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Li Q, Wang YF, Wang B, Lv TT, Zhang P. Induced Pluripotent Stem Cells in Congenital Long QT Syndrome: Research Progress and Clinical Applications. Rev Cardiovasc Med 2025; 26:28251. [PMID: 40351699 PMCID: PMC12059747 DOI: 10.31083/rcm28251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2024] [Revised: 12/26/2024] [Accepted: 01/02/2025] [Indexed: 05/14/2025] Open
Abstract
Congenital long QT syndrome (LQTS) is a potentially life-threatening hereditary arrhythmia characterized by a prolonged QT interval on electrocardiogram (ECG) due to delayed ventricular repolarization. This condition predisposes individuals to severe arrhythmic events, including ventricular tachycardia and sudden cardiac death. Traditional approaches to LQTS research and treatment are limited by an incomplete understanding of its gene-specific pathophysiology, variable clinical presentation, and the challenges associated with developing effective, personalized therapies. Recent advances in human induced pluripotent stem cell (iPSC) technology have opened new avenues for elucidating LQTS mechanisms and testing therapeutic strategies. By generating cardiomyocytes from patient-specific iPSCs (iPSC-CMs), it is now possible to recreate the patient's genetic context and study LQTS in a controlled environment. This comprehensive review describes how iPSC technology deepens our understanding of LQTS and accelerates the development of tailored treatments, as well as ongoing challenges such as incomplete cell maturation and cellular heterogeneity.
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Affiliation(s)
- Qing Li
- School of Clinical Medicine, Tsinghua University, 100084 Beijing, China
| | - Yi-Fei Wang
- School of Clinical Medicine, Tsinghua University, 100084 Beijing, China
| | - Bin Wang
- School of Clinical Medicine, Tsinghua University, 100084 Beijing, China
| | - Ting-Ting Lv
- Department of Cardiology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, 102218 Beijing, China
| | - Ping Zhang
- School of Clinical Medicine, Tsinghua University, 100084 Beijing, China
- Department of Cardiology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, 102218 Beijing, China
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Ali M, Javeriya S, Ahmad MH, Babar I, Rehan MMB, Iman H, Saeed H. Jervell and Lange-Nielsen Syndrome (JLNS) in a 13-Year-Old Girl: A Rare Case Report. Clin Case Rep 2025; 13:e70426. [PMID: 40248607 PMCID: PMC12003554 DOI: 10.1002/ccr3.70426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2024] [Revised: 03/10/2025] [Accepted: 04/03/2025] [Indexed: 04/19/2025] Open
Abstract
JLNS is a rare genetic disorder characterized by congenital sensorineural hearing loss and a prolonged QTc interval, leading to life-threatening arrhythmias. Early diagnosis, beta-blocker therapy, lifestyle modifications, and consideration of ICD surgery are critical in managing sudden cardiac death risk.
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Affiliation(s)
- Masab Ali
- Department of Internal MedicinePunjab Medical CollegeFaisalabadPakistan
| | - Sana Javeriya
- Department of MedicineJiius Indian Institute of Medical Science and ResearchJalnaMaharashtraIndia
| | - Muhammad Husnain Ahmad
- Department of MedicineTentishev Satkynbai Memorial Asian Medical InstituteGagarinaKantKyrgyzstan
| | - Ilsa Babar
- Department of Internal MedicineKing Edward Medical UniversityLahorePakistan
| | | | - Hafiza Iman
- Department of Internal MedicinePunjab Medical CollegeFaisalabadPakistan
| | - Humza Saeed
- Department of Internal MedicineRawalpindi Medical UniversityRawalpindiPakistan
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Stava TT, Berge KE, Haugaa KH, Smedsrud MK, Leren TP, Bogsrud MP. Molecular genetics in 1991 arrhythmia probands and 2782 relatives in Norway: Results from 17 years of genetic testing in a national laboratory. Clin Genet 2024; 106:585-602. [PMID: 39073097 DOI: 10.1111/cge.14593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 07/03/2024] [Accepted: 07/11/2024] [Indexed: 07/30/2024]
Abstract
The aim of this study was to explore the prevalence of likely pathogenic or pathogenic variants and assess the diagnostic yield from genetic testing for cardiac arrhythmias in Norway since 2003. Data from 1991 probands and 2782 relatives were retrospectively collected from the laboratory information management system at Unit for Cardiac and Cardiovascular Genetics, Oslo University hospital. Of 1991 probands, 57.4% were females, age at genetic testing was 33.1 (±22.7) years, and 32.5% were under the age of 18. A likely pathogenic or pathogenic variant (including 14 novel) was detected in 15.4% in total. Of the 2782 relatives, 53.7% were females, age at genetic testing was 35.6 (±22.5) years, 27.3% were under the age of 18, and 45.3% carried the family variant. Probands and relatives combined, 1/3356 persons in the Norwegian population were heterozygous for an arrhythmia-causing variant. The founder variant p.Q530X (NM_000218.2: c.1588C>T) in KCNQ1 accounted for 34% of all variants in Norway. In conclusion, genetic testing provided a genetic basis of the arrhythmia in 15.4% of the probands. Familial cascade screening identified four times as many variant-positive relatives, allowing early detection and prompt stratification of arrhythmic risk of those variant carriers.
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Affiliation(s)
- Tonje Talsnes Stava
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Knut Erik Berge
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Kristina Hermann Haugaa
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Marit Kristine Smedsrud
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Department of Paediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Trond P Leren
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Martin Prøven Bogsrud
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
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Morgat C, Fressart V, Porretta AP, Neyroud N, Messali A, Temmar Y, Algalarrondo V, Surget E, Bloch A, Leenhardt A, Denjoy I, Extramiana F. Genetic characterization of KCNQ1 variants improves risk stratification in type 1 long QT syndrome patients. Europace 2024; 26:euae136. [PMID: 38825991 PMCID: PMC11203906 DOI: 10.1093/europace/euae136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 05/21/2024] [Indexed: 06/04/2024] Open
Abstract
AIMS KCNQ1 mutations cause QTc prolongation increasing life-threatening arrhythmias risks. Heterozygous mutations [type 1 long QT syndrome (LQT1)] are common. Homozygous KCNQ1 mutations cause type 1 Jervell and Lange-Nielsen syndrome (JLNS) with deafness and higher sudden cardiac death risk. KCNQ1 variants causing JLNS or LQT1 might have distinct phenotypic expressions in heterozygous patients. The aim of this study is to evaluate QTc duration and incidence of long QT syndrome-related cardiac events according to genetic presentation. METHODS AND RESULTS We enrolled LQT1 or JLNS patients with class IV/V KCNQ1 variants from our inherited arrhythmia clinic (September 1993 to January 2023). Medical history, ECG, and follow-up were collected. Additionally, we conducted a thorough literature review for JLNS variants. Survival curves were compared between groups, and multivariate Cox regression models identified genetic and clinical risk factors. Among the 789 KCNQ1 variant carriers, 3 groups were identified: 30 JLNS, 161 heterozygous carriers of JLNS variants (HTZ-JLNS), and 550 LQT1 heterozygous carriers of non-JLNS variants (HTZ-Non-JLNS). At diagnosis, mean age was 3.4 ± 4.7 years for JLNS, 26.7 ± 21 years for HTZ-JLNS, and 26 ± 21 years for HTZ-non-JLNS; 55.3% were female; and the mean QTc was 551 ± 54 ms for JLNS, 441 ± 32 ms for HTZ-JLNS, and 467 ± 36 ms for HTZ-Non-JLNS. Patients with heterozygous JLNS mutations (HTZ-JLNS) represented 22% of heterozygous KCNQ1 variant carriers and had a lower risk of cardiac events than heterozygous non-JLNS variant carriers (HTZ-Non-JLNS) [hazard ratio (HR) = 0.34 (0.22-0.54); P < 0.01]. After multivariate analysis, four genetic parameters were independently associated with events: haploinsufficiency [HR = 0.60 (0.37-0.97); P = 0.04], pore localization [HR = 1.61 (1.14-1.2.26); P < 0.01], C-terminal localization [HR = 0.67 (0.46-0.98); P = 0.04], and group [HR = 0.43 (0.27-0.69); P < 0.01]. CONCLUSION Heterozygous carriers of JLNS variants have a lower risk of cardiac arrhythmic events than other LQT1 patients.
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Affiliation(s)
- Charles Morgat
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Véronique Fressart
- AP-HP, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Alessandra Pia Porretta
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
- Service of Cardiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Nathalie Neyroud
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France
| | - Anne Messali
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Yassine Temmar
- AP-HP, Unité Rythmologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Vincent Algalarrondo
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Elodie Surget
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Adrien Bloch
- AP-HP, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Antoine Leenhardt
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Isabelle Denjoy
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Fabrice Extramiana
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
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Neves R, Bains S, Bos JM, MacIntyre C, Giudicessi JR, Ackerman MJ. Precision therapy in congenital long QT syndrome. Trends Cardiovasc Med 2024; 34:39-47. [PMID: 35772688 DOI: 10.1016/j.tcm.2022.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/16/2022] [Accepted: 06/20/2022] [Indexed: 10/17/2022]
Abstract
Long QT syndrome (LQTS) is a potentially life-threatening, but highly treatable genetic heart disease. LQTS-directed therapies often consist of beta-blockers (BBs), left cardiac sympathetic denervation (LCSD), and/or an implantable cardioverter defibrillator (ICD). However, in clinical practice, many patient-specific and genotype-directed permutations exist. Herein, we aim to review the spectrum of treatment configurations utilized at a single, tertiary center specializing in the care of patients with LQTS to demonstrate optimal LQTS-directed management is not amenable to a "one-size-fits-all" approach but instead benefits from patient- and genotype-tailored strategies.
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Affiliation(s)
- Raquel Neves
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Department of Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), Mayo Clinic, Rochester, MN; Department of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN
| | - Sahej Bains
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Mayo Clinic Alix School of Medicine's Medical Scientist Training Program, Mayo Clinic, Rochester, MN
| | - J Martijn Bos
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Department of Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), Mayo Clinic, Rochester, MN; Department of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN
| | - Ciorsti MacIntyre
- Department of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN
| | - John R Giudicessi
- Department of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Department of Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), Mayo Clinic, Rochester, MN; Department of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN.
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Righi D, Porco L, Di Mambro C, Gnazzo M, Baban A, Paglia S, Silvetti MS, Novelli A, Tozzi AE, Drago F. Autosomal Recessive Long QT Syndrome: Clinical Aspects and Therapy. Pediatr Cardiol 2023; 44:1736-1740. [PMID: 37597120 DOI: 10.1007/s00246-023-03266-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/04/2023] [Indexed: 08/21/2023]
Abstract
The autosomal recessive (AR) form of Long QT Syndrome (LQTS) is described both associated with deafness known as Jervell and Lange-Nielsen (JLN) syndrome, and without deafness (WD). The aim of the study is to report the characteristics of AR LQTS patients and the efficacy of the therapy. Data of all children with AR LQTS referred to the Bambino Gesù Children's Hospital IRCCS from September 2012 to September 2021were included. Three (30%) patients had compound heterozygosity and 7 (70%) had homozygous variants of the KCNQ1 gene, the latter showing deafness. Four patients (40%) presented aborted sudden cardiac death (aSCD): three with previous episodes of syncope (75%), the other without previous symptoms (16.6% of asymptomatic patients). An episode of aSCD occurred in 2/3 (66.7%) of WD and heterozygous patients, while in 2/7 (28%) JLN and homozygous patients and in 2/2 patients with QTC > 600 ms. All patients were treated with Nadolol. In 5 Mexiletine was added, shortening QTc and obtaining the disappearance of the T-wave alternance (TWA) in 3/3. Episodes of aSCD seem to be more frequent in LQTS patients with compound heterozygous variants and WD than in those with JLN and homozygous variants. Episodes of aSCD also appear more frequent in children with syncope or with QTc value > 600 ms, even on beta-blocker therapy, than in patients without syncope or with Qtc < 600 ms. However, our descriptive results should be confirmed by larger studies. Moreover, Mexiletine addition reduced QTc value and eliminated TWA.
