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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. [PMID: 39073097 DOI: 10.1111/cge.14593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [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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Kashiwa A, Itoh H, Makiyama T, Wada Y, Ozawa J, Kato K, Fukuyama M, Nakajima T, Ohno S, Horie M. Clinical characterization of type 1 long QT syndrome caused by C-terminus Kv7.1 variants. Heart Rhythm 2024; 21:1113-1120. [PMID: 38367891 DOI: 10.1016/j.hrthm.2024.02.021] [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: 07/31/2023] [Revised: 01/27/2024] [Accepted: 02/07/2024] [Indexed: 02/19/2024]
Abstract
BACKGROUND Variants in the KCNQ1 gene, encoding the α-subunit of the slow component of delayed rectifier K+ channel Kv7.1, cause long QT syndrome (LQTS) type 1. The location of variants may be one of the factors in determining prognosis. However, detailed genotype-phenotype relationships associated with C-terminus variants remain unelucidated. OBJECTIVE We investigated the clinical characteristics and variant-specific arrhythmic risks in patients with LQTS carrying Kv7.1 C-terminus variants. METHODS The study comprises 202 consecutive patients with LQTS (98 probands and 104 family members) who carry a rare heterozygous variant in the Kv7.1 C-terminus. Their clinical characteristics and arrhythmic events were investigated. RESULTS We identified 36 unique C-terminus variants (25 missense and 11 non-missense). The p.R366W variant was identified in 8 families, and p.T587M was identified in 21 families in large numbers from northwestern Japan. As for the location of the variant, we found that the variants in highly conserved regions and nonhelical domains were associated with longer QTc intervals compared with the variants in other regions. Both p.R366W and p.T587M variants are located in the highly conserved and functionally pivotal regions close to helices A and D, which are associated with calmodulin binding and channel assembly (tetramerization), respectively. The probands carrying p.T587M and p.R366W variants had worse arrhythmia outcomes compared with those with other C-terminus variants. The haplotype analysis of p.T587M families was suggestive of a founder effect. CONCLUSION The arrhythmic risk of C-terminus variants in Kv7.1 in LQTS is not homogeneous, and locations of variants can be a determining factor for prognosis.
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Affiliation(s)
- Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Cardiology, Niigata City General Hospital, Niigata, Japan.
| | - Hideki Itoh
- Division of Patient Safety, Hiroshima University Hospital, Minami-ku, Hiroshima, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Junichi Ozawa
- Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Koichi Kato
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Megumi Fukuyama
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Tadashi Nakajima
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
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Tore D, Faletti R, Biondo A, Carisio A, Giorgino F, Landolfi I, Rocco K, Salto S, Santonocito A, Ullo F, Anselmino M, Fonio P, Gatti M. Role of Cardiovascular Magnetic Resonance in the Management of Atrial Fibrillation: A Review. J Imaging 2022; 8:300. [PMID: 36354873 PMCID: PMC9696856 DOI: 10.3390/jimaging8110300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/26/2022] [Accepted: 09/30/2022] [Indexed: 08/30/2023] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia, and its prevalence is growing with time. Since the introduction of catheter ablation procedures for the treatment of AF, cardiovascular magnetic resonance (CMR) has had an increasingly important role for the treatment of this pathology both in clinical practice and as a research tool to provide insight into the arrhythmic substrate. The most common applications of CMR for AF catheter ablation are the angiographic study of the pulmonary veins, the sizing of the left atrium (LA), and the evaluation of the left atrial appendage (LAA) for stroke risk assessment. Moreover, CMR may provide useful information about esophageal anatomical relationship to LA to prevent thermal injuries during ablation procedures. The use of late gadolinium enhancement (LGE) imaging allows to evaluate the burden of atrial fibrosis before the ablation procedure and to assess procedural induced scarring. Recently, the possibility to assess atrial function, strain, and the burden of cardiac adipose tissue with CMR has provided more elements for risk stratification and clinical decision making in the setting of catheter ablation planning of AF. The purpose of this review is to provide a comprehensive overview of the potential applications of CMR in the workup of ablation procedures for atrial fibrillation.
