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Ukachukwu CU, Jimenez-Vazquez EN, Jain A, Jones DK. hERG1 channel subunit composition mediates proton inhibition of rapid delayed rectifier potassium current (I Kr) in cardiomyocytes derived from hiPSCs. J Biol Chem 2022; 299:102778. [PMID: 36496073 PMCID: PMC9867984 DOI: 10.1016/j.jbc.2022.102778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/29/2022] [Accepted: 12/04/2022] [Indexed: 12/13/2022] Open
Abstract
The voltage-gated channel, hERG1, conducts the rapid delayed rectifier potassium current (IKr) and is critical for human cardiac repolarization. Reduced IKr causes long QT syndrome and increases the risk for cardiac arrhythmia and sudden death. At least two subunits form functional hERG1 channels, hERG1a and hERG1b. Changes in hERG1a/1b abundance modulate IKr kinetics, magnitude, and drug sensitivity. Studies from native cardiac tissue suggest that hERG1 subunit abundance is dynamically regulated, but the impact of altered subunit abundance on IKr and its response to external stressors is not well understood. Here, we used a substrate-driven human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) maturation model to investigate how changes in relative hERG1a/1b subunit abundance impact the response of native IKr to extracellular acidosis, a known component of ischemic heart disease and sudden infant death syndrome. IKr recorded from immatured hiPSC-CMs displays a 2-fold greater inhibition by extracellular acidosis (pH 6.3) compared with matured hiPSC-CMs. Quantitative RT-PCR and immunocytochemistry demonstrated that hERG1a subunit mRNA and protein were upregulated and hERG1b subunit mRNA and protein were downregulated in matured hiPSC-CMs compared with immatured hiPSC-CMs. The shift in subunit abundance in matured hiPSC-CMs was accompanied by increased IKr. Silencing hERG1b's impact on native IKr kinetics by overexpressing a polypeptide identical to the hERG1a N-terminal Per-Arnt-Sim domain reduced the magnitude of IKr proton inhibition in immatured hiPSC-CMs to levels comparable to those observed in matured hiPSC-CMs. These data demonstrate that hERG1 subunit abundance is dynamically regulated and determines IKr proton sensitivity in hiPSC-CMs.
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Affiliation(s)
- Chiamaka U. Ukachukwu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Abhilasha Jain
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA,Department of Internal Medicine, University of Michigan Medical School,For correspondence: David K. Jones
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Hayama E, Furutani Y, Kawaguchi N, Seki A, Nagashima Y, Okita K, Takeuchi D, Matsuoka R, Inai K, Hagiwara N, Nakanishi T. Induced Pluripotent Stem Cell-Derived Cardiomyocytes with SCN5A R1623Q Mutation Associated with Severe Long QT Syndrome in Fetuses and Neonates Recapitulates Pathophysiological Phenotypes. BIOLOGY 2021; 10:biology10101062. [PMID: 34681161 PMCID: PMC8533193 DOI: 10.3390/biology10101062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/08/2021] [Accepted: 10/13/2021] [Indexed: 12/19/2022]
Abstract
Simple Summary In this study, the induced pluripotent stem cell-derived cardiomyocyte model from a patient with long QT syndrome harboring a heterozygous Nav1.5 R1623Q mutation exhibited prolonged field potential duration corrected by Fridericia’s formula (FPDcF, analogous to QTcF). FPDcF was shortened with mexiletine treatment and increased the frequency of arrhythmia-like EAD events following E4031, an Ikr blocker, administration. These characteristics partly reflect the patient phenotypes. As the R1623Q mutation is related to severe congenital LQT syndrome in fetuses and neonates, the effect of the neonatal variants on the electrophysiological properties of the R1623Q mutant was examined using an automated patch-clamp system. Our results demonstrated that both R1623Q and neonatal R1623Q delayed inactivation of INa and increased late Na current. We speculated that neonatal Nav1.5 ameliorates QTc prolongation. Developmental switching of neonatal/adult Nav1.5 isoforms might play a role in the mechanisms underlying severe long QT syndrome in fetuses and neonates. Abstract The SCN5A R1623Q mutation is one of the most common genetic variants associated with severe congenital long QT syndrome 3 (LQT3) in fetal and neonatal patients. To investigate the properties of the R1623Q mutation, we established an induced pluripotent stem cell (iPSC) cardiomyocyte (CM) model from a patient with LQTS harboring a heterozygous R1623Q mutation. The properties and pharmacological responses of iPSC-CMs were characterized using a multi-electrode array system. The biophysical characteristic analysis revealed that R1623Q increased open probability and persistent currents of sodium channel, indicating a gain-of-function mutation. In the pharmacological study, mexiletine shortened FPDcF in R1623Q-iPSC-CMs, which exhibited prolonged field potential duration corrected by Fridericia’s formula (FPDcF, analogous to QTcF). Meanwhile, E4031, a specific inhibitor of human ether-a-go-go-related gene (hERG) channel, significantly increased the frequency of arrhythmia-like early after depolarization (EAD) events. These characteristics partly reflect the patient phenotypes. To further analyze the effect of neonatal isoform, which is predominantly expressed in the fetal period, on the R1623Q mutant properties, we transfected adult form and neonatal isoform SCN5A of control and R1623Q mutant SCN5A genes to 293T cells. Whole-cell automated patch-clamp recordings revealed that R1623Q increased persistent Na+ currents, indicating a gain-of-function mutation. Our findings demonstrate the utility of LQT3-associated R1623Q mutation-harboring iPSC-CMs for assessing pharmacological responses to therapeutic drugs and improving treatment efficacy. Furthermore, developmental switching of neonatal/adult Nav1.5 isoforms may be involved in the pathological mechanisms underlying severe long QT syndrome in fetuses and neonates.
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Affiliation(s)
- Emiko Hayama
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
- Correspondence:
| | - Yoshiyuki Furutani
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
| | - Nanako Kawaguchi
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
| | - Akiko Seki
- Department of Preventive Medicine, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan;
- Department of General Medicine, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
- Department of Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan;
| | - Yoji Nagashima
- Department of Surgical Pathology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan;
| | - Keisuke Okita
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan;
| | - Daiji Takeuchi
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
| | - Rumiko Matsuoka
- Wakamatsukawada Clinic, 10-7 Kawada-cho, Shinjuku-ku, Tokyo 162-0054, Japan;
| | - Kei Inai
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
| | - Nobuhisa Hagiwara
- Department of Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan;
| | - Toshio Nakanishi
- Department of Pediatric Cardiology and Adult Congenital Cardiology, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan; (Y.F.); (N.K.); (D.T.); (K.I.); (T.N.)
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3
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Breuss MW, Yang X, Gleeson JG. Sperm mosaicism: implications for genomic diversity and disease. Trends Genet 2021; 37:890-902. [PMID: 34158173 PMCID: PMC9484299 DOI: 10.1016/j.tig.2021.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 12/18/2022]
Abstract
While sperm mosaicism has few consequences for men, the offspring and future generations are unwitting recipients of gonadal cell mutations, often yielding severe disease. Recent studies, fueled by emergent technologies, show that sperm mosaicism is a common source of de novo mutations (DNMs) that underlie severe pediatric disease as well as human genetic diversity. Sperm mosaicism can be divided into three types: Type I arises during sperm meiosis and is non-age dependent; Type II arises in spermatogonia and increases as men age; and Type III arises during paternal embryogenesis, spreads throughout the body, and contributes stably to sperm throughout life. Where Types I and II confer little risk of recurrence, Type III may confer identifiable risk to future offspring. These mutations are likely to be the single largest contributor to human genetic diversity. New sequencing approaches may leverage this framework to evaluate and reduce disease risk for future generations.
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Affiliation(s)
- Martin W Breuss
- Department of Pediatrics, Section of Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Xiaoxu Yang
- Rady Children's Institute for Genomic Medicine, Department of Neurosciences, University of California, San Diego, CA, USA
| | - Joseph G Gleeson
- Rady Children's Institute for Genomic Medicine, Department of Neurosciences, University of California, San Diego, CA, USA.
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Sawyer BL, Tristani-Firouzi M, Wells LE, Vatta M, Etheridge SP. Maternal mosaicism in long QT syndrome due to a pathogenic variant in KCNH2. HeartRhythm Case Rep 2021; 7:74-78. [PMID: 33665105 PMCID: PMC7897747 DOI: 10.1016/j.hrcr.2020.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Briana L. Sawyer
- Division of Pediatric Cardiology, Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - Martin Tristani-Firouzi
- Division of Pediatric Cardiology, Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - Layne E. Wells
- Department of Precision Genomics, Intermountain Primary Children’s Hospital, Salt Lake City, Utah
| | - Matteo Vatta
- Invitae Corporation, San Francisco, California
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Susan P. Etheridge
- Division of Pediatric Cardiology, Department of Pediatrics, University of Utah, Salt Lake City, Utah
- Address reprint requests and correspondence: Dr Susan P. Etheridge, University of Utah Division of Pediatric Cardiology, Department of Pediatrics, 81 N. Mario Capecchi Dr, Salt Lake City, UT 84113.