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Affiliation(s)
- Daniela Righi
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
| | - Luigina Porco
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Corrado Di Mambro
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Maria Gnazzo
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Anwar Baban
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Simone Paglia
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Massimo Stefano Silvetti
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Alberto Eugenio Tozzi
- Predictive and Preventive Medicine Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Fabrizio Drago
- Cardiac Arrhythmias Complex Unit, Department of Pediatric Cardiology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
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Satish H, Machireddy RR. Computational Study on Effect of KCNQ1 P535T Mutation in a Cardiac Ventricular Tissue. J Membr Biol 2023; 256:287-297. [PMID: 37166559 DOI: 10.1007/s00232-023-00287-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 04/20/2023] [Indexed: 05/12/2023]
Abstract
Heart diseases such as arrhythmia are the main causes of sudden death. Arrhythmias are typically caused by mutations in specific genes, damage in the cardiac tissue, or due to some chemical exposure. Arrhythmias caused due to mutation is called inherited arrhythmia. Induced arrhythmias are caused due to tissue damage or chemical exposure. Mutations in genes that encode ion channels of the cardiac cells usually result in (dysfunction) improper functioning of the channel. Improper functioning of the ion channel may lead to major changes in the action potential (AP) of the cardiac cells. This further leads to distorted electrical activity of the heart. Distorted electrical activity will affect the ECG that results in arrhythmia. KCNQ1 P535T mutation is one such gene mutation that encodes the potassium ion channel (KV7.1) of the cardiac ventricular tissue. Its clinical significance is not known. This study aims to perform a simulation study on P535T mutation in the KCNQ1 gene that encodes the potassium ion channel KV7.1 in the ventricular tissue grid. The effect of P535T mutation on transmural tissue grids for three genotypes (wild type, heterozygous, and homozygous) of cells are studied and the generated pseudo-ECGs are compared. Results show the delayed repolarization in the cells of ventricular tissue grid. Slower propagation of action potential in the transmural tissue grid is observed in the mutated (heterozygous and homozygous) genotypes. Longer QT interval is also observed in the pseudo-ECG of heterozygous and homozygous genotype tissue grids. From the pseudo-ECGs, it is observed that KCNQ1 P535T mutation leads to Long QT Syndrome (LQTS) which may result in life-threatening arrhythmias, such as Torsade de Pointes (TdP), Jervell and Lange-Nielsen syndrome (JLNS), and Romano-Ward syndrome (RWS).
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Affiliation(s)
- Helan Satish
- Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai, India.
| | - Ramasubba Reddy Machireddy
- Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai, India
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Rinné S, Oertli A, Nagel C, Tomsits P, Jenewein T, Kääb S, Kauferstein S, Loewe A, Beckmann BM, Decher N. Functional Characterization of a Spectrum of Novel Romano-Ward Syndrome KCNQ1 Variants. Int J Mol Sci 2023; 24:ijms24021350. [PMID: 36674868 PMCID: PMC9865342 DOI: 10.3390/ijms24021350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/20/2022] [Accepted: 12/23/2022] [Indexed: 01/13/2023] Open
Abstract
The KCNQ1 gene encodes the α-subunit of the cardiac voltage-gated potassium (Kv) channel KCNQ1, also denoted as Kv7.1 or KvLQT1. The channel assembles with the ß-subunit KCNE1, also known as minK, to generate the slowly activating cardiac delayed rectifier current IKs, a key regulator of the heart rate dependent adaptation of the cardiac action potential duration (APD). Loss-of-function variants in KCNQ1 cause the congenital Long QT1 (LQT1) syndrome, characterized by delayed cardiac repolarization and a QT interval prolongation in the surface electrocardiogram (ECG). Autosomal dominant loss-of-function variants in KCNQ1 result in the LQT syndrome called Romano-Ward syndrome (RWS), while autosomal recessive variants affecting function, lead to Jervell and Lange-Nielsen syndrome (JLNS), associated with deafness. The aim of this study was the characterization of novel KCNQ1 variants identified in patients with RWS to widen the spectrum of known LQT1 variants, and improve the interpretation of the clinical relevance of variants in the KCNQ1 gene. We functionally characterized nine human KCNQ1 variants using the voltage-clamp technique in Xenopus laevis oocytes, from which we report seven novel variants. The functional data was taken as input to model surface ECGs, to subsequently compare the functional changes with the clinically observed QTc times, allowing a further interpretation of the severity of the different LQTS variants. We found that the electrophysiological properties of the variants correlate with the severity of the clinically diagnosed phenotype in most cases, however, not in all. Electrophysiological studies combined with in silico modelling approaches are valuable components for the interpretation of the pathogenicity of KCNQ1 variants, but assessing the clinical severity demands the consideration of other factors that are included, for example in the Schwartz score.
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Affiliation(s)
- Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
| | - Annemarie Oertli
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
| | - Claudia Nagel
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Philipp Tomsits
- Department of Medicine I, University Hospital, LMU Munich, 80802 Munich, Germany
- Deutsches Zentrum für Herz-Kreislauferkrankungen (DZHK), Partner Site Munich, 80636 Munich, Germany
- Member of the European Reference Network for Rare, Low Prevalance and Complex Diseases of the Heart (ERN GUARD-Heart), 81377 Munich, Germany
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistrasse 27, 81377 Munich, Germany
| | - Tina Jenewein
- Institute of Legal Medicine, Goethe University, University Hospital Frankfurt, 60590 Frankfurt, Germany
- Institute for Transfusion Medicine and Immunohematology, German Red Cross Blood Service Baden-Württemberg-Hessen, Goethe University Frankfurt, 60528 Frankfurt, Germany
| | - Stefan Kääb
- Department of Medicine I, University Hospital, LMU Munich, 80802 Munich, Germany
- Deutsches Zentrum für Herz-Kreislauferkrankungen (DZHK), Partner Site Munich, 80636 Munich, Germany
- Member of the European Reference Network for Rare, Low Prevalance and Complex Diseases of the Heart (ERN GUARD-Heart), 81377 Munich, Germany
| | - Silke Kauferstein
- Institute of Legal Medicine, Goethe University, University Hospital Frankfurt, 60590 Frankfurt, Germany
- Deutsches Zentrum für Herz-Kreislauferkrankungen (DZHK), Partner Site Frankfurt, 60596 Frankfurt, Germany
| | - Axel Loewe
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Britt Maria Beckmann
- Department of Medicine I, University Hospital, LMU Munich, 80802 Munich, Germany
- Institute of Legal Medicine, Goethe University, University Hospital Frankfurt, 60590 Frankfurt, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
- Correspondence: ; Tel.: +49-(0)6421-28-62148
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Abstract
Long QT syndrome (LQTS) is a detrimental arrhythmia syndrome mainly caused by dysregulated expression or aberrant function of ion channels. The major clinical symptoms of ventricular arrhythmia, palpitations and syncope vary among LQTS subtypes. Susceptibility to malignant arrhythmia is a result of delayed repolarisation of the cardiomyocyte action potential (AP). There are 17 distinct subtypes of LQTS linked to 15 autosomal dominant genes with monogenic mutations. However, due to the presence of modifier genes, the identical mutation may result in completely different clinical manifestations in different carriers. In this review, we describe the roles of various ion channels in orchestrating APs and discuss molecular aetiologies of various types of LQTS. We highlight the usage of patient-specific induced pluripotent stem cell (iPSC) models in characterising fundamental mechanisms associated with LQTS. To mitigate the outcomes of LQTS, treatment strategies are initially focused on small molecules targeting ion channel activities. Next-generation treatments will reap the benefits from development of LQTS patient-specific iPSC platform, which is bolstered by the state-of-the-art technologies including whole-genome sequencing, CRISPR genome editing and machine learning. Deep phenotyping and high-throughput drug testing using LQTS patient-specific cardiomyocytes herald the upcoming precision medicine in LQTS.
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Singh SP, William M, Malavia M, Chu XP. Behavior of KCNQ Channels in Neural Plasticity and Motor Disorders. MEMBRANES 2022; 12:membranes12050499. [PMID: 35629827 PMCID: PMC9143857 DOI: 10.3390/membranes12050499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/26/2022] [Accepted: 05/03/2022] [Indexed: 02/01/2023]
Abstract
The broad distribution of voltage-gated potassium channels (VGKCs) in the human body makes them a critical component for the study of physiological and pathological function. Within the KCNQ family of VGKCs, these aqueous conduits serve an array of critical roles in homeostasis, especially in neural tissue. Moreover, the greater emphasis on genomic identification in the past century has led to a growth in literature on the role of the ion channels in pathological disease as well. Despite this, there is a need to consolidate the updated findings regarding both the pharmacotherapeutic and pathological roles of KCNQ channels, especially regarding neural plasticity and motor disorders which have the largest body of literature on this channel. Specifically, KCNQ channels serve a remarkable role in modulating the synaptic efficiency required to create appropriate plasticity in the brain. This role can serve as a foundation for clinical approaches to chronic pain. Additionally, KCNQ channels in motor disorders have been utilized as a direction for contemporary pharmacotherapeutic developments due to the muscarinic properties of this channel. The aim of this study is to provide a contemporary review of the behavior of these channels in neural plasticity and motor disorders. Upon review, the behavior of these channels is largely dependent on the physiological role that KCNQ modulatory factors (i.e., pharmacotherapeutic options) serve in pathological diseases.
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Precision Medicine Approaches to Cardiac Arrhythmias: JACC Focus Seminar 4/5. J Am Coll Cardiol 2021; 77:2573-2591. [PMID: 34016268 DOI: 10.1016/j.jacc.2021.03.325] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 12/15/2022]
Abstract
In the initial 3 papers in this Focus Seminar series, the fundamentals and key concepts of precision medicine were reviewed, followed by a focus on precision medicine in the context of vascular disease and cardiomyopathy. For the remaining 2 papers, we focus on precision medicine in the context of arrhythmias. Specifically, in this fourth paper we focus on long QT syndrome, Brugada syndrome, and atrial fibrillation. The final (fifth) paper will deal with catecholaminergic polymorphic ventricular tachycardia. These arrhythmias represent a spectrum of disease ranging from common to relatively rare, with very different genetic and environmental causative factors, and with differing clinical manifestations that range from almost no consequences to lethality in childhood or adolescence if untreated. Accordingly, the emerging precision medicine approaches to these arrhythmias vary significantly, but several common themes include increased use of genetic testing, avoidance of triggers, and personalized risk stratification to guide the use of arrhythmia-specific therapies.
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A cryptic splice-altering KCNQ1 variant in trans with R259L leading to Jervell and Lange-Nielsen syndrome. NPJ Genom Med 2021; 6:21. [PMID: 33664273 PMCID: PMC7933243 DOI: 10.1038/s41525-021-00183-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 01/25/2021] [Indexed: 11/19/2022] Open
Abstract
Here we report an infant with clinical findings suggestive of Jervell and Lange-Nielsen syndrome (JLNS), including a prolonged QT interval (LQTS) and chronic bilateral sensorineural deafness. NGS analysis revealed one known heterozygous pathogenic missense variant, KCNQ1 p.R259L, previously associated with LQTS but insufficient to explain the cardioauditory disorder. In a screening of proximal intronic regions, we found a heterozygous variant, KCNQ1 c.1686−9 T > C, absent from controls and previously undescribed. Several splicing prediction tools returned low scores for this intronic variant. Driven by the proband’s phenotype rather than the neutral predictions, we have characterized this rare intronic variant. Family analysis has shown that the proband inherited the missense and the intronic variants from his mother and father, respectively. A minigene splicing assay revealed that the intronic variant induced an additional transcript, arising from skipping of exon 14, which was translated into a truncated protein in transfected cells. The splice-out of exon 14 creates a frameshift in exon 15 and a stop codon in exon 16, which is the last exon of KCNQ1. This mis-spliced transcript is expected to escape nonsense-mediated decay and predicted to encode a truncated loss-of-function protein, KCNQ1 p.L563Kfs*73. The analysis of endogenous KCNQ1 expression in the blood of the proband’s parents detected the aberrant transcript only in the patient’s father. Taken together, these analyses confirmed the proband’s diagnosis of JLNS1 and indicated that c.1686−9 T > C is a cryptic splice-altering variant, expanding the known genetic spectrum of biallelic KCNQ1 variant combinations leading to JLNS1.