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Affiliation(s)
- Davide Tore
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Riccardo Faletti
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Andrea Biondo
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Andrea Carisio
- Department of Radiology, Humanitas Gradenigo Hospital, 10126 Turin, Italy
| | - Fabio Giorgino
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Ilenia Landolfi
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Katia Rocco
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Sara Salto
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Ambra Santonocito
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Federica Ullo
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Matteo Anselmino
- Division of Cardiology, Department of Medical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Paolo Fonio
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
| | - Marco Gatti
- Radiology Unit, Department of Surgical Sciences, University of Turin, Azienda Ospedaliero Universitaria (A.O.U.) Città della Salute e della Scienza di Torino, 10126 Turin, Italy
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Eosinophilic Infiltration of the Sino-Atrial Node in Sudden Cardiac Death Caused by Long QT Syndrome. Int J Mol Sci 2022; 23:ijms231911666. [PMID: 36232963 PMCID: PMC9569895 DOI: 10.3390/ijms231911666] [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: 08/31/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 11/09/2022] Open
Abstract
Sudden death is defined as the unexpected death of a healthy person that occurs within the first hour of the onset of symptoms or within 24 h of the victim being last seen alive. In some of these cases, rare deleterious variants of genes associated with inherited cardiac disorders can provide a highly probable explanation for the fatal event. We report the case of a 21-year-old obese woman who lost consciousness suddenly in a public place and was pronounced dead after hospital admission. Clinical autopsy showed an inconclusive gross examination, while in the histopathological analysis an eosinophilic inflammatory focus and interstitial fibrosis in the sino-atrial node were found. Molecular autopsy revealed an intronic variant in the KCNQ1 gene (c.683 + 5G > A), classified as likely pathogenic for long QT syndrome according to the guidelines provided by the American College of Medical Genetics and Genomics. Therefore, there were many anomalies that could have played a role in the causation of the sudden death, such as the extreme obesity, the cardiac anomalies and the KNCQ1 variant. This case depicts the difficult interpretation of rare cardiac structural abnormalities in subjects carrying rare variants responsible for inherited arrhythmic disorders and the challenge for the forensic pathologist to make causal inferences in the determinism of the unexpected decease.
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5
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Potapova NA. Nonsense Mutations in Eukaryotes. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:400-412. [PMID: 35790376 DOI: 10.1134/s0006297922050029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/14/2022] [Accepted: 03/22/2022] [Indexed: 06/15/2023]
Abstract
Nonsense mutations are a type of mutations which results in a premature termination codon occurrence. In general, these mutations have been considered to be among the most harmful ones which lead to premature protein translation termination and result in shortened nonfunctional polypeptide. However, there is evidence that not all nonsense mutations are harmful as well as some molecular mechanisms exist which allow to avoid pathogenic effects of these mutations. This review addresses relevant information on nonsense mutations in eukaryotic genomes, characteristics of these mutations, and different molecular mechanisms preventing or mitigating harmful effects thereof.
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Affiliation(s)
- Nadezhda A Potapova
- Kharkevich Institute for Information Transmission Problems (IITP), Russian Academy of Sciences, Moscow, 127051, Russia.