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Moore JP, Gallotti RG, Shannon KM, Bos JM, Sadeghi E, Strasburger JF, Wakai RT, Horigome H, Clur SA, Hill AC, Shah MJ, Behere S, Sarquella-Brugada G, Czosek R, Etheridge SP, Fischbach P, Kannankeril PJ, Motonaga K, Landstrom AP, Williams M, Patel A, Dagradi F, Tan RB, Stephenson E, Krishna MR, Miyake CY, Lee ME, Sanatani S, Balaji S, Young ML, Siddiqui S, Schwartz PJ, Shivkumar K, Ackerman MJ. Genotype Predicts Outcomes in Fetuses and Neonates With Severe Congenital Long QT Syndrome. JACC Clin Electrophysiol 2020; 6:1561-1570. [PMID: 33213816 DOI: 10.1016/j.jacep.2020.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/26/2020] [Accepted: 06/02/2020] [Indexed: 11/16/2022]
Abstract
OBJECTIVES This study sought to determine the relationship between long QT syndrome (LQTS) subtype (LTQ1, LTQ2, LTQ3) and postnatal cardiac events (CEs). BACKGROUND LQTS presenting with 2:1 atrioventricular block or torsades de pointes in the fetus and/or neonate has been associated with risk for major CEs, but overall outcomes and predictors remain unknown. METHODS A retrospective study involving 25 international centers evaluated the course of fetuses/newborns diagnosed with congenital LQTS and either 2:1 atrioventricular block or torsades de pointes. The primary outcomes were age at first CE after dismissal from the newborn hospitalization and death and/or cardiac transplantation during follow-up. CE was defined as aborted cardiac arrest, appropriate shock from implantable cardioverter-defibrillator, or sudden cardiac death. RESULTS A total of 84 fetuses and/or neonates were identified with LQTS (12 as LQT1, 35 as LQT2, 37 as LQT3). Median gestational age at delivery was 37 weeks (interquartile range: 35 to 39 weeks) and age at hospital discharge was 3 weeks (interquartile range: 2 to 5 weeks). Fetal demise occurred in 2 and pre-discharge death in 1. Over a median of 5.2 years, there were 1 LQT1, 3 LQT2, and 23 LQT3 CEs (13 aborted cardiac arrests, 5 sudden cardiac deaths, and 9 appropriate shocks). One patient with LQT1 and 11 patients with LQT3 died or received cardiac transplant during follow-up. The only multivariate predictor of post-discharge CEs was LQT3 status (LQT3 vs. LQT2: hazard ratio: 8.4; 95% confidence interval: 2.6 to 38.9; p < 0.001), and LQT3, relative to LQT2, genotype predicted death and/or cardiac transplant (p < 0.001). CONCLUSIONS In this large multicenter study, fetuses and/or neonates with LQT3 but not those with LQT1 or LQT2 presenting with severe arrhythmias were at high risk of not only frequent, but lethal CEs.
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Affiliation(s)
- Jeremy P Moore
- Division of Pediatric Cardiology, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California, USA; UCLA Cardiac Arrhythmia Center and Ahmanson Adult Congenital Heart Disease Center, UCLA Health System, Los Angeles, California, USA.
| | - Roberto G Gallotti
- Division of Pediatric Cardiology, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California, USA; UCLA Cardiac Arrhythmia Center and Ahmanson Adult Congenital Heart Disease Center, UCLA Health System, Los Angeles, California, USA
| | - Kevin M Shannon
- Division of Pediatric Cardiology, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California, USA; UCLA Cardiac Arrhythmia Center and Ahmanson Adult Congenital Heart Disease Center, UCLA Health System, Los Angeles, California, USA
| | - J Martijn Bos
- Department of Cardiovascular Medicine (Division of Heart Rhythm Services), Mayo Clinic, Rochester, Minnesota, USA; Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Elham Sadeghi
- Department of Pediatrics, Medical College of Wisconsin, Herma Heart Institute, Milwaukee, Wisconsin, USA
| | - Janette F Strasburger
- Department of Pediatrics, Medical College of Wisconsin, Herma Heart Institute, Milwaukee, Wisconsin, USA
| | - Ronald T Wakai
- Biomagnetism Laboratory, Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Sally-Ann Clur
- Department of Pediatric Cardiology, Emma Children's Hospital, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Allison C Hill
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Maully J Shah
- Division of Cardiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Shashank Behere
- Division of Cardiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Georgia Sarquella-Brugada
- Arrhythmia, Inherited Cardiac Diseases Unit, Hospital Sant Joan de Déu, Barcelona, Spain; Medical Sciences Department, School of Medicine, University of Girona, Girona, Spain
| | - Richard Czosek
- The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Susan P Etheridge
- Primary Children's Hospital, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Peter Fischbach
- Division of Pediatric Cardiology, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia, USA
| | - Prince J Kannankeril
- Monroe Carrell Children's Hospital, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Kara Motonaga
- Division of Pediatric Cardiology, Stanford University, Palo Alto, California, USA
| | - Andrew P Landstrom
- Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, North Carolina, USA; Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Matthew Williams
- Division of Cardiology, Rady Children's Hospital, University of California San Diego, San Diego, California, USA
| | - Akash Patel
- Division of Pediatric Cardiology, University of California San Francisco Benioff Children's Hospital, University of California, San Francisco, California, USA
| | - Federica Dagradi
- Center for Cardiac Arrhythmias of Genetic Origin, Istituto di Ricovero e Cura a Carattere Scientifico, Istituto Auxologico Italiano, Milan, Italy
| | - Reina B Tan
- Division of Pediatric Cardiology, New York University Langone School of Medicine, New York, New York, USA
| | - Elizabeth Stephenson
- Labbatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | | | - Christina Y Miyake
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
| | - Michelle E Lee
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
| | - Shubhayan Sanatani
- Division of Cardiology, British Columbia Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Seshadri Balaji
- Division of Pediatric Cardiology, Oregon Health and Science University, Portland, Oregon, USA
| | - Ming-Lon Young
- Joe DiMaggio Children's Hospital Heart Institute, Memorial Healthcare System, Hollywood, Florida, USA
| | - Saad Siddiqui
- The Heart Institute for Children, Advocate Children's Hospital, Oak Lawn, Illinois, USA
| | - Peter J Schwartz
- Center for Cardiac Arrhythmias of Genetic Origin, Istituto di Ricovero e Cura a Carattere Scientifico, Istituto Auxologico Italiano, Milan, Italy; Department of Cardiology, Fondazione IRCCS Policlinico S. Matteo, Pavia, Italy; Molecular Cardiology Laboratory, Fondazione IRCCS Policlinico S. Matteo, Pavia, Italy
| | - Kalyanam Shivkumar
- Division of Pediatric Cardiology, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California, USA; UCLA Cardiac Arrhythmia Center and Ahmanson Adult Congenital Heart Disease Center, UCLA Health System, Los Angeles, California, USA
| | - Michael J Ackerman
- Department of Cardiovascular Medicine (Division of Heart Rhythm Services), Mayo Clinic, Rochester, Minnesota, USA; Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA
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A missense mutation of ErbB2 produces a novel mouse model of stillbirth associated with a cardiac abnormality but lacking abnormalities of placental structure. PLoS One 2020; 15:e0233007. [PMID: 32492036 PMCID: PMC7269201 DOI: 10.1371/journal.pone.0233007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 04/28/2020] [Indexed: 12/02/2022] Open
Abstract
Background In humans, stillbirth describes the death of a fetus before birth after 28 weeks gestation, and accounts for approximately 2.6 million deaths worldwide annually. In high-income countries, up to half of stillbirths have an unknown cause and are described as “unexplained stillbirths”; this lack of understanding impairs efforts to prevent stillbirth. There are also few animal models of stillbirth, but those that have been described usually have significant placental abnormalities. This study describes a novel mutant murine model of fetal death with atrial conduction block due to an ErbB2 missense mutation which is not associated with abnormal placental morphology. Methods Phenotypic characterisation and histological analysis of the mutant mouse model was conducted. The mRNA distribution of the early cardiomyocyte marker Nkx2-5 was assessed via in situ hybridisation. Cardiac structure was quantified and cellular morphology evaluated by electron microscopy. Immunostaining was employed to quantify placental structure and cell characteristics on matched heterozygous and homozygous mutant placental samples. Results There were no structural abnormalities observed in hearts of mutant embryos. Comparable Nkx2-5 expression was observed in hearts of mutants and controls, suggesting normal cardiac specification. Additionally, there was no significant difference in the weight, placenta dimensions, giant cell characteristics, labyrinth tissue composition, levels of apoptosis, proliferation or vascularisation between placentas of homozygous mutant mice and controls. Conclusion Embryonic lethality in the ErbB2 homozygous mutant mouse cannot be attributed to placental pathology. As such, we conclude the ErbB2M802R mutant is a model of stillbirth with a non-placental cause of death. The mechanism of the atrial block resulting from ErbB2 mutation and its role in embryonic death is still unclear. Studying this mutant mouse model could identify candidate genes involved in stillbirth associated with structural or functional cardiac defects.
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Pacora P, Romero R, Jaiman S, Erez O, Bhatti G, Panaitescu B, Benshalom-Tirosh N, Jung Jung E, Hsu CD, Hassan SS, Yeo L, Kadar N. Mechanisms of death in structurally normal stillbirths. J Perinat Med 2019; 47:222-240. [PMID: 30231013 PMCID: PMC6349478 DOI: 10.1515/jpm-2018-0216] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 07/20/2018] [Indexed: 01/05/2023]
Abstract
Objectives To investigate mechanisms of in utero death in normally formed fetuses by measuring amniotic fluid (AF) biomarkers for hypoxia (erythropoietin [EPO]), myocardial damage (cardiac troponin I [cTnI]) and brain injury (glial fibrillary acidic protein [GFAP]), correlated with risk factors for fetal death and placental histopathology. Methods This retrospective, observational cohort study included intrauterine deaths with transabdominal amniocentesis prior to induction of labor. Women with a normal pregnancy and an indicated amniocentesis at term were randomly selected as controls. AF was assayed for EPO, cTnI and GFAP using commercial immunoassays. Placental histopathology was reviewed, and CD15-immunohistochemistry was used. Analyte concentrations >90th centile for controls were considered "raised". Raised AF EPO, AF cTnI and AF GFAP concentrations were considered evidence of hypoxia, myocardial and brain injury, respectively. Results There were 60 cases and 60 controls. Hypoxia was present in 88% (53/60), myocardial damage in 70% (42/60) and brain injury in 45% (27/60) of fetal deaths. Hypoxic fetuses had evidence of myocardial injury, brain injury or both in 77% (41/53), 49% (26/53) and 13% (7/53) of cases, respectively. Histopathological evidence for placental dysfunction was found in 74% (43/58) of these cases. Conclusion Hypoxia, secondary to placental dysfunction, was found to be the mechanism of death in the majority of fetal deaths among structurally normal fetuses. Ninety-one percent of hypoxic fetal deaths sustained brain, myocardial or both brain and myocardial injuries in utero. Hypoxic myocardial injury was an attributable mechanism of death in 70% of the cases. Non-hypoxic cases may be caused by cardiac arrhythmia secondary to a cardiac conduction defect.