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13
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Molecular Mechanism of Autosomal Recessive Long QT-Syndrome 1 without Deafness. Int J Mol Sci 2021; 22:ijms22031112. [PMID: 33498651 PMCID: PMC7865240 DOI: 10.3390/ijms22031112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/16/2021] [Accepted: 01/19/2021] [Indexed: 11/16/2022] Open
Abstract
KCNQ1 encodes the voltage-gated potassium (Kv) channel KCNQ1, also known as KvLQT1 or Kv7.1. Together with its ß-subunit KCNE1, also denoted as minK, this channel generates the slowly activating cardiac delayed rectifier current IKs, which is a key regulator of the heart rate dependent adaptation of the cardiac action potential duration (APD). Loss-of-function mutations in KCNQ1 cause congenital long QT1 (LQT1) syndrome, characterized by a delayed cardiac repolarization and a prolonged QT interval in the surface electrocardiogram. Autosomal dominant loss-of-function mutations in KCNQ1 result in long QT syndrome, called Romano–Ward Syndrome (RWS), while autosomal recessive mutations lead to Jervell and Lange-Nielsen syndrome (JLNS), associated with deafness. Here, we identified a homozygous KCNQ1 mutation, c.1892_1893insC (p.P631fs*20), in a patient with an isolated LQT syndrome (LQTS) without hearing loss. Nevertheless, the inheritance trait is autosomal recessive, with heterozygous family members being asymptomatic. The results of the electrophysiological characterization of the mutant, using voltage-clamp recordings in Xenopus laevis oocytes, are in agreement with an autosomal recessive disorder, since the IKs reduction was only observed in homomeric mutants, but not in heteromeric IKs channel complexes containing wild-type channel subunits. We found that KCNE1 rescues the KCNQ1 loss-of-function in mutant IKs channel complexes when they contain wild-type KCNQ1 subunits, as found in the heterozygous state. Action potential modellings confirmed that the recessive c.1892_1893insC LQT1 mutation only affects the APD of homozygous mutation carriers. Thus, our study provides the molecular mechanism for an atypical autosomal recessive LQT trait that lacks hearing impairment.
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14
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Metcalfe C, Muzaffar J, Monksfield P, Bance M. Outcomes of Cochlear Implantation in Patients with Jervell and Lange-Nielsen Syndrome: A Systematic Review and Narrative Synthesis. J Int Adv Otol 2020; 16:456-462. [PMID: 33136028 DOI: 10.5152/iao.2020.9025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Establish outcomes following cochlear implantation (CI) in patients with Jervell and Lange-Nielsen Syndrome (JLNS). Methods Systematic review and narrative synthesis. Databases searched on Medline, Pubmed, Embase, Web of Science, Cochrane Collection and ClinicalTrials.gov. No limits placed on language or year of publication. Review conducted in accordance with the PRISMA statement. Searches identified 63 abstracts and 19 full texts. Of these, 9 studies met inclusion criteria reporting outcomes in 66 patients with at least 72 implants. Hearing outcomes were generally good. Mortality secondary to cardiac complications within the follow up period occurred in at least five cases (7.6%), though three of these were thought to be unrelated to surgery. Potentially dangerous arrhythmias without associated morbidity were also noted in at least five patients. The methodological quality of included studies was modest, predominantly consisting of case reports and non-controlled case series with small numbers of patients. All studies were OCEBM grade IV. One study contributed 41/66 patients (62%). Hearing outcomes following CI in JLNS are generally good with the majority of patients experiencing useful hearing improvement. Significant peri-operative cardiac risks exist and should be discussed with the patient and family during pre-operative counselling and prompt thorough investigation, pre-operative optimisation and peri-operative monitoring.
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Affiliation(s)
- Chris Metcalfe
- University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Bigmingham, UK
| | - Jameel Muzaffar
- University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Bigmingham, UK
| | - Peter Monksfield
- University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Bigmingham, UK
| | - Manohar Bance
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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15
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Jervell and Lange-Nielsen Syndrome due to a Novel Compound Heterozygous KCNQ1 Mutation in a Chinese Family. Neural Plast 2020; 2020:3569359. [PMID: 32508908 PMCID: PMC7246397 DOI: 10.1155/2020/3569359] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 05/02/2020] [Indexed: 11/24/2022] Open
Abstract
Jervell and Lange-Nielsen syndrome (JLNS) is a rare but severe autosomal recessive disease characterized by profound congenital deafness and a prolonged QTc interval (greater than 500 milliseconds) in the ECG waveforms. The prevalence of JLNS is about 1/1000000 to 1/200000 around the world. However, exceed 25% of JLNS patients suffered sudden cardiac death with kinds of triggers containing anesthesia. Approximately 90% of JLNS cases are caused by KCNQ1 gene mutations. Here, using next-generation sequencing (NGS), we identified a compound heterozygosity for two mutations c.1741A>T (novel) and c.477+5G>A (known) in KCNQ1 gene as the possible pathogenic cause of JLNS, which suggested a high risk of cardiac events in a deaf child. The hearing of this patient improved significantly with the help of cochlear implantation (CI). But life-threatening arrhythmias occurred with a trigger of anesthesia after the end of the CI surgery. Our findings extend the KCNQ1 gene mutation spectrum and contribute to the management of deaf children diagnosed with JLNS for otolaryngologists (especially cochlear implant teams).
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Ribes F, Marco A, Sánchez A. Response to ECG, December 2019. REVISTA ESPANOLA DE CARDIOLOGIA (ENGLISH ED.) 2020; 73:88. [PMID: 31882070 DOI: 10.1016/j.rec.2019.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Francisco Ribes
- Servicio de Cardiología, Hospital Universitario de Sant Joan, Sant Joan d'Alacant, Alicante, Spain.
| | - Antonio Marco
- Servicio de Cardiología, Hospital Universitario de Sant Joan, Sant Joan d'Alacant, Alicante, Spain
| | - Antonio Sánchez
- Sección de Cardiología Pediátrica, Servicio de Pediatría, Hospital Universitari i Politècnic La Fe, Valencia, Spain
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17
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Ribes F, Marco A, Sánchez A. Respuesta al ECG de diciembre de 2019. Rev Esp Cardiol (Engl Ed) 2020. [DOI: 10.1016/j.recesp.2019.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Marstrand P, Theilade J, Andersson C, Bundgaard H, Weeke PE, Tfelt-Hansen J, Jespersen C, Gislason G, Torp-Pedersen C, Kanters JK, Jørgensen ME. Long QT syndrome is associated with an increased burden of diabetes, psychiatric and neurological comorbidities: a nationwide cohort study. Open Heart 2019; 6:e001161. [PMID: 31749975 PMCID: PMC6827808 DOI: 10.1136/openhrt-2019-001161] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/03/2019] [Accepted: 10/08/2019] [Indexed: 12/19/2022] Open
Abstract
Objective Studies have suggested a shared genetic aetiology between congenital long QT syndrome (LQTS) and diabetes, epilepsy and mental disorders. We investigated the prevalence of metabolic, neurological and psychiatric comorbidities in LQTS patients. Methods This retrospective cohort study was based on data from nationwide Danish registries, 2003-2017. LQTS patients were matched 1:5 with controls on sex and age. Results We matched 463 LQTS patients with 2315 controls from the background population. Mean age was 35.7 (SD 21.0) years, and 38% were males in both groups. LQTS patients had a higher prevalence of atrial fibrillation (6.5% vs 2.3%, p<0.001), diabetes (3.7% vs 1.8 %, p=0.011) and hearing loss (3.2% vs 1.7%, p=0.027). LQTS patients had a higher prevalence of psychiatric disorders overall (13.0% vs 9.1%, p=0.01) but the difference could not be attributed to a specific psychiatric disease subgroup. LQTS patients had a higher prevalence of neurological disorders (22.0% vs 13.2%, p<0.001), largely driven by epilepsy (6.7% vs 1.6%, p<0.001). In 20/27 (74%) of the LQTS patients, the epilepsy diagnosis did not reappear in the registries after the LQTS diagnosis was established. Conclusions In this nationwide cohort, patients with LQTS had a significantly increased burden of diabetes, neurological and psychiatric comorbidities, compared with the background population. The higher prevalence of neurological comorbidities was largely driven by epilepsy, despite a high rate of potentially misdiagnosed patients prior to LQTS diagnosis. Our data support that LQTS may be considered a multiorgan disease and suggest that patient management should be adjusted accordingly.
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Affiliation(s)
- Peter Marstrand
- Department of Cardiology, Herlev-Gentofte Hospital, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Juliane Theilade
- Department of Cardiology, Herlev-Gentofte Hospital, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Charlotte Andersson
- Department of Cardiology, Herlev-Gentofte Hospital, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Henning Bundgaard
- Department of Cardiology, Rigshospitalet, University Hospital Copenhagen, Copenhagen, Denmark
| | - Peter E Weeke
- Department of Cardiology, Rigshospitalet, University Hospital Copenhagen, Copenhagen, Denmark
| | - Jacob Tfelt-Hansen
- Department of Cardiology, Rigshospitalet, University Hospital Copenhagen, Copenhagen, Denmark.,Department of Forensic Medicine, Faculty of Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Camilla Jespersen
- Department of Cardiology, Rigshospitalet, University Hospital Copenhagen, Copenhagen, Denmark
| | - Gunnar Gislason
- Department of Cardiology, Herlev-Gentofte Hospital, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Christian Torp-Pedersen
- Department of Health, Science and Technology, Aalborg University and Departments of Cardiology and Biostatistics/epidemiology, Aalborg University Hospital, Aalborg, Denmark
| | - Jørgen K Kanters
- Laboratory of Experimental Cardiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mads E Jørgensen
- Department of Cardiology, Herlev-Gentofte Hospital, University Hospital of Copenhagen, Copenhagen, Denmark
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19
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Amirian A, Zafari Z, Karimipoor M, Kordafshari A, Dalili M, Saber S, Fazelifar AF, Zeinali S. Identification of a Novel KCNQ1 Frameshift Mutation and Review of the Literature among Iranian Long QT Families. IRANIAN BIOMEDICAL JOURNAL 2019; 23. [PMID: 30797226 PMCID: PMC6462296 DOI: 10.29252/.23.3.228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background Long QT syndrome (LQTS) is characterized by the prolongation of QT interval, which results in syncope and sudden cardiac death in young people. KCNQ1 is the most common gene responsible for this syndrome. Methods Molecular investigation was performed by DNA Sanger sequencing in Iranian families with a history of syncope. In silico examinations were performed for predicting the pathogenicity of the novel variant. Results A novel homozygous KCNQ1 frameshift mutation, c.1426_1429delATGC (M476Pfs*4), was identified, and then the current literatures of five patients were reviewed regarding the LQTS. Conclusion The novel frameshift mutation has been reported for the first time among the Iranian population. Our finding along with the case series study of LQTS patients illustrates the importance of genetic and case series in precise detection of the frequency of LQTS carriers.
