acute isoproterenol restored entrainment for CaM‐130G and CaM‐D96V but caused irreversible cytosolic Ca2+ overload for cells expressing a CPVT‐CaM mutant. Conclusions CaM mutations associated with LQTS may not affect L‐type Na+ current but may evoke defective Ca2+‐dependent inactivation of L‐type Ca2+ current.
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Affiliation(s)
- Guo Yin
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY (G.Y., F.H., A.R.H., J.S.)
| | - Faisal Hassan
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY (G.Y., F.H., A.R.H., J.S.)
| | - Ayman R Haroun
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY (G.Y., F.H., A.R.H., J.S.)
| | - Lisa L Murphy
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN (L.L.M., A.L.G.)
| | - Lia Crotti
- Section of Cardiology, Department of Molecular Medicine, University of Pavia, Pavia, Italy (L.C.) Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany (L.C.) IRCCS Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milan, Italy (L.C., P.J.S.)
| | - Peter J Schwartz
- IRCCS Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milan, Italy (L.C., P.J.S.)
| | - Alfred L George
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN (L.L.M., A.L.G.) Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN (A.L.G.) Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (A.L.G.)
| | - Jonathan Satin
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY (G.Y., F.H., A.R.H., J.S.)
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Bers DM, Morotti S. Ca(2+) current facilitation is CaMKII-dependent and has arrhythmogenic consequences. Front Pharmacol 2014; 5:144. [PMID: 24987371 PMCID: PMC4060732 DOI: 10.3389/fphar.2014.00144] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/02/2014] [Indexed: 11/13/2022] Open
Abstract
The cardiac voltage gated Ca2+ current (ICa) is critical to the electrophysiological properties, excitation-contraction coupling, mitochondrial energetics, and transcriptional regulation in heart. Thus, it is not surprising that cardiac ICa is regulated by numerous pathways. This review will focus on changes in ICa that occur during the cardiac action potential (AP), with particular attention to Ca2+-dependent inactivation (CDI), Ca2+-dependent facilitation (CDF) and how calmodulin (CaM) and Ca2+-CaM dependent protein kinase (CaMKII) participate in the regulation of Ca2+ current during the cardiac AP. CDI depends on CaM pre-bound to the C-terminal of the L-type Ca2+ channel, such that Ca2+ influx and Ca2+ released from the sarcoplasmic reticulum bind to that CaM and cause CDI. In cardiac myocytes CDI normally pre-dominates over voltage-dependent inactivation. The decrease in ICa via CDI provides direct negative feedback on the overall Ca2+ influx during a single beat, when myocyte Ca2+ loading is high. CDF builds up over several beats, depends on CaMKII-dependent Ca2+ channel phosphorylation, and results in a staircase of increasing ICa peak, with progressively slower inactivation. CDF and CDI co-exist and in combination may fine-tune the ICa waveform during the cardiac AP. CDF may partially compensate for the tendency for Ca2+ channel availability to decrease at higher heart rates because of accumulating inactivation. CDF may also allow some reactivation of ICa during long duration cardiac APs, and contribute to early afterdepolarizations, a form of triggered arrhythmias.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California Davis Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis Davis, CA, USA
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254
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Affiliation(s)
- Geoffrey W Abbott
- 1360 Medical Surge II, Dept. of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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255