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Affiliation(s)
- Percy Pacora
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Roberto Romero
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan,Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, Michigan,Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan
| | - Sunil Jaiman
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Offer Erez
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan,Department of Obstetrics and Gynecology, Soroka University Medical Center, School of Medicine, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Gaurav Bhatti
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Bogdan Panaitescu
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Neta Benshalom-Tirosh
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan,Department of Obstetrics and Gynecology, Soroka University Medical Center, School of Medicine, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Eun Jung Jung
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Chaur-Dong Hsu
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Sonia S. Hassan
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Lami Yeo
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Nicholas Kadar
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan,Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
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Crotti L, Ghidoni A, Dagradi F. Genetics of Adult and Fetal Forms of Long QT Syndrome. GENETIC CAUSES OF CARDIAC DISEASE 2019. [DOI: 10.1007/978-3-030-27371-2_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Identification novel LQT syndrome-associated variants in Polish population and genotype-phenotype correlations in eight families. J Appl Genet 2018; 59:463-469. [PMID: 30244407 DOI: 10.1007/s13353-018-0464-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 10/28/2022]
Abstract
Congenital long QT syndrome (LQTS) is a primary cardiac channelopathy. Genetic testing has not only diagnostic but also prognostic and therapeutic implications. At present, 15 genes have been associated with the disease, with most mutations located in 3 major LQTS-susceptibility genes. During a routine genetic screening for KCNQ1, KCNH2 and SCN5A genes in index cases with LQTS, seven novel variants in KCNH2 and SCN5A genes were found. Genotype-phenotype correlations were analysed in these patients and their families. An open reading frame and splice site analysis of the exons was conducted using next-generation sequencing. In novel variants, phenotypes of carriers and their affected relatives were analysed. In 39 unrelated patients, 40 pathogenic/putative pathogenic mutations were found. Thirty-three of them, predominantly missense, were reported previously: 11 were in the KCNQ, 17 in the KCNH2 and 5 in the SCN5A gene. Seven novel missense variants were found in eight families. Among them, four variants were in typical for LQTS location. Two variants in the KCNH2 gene (p.D803Y and p.D46F) and one in the SCN5A gene (G1391R) were in amino acid (AA) position which up to present has not been reported in LQTS. Phenotype analysis showed the life-threatening course of the disease in index cases with a history of sudden cardiac death in six families. Mutation carriers presented with ECG abnormalities and some of them received beta-blocker therapy. We report three novel variants (KCNQ1 p.46, KCNH2 p.D803Y, SCN5A p.G1391R) which have never been reported for this AA location in LQTS; the phenotype-genotype correlation suggests their pathogenicity.
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Tuveng JM, Berling BM, Bunford G, Vanoye CG, Welch RC, Leren TP, George AL, Rognum TO. Long QT syndrome KCNH2 mutation with sequential fetal and maternal sudden death. Forensic Sci Med Pathol 2018; 14:367-371. [PMID: 29881912 DOI: 10.1007/s12024-018-9989-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2018] [Indexed: 11/26/2022]
Abstract
We report a case of a woman who experienced intrauterine fetal death at full term pregnancy, and then died suddenly soon after learning about the death of her fetus. At autopsy, previously undiagnosed neurofibromatosis and an adrenal gland pheochromocytoma were discovered in the mother. Genetic screening also revealed a novel KCNH2mutation in both fetus and mother indicating type 2 congenital long-QT syndrome (LQTS). A catecholamine surge was suspected as the precipitating event of fetal cardiac arrhythmia and sudden fetal death, while the addition of emotional stress provoked a lethal cardiac event in the mother. This case illustrates the potential for lethal interactions between two occult diseases (pheochromocytoma, LQTS).
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Affiliation(s)
| | | | | | - Carlos G Vanoye
- Department of Medicine, Vanderbilt University, Nashville, TN, 37232-0275, USA
| | - Richard C Welch
- Department of Medicine, Vanderbilt University, Nashville, TN, 37232-0275, USA
| | - Trond P Leren
- Section of Laboratory Diagnostics, Oslo University Hospital, Oslo, Norway
| | - Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, TN, 37232-0275, USA
| | - Torleiv Ole Rognum
- Section of Forensic Pediatric Medicine, Clinic of Laboratory Medicine, Oslo University Hospital, Oslo, Norway.
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
- Avdeling for Rettsmedisinske Fag, Seksjon for Rettsmedisinske Undersøkelser av Barn, Oslo Universitetssykehus HF, Postboks 4950 Nydalen, 0424, Oslo, Norway.
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Vink AS, Kuipers IM, De Bruin-Bon RHACM, Wilde AAM, Blom NA, Clur SAB. A Potential Diagnostic Approach for Foetal Long-QT Syndrome, Developed and Validated in Children. Pediatr Cardiol 2018; 39:1413-1422. [PMID: 29789915 PMCID: PMC6153877 DOI: 10.1007/s00246-018-1911-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 05/11/2018] [Indexed: 01/12/2023]
Abstract
In patients with Long-QT Syndrome (LQTS), mechanical abnormalities have been described. Recognition of these abnormalities could potentially be used in the diagnosis of LQTS, especially in the foetus where an ECG is not available and DNA-analysis is invasive. We aimed to develop and validate a marker for these mechanical abnormalities in children and to test its feasibility in foetuses as a proof of principle. We measured the myocardial contraction duration using colour Tissue Doppler Imaging (cTDI) in 41 LQTS children and age- and gender-matched controls. Children were chosen to develop and validate the measurement of the myocardial contraction duration, due to the availability of a simultaneously recorded ECG. Feasibility of this measurement in foetuses was tested in an additional pilot study among seven LQTS foetuses and eight controls. LQTS children had a longer myocardial contraction duration compared to controls, while there was no statistical difference in heart rate. Measuring the myocardial contraction duration in children had a high inter- and intra-observer validity and reliably correlated with the QT-interval. There was an area under the curve (AUC) of 0.71, and the optimal cut-off value showed an especially high specificity in diagnosing LQTS. Measuring the myocardial contraction duration was possible in all foetuses and had a high inter- and intra-observer validity (ICC = 0.71 and ICC = 0.88, respectively). LQTS foetuses seemed to have a longer myocardial contraction duration compared to controls. Therefore, a prolonged contraction duration may be a potential marker for the prenatal diagnosis of LQTS in the future. Further studies are required to support the measurement of the myocardial contraction duration as a diagnostic approach for foetal LQTS.
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Affiliation(s)
- Arja Suzanne Vink
- Heart Centre, Department of Cardiology, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD, Amsterdam, The Netherlands. .,Department of Paediatric Cardiology, Emma Children's Hospital, Academic Medical Centre, Amsterdam, The Netherlands.
| | - Irene M. Kuipers
- Department of Paediatric Cardiology, Emma Children’s Hospital, Academic Medical Centre, Amsterdam, The Netherlands
| | - Rianne H. A. C. M. De Bruin-Bon
- Heart Centre, Department of Cardiology, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Arthur A. M. Wilde
- Heart Centre, Department of Cardiology, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Nico A. Blom
- Department of Paediatric Cardiology, Emma Children’s Hospital, Academic Medical Centre, Amsterdam, The Netherlands ,Department of Paediatric Cardiology, Willem-Alexander Children’s Hospital, University Medical Centre Leiden, Leiden, The Netherlands
| | - Sally-Ann B. Clur
- Department of Paediatric Cardiology, Emma Children’s Hospital, Academic Medical Centre, Amsterdam, The Netherlands
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Blais BA, Satou G, Sklansky MS, Madnawat H, Moore JP. The diagnosis and management of long QT syndrome based on fetal echocardiography. HeartRhythm Case Rep 2017; 3:407-410. [PMID: 28948143 PMCID: PMC5601325 DOI: 10.1016/j.hrcr.2017.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
- Benjamin A. Blais
- Department of Pediatrics, David Geffen School of Medicine at University of California Los Angeles, and University of California Los Angeles Mattel Children's Hospital, Los Angeles, California
| | - Gary Satou
- Department of Pediatrics, David Geffen School of Medicine at University of California Los Angeles, and University of California Los Angeles Mattel Children's Hospital, Los Angeles, California
| | - Mark S. Sklansky
- Department of Pediatrics, David Geffen School of Medicine at University of California Los Angeles, and University of California Los Angeles Mattel Children's Hospital, Los Angeles, California
| | - Himani Madnawat
- College of Physical Sciences, University of California Los Angeles, Los Angeles, California
| | - Jeremy P. Moore
- Department of Pediatrics, David Geffen School of Medicine at University of California Los Angeles, and University of California Los Angeles Mattel Children's Hospital, Los Angeles, California
- Address reprint requests and correspondence: Dr Jeremy P. Moore, UCLA Medical Center, 200 Medical Plaza Dr, Suite 330, Los Angeles, CA 90095.UCLA Medical Center200 Medical Plaza Dr, Suite 330Los AngelesCA90095
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At the Heart of the Pregnancy: What Prenatal and Cardiovascular Genetic Counselors Need to Know about Maternal Heart Disease. J Genet Couns 2017; 26:669-688. [DOI: 10.1007/s10897-017-0081-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 02/14/2017] [Indexed: 01/25/2023]
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Crimmins S, Vashit S, Doyle L, Harman C, Turan O, Turan S. A multidisciplinary approach to prenatal treatment of congenital long QT syndrome. JOURNAL OF CLINICAL ULTRASOUND : JCU 2017; 45:168-170. [PMID: 27492745 DOI: 10.1002/jcu.22386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/05/2016] [Indexed: 06/06/2023]
Abstract
A 27-week fetus evaluated for bradycardia and hydrops was found to have anti-SSA-negative 2° atrioventricular block and ventricular tachycardia. A presumptive diagnosis of fetal long QT syndrome was made. Transplacental pharmacotherapy with intravenous magnesium and lidocaine restored sinus rhythm. At 30 6/7 weeks, the infant was delivered due to premature labor. Despite postnatal treatment with mexiletine and propranolol, she developed torsades de pointes. Ultimately, a de novo KCNH2 G628S mutation was diagnosed. She received an implantable cardiac defibrillator at 5 months of age. Early diagnosis and a multidisciplinary approach allowed successful in utero treatment and anticipatory postnatal management. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:168-170, 2017.