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Affiliation(s)
- Azam Amirian
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Zahra Zafari
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran,Department of Biology, Shahed University, Tehran, Iran
| | - Morteza Karimipoor
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Alireza Kordafshari
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Dalili
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Siamak Saber
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Amir Farjam Fazelifar
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical, and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sirous Zeinali
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran,Medical Genetics Laboratory, Kawsar Human Genetics Research Center, No. 41 Majlesi St., Vali Asr St., Tehran, Iran,Corresponding Authors: Sirous Zeinali Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, P. O. Box: 1316943551, Iran; Tel.: (+98-21) 66969293; E-mail:
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20
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Rediscovering the value of families for psychiatric genetics research. Mol Psychiatry 2019; 24:523-535. [PMID: 29955165 PMCID: PMC7028329 DOI: 10.1038/s41380-018-0073-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 01/11/2018] [Accepted: 03/26/2018] [Indexed: 01/09/2023]
Abstract
As it is likely that both common and rare genetic variation are important for complex disease risk, studies that examine the full range of the allelic frequency distribution should be utilized to dissect the genetic influences on mental illness. The rate limiting factor for inferring an association between a variant and a phenotype is inevitably the total number of copies of the minor allele captured in the studied sample. For rare variation, with minor allele frequencies of 0.5% or less, very large samples of unrelated individuals are necessary to unambiguously associate a locus with an illness. Unfortunately, such large samples are often cost prohibitive. However, by using alternative analytic strategies and studying related individuals, particularly those from large multiplex families, it is possible to reduce the required sample size while maintaining statistical power. We contend that using whole genome sequence (WGS) in extended pedigrees provides a cost-effective strategy for psychiatric gene mapping that complements common variant approaches and WGS in unrelated individuals. This was our impetus for forming the "Pedigree-Based Whole Genome Sequencing of Affective and Psychotic Disorders" consortium. In this review, we provide a rationale for the use of WGS with pedigrees in modern psychiatric genetics research. We begin with a focused review of the current literature, followed by a short history of family-based research in psychiatry. Next, we describe several advantages of pedigrees for WGS research, including power estimates, methods for studying the environment, and endophenotypes. We conclude with a brief description of our consortium and its goals.
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21
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Hylind RJ, Chandler SF, Skinner JR, Abrams DJ. Genetic Testing for Inherited Cardiac Arrhythmias: Current State-of-the-Art and Future Avenues. J Innov Card Rhythm Manag 2018; 9:3406-3416. [PMID: 32494476 PMCID: PMC7252877 DOI: 10.19102/icrm.2018.091102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 03/14/2018] [Indexed: 12/24/2022] Open
Abstract
The seminal discovery that sequence variation in genes encoding cardiac ion channels was behind the inherited cardiac arrhythmic syndromes has led to major advances in understanding the functional biological mechanisms of cardiomyocyte depolarization and repolarization. The cost and speed with which these genes can now be sequenced have allowed for genetic testing to become a major component of clinical care and have led to important ramifications, yet interpretation of specific variants needs to be performed within the context of the clinical findings in the proband and extended family. As technology continues to advance, the promise of therapeutic manipulation of certain genetic pathways grows ever more real.
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Affiliation(s)
- Robyn J. Hylind
- Inherited Cardiac Arrhythmia Program, Department of Cardiology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Stephanie F. Chandler
- Inherited Cardiac Arrhythmia Program, Department of Cardiology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Jonathan R. Skinner
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children’s Hospital, Auckland, New Zealand
- Department of Paediatrics, Child and Youth Health, The University of Auckland, Auckland, New Zealand
| | - Dominic J. Abrams
- Inherited Cardiac Arrhythmia Program, Department of Cardiology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
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22
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González A, Aurlien D, Haugaa KH, Taubøll E. Epilepsy in patients with long QT syndrome type 1: A Norwegian family. EPILEPSY & BEHAVIOR CASE REPORTS 2018; 10:118-121. [PMID: 30406014 PMCID: PMC6215028 DOI: 10.1016/j.ebcr.2018.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/10/2018] [Accepted: 09/11/2018] [Indexed: 01/19/2023]
Abstract
The congenital long QT syndrome (cLQTS) is an inherited cardiac disorder and is associated with sudden cardiac death. We describe a Norwegian family with mutations within the KCNQ1 gene causing cLQTS type 1 (LQT1) and epilepsy. The index patient had Jervell and Lange-Nielsen-syndrome (JLNS) with deafness and recurrent episodes of cardiac arrhythmia. The mother and the brother have Romano-Ward syndrome (RWS) with recurrent arrhythmias. Whereas the father has focal epilepsy and genetically verified LQT1, the sister has both focal epilepsy and RWS. Our findings are consistent with the notion that mutations in the KCNQ1 gene can cause epilepsy. Mutations in the LQTS1 gene are associated with syncopes and sudden cardiac death. Our case report suggest that these mutations can also cause genuine epilepsy. Correct identification of this dual pathology may be of vital importance to patients. cLQTS should be considered a cardiocerebral channelopathy.
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Affiliation(s)
- Alba González
- Department of Neurology, Oslo University Hospital - Rikshospitalet, PO Box 4950, Nydalen, 0424 Oslo, Norway.,Faculty of Medicine, University of Oslo, PO Box 1072, Blindern, 0316 Oslo, Oslo, Norway
| | - Dag Aurlien
- Neuroscience Research Group and Department of Neurology, Stavanger University Hospital, PO Box 8100, 4068 Stavanger, Norway
| | - Kristina H Haugaa
- Department of Cardiology, Oslo University Hospital - Rikshospitalet, PO Box 4950, Nydalen, 0424 Oslo, Norway.,Faculty of Medicine, University of Oslo, PO Box 1072, Blindern, 0316 Oslo, Oslo, Norway
| | - Erik Taubøll
- Department of Neurology, Oslo University Hospital - Rikshospitalet, PO Box 4950, Nydalen, 0424 Oslo, Norway.,Faculty of Medicine, University of Oslo, PO Box 1072, Blindern, 0316 Oslo, Oslo, Norway
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23
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Liu Z, Zheng R, Grushko MJ, Uversky VN, McDonald TV. Functionally Aberrant Mutant KCNQ1 With Intermediate Heterozygous and Homozygous Phenotypes. Can J Cardiol 2018; 34:1174-1184. [PMID: 30170673 DOI: 10.1016/j.cjca.2018.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 06/19/2018] [Accepted: 06/26/2018] [Indexed: 10/28/2022] Open
Abstract
BACKGROUND Deleterious mutations in KCNQ1 may lead to an autosomal dominant form of long QT syndrome (LQTS) (Romano-Ward) or autosomal recessive form (Jervell and Lange-Nielsen). Both are associated with severe ventricular tachyarrhythmias due to the reduction of the slowly activating delayed rectifier K+ current (IKs). Our objective was to investigate the functional consequences of KCNQ1-R562S mutation in an atypical form of KCNQ1-linked LQTS. METHODS Mutant KCNQ1-R562S was analyzed via confocal imaging, surface biotinylation assays, co-immunoprecipitation, phosphatidylinositol-4,5-bisphosphate pulldown test, whole-cell patch clamp, and computational intrinsic disorder analyses. RESULTS Protein expression, assembly with KCNE1, and trafficking to the surface membrane of KCNQ1-R562S were comparable with wild-type channels. The most significant functional effect of the R562S mutation was a depolarizing shift in the voltage dependence of activation that was dependent on association with KCNE1. The biophysical abnormality was only partially dominant over coexpressed wild-type channels. R562S mutation impaired C-terminal association with membrane phosphatidylinositol-4,5-bisphosphate. These changes led to compromised rate-related accumulation of repolarizing current that is an important property of normal IKs. CONCLUSIONS KCNQ1-R562S mutation reduces effective IKs due to channel gating alteration with a mild clinical expression in the heterozygous state due to minimal dominant phenotype. In the homozygous state, it is exhibited with a moderately severe LQTS phenotype due to the incomplete absence of IKs.
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Affiliation(s)
- Zhenning Liu
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Renjian Zheng
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
| | | | - Vladimir N Uversky
- Department of Molecular Medicine, and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Thomas V McDonald
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Cardiovascular Sciences, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA.
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24
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Amirian A, Zafari Z, Dalili M, Saber S, Karimipoor M, Dabbagh Bagheri S, Fazelifar AF, Zeinali S. Detection of a new KCNQ1 frameshift mutation associated with Jervell and Lange-Nielsen syndrome in 2 Iranian families. J Arrhythm 2018; 34:286-290. [PMID: 29951145 PMCID: PMC6010008 DOI: 10.1002/joa3.12042] [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] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/20/2018] [Indexed: 12/22/2022] Open
Abstract
Jervell-Lange Nielsen syndrome (JLNS) with autosomal recessive inheritance is a congenital cardiovascular disorder characterized by prolongation of QT interval on the ECG and deafness. We have performed molecular investigation by haplotype analysis and DNA Sanger sequencing in 2 unrelated Iranian families with a history of syncope. Mutational screening of KCNQ1 gene revealed the novel homozygous frameshift mutation c.733-734delGG (p.G245Rfs*39) in 2 obviously unrelated cases of JLNS which is probably a founder mutation in Iran. The novel mutation detected in this study is the first time reported among Iranian population and will be beneficial in the tribe and region-specific cascade screening of LQTS in Iran.
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Affiliation(s)
- Azam Amirian
- Biotechnology Research CenterPasteur Institute of IranTehranIran
| | - Zahra Zafari
- Department of Medical GeneticsFaculty of Medical SciencesTarbiat Modares UniversityTehranIran
| | - Mohammad Dalili
- Cardiac Electrophysiology Research CenterRajaie Cardiovascular Medical, and Research CenterIran University of Medical SciencesTehranIran
| | - Siamak Saber
- Cardiac Electrophysiology Research CenterRajaie Cardiovascular Medical, and Research CenterIran University of Medical SciencesTehranIran
| | | | | | - Amir Farjam Fazelifar
- Cardiac Electrophysiology Research CenterRajaie Cardiovascular Medical, and Research CenterIran University of Medical SciencesTehranIran
| | - Sirous Zeinali
- Biotechnology Research CenterPasteur Institute of IranTehranIran
- Medical Genetics LaboratoryKawsar Human Genetics Research CenterTehranIran
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25
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Giudicessi JR, Wilde AAM, Ackerman MJ. The genetic architecture of long QT syndrome: A critical reappraisal. Trends Cardiovasc Med 2018; 28:453-464. [PMID: 29661707 DOI: 10.1016/j.tcm.2018.03.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 12/19/2022]
Abstract
Collectively, the completion of the Human Genome Project and subsequent development of high-throughput next-generation sequencing methodologies have revolutionized genomic research. However, the rapid sequencing and analysis of thousands upon thousands of human exomes and genomes has taught us that most genes, including those known to cause heritable cardiovascular disorders such as long QT syndrome, harbor an unexpected background rate of rare, and presumably innocuous, non-synonymous genetic variation. In this Review, we aim to reappraise the genetic architecture underlying both the acquired and congenital forms of long QT syndrome by examining how the clinical phenotype associated with and background genetic variation in long QT syndrome-susceptibility genes impacts the clinical validity of existing gene-disease associations and the variant classification and reporting strategies that serve as the foundation for diagnostic long QT syndrome genetic testing.
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Affiliation(s)
- John R Giudicessi
- Department of Cardiovascular Medicine (Cardiovascular Diseases Fellowship and Clinician-Investigator Training Programs), Mayo Clinic, Rochester, MN, United States
| | - Arthur A M Wilde
- Department of Medicine (Division of Cardiology), Columbia University Irving Medical Center, New York, NY, United States; Department of Clinical & Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, United States.