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Makita N, Yagihara N, Crotti L, Johnson CN, Beckmann BM, Roh MS, Shigemizu D, Lichtner P, Ishikawa T, Aiba T, Homfray T, Behr ER, Klug D, Denjoy I, Mastantuono E, Theisen D, Tsunoda T, Satake W, Toda T, Nakagawa H, Tsuji Y, Tsuchiya T, Yamamoto H, Miyamoto Y, Endo N, Kimura A, Ozaki K, Motomura H, Suda K, Tanaka T, Schwartz PJ, Meitinger T, Kääb S, Guicheney P, Shimizu W, Bhuiyan ZA, Watanabe H, Chazin WJ, George AL. Novel calmodulin mutations associated with congenital arrhythmia susceptibility. ACTA ACUST UNITED AC 2014; 7:466-74. [PMID: 24917665 DOI: 10.1161/circgenetics.113.000459] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND Genetic predisposition to life-threatening cardiac arrhythmias such as congenital long-QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) represent treatable causes of sudden cardiac death in young adults and children. Recently, mutations in calmodulin (CALM1, CALM2) have been associated with severe forms of LQTS and CPVT, with life-threatening arrhythmias occurring very early in life. Additional mutation-positive cases are needed to discern genotype-phenotype correlations associated with calmodulin mutations. METHODS AND RESULTS We used conventional and next-generation sequencing approaches, including exome analysis, in genotype-negative LQTS probands. We identified 5 novel de novo missense mutations in CALM2 in 3 subjects with LQTS (p.N98S, p.N98I, p.D134H) and 2 subjects with clinical features of both LQTS and CPVT (p.D132E, p.Q136P). Age of onset of major symptoms (syncope or cardiac arrest) ranged from 1 to 9 years. Three of 5 probands had cardiac arrest and 1 of these subjects did not survive. The clinical severity among subjects in this series was generally less than that originally reported for CALM1 and CALM2 associated with recurrent cardiac arrest during infancy. Four of 5 probands responded to β-blocker therapy, whereas 1 subject with mutation p.Q136P died suddenly during exertion despite this treatment. Mutations affect conserved residues located within Ca(2+)-binding loops III (p.N98S, p.N98I) or IV (p.D132E, p.D134H, p.Q136P) and caused reduced Ca(2+)-binding affinity. CONCLUSIONS CALM2 mutations can be associated with LQTS and with overlapping features of LQTS and CPVT.
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256
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Limpitikul WB, Dick IE, Joshi-Mukherjee R, Overgaard MT, George AL, Yue DT. Calmodulin mutations associated with long QT syndrome prevent inactivation of cardiac L-type Ca(2+) currents and promote proarrhythmic behavior in ventricular myocytes. J Mol Cell Cardiol 2014; 74:115-24. [PMID: 24816216 DOI: 10.1016/j.yjmcc.2014.04.022] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 04/28/2014] [Indexed: 01/13/2023]
Abstract
Recent work has identified missense mutations in calmodulin (CaM) that are associated with severe early-onset long-QT syndrome (LQTS), leading to the proposition that altered CaM function may contribute to the molecular etiology of this subset of LQTS. To date, however, no experimental evidence has established these mutations as directly causative of LQTS substrates, nor have the molecular targets of CaM mutants been identified. Here, therefore, we test whether expression of CaM mutants in adult guinea-pig ventricular myocytes (aGPVM) induces action-potential prolongation, and whether affiliated alterations in the Ca(2+) regulation of L-type Ca(2+) channels (LTCC) might contribute to such prolongation. In particular, we first overexpressed CaM mutants in aGPVMs, and observed both increased action potential duration (APD) and heightened Ca(2+) transients. Next, we demonstrated that all LQTS CaM mutants have the potential to strongly suppress Ca(2+)/CaM-dependent inactivation (CDI) of LTCCs, whether channels were heterologously expressed in HEK293 cells, or present in native form within myocytes. This attenuation of CDI is predicted to promote action-potential prolongation and boost Ca(2+) influx. Finally, we demonstrated how a small fraction of LQTS CaM mutants (as in heterozygous patients) would nonetheless suffice to substantially diminish CDI, and derange electrical and Ca(2+) profiles. In all, these results highlight LTCCs as a molecular locus for understanding and treating CaM-related LQTS in this group of patients.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Rosy Joshi-Mukherjee
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Michael T Overgaard
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Denmark
| | - Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205; Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205.