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Affiliation(s)
- Sarah Crimmins
- Fetal Heart Program, Center for Advanced Fetal Care, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Sixth Floor, Room 6NE11, 22 South Greene Street, Baltimore, MD, 21201
| | - Sudhir Vashit
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, 21201
| | - Lauren Doyle
- Fetal Heart Program, Center for Advanced Fetal Care, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Sixth Floor, Room 6NE11, 22 South Greene Street, Baltimore, MD, 21201
| | - Chris Harman
- Fetal Heart Program, Center for Advanced Fetal Care, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Sixth Floor, Room 6NE11, 22 South Greene Street, Baltimore, MD, 21201
| | - Ozhan Turan
- Fetal Heart Program, Center for Advanced Fetal Care, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Sixth Floor, Room 6NE11, 22 South Greene Street, Baltimore, MD, 21201
| | - Sifa Turan
- Fetal Heart Program, Center for Advanced Fetal Care, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Sixth Floor, Room 6NE11, 22 South Greene Street, Baltimore, MD, 21201
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Abstract
Somatic mosaicism, the occurrence and propagation of genetic variation in cell lineages after fertilization, is increasingly recognized to play a causal role in a variety of human diseases. We investigated the case of life-threatening arrhythmia in a 10-day-old infant with long QT syndrome (LQTS). Rapid genome sequencing suggested a variant in the sodium channel NaV1.5 encoded by SCN5A, NM_000335:c.5284G > T predicting p.(V1762L), but read depth was insufficient to be diagnostic. Exome sequencing of the trio confirmed read ratios inconsistent with Mendelian inheritance only in the proband. Genotyping of single circulating leukocytes demonstrated the mutation in the genomes of 8% of patient cells, and RNA sequencing of cardiac tissue from the infant confirmed the expression of the mutant allele at mosaic ratios. Heterologous expression of the mutant channel revealed significantly delayed sodium current with a dominant negative effect. To investigate the mechanism by which mosaicism might cause arrhythmia, we built a finite element simulation model incorporating Purkinje fiber activation. This model confirmed the pathogenic consequences of cardiac cellular mosaicism and, under the presenting conditions of this case, recapitulated 2:1 AV block and arrhythmia. To investigate the extent to which mosaicism might explain undiagnosed arrhythmia, we studied 7,500 affected probands undergoing commercial gene-panel testing. Four individuals with pathogenic variants arising from early somatic mutation events were found. Here we establish cardiac mosaicism as a causal mechanism for LQTS and present methods by which the general phenomenon, likely to be relevant for all genetic diseases, can be detected through single-cell analysis and next-generation sequencing.
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Brugada syndrome in the paediatric population: a comprehensive approach to clinical manifestations, diagnosis, and management. Cardiol Young 2016; 26:1044-55. [PMID: 27151277 DOI: 10.1017/s1047951116000548] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Brugada syndrome is an inherited arrhythmogenic disorder, characterised by coved-type ST-segment elevation in the right precordial leads, and is associated with increased risk of sudden death. It is genetically and clinically heterogeneous, presenting typically in the fourth or fifth decade of life. The prevalence of Brugada syndrome in the paediatric population is low compared with the adult population. Interestingly, over the last several years, there has been growing evidence in the literature of onset of the disease during childhood. Most of the paediatric cases reported in the literature consist of asymptomatic Brugada syndrome; however, some patients manifest the disease at different regions of the cardiac conduction system at a young age. Early expression of the disease can be affected by multiple factors, including genetic substrate, hormonal changes, and still unknown environmental exposures. The initial manifestation of Brugada syndrome in children can include sinus node dysfunction and atrial arrhythmias. Brugada syndrome can also manifest as ventricular arrhythmias leading to sudden death at an early age. In symptomatic children, performance of the ajmaline test by an experienced team can be safely used as a diagnostic tool to unmask latent Brugada syndrome. Defining indications for an implantable cardioverter defibrillator in children with the diagnosis of Brugada syndrome remains challenging. Given the rarity of the syndrome in children, most paediatric cardiologists will only rarely see a young patient with Brugada syndrome and there is still no universal consensus regarding the optimal management approach. Care should be individualised according to the specific clinical presentation, taking into account the family history, genetic data, and the family's specific preferences.
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Cuneo BF, Strasburger JF, Wakai RT. The natural history of fetal long QT syndrome. J Electrocardiol 2016; 49:807-813. [PMID: 27539165 DOI: 10.1016/j.jelectrocard.2016.07.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Indexed: 01/13/2023]
Abstract
INTRODUCTION Fetal magnetocardiography (fMCG), the magnetic analog of ECG, has provided invaluable insight into the mechanisms of fetal arrhythmias. In the past 15years, we have evaluated over 300 fetuses with arrhythmia by fMCG. We review the unique characteristics and natural history of the long QT syndrome (LQTS) rhythms. METHODS We reviewed the fMCGs of subjects referred with suspected LQTS based on either a positive family history or echo diagnosis of the LQTS rhythms (sinus bradycardia, ventricular tachycardia, or 2:1 AV conduction) to the Biomagnetism laboratory in the Department of Medical Physics, UW-Madison. We recorded fMCGs using a 37-channel (Magnes, 4D Neuroimaging, Inc., San Diego, CA) superconducting quantum interference device (SQUID) biomagnetometer, housed in a magnetically-shielded room for 1200-6000s. Signal processing was used to remove maternal interference. Cardiac intervals (R-R, p, QRS, QT) were measured and compared to published normals. We correlated fetal heart rate (FHR) patterns and effects of fetal movement on FHR and rhythm using actocardiography. RESULTS Thirty-nine fetuses were studied at a mean of 28 (19-38) weeks of gestation. All had structurally normal hearts. One was on amiodarone for suspected supraventricular tachycardia and hydrops. Five had serial fMCGs. Isolated sinus bradycardia with a QTc >490ms was found in 35: 33 had a KCNQ1 mutation There was one false positive and one false negative LQTS diagnosis. Four fetuses had torsades de pointes (TdP) and 3 had periods of 2:1 conduction and either KCNH2 or SCN5A mutations. TdP was rarely initiated with a preceding long-short pattern and did not degenerate into ventricular fibrillation. One fetus with TdP died in utero, 2 with fetal TdP had postnatal cardiac arrest. CONCLUSION Fetal LQTS is diagnosed by an fMCG QTc >490ms with an 89% sensitivity and specificity. TdP are seen with uncharacterized, KCNH2 or SCN5A R1623q mutations. Fetal TdP occurs when QTc ≥620ms. Identifying fetal LQTS and defining its rhythms by fMCG risk stratifies postnatal management.
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Affiliation(s)
- Bettina F Cuneo
- Children's Hospital Colorado, Department of Pediatrics, Heart Institute, University of Colorado School of Medicine, Aurora, CO.
| | - Janette F Strasburger
- Children's Hospital of Wisconsin Department of Pediatrics, Section of Cardiology, the Medical College of Wisconsin, Milwaukee, WI
| | - Ronald T Wakai
- The Biomagnetism Laboratory, Department of Medical Physics, University of Wisconsin, Madison, WI
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Abstract
PURPOSE OF REVIEW The purpose of this study is to update the perinatal cardiologist and obstetrical care provider on the presentation and management of the fetus with long QT syndrome (LQTS). RECENT FINDINGS LQTS is a known cause of sudden death in childhood, adolescence and young adulthood that presents during fetal life, but is often not recognized. Torsades de pointes (TdP) ±2° atrioventricular block (AVB) are not always attributed to LQTS, although the most common LQTS rhythm, a fetal heart rate of less than third percentile for gestational age (GA), is not recognized as abnormal because it does not meet the standard obstetrical criteria for bradycardia. Early recognition and appropriate treatment can be life saving for the fetus and unsuspecting LQTS family members. Fetal rhythm phenotype and postnatal QTc can predict postnatal rhythm and suggest genotype: bradycardic fetuses usually have KCNQ1 mutation, while those with TdP and/or a postnatal QTc more than 500 ms have SCN5A, KCNH2 or uncharacterized mutations. SUMMARY The fetus with repeated heart rates of less than third percentile of GA and those with TdP ±2° AVB are likely to manifest the same rhythm after birth and have an LQTS mutation.
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Anuwutnavin S, Wanitpongpan P, Chungsomprasong P, Soongswang J, Srisantiroj N, Wataganara T. Fetal long QT syndrome manifested as atrioventricular block and ventricular tachycardia: a case report and a review of the literature. Pediatr Cardiol 2014; 34:1955-62. [PMID: 22987108 DOI: 10.1007/s00246-012-0507-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 08/26/2012] [Indexed: 11/30/2022]
Abstract
Fetal onset of congenital long QT syndrome (LQTS) is a rare manifestation, and prenatal diagnosis is difficult. This report describes a boy who presented with both atrioventricular (AV) block and ventricular tachycardia during the antenatal period. The early postnatal electrocardiogram showed prolongation of the QT interval and AV block, subsequently leading to a polymorphic ventricular tachycardia torsade de pointes. This unique feature of congenital LQTS has a poor outcome, but the boy was successfully treated with beta-blockers and implantation of an automated cardioverter-defibrillator. The intrauterine manifestation of fetal AV block and ventricular tachycardia should raise a high suspicion of congenital LQTS, and the strong association with a malignant clinical course should warrant special evaluation. The literature on the prenatal diagnosis, fetal therapy, and neonatal outcome of this condition also are reviewed.
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Affiliation(s)
- Sanitra Anuwutnavin
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkoknoi, Bangkok, 10700, Thailand,
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Hasegawa K, Ohno S, Kimura H, Itoh H, Makiyama T, Yoshida Y, Horie M. Mosaic KCNJ2 mutation in Andersen-Tawil syndrome: targeted deep sequencing is useful for the detection of mosaicism. Clin Genet 2014; 87:279-83. [PMID: 24635491 DOI: 10.1111/cge.12357] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 01/28/2014] [Accepted: 02/05/2014] [Indexed: 11/29/2022]
Abstract
Andersen-Tawil syndrome (ATS) is an inherited disease characterized by ventricular arrhythmias, periodic paralysis, and dysmorphic features. It results from a heterozygous mutation of KCNJ2, but little is known about mosaicism in ATS. We performed genetic analysis of KCNJ2 in 32 ATS probands and their family members and identified KCNJ2 mutations in 25 probands, 20 families who underwent extensive genetic testing. These tests revealed that seven probands carried de novo mutations while 13 carried inherited mutations from their parents. We then specifically assessed a single proband and the respective family. The proband was a 9 year old girl who fulfilled the ATS triad and carried an insertion mutation (p.75_76insThr). We determined that the proband's mother carried a somatic mosaicism and that the proband's younger brother also carried the ATS phenotype with the same insertion mutation. The mother, who exhibited mosaicism, was asymptomatic, although she exhibited Q(T)U prolongation. Mutant allele frequency was 11% as per TA cloning and 17.3% as per targeted deep sequencing. Our observations suggest that targeted deep sequencing is useful for the detection of mosaicism and that the detection of mosaic mutations in parents of apparently sporadic ATS patients can help in the process of genetic counseling.