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26
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A hERG mutation E1039X produced a synergistic lesion on I Ks together with KCNQ1-R174C mutation in a LQTS family with three compound mutations. Sci Rep 2018; 8:3129. [PMID: 29449639 PMCID: PMC5814447 DOI: 10.1038/s41598-018-21442-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 02/05/2018] [Indexed: 12/19/2022] Open
Abstract
Congenital long QT syndrome (LQTS) caused by compound mutations is usually associated with more severe clinical phenotypes. We identified a LQTS family harboring three compound mutations in different genes (KCNQ1-R174C, hERG-E1039X and SCN5A-E428K). KCNQ1-R174C, hERG-E1039X and SCN5A-E428K mutations and/or relevant wild-type (WT) cDNAs were respectively expressed in mammalian cells. IKs-like, IKr-like, INa-like currents and the functional interaction between KCNQ1-R174C and hERG-E1039X channels were studied using patch-clamp and immunocytochemistry techniques. (1) Expression of KCNQ1-R174C alone showed no IKs. Co-expression of KCNQ1-WT + KCNQ1-R174C caused a loss-of-function in IKs and blunted the activation of IKs in response to isoproterenol. (2) Expression of hERG-E1039X alone and co-expression of hERG-WT + hERG-E1039X negatively shifted inactivation curves and decelerated the recovery time from inactivation. (3) Expression of SCN5A-E428K increased peak INa, but had no effect on late INa. (4) IKs and IKr interact, and hERG-E1039X caused a loss-of-function in IKs. (5) Immunocytochemical studies indicated that KCNQ1-R174C is trafficking defective and hERG-E1039X is defective in biosynthesis/degradation, but the abnormities were rescued by co-expression with WT. Thus, KCNQ1-R174C and hERG-E1039X disrupted IKs and IKr functions, respectively. The synergistic lesion, caused by KCNQ1-R174C and hERG-E1039X in IKs, is very likely why patients showed more severe phenotypes in the compound mutation case.
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Amirian A, Dalili SM, Zafari Z, Saber S, Karimipoor M, Akbari V, Fazelifar AF, Zeinali S. Novel frameshift mutation in the KCNQ1 gene responsible for Jervell and Lange-Nielsen syndrome. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2018; 21:108-111. [PMID: 29372044 PMCID: PMC5776430 DOI: 10.22038/ijbms.2017.23207.5908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Objectives Jervell and Lange-Nielsen syndrome is an autosomal recessive disorder caused by mutations in KCNQ1 or KCNE1 genes. The disease is characterized by sensorineural hearing loss and long QT syndrome. Materials and Methods Here we present a 3.5-year-old female patient, an offspring of consanguineous marriage, who had a history of recurrent syncope and congenital sensorineural deafness. The patient and the family members were screened for mutations in KCNQ1 gene by linkage analysis and DNA sequencing. Results DNA sequencing showed a c.1532_1534delG (p. A512Pfs*81) mutation in the KCNQ1 gene in homozygous form. The results of short tandem repeat (STR) markers showed that the disease in the family is linked to the KCNQ1 gene. The mutation was confirmed in the parents in heterozygous form. Conclusion This is the first report of this variant in KCNQ1 gene in an Iranian family. The data of this study could be used for early diagnosis of the condition in the family and genetic counseling.
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Affiliation(s)
- Azam Amirian
- Molecular Medicine Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Seyed Mohammad Dalili
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zahra Zafari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Siamak Saber
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Morteza Karimipoor
- Molecular Medicine Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Vahid Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Amir Farjam Fazelifar
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sirous Zeinali
- Molecular Medicine Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.,Medical Genetics Laboratory, Kawsar Human Genetics Research Center, No. 41 Majlesi Street, Vali Asr Street, Tehran, Iran
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Natarajan P, Gold NB, Bick AG, McLaughlin H, Kraft P, Rehm HL, Peloso GM, Wilson JG, Correa A, Seidman JG, Seidman CE, Kathiresan S, Green RC. Aggregate penetrance of genomic variants for actionable disorders in European and African Americans. Sci Transl Med 2017; 8:364ra151. [PMID: 27831900 DOI: 10.1126/scitranslmed.aag2367] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 09/30/2016] [Indexed: 12/21/2022]
Abstract
In populations that have not been selected for family history of disease, it is unclear how commonly pathogenic variants (PVs) in disease-associated genes for rare Mendelian conditions are found and how often they are associated with clinical features of these conditions. We conducted independent, prospective analyses of participants in two community-based epidemiological studies to test the hypothesis that persons carrying PVs in any of 56 genes that lead to 24 dominantly inherited, actionable conditions are more likely to exhibit the clinical features of the corresponding diseases than those without PVs. Among 462 European American Framingham Heart Study (FHS) and 3223 African-American Jackson Heart Study (JHS) participants who were exome-sequenced, we identified and classified 642 and 4429 unique variants, respectively, in these 56 genes while blinded to clinical data. In the same participants, we ascertained related clinical features from the participants' clinical history of cancer and most recent echocardiograms, electrocardiograms, and lipid measurements, without knowledge of variant classification. PVs were found in 5 FHS (1.1%) and 31 JHS (1.0%) participants. Carriers of PVs were more likely than expected, on the basis of incidence in noncarriers, to have related clinical features in both FHS (80.0% versus 12.4%) and JHS (26.9% versus 5.4%), yielding standardized incidence ratios of 6.4 [95% confidence interval (CI), 1.7 to 16.5; P = 7 × 10-4) in FHS and 4.7 (95% CI, 1.9 to 9.7; P = 3 × 10-4) in JHS. Individuals unselected for family history who carry PVs in 56 genes for actionable conditions have an increased aggregated risk of developing clinical features associated with the corresponding diseases.
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Affiliation(s)
- Pradeep Natarajan
- Center for Human Genetic Research, Cardiovascular Research Center, and Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Nina B Gold
- Harvard Medical School, Boston, MA 02115, USA.,Boston Children's Hospital, Boston, MA 02115, USA
| | - Alexander G Bick
- Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Heather McLaughlin
- Harvard Medical School, Boston, MA 02115, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.,Partners HealthCare Personalized Medicine, Boston, MA 02115, USA
| | - Peter Kraft
- Departments of Epidemiology and Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Heidi L Rehm
- Harvard Medical School, Boston, MA 02115, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.,Partners HealthCare Personalized Medicine, Boston, MA 02115, USA
| | - Gina M Peloso
- Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - James G Wilson
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Adolfo Correa
- Departments of Pediatrics and Medicine, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Jonathan G Seidman
- Harvard Medical School, Boston, MA 02115, USA.,Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Christine E Seidman
- Harvard Medical School, Boston, MA 02115, USA.,Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sekar Kathiresan
- Center for Human Genetic Research, Cardiovascular Research Center, and Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Robert C Green
- Harvard Medical School, Boston, MA 02115, USA. .,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Partners HealthCare Personalized Medicine, Boston, MA 02115, USA.,Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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Uysal F, Turkgenc B, Toksoy G, Bostan OM, Evke E, Uyguner O, Yakicier C, Kayserili H, Cil E, Temel SG. "Homozygous, and compound heterozygous mutation in 3 Turkish family with Jervell and Lange-Nielsen syndrome: case reports". BMC MEDICAL GENETICS 2017; 18:114. [PMID: 29037160 PMCID: PMC5644177 DOI: 10.1186/s12881-017-0474-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/01/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Jervell and Lange-Nielsen syndrome (JLNS) isa recessive model of long QT syndrome which might also be related to possible hearing loss. Although the syndrome has been demonstrated to be originated from homozygous or compound heterozygous mutations in either the KCNQ1 or KCNE1 genes, additional mutations in other genetic loci should be considered, particularly in malignant course patients. CASE PRESENTATIONS Three patients were admitted into hospital due to recurrent seizures/syncope, intrauterine and postnatal bradycardia respectively; moreover all three patients had congenital sensorineural hearing-loss. Their electrocardiograms showed markedly prolonged QT interval. Implantable defibrillator was implanted and left cardiac sympathetic denervation was performed due to the progressive disease in case 1. She had countless ventricular fibrillation and appropriate shock while using an implantable defibrillator. The DNA sequencing analysis of the KCNQ1 gene disclosed a homozygous c.728G > A (p.Arg243His) missense mutation in case1. Further targeted next generation sequencing of cardiac panel comprising 68 gene revealed a heterozygous c.1346 T > G (p.Ile449Arg) variant in RYR2 gene and a heterozygous c.809G > A (p.Cys270Tyr) variant in NKX2-5 gene in the same patient. Additional gene alterations in RYR2 and NKX2-5 genes were thought to be responsible for progressive and malignant course of the disease. As a result of DNA sequencing analysis of KCNQ1 and KCNE1 genes, a compound heterozygosity for two mutations had been detected in KCNQ1 gene in case 2: a maternally derived c.477 + 1G > A splice site mutation and a paternally derived c.520C > T (p.Arg174Cys) missense mutation. Sanger sequencing of KCNQ1 and KCNE1 genes displayed a homozygous c.1097G > A (p.Arg366Gln) mutation in KCNQ1 gene in case 3. β-blocker therapy was initiated to all the index subjects. CONCLUSIONS Three families of JLNS who presented with long QT and deafness and who carry homozygous, or compound heterozygous mutation in KCNQ1 gene were presented in this report. It was emphasized that broad targeted cardiac panels may be useful to predict the outcome especially in patients with unexplained phenotype-genotype correlation. Clinical presentations and molecular findings will be discussed further to clarify the phenotype genotype associations.
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Affiliation(s)
- Fahrettin Uysal
- Department of Pediatric Cardiology, University of Uludag, School of Medicine, Bursa, Turkey
| | | | - Guven Toksoy
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
| | - Ozlem M. Bostan
- Department of Pediatric, Cardiology, Uludag University, Faculty of Medicine, Bursa, Turkey
| | - Elif Evke
- Bursa Genetic Diagnostic Center, Bursa, Turkey
| | - Oya Uyguner
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
| | - Cengiz Yakicier
- Acibadem Genetic Diagnostic Center, Istanbul, Turkey
- Department of Molecular Biology and Genetic, Acibadem University, Faculty of Science, Istanbul, Turkey
| | - Hulya Kayserili
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
- Department of Medical Genetics, Koc University, Faculty of Medicine, Istanbul, Turkey
| | - Ergun Cil
- Department of Pediatric, Cardiology, Uludag University, Faculty of Medicine, Bursa, Turkey
| | - Sehime G. Temel
- Department of Histology& Embryology, Near East University, Faculty of Medicine, Nicosia, North Cyprus
- Department of Medical Genetics, Uludag University, Faculty of Medicine, Bursa, Turkey
- Department of Histology & Embryology, Uludag University, Faculty of Medicine, Bursa, Turkey
- Gorukle campuss, Uludag University, School of Medicine, 16059, Nilufer, Bursa, Turkey
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Zafari Z, Dalili M, Zeinali S, Saber S, Fazeli Far AF, Akbari MT. Identification and characterization of a novel recessive KCNQ1 mutation associated with Romano-Ward Long-QT syndrome in two Iranian families. J Electrocardiol 2017; 50:912-918. [PMID: 29033053 DOI: 10.1016/j.jelectrocard.2017.07.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND One of the foremost causes of sudden cardiac death in the young is an inherent cardiac arrhythmia known as Long-QT syndrome (LQTS). Whereas heterozygous mutations typically lead to the Romano-Ward type of LQTS, We have provided a further evidence for the recessive transmission of a novel KCNQ1 gene mutation in two consanguineous families for the first time in Iran. METHODS Next generation sequencing, DNA Sanger sequencing and haplotype analysis were performed for genotype determination. Twelve different in silico tools were used for predicting the variant pathogenecity along with the family and population study. RESULTS A novel recessive KCNQ1 variant (p.D564G) was revealed in none of the unrelated healthy individuals but four patients in two apparently unrelated families. The variant was classified as a likely pathogenic mutation by combining the resulted criteria for the changed amino acid. CONCLUSIONS Identification of the novel mutation not only supports the genetic testing as a definitive diagnostic tool for detection of at risk family members, but also emphasizes its screening in Iranian LQTS patients as this mutation is very likely a founder mutation in Iran.