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257
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Hwang HS, Nitu FR, Yang Y, Walweel K, Pereira L, Johnson CN, Faggioni M, Chazin WJ, Laver D, George AL, Cornea RL, Bers DM, Knollmann BC. Divergent regulation of ryanodine receptor 2 calcium release channels by arrhythmogenic human calmodulin missense mutants. Circ Res 2014; 114:1114-24. [PMID: 24563457 DOI: 10.1161/circresaha.114.303391] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
RATIONALE Calmodulin (CaM) mutations are associated with an autosomal dominant syndrome of ventricular arrhythmia and sudden death that can present with divergent clinical features of catecholaminergic polymorphic ventricular tachycardia (CPVT) or long QT syndrome (LQTS). CaM binds to and inhibits ryanodine receptor (RyR2) Ca release channels in the heart, but whether arrhythmogenic CaM mutants alter RyR2 function is not known. OBJECTIVE To gain mechanistic insight into how human CaM mutations affect RyR2 Ca channels. METHODS AND RESULTS We studied recombinant CaM mutants associated with CPVT (N54I and N98S) or LQTS (D96V, D130G, and F142L). As a group, all LQTS-associated CaM mutants (LQTS-CaMs) exhibited reduced Ca affinity, whereas CPVT-associated CaM mutants (CPVT-CaMs) had either normal or modestly lower Ca affinity. In permeabilized ventricular myocytes, CPVT-CaMs at a physiological intracellular concentration (100 nmol/L) promoted significantly higher spontaneous Ca wave and spark activity, a typical cellular phenotype of CPVT. Compared with wild-type CaM, CPVT-CaMs caused greater RyR2 single-channel open probability and showed enhanced binding affinity to RyR2. Even a 1:8 mixture of CPVT-CaM:wild-type-CaM activated Ca waves, demonstrating functional dominance. In contrast, LQTS-CaMs did not promote Ca waves and exhibited either normal regulation of RyR2 single channels (D96V) or lower RyR2-binding affinity (D130G and F142L). None of the CaM mutants altered Ca/CaM binding to CaM-kinase II. CONCLUSIONS A small proportion of CPVT-CaM is sufficient to evoke arrhythmogenic Ca disturbances, whereas LQTS-CaMs do not. Our findings explain the clinical presentation and autosomal dominant inheritance of CPVT-CaM mutations and suggest that RyR2 interactions are unlikely to explain arrhythmogenicity of LQTS-CaM mutations.
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Affiliation(s)
- Hyun Seok Hwang
- From the Departments of Medicine (H.S.H., M.F., A.L.G., B.C.K.), Biochemistry (C.N.J., W.J.C.), Chemistry (W.J.C.), and Pharmacology (A.L.G., B.C.K.), Vanderbilt University, Nashville, TN; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis (F.R.N., R.L.C.); Department of Pharmacology, University of California, Davis (Y.Y., L.P., D.M.B.); and Department of School of Biomedical Sciences and Pharmacy, University of Newcastle, New South Wales, Australia (K.W., D.L.)
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258
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Crotti L, Schwartz PJ. Drug-induced long QT syndrome and exome sequencing: Chinese shadows link past and future. J Am Coll Cardiol 2014; 63:1438-40. [PMID: 24561140 DOI: 10.1016/j.jacc.2014.01.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/14/2014] [Accepted: 01/20/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Lia Crotti
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; IRCCS Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milan, Italy; Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Peter J Schwartz
- IRCCS Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milan, Italy.
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259
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Weeke P, Mosley JD, Hanna D, Delaney JT, Shaffer C, Wells QS, Van Driest S, Karnes JH, Ingram C, Guo Y, Shyr Y, Norris K, Kannankeril PJ, Ramirez AH, Smith JD, Mardis ER, Nickerson D, George AL, Roden DM. Exome sequencing implicates an increased burden of rare potassium channel variants in the risk of drug-induced long QT interval syndrome. J Am Coll Cardiol 2014; 63:1430-7. [PMID: 24561134 DOI: 10.1016/j.jacc.2014.01.031] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/09/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The aim of this study was to test the hypothesis that rare variants are associated with drug-induced long QT interval syndrome (diLQTS) and torsades de pointes. BACKGROUND diLQTS is associated with the potentially fatal arrhythmia torsades de pointes. The contribution of rare genetic variants to the underlying genetic framework predisposing to diLQTS has not been systematically examined. METHODS We performed whole-exome sequencing on 65 diLQTS patients and 148 drug-exposed control subjects of European descent. We used rare variant analyses (variable threshold and sequence kernel association test) and gene-set analyses to identify genes enriched with rare amino acid coding (AAC) variants associated with diLQTS. Significant associations were reanalyzed by comparing diLQTS patients with 515 ethnically matched control subjects from the National Heart, Lung, and Blood Grand Opportunity Exome Sequencing Project. RESULTS Rare variants in 7 genes were enriched in the diLQTS patients according to the sequence kernel association test or variable threshold compared with drug-exposed controls (p < 0.001). Of these, we replicated the diLQTS associations for KCNE1 and ACN9 using 515 Exome Sequencing Project control subjects (p < 0.05). A total of 37% of the diLQTS patients also had 1 or more rare AAC variants compared with 21% of control subjects (p = 0.009), in a pre-defined set of 7 congenital long QT interval syndrome (cLQTS) genes encoding potassium channels or channel modulators (KCNE1, KCNE2, KCNH2, KCNJ2, KCNJ5, KCNQ1, AKAP9). CONCLUSIONS By combining whole-exome sequencing with aggregated rare variant analyses, we implicate rare variants in KCNE1 and ACN9 as risk factors for diLQTS. Moreover, diLQTS patients were more burdened by rare AAC variants in cLQTS genes encoding potassium channel modulators, supporting the idea that multiple rare variants, notably across cLQTS genes, predispose to diLQTS.