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Affiliation(s)
- K Hasegawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan; Department of Cardiovascular Biology and Medicine, Niigata University School of Medical and Dental Sciences, Niigata, Japan
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Bhuiyan ZA, Al-Shahrani S, Al-Aama J, Wilde AAM, Momenah TS. Congenital Long QT Syndrome: An Update and Present Perspective in Saudi Arabia. Front Pediatr 2013; 1:39. [PMID: 24400285 PMCID: PMC3864249 DOI: 10.3389/fped.2013.00039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/05/2013] [Indexed: 12/14/2022] Open
Abstract
Primary cardiac arrhythmias are often caused by defects, predominantly in the genes responsible for generation of cardiac electrical potential, i.e., cardiac rhythm generation. Due to the variability in underlying genetic defects, type, and location of the mutations and putative modifiers, clinical phenotypes could be moderate to severe, even absent in many individuals. Clinical presentation and severity could be quite variable, syncope, or sudden cardiac death could also be the first and the only manifestation in a patient who had previously no symptoms at all. Despite usual familial occurrence of such cardiac arrhythmias, disease causal genetic defects could also be de novo in significant number of patients. Long QT syndrome (LQTS) is the most eloquently investigated primary cardiac rhythm disorder. A genetic defect can be identified in ∼70% of definitive LQTS patients, followed by Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) and Brugada syndrome (BrS), where a genetic defect is found in <40% cases. In addition to these widely investigated hereditary arrhythmia syndromes, there remain many other relatively less common arrhythmia syndromes, where researchers also have unraveled the genetic etiology, e.g., short QT syndrome (SQTS), sick sinus syndrome (SSS), cardiac conduction defect (CCD), idiopathic ventricular fibrillation (IVF), early repolarization syndrome (ERS). There exist also various other ill-defined primary cardiac rhythm disorders with strong genetic and familial predisposition. In the present review we will focus on the genetic basis of LQTS and its clinical management. We will also discuss the presently available genetic insight in this context from Saudi Arabia.
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Affiliation(s)
- Zahurul A. Bhuiyan
- Laboratoire de Génétique Moléculaire, Service de Génétique Médicale, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Safar Al-Shahrani
- Department of Pediatrics, Faculty of Medicine, King Khalid University, Abha, Saudi Arabia
| | - Jumana Al-Aama
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders, Jeddah, Saudi Arabia
- Department of Genetic Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Arthur A. M. Wilde
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders, Jeddah, Saudi Arabia
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Tarek S. Momenah
- Department of Pediatric Cardiology, King Fahad Medical City, Riyadh, Saudi Arabia
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Crotti L, Tester DJ, White WM, Bartos DC, Insolia R, Besana A, Kunic JD, Will ML, Velasco EJ, Bair JJ, Ghidoni A, Cetin I, Van Dyke DL, Wick MJ, Brost B, Delisle BP, Facchinetti F, George AL, Schwartz PJ, Ackerman MJ. Long QT syndrome-associated mutations in intrauterine fetal death. JAMA 2013; 309:1473-82. [PMID: 23571586 PMCID: PMC3852902 DOI: 10.1001/jama.2013.3219] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Intrauterine fetal death or stillbirth occurs in approximately 1 out of every 160 pregnancies and accounts for 50% of all perinatal deaths. Postmortem evaluation fails to elucidate an underlying cause in many cases. Long QT syndrome (LQTS) may contribute to this problem. OBJECTIVE To determine the spectrum and prevalence of mutations in the 3 most common LQTS susceptible genes (KCNQ1, KCNH2, and SCN5A) for a cohort of unexplained cases. DESIGN, SETTING, AND PATIENTS In this case series, retrospective postmortem genetic testing was conducted on a convenience sample of 91 unexplained intrauterine fetal deaths (mean [SD] estimated gestational age at fetal death, 26.3 [8.7] weeks) that were collected from 2006-2012 by the Mayo Clinic, Rochester, Minnesota, or the Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. More than 1300 ostensibly healthy individuals served as controls. In addition, publicly available exome databases were assessed for the general population frequency of identified genetic variants. MAIN OUTCOMES AND MEASURES Comprehensive mutational analyses of KCNQ1 (KV7.1, LQTS type 1), KCNH2 (HERG/KV11.1, LQTS type 2), and SCN5A (NaV1.5, LQTS type 3) were performed using denaturing high-performance liquid chromatography and direct DNA sequencing on genomic DNA extracted from decedent tissue. Functional analyses of novel mutations were performed using heterologous expression and patch-clamp recording. RESULTS The 3 putative LQTS susceptibility missense mutations (KCNQ1, p.A283T; KCNQ1, p.R397W; and KCNH2 [1b], p.R25W), with a heterozygous frequency of less than 0.05% in more than 10 000 publicly available exomes and absent in more than 1000 ethnically similar control patients, were discovered in 3 intrauterine fetal deaths (3.3% [95% CI, 0.68%-9.3%]). Both KV7.1-A283T (16-week male) and KV7.1-R397W (16-week female) mutations were associated with marked KV7.1 loss-of-function consistent with in utero LQTS type 1, whereas the HERG1b-R25W mutation (33.2-week male) exhibited a loss of function consistent with in utero LQTS type 2. In addition, 5 intrauterine fetal deaths hosted SCN5A rare nonsynonymous genetic variants (p.T220I, p.R1193Q, involving 2 cases, and p.P2006A, involving 2 cases) that conferred in vitro electrophysiological characteristics consistent with potentially proarrhythmic phenotypes. CONCLUSIONS AND RELEVANCE In this molecular genetic evaluation of 91 cases of intrauterine fetal death, missense mutations associated with LQTS susceptibility were discovered in 3 cases (3.3%) and overall, genetic variants leading to dysfunctional LQTS-associated ion channels in vitro were discovered in 8 cases (8.8%). These preliminary findings may provide insights into mechanisms of some cases of stillbirth.
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Affiliation(s)
- Lia Crotti
- Department of Molecular Medicine, University of Pavia, and Molecular Cardiology Laboratory, Fondazione IRRCCS Policlinico S Matteo, Pavia, Italy
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Klassen TL, Drabek J, Tomson T, Sveinsson O, von Döbeln U, Noebels JL, Goldman AM. Visual automated fluorescence electrophoresis provides simultaneous quality, quantity, and molecular weight spectra for genomic DNA from archived neonatal blood spots. J Mol Diagn 2013; 15:283-90. [PMID: 23518217 DOI: 10.1016/j.jmoldx.2013.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/15/2013] [Accepted: 01/23/2013] [Indexed: 01/26/2023] Open
Abstract
The Guthrie 903 card archived dried blood spots (DBSs) are a unique but terminal resource amenable for individual and population-wide genomic profiling. The limited amounts of DBS-derived genomic DNA (gDNA) can be whole genome amplified, producing sufficient gDNA for genomic applications, albeit with variable success; optimizing the isolation of high-quality DNA from these finite, low-yield specimens is essential. Agarose gel electrophoresis and spectrophotometry are established postextraction quality control (QC) methods but lack the power to disclose detailed structural, qualitative, or quantitative aspects that underlie gDNA failure in downstream applications. Visual automated fluorescence electrophoresis (VAFE) is a novel QC technology that affords precise quality, quantity, and molecular weight of double-stranded DNA from a single microliter of sample. We extracted DNA from 3-mm DBSs archived in the Swedish Neonatal Repository for >30 years and performed the first quantitative and qualitative analyses of DBS-derived DNA on VAFE, before and after whole genome amplified, in parallel with traditional QC methods. The VAFE QC data were correlated with subsequent sample performance in PCR, sequencing, and high-density comparative genome hybridization array. We observed improved standardization of nucleic acid quantity, quality and integrity, and high performance in the downstream genomic technologies. Addition of VAFE measures in QC increases confidence in the validity of genetic data and allows cost-effective downstream analysis of gDNA for investigational and diagnostic applications.
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Affiliation(s)
- Tara L Klassen
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA.
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24
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Crotti L, Johnson CN, Graf E, De Ferrari GM, Cuneo BF, Ovadia M, Papagiannis J, Feldkamp MD, Rathi SG, Kunic JD, Pedrazzini M, Wieland T, Lichtner P, Beckmann BM, Clark T, Shaffer C, Benson DW, Kääb S, Meitinger T, Strom TM, Chazin WJ, Schwartz PJ, George AL. Calmodulin mutations associated with recurrent cardiac arrest in infants. Circulation 2013; 127:1009-17. [PMID: 23388215 DOI: 10.1161/circulationaha.112.001216] [Citation(s) in RCA: 271] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Life-threatening disorders of heart rhythm may arise during infancy and can result in the sudden and tragic death of a child. We performed exome sequencing on 2 unrelated infants presenting with recurrent cardiac arrest to discover a genetic cause. METHODS AND RESULTS We ascertained 2 unrelated infants (probands) with recurrent cardiac arrest and dramatically prolonged QTc interval who were both born to healthy parents. The 2 parent-child trios were investigated with the use of exome sequencing to search for de novo genetic variants. We then performed follow-up candidate gene screening on an independent cohort of 82 subjects with congenital long-QT syndrome without an identified genetic cause. Biochemical studies were performed to determine the functional consequences of mutations discovered in 2 genes encoding calmodulin. We discovered 3 heterozygous de novo mutations in either CALM1 or CALM2, 2 of the 3 human genes encoding calmodulin, in the 2 probands and in 2 additional subjects with recurrent cardiac arrest. All mutation carriers were infants who exhibited life-threatening ventricular arrhythmias combined variably with epilepsy and delayed neurodevelopment. Mutations altered residues in or adjacent to critical calcium binding loops in the calmodulin carboxyl-terminal domain. Recombinant mutant calmodulins exhibited several-fold reductions in calcium binding affinity. CONCLUSIONS Human calmodulin mutations disrupt calcium ion binding to the protein and are associated with a life-threatening condition in early infancy. Defects in calmodulin function will disrupt important calcium signaling events in heart, affecting membrane ion channels, a plausible molecular mechanism for potentially deadly disturbances in heart rhythm during infancy.