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6
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Membrane pools of phosphatidylinositol-4-phosphate regulate KCNQ1/KCNE1 membrane expression. Commun Biol 2021; 4:1392. [PMID: 34907346 PMCID: PMC8671492 DOI: 10.1038/s42003-021-02909-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/24/2021] [Indexed: 11/23/2022] Open
Abstract
Plasma membrane phosphatidylinositol 4-phosphate (PI4P) is a precursor of PI(4,5)P2, an important regulator of a large number of ion channels. Although the role of the phospholipid PI(4,5)P2 in stabilizing ion channel function is well established, little is known about the role of phospholipids in channel membrane localization and specifically the role of PI4P in channel function and localization. The phosphatidylinositol 4-kinases (PI4Ks) synthesize PI4P. Our data show that inhibition of PI4K and prolonged decrease of levels of plasma membrane PI4P lead to a decrease in the KCNQ1/KCNE1 channel membrane localization and function. In addition, we show that mutations linked to Long QT syndrome that affect channel interactions with phospholipids lead to a decrease in membrane expression. We show that expression of a LQT1-associated C-terminal deletion mutant abolishes PI4Kinase-mediated decrease in membrane expression and rescues membrane expression for phospholipid-targeting mutations. Our results indicate a novel role for PI4P on ion channel regulation. Our data suggest that decreased membrane PI4P availability to the channel, either due to inhibition of PI4K or as consequence of mutations, dramatically inhibits KCNQ1/KCNE1 channel membrane localization and current. Our results may have implications to regulation of other PI4P binding channels.
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7
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Baman JR, Cox JL, McCarthy PM, Kim D, Patel RB, Passman RS, Wilcox JE. Atrial fibrillation and atrial cardiomyopathies. J Cardiovasc Electrophysiol 2021; 32:2845-2853. [PMID: 33993617 DOI: 10.1111/jce.15083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/13/2021] [Accepted: 05/03/2021] [Indexed: 12/12/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia among adults. While there have been incredible advances in the management of AF and its clinical sequelae, investigation of atrial cardiomyopathies (ACMs) is becoming increasingly more prominent. ACM refers to the electromechanical changes-appreciated subclinically and/or clinically-that underlie atrial dysfunction and create an environment ripe for the development of clinically apparent AF. There are several subtypes of ACM, distinguished by histologic features. Recent progress in cardiovascular imaging, including echocardiography with speckle-tracking (e.g., strain analysis), cardiovascular magnetic resonance imaging (CMR), and atrial 4-D flow CMR, has enabled increased recognition of ACM. Identification of ACM and its features carry clinical implications, including elevating a patient's risk for development of AF, as well as associations with outcomes related to catheter-based and surgical AF ablation. In this review, we explore the definition and classifications of ACM, its complex relationship with clinical AF, imaging modalities, and clinical implications. We propose next steps for a more unified approach to ACM recognition that can direct further research into this complex field.
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Affiliation(s)
- Jayson R Baman
- Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - James L Cox
- Department of Cardiac Surgery, Bluhm Cardiovascular Institute of Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Patrick M McCarthy
- Department of Cardiac Surgery, Bluhm Cardiovascular Institute of Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Daniel Kim
- Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Ravi B Patel
- Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rod S Passman
- Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Center for Arrhythmia Research, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Jane E Wilcox
- Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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8
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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: 1.0] [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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9
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Waddell-Smith KE, Skinner JR, Bos JM. Pre-Test Probability and Genes and Variants of Uncertain Significance in Familial Long QT Syndrome. Heart Lung Circ 2020; 29:512-519. [PMID: 32044265 DOI: 10.1016/j.hlc.2019.12.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/08/2019] [Accepted: 12/18/2019] [Indexed: 11/29/2022]
Abstract
The genetics underlying familial long QT syndrome (LQTS) are among the best characterised of all of the inherited heart conditions. Cohort and registry studies have demonstrated important genotype-phenotype correlations that are now essential in guiding clinical practice of patients with the most common three genotypes; KCNQ1 (LQT type 1), KCNH2 (LQT type 2) and SCN5A (LQT type 3). However, the growing number of genes-now more than 16-is confusing, and there is much doubt as to whether many actually cause LQTS at all. Furthermore, changes in sequencing techniques, evolving variant classification criteria and new scientific discoveries make all genes and variants subject to a continuous process of re-classification. This review discusses the nature of variant adjudication, the important concept of pre-test probability in interpreting a genetic result and how the nomenclature of LQTS is shifting in response to this new knowledge. It further discusses the role of deep phenotyping, the inclusion of evaluation of family members in interpreting a genetic test result, or even deciding if genetic testing should occur at all, and the role of specialist multidisciplinary teams to translate this continuously evolving knowledge into the best clinical advice, in partnership with referring cardiologists.