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Affiliation(s)
- Peter Weeke
- Department of Medicine, Vanderbilt University, Nashville, Tennessee; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark
| | | | - David Hanna
- Department of Genome Sciences, University of Washington, Seattle, Washington
| | | | | | - Quinn S Wells
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Sara Van Driest
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jason H Karnes
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Christie Ingram
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Yan Guo
- Vanderbilt Technologies for Advanced Genomics Analysis and Research Design, Nashville, Tennessee
| | - Yu Shyr
- Vanderbilt Technologies for Advanced Genomics Analysis and Research Design, Nashville, Tennessee
| | - Kris Norris
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Prince J Kannankeril
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Andrea H Ramirez
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Joshua D Smith
- Department of Genome Sciences, University of Washington, Seattle, Washington
| | - Elaine R Mardis
- The Genome Institute, Washington University, St. Louis, Missouri
| | - Deborah Nickerson
- Department of Genome Sciences, University of Washington, Seattle, Washington
| | - Alfred L George
- Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Dan M Roden
- Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee.
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260
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Cuneo BF, Strasburger JF, Yu S, Horigome H, Hosono T, Kandori A, Wakai RT. In utero diagnosis of long QT syndrome by magnetocardiography. Circulation 2014; 128:2183-91. [PMID: 24218437 DOI: 10.1161/circulationaha.113.004840] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND The electrophysiology of long QT syndrome (LQTS) in utero is virtually unstudied. Our goal here was to evaluate the efficacy of fetal magnetocardiography (fMCG) for diagnosis and prognosis of fetuses at risk of LQTS. METHODS AND RESULTS We reviewed the pre/postnatal medical records of 30 fetuses referred for fMCG because of a family history of LQTS (n=17); neonatal/childhood sudden cardiac death (n=3), or presentation of prenatal LQTS rhythms (n=12): 2° atrioventricular block, ventricular tachycardia, heart rate < 3(rd) percentile. We evaluated heart rate and reactivity, cardiac time intervals, T-wave characteristics, and initiation/termination of Torsade de Pointes, and compared these with neonatal ECG findings. After birth, subjects were tested for LQTS mutations. Based on accepted clinical criteria, 21 subjects (70%; 9 KCNQ1, 5 KCNH2, 2 SCN5A, 2 other, 3 untested) had LQTS. Using a threshold of corrected QT= 490 ms, fMCG accurately identified LQTS fetuses with 89% (24/27) sensitivity and 89% (8/9) specificity in 36 sessions. Four fetuses (2 KCNH2 and 2 SCN5A), all with corrected QT ≥ 620 ms, had frequent episodes of Torsade de Pointes, which were present 22-79% of the time. Although some episodes initiated with a long-short sequence, most initiations showed QRS aberrancy and a notable lack of pause dependency. T-wave alternans was strongly associated with severe LQTS phenotype. CONCLUSIONS Corrected QT prolongation (≥490 ms) assessed by fMCG accurately identified LQTS in utero; extreme corrected QT prolongation (≥620 ms) predicted Torsade de Pointes. FMCG can play a critical role in the diagnosis and management of fetuses at risk of LQTS.