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Affiliation(s)
- Zahra Zafari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Dalili
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sirus Zeinali
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Siamak Saber
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Amir Farjam Fazeli Far
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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31
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Harmer SC, Tinker A. The impact of recent advances in genetics in understanding disease mechanisms underlying the long QT syndromes. Biol Chem 2017; 397:679-93. [PMID: 26910742 DOI: 10.1515/hsz-2015-0306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/18/2016] [Indexed: 11/15/2022]
Abstract
Long QT syndrome refers to a characteristic abnormality of the electrocardiogram and it is associated with a form of ventricular tachycardia known as torsade-de-pointes and sudden arrhythmic death. It can occur as part of a hereditary syndrome or can be acquired usually because of drug administration. Here we review recent genetic, molecular and cellular discoveries and outline how they have furthered our understanding of this disease. Specifically we focus on compound mutations, genome wide association studies of QT interval, modifier genes and the therapeutic implications of this recent work.
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Bdier AY, Al-Ghamdi S, Verma PK, Dagriri K, Alshehri B, Jiman OA, Ahmed SE, Wilde AAM, Bhuiyan ZA, Al-Aama JY. Autosomal recessive long QT syndrome, type 1 in eight families from Saudi Arabia. Mol Genet Genomic Med 2017; 5:592-601. [PMID: 28944242 PMCID: PMC5606890 DOI: 10.1002/mgg3.305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/18/2017] [Accepted: 05/22/2017] [Indexed: 01/08/2023] Open
Abstract
Background One of the most common primary cardiac arrhythmia syndromes is autosomal dominant long QT syndrome, type 1 (LQT1), chiefly caused by mono‐allelic mutations in the KCNQ1 gene. Bi‐allelic mutations in the KCNQ1 gene are causal to Jervell and Lange‐Nielsen syndrome (JLNS), characterized by severe and early‐onset arrhythmias with prolonged QTc interval on surface ECG and sensorineural deafness. Occasionally, bi‐allelic mutations in KCNQ1 are also found in patients without any deafness, referred to as autosomal recessive long QT syndrome, type 1 (AR LQT1). Methods We used Sanger sequencing to detect the pathogenic mutations in KCNQ1 gene in eight families from Saudi Arabia with autosomal recessive LQT1. Results We have detected pathogenic mutations in all eight families, two of the mutations are founder mutations, which are c.387‐5T>A and p.Val172Met/p.Arg293Cys (in cis). QTc and cardiac phenotype was found to be pronounced in all the probands comparable to the cardiac phenotype in JLNS patients. Heterozygous carriers for these mutations did not exhibit any clinical phenotype, but a significant number of them have sinus bradycardia. Conclusion To the best of our knowledge, this is the first description of a large series of patients with familial autosomal recessive LQT, type 1. These mutations could be used for targeted screening in cardiac arrhythmia patients in Saudi Arabia and in people of Arabic ancestry.
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Affiliation(s)
- Amnah Y Bdier
- Department of Biological SciencesFaculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia.,Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Saleh Al-Ghamdi
- Department of Genetic MedicineKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Prashant K Verma
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of CardiologyNGHRiyadhSaudi Arabia
| | - Khalid Dagriri
- Department of Pediatric CardiologyPrince Sultan Cardiac CenterRiyadhSaudi Arabia
| | - Bandar Alshehri
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Omamah A Jiman
- Department of Genetic MedicineKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Sherif E Ahmed
- Department of Biological SciencesFaculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia.,Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of GeneticsFaculty of AgricultureAin shams UniversityCairoEgypt
| | - Arthur A M Wilde
- Department of CardiologyAcademic Medical CenterUniversity of AmsterdamAmsterdamthe Netherlands
| | - Zahurul A Bhuiyan
- Laboratoire de Génétique MoléculaireService de médecine génétiqueCHUVLausanneSwitzerland
| | - Jumana Y Al-Aama
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of CardiologyNGHRiyadhSaudi Arabia
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Antúnez-Argüelles E, Rojo-Domínguez A, Arregui-Mena AL, Jacobo-Albavera L, Márquez MF, Iturralde-Torres P, Villarreal-Molina MT. Compound heterozygous KCNQ1 mutations (A300T/P535T) in a child with sudden unexplained death: Insights into possible molecular mechanisms based on protein modeling. Gene 2017; 627:40-48. [PMID: 28600177 DOI: 10.1016/j.gene.2017.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/18/2017] [Accepted: 06/05/2017] [Indexed: 11/26/2022]
Abstract
Sudden death in a child is a devastating event with important medical implications for surviving relatives. Because it may be the first manifestation of unknown inherited cardiac disease, molecular autopsy can be helpful to determine the cause of death and identify at risk family members. The aim of the study was to perform a molecular autopsy in a seven year-old girl with sudden unexplained death, to find evidence supporting the possible pathogenicity of mutations identified in inherited cardiac disease genes, and to clinically and genetically assess first-degree relatives. DNA from the index case was extracted from umbilical cord cells stored at birth, and DNA of first-degree relatives from blood samples. Targeted sequencing was performed using a Haloplex design including 81 cardiogenes. Possible functional consequences of the mutations were analyzed using protein modeling and structural mobility analyses. The child was compound heterozygous for KCNQ1 variants p.Ala300Thr and p.Pro535Thr. Ala300Thr is known to cause long QT syndrome in the homozygous state, while Pro535Thr is novel and of unknown clinical significance. The father and sibling were Ala300Thr heterozygous, and had normal QTc intervals at rest and during exercise. The asymptomatic mother was heterozygous for Pro535Thr, and showed borderline QTc at rest, but prolonged QTc during exercise. Protein modeling predicted that Ala300Thr alters the mobility profile of the Kv7.1 tetramer and Thr535 disrupts a calmodulin-binding site, probably causing co-assembly or trafficking defects of the mutant monomer. Altogether, the evidence strongly suggests that this child was affected with a recessive form of Romano Ward syndrome.
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Affiliation(s)
- Erika Antúnez-Argüelles
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico
| | - Arturo Rojo-Domínguez
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa, Mexico
| | - Ana Leticia Arregui-Mena
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa, Mexico
| | - Leonor Jacobo-Albavera
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico
| | - Manlio Fabio Márquez
- Departamento de Electrofisiología, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico
| | - Pedro Iturralde-Torres
- Departamento de Electrofisiología, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico
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Al-Hassnan ZN, Al-Fayyadh M, Al-Ghamdi B, Shafquat A, Mallawi Y, Al-Hadeq F, Tulbah S, Shinwari ZMA, Almesned A, Alakhfash A, Al Fadly F, Hersi AS, Alhayani A, Al-Hashem A, Arafah D, Dzimiri N, Meyer B, Rababh M, Al-Manea W. Clinical profile and mutation spectrum of long QT syndrome in Saudi Arabia: The impact of consanguinity. Heart Rhythm 2017; 14:1191-1199. [PMID: 28438721 DOI: 10.1016/j.hrthm.2017.04.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Congenital long QT syndrome (LQTS) is an inherited, potentially fatal arrhythmogenic disorder. At least 16 genes have been implicated in LQTS; the yield of genetic analysis of 3 genes (KCNQ1, KCNH2, and SCN5A) is about 70%, with KCNQ1 mutations accounting for ∼50% of positive cases. LQTS is mostly inherited in an autosomal dominant pattern. Systemic analysis of LQTS has not been previously conducted in a population with a high degree of consanguinity. OBJECTIVES To describe the clinical and molecular profiles of LQTS in the highly consanguineous Saudi population. METHODS Fifty-six Saudi families with LQTS were consecutively recruited and evaluated. Sequencing of KCNQ1, KCNH2, and SCN5A genes was conducted on all probands, followed by screening of family relatives. RESULTS Genetic analysis was positive in 32 (57.2%) families, with mutations in KCNQ1 identified in 28 families (50%). Surprisingly, 17 (53.1%) probands were segregating homozygous mutations. Family screening identified 123 individuals with mutations; 89 (72.4%) were heterozygous, 23 (18.7%) were homozygous, and 11 (8.9%) were compound heterozygous. Compared to heterozygous, the phenotype was more severe in homozygous individuals, with cardiac symptoms in 78.3% (vs 12.4%), family history of sudden death in 64.7% (vs 44.4%), and prolonged QT interval in 100% (vs 43.8%). Congenital deafness was found in 11 (47.8%) homozygous probands. CONCLUSION Our study provides insight into the clinical and molecular profiles of LQTS in a consanguineous population. It underscores the importance of preemptive management in homozygous patients with LQTS and the value of clinical and molecular screening of at-risk relatives.
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Affiliation(s)
- Zuhair N Al-Hassnan
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia; College of Medicine, Alfaisal University, Riyadh, Saudi Arabia; Department of Medical Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia.
| | - Majid Al-Fayyadh
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia; Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Bander Al-Ghamdi
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Azam Shafquat
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Yaseen Mallawi
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Faten Al-Hadeq
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Sahar Tulbah
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Zarghuna M A Shinwari
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | | | | | - Fadel Al Fadly
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Ahmed S Hersi
- Cardiac Sciences Department, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | | | - Amal Al-Hashem
- Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Dia Arafah
- Maternity and Children Hospital, Makkah, Saudi Arabia
| | - Nduna Dzimiri
- Department of Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Brian Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Monther Rababh
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Waleed Al-Manea
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
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The Jervell and Lange-Nielsen syndrome; atrial pacing combined with ß-blocker therapy, a favorable approach in young high-risk patients with long QT syndrome? Heart Rhythm 2016; 13:2186-2192. [DOI: 10.1016/j.hrthm.2016.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 11/17/2022]
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Kaya N, Alsagob M, D'Adamo MC, Al-Bakheet A, Hasan S, Muccioli M, Almutairi FB, Almass R, Aldosary M, Monies D, Mustafa OM, Alyounes B, Kenana R, Al-Zahrani J, Naim E, Binhumaid FS, Qari A, Almutairi F, Meyer B, Plageman TF, Pessia M, Colak D, Al-Owain M. KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability. J Med Genet 2016; 53:786-792. [PMID: 27582084 DOI: 10.1136/jmedgenet-2015-103637] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 07/20/2016] [Accepted: 08/06/2016] [Indexed: 12/24/2022]
Abstract
BACKGROUND Voltage-gated potassium channels are highly diverse proteins representing the most complex class of voltage-gated ion channels from structural and functional perspectives. Deficiency of these channels usually results in various human disorders. OBJECTIVES To describe a novel autosomal recessive syndrome associated with KCNA4 deficiency leading to congenital cataract, abnormal striatum, intellectual disability and attention deficit hyperactivity disorder. METHODS We used SNP arrays, linkage analyses, autozygosity mapping, whole-exome sequencing, RT-PCR and two-electrode voltage-clamp recording. RESULTS We identified a missense variant (p.Arg89Gln) in KCNA4 in four patients from a consanguineous family manifesting a novel syndrome of congenital cataract, abnormal striatum, intellectual disability and attention deficit hyperactivity disorder. The variant was fully segregated with the disease and absent in 747 ethnically matched exomes. Xenopus oocytes were injected with human Kv1.4 wild-type mRNA, R89Q and WT/R89Q channels. The wild type had mean current amplitude that was significantly greater than those recorded from the cells expressing the same amount of mutant mRNA. Co-expression of the wild type and mutant mRNAs resulted in mean current amplitude that was significantly different from that of the wild type. RT-PCR indicated that KCNA4 is present in mouse brain, lens and retina. KCNA4 interacts with several molecules including synaptotagmin I, DLG1 and DLG2. The channel co-localises with cholinergic amacrine and rod bipolar cells in rats and is widely distributed in the central nervous system. Based on previous studies, the channel is highly expressed in outer retina, rod inner segments, hippocampus and concentrated in axonal membranes. CONCLUSION KCNA4 (Kv1.4) is implicated in a novel syndrome characterised by striatal thinning, congenital cataract and attention deficit hyperactivity disorder. Our study highlights potassium channels' role in ocular and neuronal genetics.