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Affiliation(s)
- Kathryn E Waddell-Smith
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia; Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, SA, Australia.
| | - Jonathan R Skinner
- Green Lane Paediatric and Congenital Cardiac Service, Starship Children's Hospital, Auckland, New Zealand; Department of Paediatrics, Child and Youth Health, University of Auckland, Auckland, New Zealand
| | - J Martijn Bos
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
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10
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Wu J, Sakaguchi T, Takenaka K, Toyoda F, Tsuji K, Matsuura H, Horie M. A trafficking-deficient KCNQ1 mutation, T587M, causes a severe phenotype of long QT syndrome by interfering with intracellular hERG transport. J Cardiol 2019; 73:343-350. [DOI: 10.1016/j.jjcc.2018.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/11/2018] [Accepted: 10/24/2018] [Indexed: 11/29/2022]
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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: 1] [Impact Index Per Article: 0.2] [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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Mackley M, McGuire K, Taylor J, Watkins H, Ormondroyd E. From Genotype to Phenotype. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2018; 11:e002316. [PMID: 30354302 PMCID: PMC6217934 DOI: 10.1161/circgen.118.002316] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Genomic variants associated with inherited cardiac conditions yet detected incidentally (‘secondary findings’) are likely to arise with increasing frequency as genome sequencing transitions into clinical practice. Since genotyping has until recently been directed by clinical diagnosis, assessment and management of individuals found to harbour such a variant as a secondary finding is unclear. Here we illustrate some diagnostic and psychosocial complexities of inherited cardiac condition secondary findings, exemplified by disclosure of a pathogenic variant in KCNQ1 , associated with long QT syndrome, to a healthy male enrolled in diagnostic genome sequencing as an unaffected relative. This early case represents a shift from ‘phenotype-to-genotype’ to ‘genotype-to-phenotype’; we describe clinical evaluation, family history and a qualitative research interview with the secondary finding recipient, discuss the role of specialist services in variant interpretation, genetic counselling and clinical assessment, and some challenges of realising improved health outcomes following disclosure of a secondary finding.
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Affiliation(s)
- Michael Mackley
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford
| | - Karen McGuire
- Oxford University Hospitals NHS Foundation Trust (OUHFT)
| | - Jenny Taylor
- Wellcome Trust Centre for Human Genetics, University of Oxford
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford
- Wellcome Trust Centre for Human Genetics, University of Oxford
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Elizabeth Ormondroyd
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, United Kingdom
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13
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Gibbs C, Thalamus J, Tveten K, Busk ØL, Hysing J, Haugaa KH, Holla ØL. Genetic and Phenotypic Characterization of Community Hospital Patients With QT Prolongation. J Am Heart Assoc 2018; 7:e009706. [PMID: 30369311 PMCID: PMC6201409 DOI: 10.1161/jaha.118.009706] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/09/2018] [Indexed: 12/19/2022]
Abstract
Background Congenital long- QT syndrome ( LQTS ) is a genetic disorder characterized by prolongation of the corrected QT interval ( QT c) on an ECG . The aim of the present study was to estimate the prevalence of pathogenic and likely pathogenic sequence variants in patients who had at least 1 ECG with a QT c ≥500 ms. Methods and Results Telemark Hospital Trust is a community hospital within the Norwegian national health system, serving ≈173 000 inhabitants. We searched the ECG database at Telemark Hospital Trust, Norway, from January 2004 to December 2014, and identified 1531 patients with at least 1 ECG with a QT c ≥500 ms. At the time of inclusion in this study (2015), 766 patients were alive. A total of 733 patients were invited to participate, and 475 accepted. The 17 genes that have been reported to cause monogenic LQTS were sequenced among the patients. Pro- QT c score was calculated for each patient. A molecular genetic cause of LQTS was detected in 31 (6.5%) of 475 patients. These patients had a lower pro- QT c score than those without pathogenic or likely pathogenic variants (1.7±1.0 versus 2.8±1.6; P<0.001). Conclusions Compared with the general population, hospitalized patients with a QT c ≥500 ms in at least 1 ECG recording had an increased likelihood for pathogenic and likely pathogenic variants in LQTS genes. We recommend increased awareness of the possibility of LQTS in patients with at least 1 ECG with a QT c ≥500 ms.