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Affiliation(s)
- Lia Crotti
- Section of Cardiology, Department of Molecular Medicine, University of Pavia, Pavia, Italy
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25
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Abriel H, Zaklyazminskaya EV. Cardiac channelopathies: genetic and molecular mechanisms. Gene 2012; 517:1-11. [PMID: 23266818 DOI: 10.1016/j.gene.2012.12.061] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/03/2012] [Indexed: 12/20/2022]
Abstract
Channelopathies are diseases caused by dysfunctional ion channels, due to either genetic or acquired pathological factors. Inherited cardiac arrhythmic syndromes are among the most studied human disorders involving ion channels. Since seminal observations made in 1995, thousands of mutations have been found in many of the different genes that code for cardiac ion channel subunits and proteins that regulate the cardiac ion channels. The main phenotypes observed in patients carrying these mutations are congenital long QT syndrome (LQTS), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), short QT syndrome (SQTS) and variable types of conduction defects (CD). The goal of this review is to present an update of the main genetic and molecular mechanisms, as well as the associated phenotypes of cardiac channelopathies as of 2012.
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Affiliation(s)
- Hugues Abriel
- Department of Clinical Research, University of Bern, Switzerland.
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26
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Wilders R. Cardiac ion channelopathies and the sudden infant death syndrome. ISRN CARDIOLOGY 2012; 2012:846171. [PMID: 23304551 PMCID: PMC3529486 DOI: 10.5402/2012/846171] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 10/23/2012] [Indexed: 12/13/2022]
Abstract
The sudden infant death syndrome (SIDS) causes the sudden death of an apparently healthy infant, which remains unexplained despite a thorough investigation, including the performance of a complete autopsy. The triple risk model for the pathogenesis of SIDS points to the coincidence of a vulnerable infant, a critical developmental period, and an exogenous stressor. Primary electrical diseases of the heart, which may cause lethal arrhythmias as a result of dysfunctioning cardiac ion channels (“cardiac ion channelopathies”) and are not detectable during a standard postmortem examination, may create the vulnerable infant and thus contribute to SIDS. Evidence comes from clinical correlations between the long QT syndrome and SIDS as well as genetic analyses in cohorts of SIDS victims (“molecular autopsy”), which have revealed a large number of mutations in ion channel-related genes linked to inheritable arrhythmogenic syndromes, in particular the long QT syndrome, the short QT syndrome, the Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. Combining data from population-based cohort studies, it can be concluded that at least one out of five SIDS victims carries a mutation in a cardiac ion channel-related gene and that the majority of these mutations are of a known malignant phenotype.
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Affiliation(s)
- Ronald Wilders
- Department of Anatomy, Embryology and Physiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands
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27
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Mitchell JL, Cuneo BF, Etheridge SP, Horigome H, Weng HY, Benson DW. Fetal Heart Rate Predictors of Long QT Syndrome. Circulation 2012; 126:2688-95. [DOI: 10.1161/circulationaha.112.114132] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background—
Fetal long QT syndrome (LQTS) is associated with complex arrhythmias including torsades de pointes and 2° atrioventricular block. Sinus bradycardia has also been associated with fetal LQTS, but little is known of this rhythm manifestation. Our purpose was to characterize the fetal heart rate (FHR)/gestational age (GA) profile of fetal LQTS.
Methods and Results—
We ascertained fetal LQTS subjects by family history (Group 1) or fetal arrhythmia referral (Group 2). We compared FHR in LQTS subjects versus normal fetuses. To identify FHR predictors of LQTS, we calculated a bradycardia index as % of LQTS FHR recordings either ≤110 beats per minute (obstetric standard) or ≤3
rd
percentile for GA. Among 42 LQTS subjects, 26 were in Group 1 and 16 in Group 2. There were 536 normal fetuses. The bradycardia index was only 15% for FHR ≤110 beats per minute, but 66% for FHR ≤3rd percentile for GA. Ten fetuses with complex arrhythmias also had severe and sustained sinus bradycardia throughout gestation. Identifying a fetal proband in Group 2 resulted in LQTS diagnosis in 9 unsuspected members of 6 families.
Conclusions—
FHR varies by GA in both normal and LQTS fetuses. Postnatal evaluation of neonates with FHR ≤3
rd
percentile for GA may improve ascertainment of LQTS in fetuses, neonates, and undiagnosed family members.
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Affiliation(s)
- Jason L. Mitchell
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Bettina F. Cuneo
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Susan P. Etheridge
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Hitoshi Horigome
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - Hsin-Yi Weng
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
| | - D. Woodrow Benson
- From the Heart Institute for Children, Oak Lawn, IL (J.L.M., B.F.C.); Primary Children's Medical Center, The University of Utah, Salt Lake City (S.P.E., H.-Y.W.); the Department of Pediatrics, University of Tskuba, Tskuba, Ibaraki, Japan (H.H.); and Cincinnati Children's Hospital Medical Center, The University of Cincinnati Medical School, Cincinnati, OH (D.W.B.)
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Chabaneix J, Andelfinger G, Fournier A, Fouron JC, Raboisson MJ. Prenatal diagnosis of long QT syndrome with the superior vena cava-aorta Doppler approach. Am J Obstet Gynecol 2012; 207:e3-7. [PMID: 22917482 DOI: 10.1016/j.ajog.2012.06.058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 06/15/2012] [Accepted: 06/29/2012] [Indexed: 10/28/2022]
Abstract
We describe a fetus at 36 weeks with long QT syndrome presenting with variable types of atrioventricular blocks, ventricular premature beats, and torsades de pointes. All these diagnoses were made with the superior vena cava-aorta Doppler approach and confirmed with postnatal electrocardiography.
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29
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Klassen TL, von Rüden EL, Drabek J, Noebels JL, Goldman AM. Comparative analytical utility of DNA derived from alternative human specimens for molecular autopsy and diagnostics. J Mol Diagn 2012; 14:451-7. [PMID: 22796560 PMCID: PMC5803546 DOI: 10.1016/j.jmoldx.2012.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 04/24/2012] [Accepted: 04/27/2012] [Indexed: 11/22/2022] Open
Abstract
Genetic testing and research have increased the demand for high-quality DNA that has traditionally been obtained by venipuncture. However, venous blood collection may prove difficult in special populations and when large-scale specimen collection or exchange is prerequisite for international collaborative investigations. Guthrie/FTA card-based blood spots, buccal scrapes, and finger nail clippings are DNA-containing specimens that are uniquely accessible and thus attractive as alternative tissue sources (ATS). The literature details a variety of protocols for extraction of nucleic acids from a singular ATS type, but their utility has not been systematically analyzed in comparison with conventional sources such as venous blood. Additionally, the efficacy of each protocol is often equated with the overall nucleic acid yield but not with the analytical performance of the DNA during mutation detection. Together with a critical in-depth literature review of published extraction methods, we developed and evaluated an all-inclusive approach for serial, systematic, and direct comparison of DNA utility from multiple biological samples. Our results point to the often underappreciated value of these alternative tissue sources and highlight ways to maximize the ATS-derived DNA for optimal quantity, quality, and utility as a function of extraction method. Our comparative analysis clarifies the value of ATS in genomic analysis projects for population-based screening, diagnostics, molecular autopsy, medico-legal investigations, or multi-organ surveys of suspected mosaicisms.
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Affiliation(s)
- Tara L. Klassen
- Department of Neurology, Baylor College of Medicine, Houston, Texas
| | - Eva-Lotta von Rüden
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University, Munich, Germany
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Janice Drabek
- Department of Neurology, Baylor College of Medicine, Houston, Texas
| | - Jeffrey L. Noebels
- Department of Neurology, Baylor College of Medicine, Houston, Texas
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Alica M. Goldman
- Department of Neurology, Baylor College of Medicine, Houston, Texas
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30
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Zaklyazminskaya EV, Abriel H. Prevalence of Significant Genetic Variants in Congenital Long QT Syndrome is Largely Underestimated. Front Pharmacol 2012; 3:72. [PMID: 22557970 PMCID: PMC3338122 DOI: 10.3389/fphar.2012.00072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 04/06/2012] [Indexed: 11/17/2022] Open
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31
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Wang T, Wehrens XHT. Enhanced impact of SCN5A mutation associated with long QT syndrome in fetal splice isoform. Heart Rhythm 2011; 9:598-9. [PMID: 22138134 PMCID: PMC4324321 DOI: 10.1016/j.hrthm.2011.11.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Indexed: 01/26/2023]
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Developmentally regulated SCN5A splice variant potentiates dysfunction of a novel mutation associated with severe fetal arrhythmia. Heart Rhythm 2011; 9:590-7. [PMID: 22064211 DOI: 10.1016/j.hrthm.2011.11.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Indexed: 11/23/2022]
Abstract
BACKGROUND Congenital long-QT syndrome (LQTS) may present during fetal development and can be life-threatening. The molecular mechanism for the unusual early onset of LQTS during fetal development is unknown. OBJECTIVE We sought to elucidate the molecular basis for severe fetal LQTS presenting at 19 weeks' gestation, the earliest known presentation of this disease. METHODS Fetal magnetocardiography was used to demonstrated torsades de pointes and a prolonged rate-corrected QT interval. In vitro electrophysiological studies were performed to determine functional consequences of a novel SCN5A mutation found in the fetus. RESULTS The fetus presented with episodes of ventricular ectopy progressing to incessant ventricular tachycardia and hydrops fetalis. Genetic analysis disclosed a novel, de novo heterozygous mutation (L409P) and a homozygous common variant (R558 in SCN5A). In vitro electrophysiological studies demonstrated that the mutation in combination with R558 caused significant depolarized shifts in the voltage dependence of inactivation and activation, faster recovery from inactivation, and a 7-fold higher level of persistent current. When the mutation was engineered in a fetal-expressed SCN5A splice isoform, channel dysfunction was markedly potentiated. Also, R558 alone in the fetal splice isoform evoked a large persistent current, and hence both alleles were dysfunctional. CONCLUSION We report the earliest confirmed diagnosis of symptomatic LQTS and present evidence that mutant cardiac sodium channel dysfunction is potentiated by a developmentally regulated alternative splicing event in SCN5A. Our findings provide a plausible mechanism for the unusual severity and early onset of cardiac arrhythmia in fetal LQTS.