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Affiliation(s)
- Bettina F Cuneo
- Department of Pediatrics, Children's Hospital of Colorado, University of Colorado School of Medicine, Denver (B.F.C.); Division of Cardiology, Department of Pediatrics, Children's Hospital of Wisconsin and Medical College of Wisconsin, Milwaukee (J.F.S.); Department of Medical Physics, University of Wisconsin-Madison, (S.Y., R.T.W.); Department of Child Health, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan (H.H.); Department of Biomedical Engineering, Osaka Electro-Communication University, Osaka, Japan (T.H.); and Central Research Laboratory, Hitachi, Ltd, Tokyo, Japan (A.K.)
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261
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Chugh SS, Huertas-Vazquez A. Inherited Arrhythmia Syndromes. J Am Coll Cardiol 2014; 63:267-8. [DOI: 10.1016/j.jacc.2013.07.089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 07/23/2013] [Indexed: 12/23/2022]
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262
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Affiliation(s)
- Yuka Mizusawa
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Arthur AM Wilde
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
- Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, King Abdulaziz University
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263
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Roden DM. Personalized medicine to treat arrhythmias. Curr Opin Pharmacol 2013; 15:61-7. [PMID: 24721655 DOI: 10.1016/j.coph.2013.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 11/27/2013] [Accepted: 11/28/2013] [Indexed: 11/26/2022]
Abstract
The efficacy of antiarrhythmic drug therapy is incomplete, with responses ranging from efficacy to no effect to severe adverse effects, including paradoxical drug-induced arrhythmia. Most antiarrhythmic drugs were developed at a time when the mechanisms underlying arrhythmias were not well understood. In the last decade, a range of experimental approaches have advanced our understanding of the molecular and genomic contributors to the generation of an arrhythmia-prone heart, and this information is directly informing targeted therapy with existing drugs or the development of new ones. The development of inexpensive whole genome sequencing holds the promise of identifying patients susceptible to arrhythmias in a presymptomatic phase, and thus implementing preventive therapies.
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Affiliation(s)
- Dan M Roden
- Vanderbilt University School of Medicine, Nashville, USA.
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264
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Inherited arrhythmia syndromes leading to sudden cardiac death in the young: a global update and an Indian perspective. Indian Heart J 2013; 66 Suppl 1:S49-57. [PMID: 24568830 DOI: 10.1016/j.ihj.2013.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 11/07/2013] [Indexed: 12/15/2022] Open
Abstract
Inherited primary arrhythmias, namely congenital long QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia, account for a significant proportion of sudden cardiac deaths in young and apparently healthy individuals. Genetic testing plays an integral role in the diagnosis, risk-stratification and treatment of probands and family members. It is increasingly obvious that collaborative efforts are required to understand and manage these relatively rare but potentially lethal diseases. This article aims to update readers on the recent developments in our knowledge of inherited arrhythmias and to lay the foundation for a national synergistic effort to characterize them in the Indian population.
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265
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George AL. Recent genetic discoveries implicating ion channels in human cardiovascular diseases. Curr Opin Pharmacol 2013; 15:47-52. [PMID: 24721653 DOI: 10.1016/j.coph.2013.11.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 11/18/2013] [Accepted: 11/20/2013] [Indexed: 12/19/2022]
Abstract
The term 'channelopathy' refers to human genetic disorders caused by mutations in genes encoding ion channels or their interacting proteins. Recent advances in this field have been enabled by next-generation DNA sequencing strategies such as whole exome sequencing with several intriguing and unexpected discoveries. This review highlights important discoveries implicating ion channels or ion channel modulators in cardiovascular disorders including cardiac arrhythmia susceptibility, cardiac conduction phenotypes, pulmonary and systemic hypertension. These recent discoveries further emphasize the importance of ion channels in the pathophysiology of human disease and as important druggable targets.