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Affiliation(s)
- Namik Kaya
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Maysoon Alsagob
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Maria Cristina D'Adamo
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia School of Medicine, Perugia, Italy
| | - Albandary Al-Bakheet
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Sonia Hasan
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia School of Medicine, Perugia, Italy
| | - Maria Muccioli
- College of Optometry, The Ohio State University, Columbus, Ohio, USA
| | - Faten B Almutairi
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Rawan Almass
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Mazhor Aldosary
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Dorota Monies
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Osama M Mustafa
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.,College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Banan Alyounes
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Rosan Kenana
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Jawaher Al-Zahrani
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Eva Naim
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Faisal S Binhumaid
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Alya Qari
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Fatema Almutairi
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Brian Meyer
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | | | - Mauro Pessia
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia School of Medicine, Perugia, Italy.,Department of Physiology & Biochemistry Faculty of Medicine & Surgery, University of Malta, Msida, Malta
| | - Dilek Colak
- Department of Biostatistics, Epidemiology and Scientific Computing, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Mohammed Al-Owain
- College of Optometry, The Ohio State University, Columbus, Ohio, USA.,College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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Vyas B, Puri RD, Namboodiri N, Nair M, Sharma D, Movva S, Saxena R, Bohora S, Aggarwal N, Vora A, Kumar J, Singh T, Verma IC. KCNQ1 mutations associated with Jervell and Lange-Nielsen syndrome and autosomal recessive Romano-Ward syndrome in India-expanding the spectrum of long QT syndrome type 1. Am J Med Genet A 2016; 170:1510-9. [PMID: 27041150 DOI: 10.1002/ajmg.a.37636] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 03/07/2016] [Indexed: 01/07/2023]
Abstract
Long QT syndrome type 1 (LQT1) is the most common type of all Long QT syndromes (LQTS) and occurs due to mutations in KCNQ1. Biallelic mutations with deafness is called Jervell and Lange-Nielsen syndrome (JLNS) and without deafness is autosomal recessive Romano-Ward syndrome (AR RWS). In this prospective study, we report biallelic mutations in KCNQ1 in Indian patients with LQT1 syndrome. Forty patients with a clinical diagnosis of LQT1 syndrome were referred for molecular testing. Of these, 18 were excluded from the analysis as they did not fulfill the inclusion criteria of broad T wave ECG pattern of the study. Direct sequencing of KCNQ1 was performed in 22 unrelated probands, parents and at-risk family members. Mutations were identified in 17 patients, of which seven had heterozygous mutations and were excluded in this analysis. Biallelic mutations were identified in 10 patients. Five of 10 patients did not have deafness and were categorized as AR RWS, the rest being JLNS. Eight mutations identified in this study have not been reported in the literature and predicted to be pathogenic by in silico analysis. We hypothesize that the homozygous biallelic mutations identified in 67% of families was due to endogamous marriages in the absence of consanguinity. This study presents biallelic gene mutations in KCNQ1 in Asian Indian patients with AR JLNS and RWS. It adds to the scant worldwide literature of mutation studies in AR RWS. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Bijal Vyas
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Ratna D Puri
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Narayanan Namboodiri
- Department of Cardiology, Sree Chitra Institute for Medical Sciences & Technology, Kerala, India
| | - Mohan Nair
- Department of Cardiology, Holy Family Hospital, Delhi, India
| | - Deepak Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Sireesha Movva
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Renu Saxena
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Shomu Bohora
- Department of Cardiology, Baroda Heart Institute & Research Centre, Gujarat, India
| | - Neeraj Aggarwal
- Department of Paediatric Cardiology, Sir Ganga Ram Hospital, Delhi, India
| | - Amit Vora
- Department of Cardiology, Glenmark Cardiac Centre, Mumbai, Maharashtra, India
| | - Jatinder Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Tarandeep Singh
- Department of Cardiology, U N Mehta Institute of Cardiology & Research Centre, Gujarat, India
| | - Ishwar C Verma
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
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Ruwald MH, Xu Parks X, Moss AJ, Zareba W, Baman J, McNitt S, Kanters JK, Shimizu W, Wilde AA, Jons C, Lopes CM. Stop-codon and C-terminal nonsense mutations are associated with a lower risk of cardiac events in patients with long QT syndrome type 1. Heart Rhythm 2015; 13:122-31. [PMID: 26318259 DOI: 10.1016/j.hrthm.2015.08.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND In long QT syndrome type 1 (LQT1), the location and type of mutations have been shown to affect the clinical outcome. Although haploinsufficiency, including stop-codon and frameshift mutations, has been associated with a lower risk of cardiac events in patients with LQT1, nonsense mutations have been presumed functionally equivalent. OBJECTIVE The purpose of this study was to evaluate clinical differences between patients with nonsense mutations. METHODS The study sample comprised 1090 patients with genetically confirmed mutations. Patients were categorized into 5 groups, depending on mutation type and location: missense not located in the high-risk cytoplasmic loop (c-loop) (n = 698), which is used as reference; missense c-loop (n = 192); stop-codon (n = 67); frameshift (n = 39); and others (n = 94). The primary outcome was a composite end point of syncope, aborted cardiac arrest, and long QT syndrome-related death (cardiac events). Outcomes were evaluated using the multivariate Cox proportional hazards regression analysis. Standard patch clamp techniques were used. RESULTS Compared to patients with missense non-c-loop mutations, the risk of cardiac events was reduced significantly in patients with stop-codon mutations (hazard ratio [HR] 0.57; 95% confidence interval [CI] 0.34-0.96; P = .035), but not in patients with frameshift mutations (HR 1.01; 95% CI 0.58-1.77; P = .97). Our data suggest that currents of the most common stop-codon mutant channel (Q530X) were larger than those of haploinsufficient channels (wild type: 42 ± 6 pA/pF, n = 20; Q530X+wild type: 79 ± 14 pA/pF, n = 20; P < .05) and voltage dependence of activation was altered. CONCLUSION Stop-codon mutations are associated with a lower risk of cardiac events in patients with LQT1, while frameshift mutations are associated with the same risk as the majority of the missense mutations. Our data indicate functional differences between these previously considered equivalent mutation subtypes.
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Affiliation(s)
- Martin H Ruwald
- Heart Research Follow-up Program, Division of Cardiology, University of Rochester Medical Center, Rochester, New York; Department of Cardiology, Gentofte Hospital, Hellerup, Denmark
| | - Xiaorong Xu Parks
- Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York
| | - Arthur J Moss
- Heart Research Follow-up Program, Division of Cardiology, University of Rochester Medical Center, Rochester, New York
| | - Wojciech Zareba
- Heart Research Follow-up Program, Division of Cardiology, University of Rochester Medical Center, Rochester, New York
| | - Jayson Baman
- Heart Research Follow-up Program, Division of Cardiology, University of Rochester Medical Center, Rochester, New York
| | - Scott McNitt
- Heart Research Follow-up Program, Division of Cardiology, University of Rochester Medical Center, Rochester, New York
| | - Jorgen K Kanters
- Department of Cardiology, Gentofte Hospital, Hellerup, Denmark; Laboratory of Experimental Cardiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Arthur A Wilde
- AMC Heart Centre, Department of Clinical and Experimental Cardiology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Christian Jons
- Department of Cardiology, Gentofte Hospital, Hellerup, Denmark
| | - Coeli M Lopes
- Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York.
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Cellular mechanisms underlying the increased disease severity seen for patients with long QT syndrome caused by compound mutations in KCNQ1. Biochem J 2014; 462:133-42. [PMID: 24912595 DOI: 10.1042/bj20140425] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The KCNQ1 (potassium voltage-gated channel, KQT-like subfamily, member 1) gene encodes the Kv7.1 potassium channel which forms a complex with KCNE1 (potassium voltage-gated channel Isk-related family member 1) in the human heart to produce the repolarizing IKs (slow delayed rectifier potassium current). Mutations in KCNQ1 can perturb IKs function and cause LQT1 (long QT syndrome type 1). In LQT1, compound mutations are relatively common and are associated with increased disease severity. LQT1 compound mutations have been shown to increase channel dysfunction, but whether other disease mechanisms, such as defective channel trafficking, contribute to the increase in arrhythmic risk has not been determined. Using an imaging-based assay we investigated the effects of four compound heterozygous mutations (V310I/R594Q, A341V/P127T, T391I/Q530X and A525T/R518X), one homozygous mutation (W248F) and one novel compound heterozygous mutation (A178T/K422fs39X) (where fs denotes frameshift) on channel trafficking. By analysing the effects in the equivalent of a homozygous, heterozygous and compound heterozygous condition, we identify three different types of behaviour. A341V/P127T and W248F/W248F had no effect, whereas V310I/R594Q had a moderate, but not compound, effect on channel trafficking. In contrast, T391I/Q530X, A525T/R518X and A178T/K422fs39X severely disrupted channel trafficking when expressed in compound form. In conclusion, we have characterized the disease mechanisms for six LQT1 compound mutations and report that, for four of these, defective channel trafficking underlies the severe clinical phenotype.
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40
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Sung JY, Bae EJ, Park S, Kim SY, Hyun YJ, Park SS, Seong MW. Large deletion in KCNQ1 identified in a family with Jervell and Lange-Nielsen syndrome. Ann Lab Med 2014; 34:395-8. [PMID: 25187895 PMCID: PMC4151011 DOI: 10.3343/alm.2014.34.5.395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/23/2014] [Accepted: 06/24/2014] [Indexed: 11/19/2022] Open
Abstract
Long QT syndrome (LQTS) is a genetically heterogeneous disorder associated with sequence variations in more than 10 genes; in some cases, it is caused by large deletions or duplications among the main, known LQTS-associated genes. Here, we describe a 14-month-old Korean boy with congenital hearing loss and prolonged QT interval whose condition was clinically diagnosed as Jervell and Lange-Nielsen syndrome (JLNS), a recessive form of LQTS. Genetic analyses using sequence analysis and multiplex ligation-dependent probe amplification (MLPA) assay revealed a large deletion spanning exons 7-10 as well as a frameshift mutation (c.1893dup; p.Arg632Glnfs*20). To our knowledge, this is the first report of a large deletion in KCNQ1 identified in JLNS patients. This case indicates that a method such as MLPA, which can identify large deletions or duplications needs to be considered in addition to sequence analysis to diagnose JLNS.