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33
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Ichikawa Y, Iwamoto M, Yanagi S, Masuda M. Intrapericardial and retrocardial implantation of implantable cardioverter-defibrillator lead in a child with type 3 long QT syndrome. Pediatr Cardiol 2011; 32:1048-52. [PMID: 21818650 DOI: 10.1007/s00246-011-0065-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 07/09/2011] [Indexed: 11/29/2022]
Abstract
A 6-year-old girl with type 3 long QT syndrome was safely and successfully implanted with an implantable cardioverter-defibrillator (ICD) system. Prior to implantation, she had experienced uncontrollable life-threatening arrhythmia in spite of high-dose administration of mexiletine. An ICD coil lead for transvenous use was placed in the intrapericardial and retrocardial space and was connected to a generator placed in front of the posterior sheath of the right abdominal rectal muscle. Administration of a beta-blocker in addition to atrial pacing almost completely eliminated the patient's life-threatening arrhythmia attacks. Intrapericardial and retrocardial implantation of ICD coil leads might be useful for children.
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Affiliation(s)
- Yasuhiro Ichikawa
- Department of Pediatric Cardiology, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama City, Kanagawa 236-0004, Japan
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34
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Etheridge SP, Bowles NE, Arrington CB, Pilcher T, Rope A, Wilde AAM, Alders M, Saarel EV, Tavernier R, Timothy KW, Tristani-Firouzi M. Somatic mosaicism contributes to phenotypic variation in Timothy syndrome. Am J Med Genet A 2011; 155A:2578-83. [PMID: 21910241 DOI: 10.1002/ajmg.a.34223] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 06/30/2011] [Indexed: 11/07/2022]
Abstract
Timothy syndrome type 1 (TS-1) is a rare disorder that affects multiple organ systems and has a high incidence of sudden death due to profound QT prolongation and resultant ventricular arrhythmias. All previously described cases of TS-1 are the result of a missense mutation in exon 8A (p.G406R), an alternatively spliced variant of the L-type calcium channel gene (Ca(v)1.2, CACNA1C). Most patients reported in the literature represent highly affected individuals who present early in life with severe cardiac and neurological manifestations. Here, we describe somatic mosaicism in TS-1 patients with less severe manifestations than the typical TS-1 patient. These findings suggest that the TS prognosis may not be as dismal as previously reported. Moreover, our findings have implications for genetic counseling in that previously described de novo TS mutations may represent cases of parental mosaicism and warrant careful genotyping of parental tissue other than peripheral blood lymphocytes.
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Affiliation(s)
- Susan P Etheridge
- Division of Pediatric Cardiology, University of Utah, Salt Lake City, USA.
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35
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Tester DJ, Ackerman MJ. Genetic testing for potentially lethal, highly treatable inherited cardiomyopathies/channelopathies in clinical practice. Circulation 2011; 123:1021-37. [PMID: 21382904 PMCID: PMC3073829 DOI: 10.1161/circulationaha.109.914838] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- David J Tester
- Long QT Syndrome Clinic and the Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
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Abstract
The human fetal heart develops arrhythmias and conduction disturbances in response to ischemia, inflammation, electrolyte disturbances, altered load states, structural defects, inherited genetic conditions, and many other causes. Yet sinus rhythm is present without altered rate or rhythm in some of the most serious electrophysiological diseases, which makes detection of diseases of the fetal conduction system challenging in the absence of magnetocardiographic or electrocardiographic recording techniques. Life-threatening changes in QRS or QT intervals can be completely unrecognized if heart rate is the only feature to be altered. For many fetal arrhythmias, echocardiography alone can assess important clinical parameters for diagnosis. Appropriate treatment of the fetus requires awareness of arrhythmia characteristics, mechanisms, and potential associations. Criteria to define fetal bradycardia specific to gestational age are now available and may allow detection of ion channelopathies, which are associated with fetal and neonatal bradycardia. Ectopic beats, once thought to be entirely benign, are now recognized to have important pathologic associations. Fetal tachyarrhythmias can now be defined precisely for mechanism-specific therapy and for subsequent monitoring of response. This article reviews the current and future diagnostic techniques and pharmacologic treatments for fetal arrhythmia.
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37
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Chang B, Momoi N, Shan L, Mitomo M, Aoyagi Y, Endo K, Takeda I, Chen R, Xing Y, Yu X, Watanabe S, Yoshida T, Kanegane H, Tsubata S, Bowles NE, Ichida F, Miyawaki T. Gonadal mosaicism of a TAZ (G4.5) mutation in a Japanese family with Barth syndrome and left ventricular noncompaction. Mol Genet Metab 2010; 100:198-203. [PMID: 20303308 DOI: 10.1016/j.ymgme.2010.02.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 02/24/2010] [Accepted: 02/25/2010] [Indexed: 11/18/2022]
Abstract
TAZ (G4.5) was initially identified as the gene associated with Barth syndrome and left ventricular noncompaction (LVNC). The purpose of this study was to investigate patients with LVNC for disease-causing mutations in TAZ. In 124 Japanese patients, including 50 families, mutation analysis of TAZ was performed using DNA sequencing. A splice donor mutation was identified in two brothers with Barth syndrome and LVNC, and a sister who was asymptomatic. However, the variant was not identified in either parent or the maternal grandparents, all of whom were asymptomatic. Due to the recurrent inheritance of this variant by each of the children we concluded that this was evidence of gonadal mosaicism in the obligate carrier mother, the first reported occurrence of this in Barth syndrome.
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Affiliation(s)
- Bo Chang
- Department of Pediatrics, Toyama University, Sugitani, Toyama, Japan
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Nof E, Cordeiro JM, Pérez GJ, Scornik FS, Calloe K, Love B, Burashnikov E, Caceres G, Gunsburg M, Antzelevitch C. A common single nucleotide polymorphism can exacerbate long-QT type 2 syndrome leading to sudden infant death. ACTA ACUST UNITED AC 2010; 3:199-206. [PMID: 20181576 DOI: 10.1161/circgenetics.109.898569] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Identification of infants at risk for sudden arrhythmic death remains one of the leading challenges of modern medicine. We present a family in which a common polymorphism (single nucleotide polymorphism) inherited from the father, combined with a stop codon mutation inherited from the mother (both asymptomatic), led to 2 cases of sudden infant death. METHODS AND RESULTS KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, CACNA1c, CACNB2b, and KCNJ2 genes were amplified and analyzed by direct sequencing. Functional electrophysiological studies were performed with the single nucleotide polymorphism and mutation expressed singly and in combination in Chinese ovary (CHO-K1) and COS-1 cells. An asymptomatic woman presenting after the death of her 2-day-old infant and spontaneous abortion of a second baby in the first trimester was referred for genetic analysis. The newborn infant had nearly incessant ventricular tachycardia while in utero and a prolonged QTc (560 ms). The mother was asymptomatic but displayed a prolonged QTc. Genetic screening of the mother revealed a heterozygous nonsense mutation (P926AfsX14) in KCNH2, predicting a stop codon. The father was asymptomatic with a normal QTc but had a heterozygous polymorphism (K897T) in KCNH2. The baby who died at 2 days of age and the aborted fetus inherited both K897T and P926AfsX14. Heterologous coexpression of K897T and P926AfsX14 led to loss of function of HERG current much greater than expression of K897T or P926AfsX14 alone. CONCLUSIONS Our data suggest that a common polymorphism (K897T) can markedly accentuate the loss of function of mildly defective HERG channels, leading to long-QT syndrome-mediated arrhythmias and sudden infant death.
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Affiliation(s)
- Eyal Nof
- Masonic Medical Research Laboratory, Utica, NY 13501, USA
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39
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Hedley PL, Jørgensen P, Schlamowitz S, Wangari R, Moolman-Smook J, Brink PA, Kanters JK, Corfield VA, Christiansen M. The genetic basis of long QT and short QT syndromes: A mutation update. Hum Mutat 2009; 30:1486-511. [DOI: 10.1002/humu.21106] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tfelt-Hansen J, Winkel BG, Grunnet M, Jespersen T. Inherited cardiac diseases caused by mutations in the Nav1.5 sodium channel. J Cardiovasc Electrophysiol 2009; 21:107-15. [PMID: 19845816 DOI: 10.1111/j.1540-8167.2009.01633.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A prerequisite for a normal cardiac function is a proper generation and propagation of electrical impulses. Contraction of the heart is obtained through a delicate matched transmission of the electrical impulses. A pivotal element of the impulse propagation is the depolarizing sodium current, responsible for the initial depolarization of the cardiomyocytes. Recent research has shown that mutations in the SCN5A gene, encoding the cardiac sodium channel Nav1.5, are associated with both rare forms of ventricular arrhythmia, as well as the most frequent form of arrhythmia, atrial fibrillation (AF). In this comprehensive review, we describe the functional role of Nav1.5 and its associated proteins in propagation and depolarization both in a normal- and in a pathophysiological setting. Furthermore, several of the arrhythmogenic diseases, such as long-QT syndrome, Brugada syndrome, and AF, reported to be associated with mutations in SCN5A, are thoroughly described.
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Affiliation(s)
- Jacob Tfelt-Hansen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark.
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Simpson JM, Maxwell D, Rosenthal E, Gill H. Fetal ventricular tachycardia secondary to long QT syndrome treated with maternal intravenous magnesium: case report and review of the literature. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2009; 34:475-480. [PMID: 19731233 DOI: 10.1002/uog.6433] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ventricular tachycardia is a very rare fetal arrhythmia accounting for fewer than 2% of fetal tachycardias. We describe a fetus presenting at 30 weeks' gestation with ventricular tachycardia at a rate of 220 beats per min and fetal hydrops. The tachycardia was unresponsive to flecainide but was controlled within 12 h by an intravenous infusion of magnesium to the mother. Despite rapid control of the arrhythmia the fetus developed severe periventricular leukomalacia before birth for which a poor neurological prognosis was given. The baby was delivered preterm at 32 weeks' gestation and died on the sixth day after birth. Long QT syndrome was identified postnatally on the electrocardiogram, and was confirmed by genetic testing which showed a mutation in the KCNH2 gene (p.T613M).
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Affiliation(s)
- J M Simpson
- Department of Congenital Heart Disease, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK.