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Affiliation(s)
- Charlotte Gibbs
- Department of Internal MedicineTelemark Hospital TrustSkienNorway
- Institute of Clinical MedicineFaculty of MedicineUniversity of OsloNorway
| | - Jacob Thalamus
- Department of Internal MedicineTelemark Hospital TrustSkienNorway
| | - Kristian Tveten
- Department of Medical GeneticsTelemark Hospital TrustSkienNorway
| | - Øyvind L. Busk
- Department of Medical GeneticsTelemark Hospital TrustSkienNorway
| | - Jan Hysing
- Department of Internal MedicineTelemark Hospital TrustSkienNorway
| | - Kristina H. Haugaa
- Institute of Clinical MedicineFaculty of MedicineUniversity of OsloNorway
- Center for Cardiological InnovationDepartment of CardiologyOslo University HospitalRikshospitalet and University of OsloNorway
| | - Øystein L. Holla
- Department of Medical GeneticsTelemark Hospital TrustSkienNorway
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14
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Chen XM, Guo K, Li H, Lu QF, Yang C, Yu Y, Hou JW, Fei YD, Sun J, Wang J, Li YX, Li YG. A novel mutation KCNQ1p.Thr312del is responsible for long QT syndrome type 1. Heart Vessels 2018; 34:177-188. [DOI: 10.1007/s00380-018-1223-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/06/2018] [Indexed: 11/29/2022]
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15
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Bhuiyan ZA. Mechanistic insight into an exonic splice defect mutation from native induced pluripotent stem cell-derived cardiomyocytes. Heart Rhythm 2018; 15:1575-1576. [PMID: 29890319 DOI: 10.1016/j.hrthm.2018.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Indexed: 11/26/2022]
Affiliation(s)
- Zahurul A Bhuiyan
- Laboratoire de Génétique, Service de Médecine Génétique, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
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16
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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: 14.0] [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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17
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Abstract
PURPOSE OF REVIEW The modern field of clinical genetics has advanced beyond the traditional teachings familiar to most practicing cardiologists. Increased understanding of the roles of genetic testing may improve uptake and appropriateness of use. RECENT FINDINGS Clinical genetics has become integral to the management of patients with hereditary arrhythmia and cardiomyopathy diagnoses. Depending on the condition, genetic testing may be useful for diagnosis, prognosis, treatment, family screening, and reproductive planning. However, genetic testing is a powerful tool with potential for underuse, overuse, and misuse. In the absence of a substantial body of literature on how these guidelines are applied in clinical practice, we use a case-based approach to highlight key lessons and pitfalls. Importantly, in many scenarios genetic testing has become the standard of care supported by numerous class I recommendations; genetic counselors can improve accessibility to and appropriate use and application of testing. SUMMARY Optimal management of hereditary arrhythmias and cardiomyopathies incorporates genetic testing, applied as per consensus guidelines, with involvement of a multidisciplinary team.
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18
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Bohnen MS, Peng G, Robey SH, Terrenoire C, Iyer V, Sampson KJ, Kass RS. Molecular Pathophysiology of Congenital Long QT Syndrome. Physiol Rev 2017; 97:89-134. [PMID: 27807201 PMCID: PMC5539372 DOI: 10.1152/physrev.00008.2016] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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