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Affiliation(s)
- Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
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266
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Marsman RF, Tan HL, Bezzina CR. Genetics of sudden cardiac death caused by ventricular arrhythmias. Nat Rev Cardiol 2013; 11:96-111. [PMID: 24322550 DOI: 10.1038/nrcardio.2013.186] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sudden cardiac death (SCD) resulting from ventricular tachyarrhythmia is a major contributor to mortality. Clinical management of SCD, currently based on clinical markers of SCD risk, can be improved by integrating genetic information. The identification of multiple disease-causing gene variants has already improved patient management and increased our understanding of the rare Mendelian diseases associated with SCD risk in the young, but marked variability in disease severity suggests that additional genetic modifiers exist. Next-generation DNA sequencing could be crucial to the discovery of SCD-associated genes, but large data sets can be difficult to interpret. SCD usually occurs in patients with an average age of 65 years who have complex cardiac disease stemming from multiple, common, acquired disorders. Heritable factors are largely unknown, but are likely to have a role in determining the risk of SCD in these patients. Numerous genetic loci have been identified that affect electrocardiogram indices, which are regarded as intermediate phenotypes for tachyarrhythmia. These loci could help to identify new molecules and pathways affecting cardiac electrical function. These loci are often located in intergenic regions, so our evolving understanding of the noncoding regulatory regions of the genome are likely to aid in the identification of novel genes that are important for cardiac electrical function and possibly SCD.
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Affiliation(s)
- Roos F Marsman
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Hanno L Tan
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Connie R Bezzina
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
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267
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Makita N. Paradigm shifts in the genetics of inherited arrhythmias: Using next-generation sequencing technologies to uncover hidden etiologies. J Arrhythm 2013. [DOI: 10.1016/j.joa.2013.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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268
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Abstract
Congenital long QT syndrome (LQTS) is a genetically heterogeneous group of heritable disorders of myocardial repolarization linked by the shared clinical phenotype of QT prolongation on electrocardiogram and an increased risk of potentially life-threatening cardiac arrhythmias. At the molecular level, mutations in 15 distinct LQTS-susceptibility genes that encode ion channel pore-forming α-subunits and accessory β-subunits central to the electromechanical function of the heart have been implicated in its pathogenesis. Over the past 2 decades, our evolving understanding of the electrophysiological mechanisms by which specific genetic substrates perturb the cardiac action potential has translated into vastly improved approaches to the diagnosis, risk stratification, and treatment of patients with LQTS. In this review, we describe how our understanding of the molecular underpinnings of LQTS has yielded numerous clinically meaningful genotype-phenotype correlations and how these insights have translated into genotype- and phenotype-guided approaches to the clinical management of LQTS.
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Affiliation(s)
| | - Michael J. Ackerman
- Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
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269
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Marsman RF, Barc J, Beekman L, Alders M, Dooijes D, van den Wijngaard A, Ratbi I, Sefiani A, Bhuiyan ZA, Wilde AAM, Bezzina CR. A mutation in CALM1 encoding calmodulin in familial idiopathic ventricular fibrillation in childhood and adolescence. J Am Coll Cardiol 2013; 63:259-66. [PMID: 24076290 DOI: 10.1016/j.jacc.2013.07.091] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/24/2013] [Accepted: 07/01/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVES This study aimed to identify the genetic defect in a family with idiopathic ventricular fibrillation (IVF) manifesting in childhood and adolescence. BACKGROUND Although sudden cardiac death in the young is rare, it frequently presents as the first clinical manifestation of an underlying inherited arrhythmia syndrome. Gene discovery for IVF is important as it enables the identification of individuals at risk, because except for arrhythmia, IVF does not manifest with identifiable clinical abnormalities. METHODS Exome sequencing was carried out on 2 family members who were both successfully resuscitated from a cardiac arrest. RESULTS We characterized a family presenting with a history of ventricular fibrillation (VF) and sudden death without electrocardiographic or echocardiographic abnormalities at rest. Two siblings died suddenly at the ages of 9 and 10 years, and another 2 were resuscitated from out-of-hospital cardiac arrest with documented VF at ages 10 and 16 years, respectively. Exome sequencing identified a missense mutation affecting a highly conserved residue (p.F90L) in the CALM1 gene encoding calmodulin. This mutation was also carried by 1 of the siblings who died suddenly, from whom DNA was available. The mutation was present in the mother and in another sibling, both asymptomatic but displaying a marginally prolonged QT interval during exercise. CONCLUSIONS We identified a mutation in CALM1 underlying IVF manifesting in childhood and adolescence. The causality of the mutation is supported by previous studies demonstrating that F90 mediates the direct interaction of CaM with target peptides. Our approach highlights the utility of exome sequencing in uncovering the genetic defect even in families with a small number of affected individuals.