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Affiliation(s)
- Ji Yeon Sung
- Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea
| | - Eun Jung Bae
- Department of Pediatrics, Seoul National University Hospital, Seoul, Korea
| | | | - So Yeon Kim
- Department of Laboratory Medicine, National Medical Center, Seoul, Korea
| | - Ye Jin Hyun
- Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea
| | - Sung Sup Park
- Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea
| | - Moon-Woo Seong
- Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea
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GIUDICI VALENTINA, SPANAKI ADRIANI, HENDRY JENNIFER, MEAD-REGAN SARAH, FIELD ELLA, ZUCCOTTI GIANVINCENZO, ABRAMS DOMINIC, LOWE MARTIN, KASKI JUANPABLO. Sudden Arrhythmic Death Syndrome: Diagnostic Yield of Comprehensive Clinical Evaluation of Pediatric First-Degree Relatives. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2014; 37:1681-5. [DOI: 10.1111/pace.12479] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 05/21/2014] [Accepted: 06/17/2014] [Indexed: 01/13/2023]
Affiliation(s)
- VALENTINA GIUDICI
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
- Department of Paediatrics; Ospedale Luigi Sacco; University of Milan; Italy
| | - ADRIANI SPANAKI
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
| | - JENNIFER HENDRY
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
| | - SARAH MEAD-REGAN
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
| | - ELLA FIELD
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
| | | | - DOMINIC ABRAMS
- Department of Cardiology; Boston Children's Hospital; Boston Massachusetts
| | - MARTIN LOWE
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
| | - JUAN PABLO KASKI
- Inherited Cardiovascular Diseases Unit; Department of Cardiology; Great Ormond Street Hospital; London United Kingdom
- Institute of Cardiovascular Science; University College London; United Kingdom
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42
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Application of Massively Parallel Sequencing in the Clinical Diagnostic Testing of Inherited Cardiac Conditions. Med Sci (Basel) 2014. [DOI: 10.3390/medsci2020098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Chang RKR, Lan YT, Silka MJ, Morrow H, Kwong A, Smith-Lang J, Wallerstein R, Lin HJ. Genetic variants for long QT syndrome among infants and children from a statewide newborn hearing screening program cohort. J Pediatr 2014; 164:590-5.e1-3. [PMID: 24388587 PMCID: PMC3943925 DOI: 10.1016/j.jpeds.2013.11.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/01/2013] [Accepted: 11/06/2013] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Autosomal recessive long QT syndrome (LQTS), or Jervell and Lange-Nielsen syndrome (JLNS), can be associated with sensorineural hearing loss. We aimed to explore newborn hearing screening combined with electrocardiograms (ECGs) for early JLNS detection. STUDY DESIGN In California, we conducted statewide, prospective ECG screening of children ≤ 6 years of age with unilateral or bilateral, severe or profound, sensorineural or mixed hearing loss. Families were identified through newborn hearing screening and interviewed about medical and family histories. Twelve-lead ECGs were obtained. Those with positive histories or heart rate corrected QT (QTc) intervals ≥ 450 ms had repeat ECGs. DNA sequencing of 12 LQTS genes was performed for repeat QTc intervals ≥ 450 ms. RESULTS We screened 707 subjects by ECGs (number screened/number of responses = 91%; number of responses/number of families who were mailed invitations = 54%). Of these, 73 had repeat ECGs, and 19 underwent gene testing. No subject had homozygous or compound heterozygous LQTS mutations, as in JLNS. However, 3 individuals (with QTc intervals of 472, 457, and 456 ms, respectively) were heterozygous for variants that cause truncation or missplicing: 2 in KCNQ1 (c.1343dupC or p.Glu449Argfs*14; c.1590+1G>A or p.Glu530sp) and 1 in SCN5A (c.5872C>T or p.Arg1958*). CONCLUSIONS In contrast to reports of JLNS in up to 4% of children with sensorineural hearing loss, we found no examples of JLNS. Because the 3 variants identified were unrelated to hearing, they likely represent the prevalence of potential LQTS mutations in the general population. Further studies are needed to define consequences of such mutations and assess the overall prevalence.
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Affiliation(s)
- Ruey-Kang R. Chang
- Department of Pediatrics, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California
| | | | - Michael J. Silka
- Children’s Hospital Los Angeles – University of Southern California, Los Angeles, CA
| | - Hallie Morrow
- California Department of Health Care Services, Sacramento, CA
| | - Alan Kwong
- Department of Pediatrics, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California
| | | | | | - Henry J. Lin
- Department of Pediatrics, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California
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44
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Al-Aama J, Al-Ghamdi S, Bdier A, AlQarawi A, Jiman O, Al-Aama N, Al-Aata J, Wilde A, Bhuiyan Z. Genotype-phenotype analysis of Jervell and Lange-Nielsen syndrome in six families from Saudi Arabia. Clin Genet 2013; 87:74-9. [DOI: 10.1111/cge.12330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 11/29/2022]
Affiliation(s)
- J.Y. Al-Aama
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - S. Al-Ghamdi
- Department of Pediatric Cardiology; Prince Sultan Cardiac Center; Riyadh Saudi Arabia
| | - A.Y. Bdier
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - A. AlQarawi
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - O.A. Jiman
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - N. Al-Aama
- Department of Cardiology; King Abdulaziz University Hospital; Jeddah Saudi Arabia
| | - J. Al-Aata
- Department of Cardiology; King Abdulaziz University Hospital; Jeddah Saudi Arabia
| | - A.A.M. Wilde
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
- Department of Cardiology, Academic Medical Center; University of Amsterdam; Amsterdam the Netherlands
| | - Z.A. Bhuiyan
- Laboratoire de Génétique Moléculaire, Service de Génétique Médicale; CHUV; Lausanne Switzerland
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Marsman RF, Tan HL, Bezzina CR. Genetics of sudden cardiac death caused by ventricular arrhythmias. Nat Rev Cardiol 2013; 11:96-111. [PMID: 24322550 DOI: 10.1038/nrcardio.2013.186] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sudden cardiac death (SCD) resulting from ventricular tachyarrhythmia is a major contributor to mortality. Clinical management of SCD, currently based on clinical markers of SCD risk, can be improved by integrating genetic information. The identification of multiple disease-causing gene variants has already improved patient management and increased our understanding of the rare Mendelian diseases associated with SCD risk in the young, but marked variability in disease severity suggests that additional genetic modifiers exist. Next-generation DNA sequencing could be crucial to the discovery of SCD-associated genes, but large data sets can be difficult to interpret. SCD usually occurs in patients with an average age of 65 years who have complex cardiac disease stemming from multiple, common, acquired disorders. Heritable factors are largely unknown, but are likely to have a role in determining the risk of SCD in these patients. Numerous genetic loci have been identified that affect electrocardiogram indices, which are regarded as intermediate phenotypes for tachyarrhythmia. These loci could help to identify new molecules and pathways affecting cardiac electrical function. These loci are often located in intergenic regions, so our evolving understanding of the noncoding regulatory regions of the genome are likely to aid in the identification of novel genes that are important for cardiac electrical function and possibly SCD.
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Affiliation(s)
- Roos F Marsman
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Hanno L Tan
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Connie R Bezzina
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Room L2-108, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
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Bartos DC, Giudicessi JR, Tester DJ, Ackerman MJ, Ohno S, Horie M, Gollob MH, Burgess DE, Delisle BP. A KCNQ1 mutation contributes to the concealed type 1 long QT phenotype by limiting the Kv7.1 channel conformational changes associated with protein kinase A phosphorylation. Heart Rhythm 2013; 11:459-68. [PMID: 24269949 DOI: 10.1016/j.hrthm.2013.11.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND Type 1 long QT syndrome (LQT1) is caused by loss-of-function mutations in the KCNQ1-encoded Kv7.1 channel that conducts the slowly activating component of the delayed rectifier K(+) current (IKs). Clinically, the diagnosis of LQT1 is complicated by variable phenotypic expressivity, whereby approximately 25% of genotype-positive individuals present with concealed LQT1 (resting corrected QT [QTc] interval ≤460 ms). OBJECTIVE To determine whether a specific molecular mechanism contributes to concealed LQT1. METHODS We identified a multigenerational LQT1 family whereby 79% of the patients genotype-positive for p.Ile235Asn-KCNQ1 (I235N-Kv7.1) have concealed LQT1. We assessed the effect I235N-Kv7.1 has on IKs and the ventricular action potential (AP) by using in vitro analysis and computational simulations. RESULTS Clinical data showed that all 10 patients with I235N-Kv7.1 have normal resting QTc intervals but abnormal QTc interval prolongation during the recovery phase of an electrocardiographic treadmill stress test. Voltage-clamping HEK293 cells coexpressing wild-type Kv7.1 and I235N-Kv7.1 (to mimic the patients' genotypes) showed that I235N-Kv7.1 generated relatively normal functioning Kv7.1 channels but were insensitive to protein kinase A (PKA) activation. Phosphomimetic and quinidine sensitivity studies suggest that I235N-Kv7.1 limits the conformational changes in Kv7.1 channels, which are necessary to upregulate IKs after PKA phosphorylation. Computational ventricular AP simulations predicted that the PKA insensitivity of I235N-Kv7.1 is primarily responsible for prolonging the AP with β-adrenergic stimulation, especially at slower cycle lengths. CONCLUSIONS KCNQ1 mutations that generate relatively normal Kv7.1 channels, but limit the upregulation of IKs by PKA activation, likely contribute to concealed LQT1.
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Affiliation(s)
- Daniel C Bartos
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - John R Giudicessi
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Divisions of Cardiovascular Diseases and Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota
| | - David J Tester
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Divisions of Cardiovascular Diseases and Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota
| | - Michael J Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Divisions of Cardiovascular Diseases and Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Sciences, Seta-tsukinowa, Otsu, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Sciences, Seta-tsukinowa, Otsu, Japan
| | - Michael H Gollob
- Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Don E Burgess
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Brian P Delisle
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.
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Abstract
Congenital long QT syndrome (LQTS) is a genetically heterogeneous group of heritable disorders of myocardial repolarization linked by the shared clinical phenotype of QT prolongation on electrocardiogram and an increased risk of potentially life-threatening cardiac arrhythmias. At the molecular level, mutations in 15 distinct LQTS-susceptibility genes that encode ion channel pore-forming α-subunits and accessory β-subunits central to the electromechanical function of the heart have been implicated in its pathogenesis. Over the past 2 decades, our evolving understanding of the electrophysiological mechanisms by which specific genetic substrates perturb the cardiac action potential has translated into vastly improved approaches to the diagnosis, risk stratification, and treatment of patients with LQTS. In this review, we describe how our understanding of the molecular underpinnings of LQTS has yielded numerous clinically meaningful genotype-phenotype correlations and how these insights have translated into genotype- and phenotype-guided approaches to the clinical management of LQTS.
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Affiliation(s)
| | - Michael J. Ackerman
- Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
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Jackson HA, McIntosh S, Whittome B, Asuri S, Casey B, Kerr C, Tang A, Arbour LT. LQTS in Northern BC: homozygosity for KCNQ1 V205M presents with a more severe cardiac phenotype but with minimal impact on auditory function. Clin Genet 2013; 86:85-90. [PMID: 23844633 DOI: 10.1111/cge.12235] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/03/2013] [Accepted: 07/08/2013] [Indexed: 01/02/2023]
Abstract
Long QT syndrome (LQTS), a rare congenital cardiac condition associated with life-threatening ventricular arrhythmias is characterized by a prolonged QT interval on electrocardiograph corrected for heart rate [corrected QT (QTc)]. LQTS has been historically categorized into the autosomal dominant Romano-Ward syndrome (RWS) and the autosomal recessive Jervell and Lange-Nielsen syndrome (JLNS). JLNS is associated with prelingual sensorineural deafness. Both types of LQTS can be caused by mutations in channel genes (e.g. KCNQ1) responsible for potassium homeostasis in cardiac myocytes and cochlea. Autosomal dominant mutations often cause the RWS phenotype and homozygous or compound heterozygous mutations contribute to JLNS. Two First Nations communities in northern British Columbia are affected disproportionately with LQTS largely due to the V205M mutation in KCNQ1, however, the pathology and phenotypic expression for those V205M homozygous has been unknown. Here, we show that four V205M homozygous individuals have a significantly higher 'peak' QTc, and a more severe cardiac phenotype compared with 41 V205M heterozygous carriers and 57 first to third degree relatives without mutations. Given the lack of prelingual deafness the homozygous V205M LQTS patients present with a phenotype more typical of RWS than JLNS.
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Affiliation(s)
- H A Jackson
- Department of Medical Genetics and the Island Medical program, University of British Columbia, Victoria, British Columbia, Canada
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