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42
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A novel SCN5A mutation associated with the linker between III and IV domains of Nav1.5 in a neonate with fatal long QT syndrome. Int J Cardiol 2009; 145:61-4. [PMID: 19419784 DOI: 10.1016/j.ijcard.2009.04.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 04/11/2009] [Indexed: 11/23/2022]
Abstract
A male newborn weighing 2334 g was delivered at 37 weeks of gestation by caesarean section because of prenatal ultrasound findings of fetal hydrops with atrioventricualr block, ventriucular tachycardia (VT), and impaired ventricular function. In spite of the intravenous administration of lidocaine, VT continued. He developed poor perfusion and systemic hypotension. After the intravenous administration of amiodarone, VT was terminated. The electrocardiogram revealed an extremely prolonged corrected QT interval (860 ms) with 2:1 atrioventricular block. Unfortunately, he died 18 h after birth in spite of the administration of lidocaine, beta-blocker and magnesium. Mutational analysis identified a novel heterozygous de novo mutation (F1486del) in SCN5A. This mutation is associated with the IFM motif in the linker between III and IV domains of Na(v)1.5, which serves as an inactivation particle binding within the pore of sodium channels. This report demonstrates an interesting relationship between the clinical phenotype and the location of the mutation in long QT syndrome.
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Wang DW, Crotti L, Shimizu W, Pedrazzini M, Cantu F, De Filippo P, Kishiki K, Miyazaki A, Ikeda T, Schwartz PJ, George AL. Malignant perinatal variant of long-QT syndrome caused by a profoundly dysfunctional cardiac sodium channel. Circ Arrhythm Electrophysiol 2008; 1:370-8. [PMID: 19808432 DOI: 10.1161/circep.108.788349] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Inherited cardiac arrhythmia susceptibility contributes to sudden death during infancy and may contribute to perinatal and neonatal mortality, but the molecular basis of this risk and the relationship to genetic disorders presenting later in life is unclear. We studied the functional and pharmacological properties of a novel de novo cardiac sodium channel gene (SCN5A) mutation associated with an extremely severe perinatal presentation of long-QT syndrome in unrelated probands of different ethnicity. METHODS AND RESULTS Two subjects exhibiting severe fetal and perinatal ventricular arrhythmias were screened for SCN5A mutations, and the functional properties of a novel missense mutation (G1631D) were determined by whole-cell patch clamp recording. In vitro electrophysiological studies revealed a profound defect in sodium channel function characterized by approximately 10-fold slowing of inactivation, increased persistent current, slowing of recovery from inactivation, and depolarized voltage dependence of activation and inactivation. Single-channel recordings demonstrated increased frequency of late openings, prolonged mean open time, and increased latency to first opening for the mutant. Subjects carrying this mutation responded clinically to the combination of mexiletine with propranolol and survived. Pharmacologically, the mutant exhibited 2-fold greater tonic and use-dependent mexiletine block than wild-type channels. The mutant also exhibited enhanced tonic (2.4-fold) and use-dependent block ( approximately 5-fold) by propranolol, and we observed additive effects of the 2 drugs on the mutant. CONCLUSIONS Our study demonstrates the molecular basis for a malignant perinatal presentation of long-QT syndrome, illustrates novel functional and pharmacological properties of SCN5A-G1631D, which caused the disorder, and reveals therapeutic benefits of propranolol block of mutant sodium channels in this setting.
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Affiliation(s)
- Dao W Wang
- Department of Medicine, Vanderbilt University, Nashville, TN 37232-0275, USA
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Antenatal presentation of congenital long QT syndrome: A prenatal diagnosis not to be missed. Pediatr Cardiol 2008; 29:1131-2. [PMID: 18661168 DOI: 10.1007/s00246-008-9271-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 06/30/2008] [Indexed: 10/21/2022]
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Patel C, Antzelevitch C. Pharmacological approach to the treatment of long and short QT syndromes. Pharmacol Ther 2008; 118:138-51. [PMID: 18378319 DOI: 10.1016/j.pharmthera.2008.02.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 02/05/2008] [Indexed: 12/30/2022]
Abstract
Inherited channelopathies have received increasing attention in recent years. The past decade has witnessed impressive progress in our understanding of the molecular and cellular basis of arrhythmogenesis associated with inherited channelopathies. An imbalance in ionic forces induced by these channelopathies affects the duration of ventricular repolarization and amplifies the intrinsic electrical heterogeneity of the myocardium, creating an arrhythmogenic milieu. Today, many of the channelopathies have been linked to mutations in specific genes encoding either components of ion channels or membrane or regulatory proteins. Many of the channelopathies are genetically heterogeneous with a variable degree of expression of the disease. Defining the molecular basis of channelopathies can have a profound impact on patient management, particularly in cases in which genotype-specific pharmacotherapy is available. The long QT syndrome (LQTS) is one of the first identified and most studied channelopathies where abnormal prolongation of ventricular repolarization predisposes an individual to life threatening ventricular arrhythmia called Torsade de Pointes. On the other hand of the spectrum, molecular defects favoring premature repolarization lead to Short QT syndrome (SQTS), a recently described inherited channelopathy. Both of these channelopathies are associated with a high risk of sudden cardiac death due to malignant ventricular arrhythmia. Whereas pharmacological therapy is first line treatment for LQTS, defibrillators are considered as primary treatment for SQTS. This review provides a comprehensive review of the molecular genetics, clinical features, genotype-phenotype correlations and genotype-specific approach to pharmacotherapy of these two mirror-image channelopathies, SQTS and LQTS.
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Drake E, Preston R, Douglas J. Brief review: anesthetic implications of long QT syndrome in pregnancy. Can J Anaesth 2007; 54:561-72. [PMID: 17602043 DOI: 10.1007/bf03022321] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To review the effects of the long QT syndrome (LQTS) in the parturient and the current anesthetic management of patients with LQTS. SOURCE Relevant articles were obtained from a MEDLINE search spanning the years 1980-2006 and a PubMed search spanning the years 1949-2006. Bibliographies of retrieved articles were searched for additional articles. PRINCIPAL FINDINGS The prevalence of LQTS in the developed world is one per 1,100 to 3,000 of the population. Clinically, LQTS is characterized by syncope, cardiac arrest and occasionally, by a history of seizures. The QT interval can also be prolonged by drugs, electrolyte imbalances, toxins and certain medical conditions. Long QT syndrome patients are at risk of torsades de pointes and ventricular fibrillation. Medical management aims to reduce dysrhythmia frequency. The LQTS is subdivided into different groups (LQT1-6) depending on the cardiac ion channel abnormality. Torsades can be precipitated by adrenergic stimuli such as stress or pain (LQT1 and 2), sudden noises (LQT2) or whilst sleeping (LQT3). Patients with LQTS require careful anesthetic management as they are at high risk of torsades perioperatively despite minimal data on the effects of anesthetic agents on the QT interval. While information on effects of LQTS in pregnancy is limited, the incidence of dysrhythmia increases postpartum. Isolated case reports of patients with LQTS women highlight several peripartum dysrhythmias. CONCLUSION An understanding of LQTS and the associated risk factors contributing to dysrhythmias is important for anesthesthesiologists caring for parturients with LQTS.
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Affiliation(s)
- Elizabeth Drake
- Department of Anesthesia, BC Women's Hospital, Vancouver, British Columbia V6H 3N1, Canada.
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Papantoniou N, Katsoulis I, Papageorgiou I, Antsaklis A. Hereditary long QT syndrome in pregnancy: antenatal and intrapartum management options. J Matern Fetal Neonatal Med 2007; 20:419-21. [PMID: 17674248 DOI: 10.1080/14767050701286626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Long QT syndrome is a rare but severe cardiac arrhythmia. We report the antenatal and intrapartum management of a primigravida carrying the hereditary form of the disease and specifically the Romano-Ward syndrome. A multidisciplinary approach and close obstetric surveillance are mandatory for a good maternal and perinatal outcome. Follow-up of the neonate is equally important.
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Medeiros-Domingo A, Iturralde-Torres P, Ackerman MJ. Clínica y genética en el síndrome de QT largo. Rev Esp Cardiol 2007. [DOI: 10.1157/13108280] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Schwartz PJ, Crotti L. Can a Message From the Dead Save Lives?⁎⁎Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology. J Am Coll Cardiol 2007; 49:247-9. [PMID: 17222737 DOI: 10.1016/j.jacc.2006.10.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Heradien MJ, Goosen A, Crotti L, Durrheim G, Corfield V, Brink PA, Schwartz PJ. Does pregnancy increase cardiac risk for LQT1 patients with the KCNQ1-A341V mutation? J Am Coll Cardiol 2006; 48:1410-5. [PMID: 17010804 DOI: 10.1016/j.jacc.2006.05.060] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 04/21/2006] [Accepted: 05/31/2006] [Indexed: 11/15/2022]
Abstract
OBJECTIVES The purpose of this study was to assess the pregnancy-related cardiovascular risk in LQT1 patients. BACKGROUND Only 1 study addressed this issue in genotyped patients and reported that the highest risk is for LQT2 patients. METHODS This case-control study, performed in a cohort of patients from 22 families affected by LQT1 and all sharing the common KCNQ1-A341V mutation, involved 36 mutation carriers and 24 of their unaffected sisters for a total of 182 pregnancies. RESULTS There were 3 (2.6%) cardiac events (2 cardiac arrests) in the 115 LQT1 pregnancies. Because they occurred only among the 27 mothers with previous symptoms, all off-therapy, the risk for symptomatic patients is 11%, but decreases to 0 in symptomatic patients treated with beta-blockers. Carriers and control subjects did not differ for the incidence of miscarriage (10% vs. 15%). Cesarean sections (C-sections), elective or owing to fetal distress, were performed more often in carriers than in non-carriers (27% vs. 14%). Beta-blocker therapy did not influence the prevalence of fetal distress. Among the infants born to carriers, all those with fetal distress were carriers of the A341V mutation (10 of 10, 100%). Among the offspring of the carriers, 48 of 92 (52%) were mutation carriers, and of those, 15% died suddenly at age 14 +/- 6 years. CONCLUSIONS Women affected by the common KCNQ1-A341V mutation are at low risk for cardiac events during pregnancy and without excess risk of miscarriage; their infants delivered by C-section because of fetal distress are extremely likely to also be mutation carriers. Beta-blockers remain recommended. These conclusions likely apply to most LQT1 patients.
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Affiliation(s)
- Marshall J Heradien
- Department of Internal Medicine, University of Stellenbosch, Stellenbosch, South Africa
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