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Affiliation(s)
- Roos F Marsman
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, the Netherlands
| | - Julien Barc
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, the Netherlands; ICIN-Netherlands Heart Institute, Utrecht, the Netherlands
| | - Leander Beekman
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, the Netherlands
| | - Marielle Alders
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands
| | - Dennis Dooijes
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Arthur van den Wijngaard
- Department of Clinical Genetics, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Ilham Ratbi
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohamed V Souissi, Rabat, Morocco
| | - Abdelaziz Sefiani
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohamed V Souissi, Rabat, Morocco
| | - Zahurul A Bhuiyan
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands; Laboratoire de Génétique Moléculaire, Service de Génétique Médicale, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, the Netherlands; Princess Al Jawhara Albrahim Centre of Excellence in Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Connie R Bezzina
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, the Netherlands.
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270
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KATO KOICHI, MAKIYAMA TAKERU, WU JIE, DING WEIGUANG, KIMURA HIROMI, NAIKI NOBU, OHNO SEIKO, ITOH HIDEKI, NAKANISHI TOSHIO, MATSUURA HIROSHI, HORIE MINORU. Cardiac Channelopathies Associated with Infantile Fatal Ventricular Arrhythmias: From the Cradle to the Bench. J Cardiovasc Electrophysiol 2013; 25:66-73. [DOI: 10.1111/jce.12270] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/16/2013] [Accepted: 08/12/2013] [Indexed: 11/29/2022]
Affiliation(s)
- KOICHI KATO
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
| | - TAKERU MAKIYAMA
- Department of Cardiovascular Medicine; Kyoto University Graduate School of Medicine; Kyoto Japan
| | - JIE WU
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
- Department of Pharmacology; Medical School of Xi'an Jiaotong University; Xi'an China
| | - WEI-GUANG DING
- Department of Physiology; Shiga University of Medical Science; Shiga Japan
| | - HIROMI KIMURA
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
| | - NOBU NAIKI
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
| | - SEIKO OHNO
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
| | - HIDEKI ITOH
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
| | - TOSHIO NAKANISHI
- Department of Pediatric Cardiology; Tokyo Women's Medical University; Tokyo Japan
| | - HIROSHI MATSUURA
- Department of Physiology; Shiga University of Medical Science; Shiga Japan
| | - MINORU HORIE
- Department of Cardiovascular and Respiratory Medicine; Shiga University of Medical Science; Shiga Japan
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271
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Cuneo BF, Etheridge SP, Horigome H, Sallee D, Moon-Grady A, Weng HY, Ackerman MJ, Benson DW. Arrhythmia phenotype during fetal life suggests long-QT syndrome genotype: risk stratification of perinatal long-QT syndrome. Circ Arrhythm Electrophysiol 2013; 6:946-51. [PMID: 23995044 DOI: 10.1161/circep.113.000618] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Fetal arrhythmias characteristic of long QT syndrome (LQTS) include torsades de pointes (TdP) and/or 2° atrioventricular block, but sinus bradycardia, defined as fetal heart rate<3% for gestational age, is most common. We hypothesized that prenatal rhythm phenotype might predict LQTS genotype and facilitate improved risk stratification and management. METHOD AND RESULTS Records of subjects exhibiting fetal LQTS arrhythmias were reviewed. Fetal echocardiograms, neonatal ECG, and genetic testing were evaluated. We studied 43 subjects exhibiting fetal LQTS arrhythmias: TdP±2° atrioventricular block (group 1, n=7), isolated 2° atrioventricular block (group 2, n=4), and sinus bradycardia (group 3, n=32). Mutations in known LQTS genes were found in 95% of subjects tested. SCN5A mutations occurred in 71% of group 1, whereas 91% of subjects with KCNQ1 mutations were in group 3. Small numbers of subjects with KCNH2 mutations (n=4) were scattered in all 3 groups. Age at presentation did not differ among groups, and most subjects (n=42) were live-born with gestational ages of 37.5±2.8 weeks (mean±SD). However, those with TdP were typically delivered earlier. Prenatal treatment in group 1 terminated (n=2) or improved (n=4) TdP. The neonatal heart rate-corrected QT interval (mean±SE) of group 1 (664.7±24.9) was longer than neonatal heart rate-corrected QT interval in both group 2 (491.2±27.6; P=0.004) and group 3 (483.1±13.7; P<0.001). Despite medical and pacemaker therapy, postnatal cardiac arrest (n=4) or sudden death (n=1) was common among subjects with fetal/neonatal TdP. CONCLUSIONS Rhythm phenotypes of fetal LQTS have genotype-suggestive features that, along with heart rate-corrected QT interval duration, may risk stratify perinatal management.
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Affiliation(s)
- Bettina F Cuneo
- Department of Pediatrics, Rosalind Franklin School of Medicine and Science, North Chicago, IL
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272
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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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273
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274
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Sorensen AB, Søndergaard MT, Overgaard MT. Calmodulin in a Heartbeat. FEBS J 2013; 280:5511-32. [DOI: 10.1111/febs.12337] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/28/2013] [Accepted: 05/07/2013] [Indexed: 01/16/2023]
Affiliation(s)
- Anders B. Sorensen
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
| | - Mads T. Søndergaard
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
| | - Michael T. Overgaard
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
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275
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Abstract
Congenital long QT syndrome (LQTS) is caused by single autosomal-dominant mutations in a gene encoding for a cardiac ion channel or an accessory ion channel subunit. These single mutations can cause life-threatening arrhythmias and sudden death in heterozygous mutation carriers. This recognition has been the basis for world-wide staggering numbers of subjects and families counselled for LQTS and treated based on finding (putative) disease-causing mutations. However, prophylactic treatment of patients is greatly hampered by the growing awareness that simple carriership of a mutation often fails to predict clinical outcome: many carriers never develop clinically relevant disease while others are severely affected at a young age. It is still largely elusive what determines this large variability in disease severity, where even within one pedigree, an identical mutation can cause life-threatening arrhythmias in some carriers while in other carriers no disease becomes clinically manifested. This suggests that additional factors modify the clinical manifestations of a particular disease-causing mutation. In this article, potential demographic, environmental and genetic factors are reviewed, which, in conjunction with a mutation, may modify the phenotype in LQTS, and thereby determine, at least partially, the large variability in disease severity.
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Affiliation(s)
- Ahmad S Amin
- A. A. M. Wilde: Department of Cardiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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276
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Schwartz PJ, Ackerman MJ, George AL, Wilde AAM. Impact of genetics on the clinical management of channelopathies. J Am Coll Cardiol 2013; 62:169-180. [PMID: 23684683 DOI: 10.1016/j.jacc.2013.04.044] [Citation(s) in RCA: 220] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/11/2013] [Accepted: 04/24/2013] [Indexed: 12/29/2022]
Abstract
There are few areas in cardiology in which the impact of genetics and genetic testing on clinical management has been as great as in cardiac channelopathies, arrhythmic disorders of genetic origin related to the ionic control of the cardiac action potential. Among the growing number of diseases identified as channelopathies, 3 are sufficiently prevalent to represent significant clinical and societal problems and to warrant adequate understanding by practicing cardiologists: long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and Brugada syndrome. This review will focus selectively on the impact of genetic discoveries on clinical management of these 3 diseases. For each disorder, we will discuss to what extent genetic knowledge and clinical genetic test results modify the way cardiologists should approach and manage affected patients. We will also address the optimal use of genetic testing, including its potential limitations and the potential medico-legal implications when such testing is not performed. We will highlight how important it is to understand the ways that genotype can affect clinical manifestations, risk stratification, and responses to the therapy. We will also illustrate the close bridge between molecular biology and clinical medicine, and will emphasize that consideration of the genetic basis for these heritable arrhythmia syndromes and the proper use and interpretation of clinical genetic testing should remain the standard of care.
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Affiliation(s)
- Peter J Schwartz
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Department of Cardiology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, University of Cape Town, Cape Town, South Africa; Department of Medicine, University of Stellenbosch, Stellenbosch, South Africa; Chair of Sudden Death, Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
| | - Michael J Ackerman
- Department of Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota; Department of Pediatrics, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Alfred L George
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University, Nashville, Tennessee; Institute for Integrative Genomics, Vanderbilt University, Nashville, Tennessee
| | - Arthur A M Wilde
- Department of Cardiology, Heart Failure Research Centre, Academic Medical Centre, Amsterdam, the Netherlands; Princess Al Jawhara Albrahim Centre of Excellence in Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia
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