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Li E, van der Heyden MAG. The network of cardiac K IR2.1: its function, cellular regulation, electrical signaling, diseases and new drug avenues. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03116-5. [PMID: 38683369 DOI: 10.1007/s00210-024-03116-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
The functioning of the human heart relies on complex electrical and communication systems that coordinate cardiac contractions and sustain rhythmicity. One of the key players contributing to this intricate system is the KIR2.1 potassium ion channel, which is encoded by the KCNJ2 gene. KIR2.1 channels exhibit abundant expression in both ventricular myocytes and Purkinje fibers, exerting an important role in maintaining the balance of intracellular potassium ion levels within the heart. And by stabilizing the resting membrane potential and contributing to action potential repolarization, these channels have an important role in cardiac excitability also. Either gain- or loss-of-function mutations, but also acquired impairments of their function, are implicated in the pathogenesis of diverse types of cardiac arrhythmias. In this review, we aim to elucidate the system functions of KIR2.1 channels related to cellular electrical signaling, communication, and their contributions to cardiovascular disease. Based on this knowledge, we will discuss existing and new pharmacological avenues to modulate their function.
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Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands.
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2
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Wu Y, Lan Y, Mao J, Shen J, Kang T, Xie Z. The interaction between the nervous system and the stomatognathic system: from development to diseases. Int J Oral Sci 2023; 15:34. [PMID: 37580325 PMCID: PMC10425412 DOI: 10.1038/s41368-023-00241-4] [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: 03/29/2023] [Revised: 07/30/2023] [Accepted: 07/31/2023] [Indexed: 08/16/2023] Open
Abstract
The crosstalk between the nerve and stomatognathic systems plays a more important role in organismal health than previously appreciated with the presence of emerging concept of the "brain-oral axis". A deeper understanding of the intricate interaction between the nervous system and the stomatognathic system is warranted, considering their significant developmental homology and anatomical proximity, and the more complex innervation of the jawbone compared to other skeletons. In this review, we provide an in-depth look at studies concerning neurodevelopment, craniofacial development, and congenital anomalies that occur when the two systems develop abnormally. It summarizes the cross-regulation between nerves and jawbones and the effects of various states of the jawbone on intrabony nerve distribution. Diseases closely related to both the nervous system and the stomatognathic system are divided into craniofacial diseases caused by neurological illnesses, and neurological diseases caused by an aberrant stomatognathic system. The two-way relationships between common diseases, such as periodontitis and neurodegenerative disorders, and depression and oral diseases were also discussed. This review provides valuable insights into novel strategies for neuro-skeletal tissue engineering and early prevention and treatment of orofacial and neurological diseases.
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Affiliation(s)
- Yuzhu Wu
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Yanhua Lan
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Jiajie Mao
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Jiahui Shen
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Ting Kang
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China.
| | - Zhijian Xie
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China.
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3
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [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: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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4
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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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5
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Manuel AIM, Gutiérrez LK, Pedrosa MLV, Uréndez FMC, Jiménez FJB, Carrascoso IM, Pérez PS, Macías Á, Jalife J. Molecular stratification of arrhythmogenic mechanisms in the Andersen Tawil Syndrome. Cardiovasc Res 2022; 119:919-932. [PMID: 35892314 PMCID: PMC10153646 DOI: 10.1093/cvr/cvac118] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/20/2022] [Accepted: 07/01/2022] [Indexed: 11/12/2022] Open
Abstract
Andersen Tawil Syndrome (ATS) is a rare inheritable disease associated with loss-of-function mutations in KCNJ2, the gene coding the strong inward rectifier potassium channel Kir2.1, which forms an essential membrane protein controlling cardiac excitability. ATS is usually marked by a triad of periodic paralysis, life-threatening cardiac arrhythmias and dysmorphic features, but its expression is variable and not all patients with a phenotype linked to ATS have a known genetic alteration. The mechanisms underlying this arrhythmogenic syndrome are poorly understood. Knowing such mechanisms would be essential to distinguish ATS from other channelopathies with overlapping phenotypes and to develop individualized therapies. For example, the recently suggested role of Kir2.1 as a countercurrent to sarcoplasmic calcium reuptake might explain the arrhythmogenic mechanisms of ATS and its overlap with catecholaminergic polymorphic ventricular tachycardia (CPVT). Here we summarize current knowledge on the mechanisms of arrhythmias leading to sudden cardiac death in ATS. We first provide an overview of the syndrome and its pathophysiology, from the patient´s bedside to the protein, and discuss the role of essential regulators and interactors that could play a role in cases of ATS. The review highlights novel ideas related to some post-translational channel interactions with partner proteins that might help define the molecular bases of the arrhythmia phenotype. We then propose a new all-embracing classification of the currently known ATS loss-of-function mutations according to their position in the Kir2.1 channel structure and their functional implications. We also discuss specific ATS pathogenic variants, their clinical manifestations and treatment stratification. The goal is to provide a deeper mechanistic understanding of the syndrome toward the development of novel targets and personalized treatment strategies.
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Affiliation(s)
| | - Lilian K Gutiérrez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | | | | | - Francisco José Bermúdez Jiménez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain.,Departamento de Cardiología, Hospital Virgen de las Nieves, GranadaSpain
| | | | - Patricia Sánchez Pérez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | - Álvaro Macías
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | - José Jalife
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain.,CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,Departments of Medicine and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
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6
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Vivekanandam V, Männikkö R, Skorupinska I, Germain L, Gray B, Wedderburn S, Kozyra D, Sud R, James N, Holmes S, Savvatis K, Fialho D, Merve A, Pattni J, Farrugia M, Behr ER, Marini-Bettolo C, Hanna MG, Matthews E. Andersen-Tawil syndrome: deep phenotyping reveals significant cardiac and neuromuscular morbidity. Brain 2022; 145:2108-2120. [PMID: 34919635 DOI: 10.1093/brain/awab445] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 09/21/2021] [Accepted: 12/13/2021] [Indexed: 11/14/2022] Open
Abstract
Andersen-Tawil syndrome is a neurological channelopathy caused by mutations in the KCNJ2 gene that encodes the ubiquitously expressed Kir2.1 potassium channel. The syndrome is characterized by episodic weakness, cardiac arrythmias and dysmorphic features. However, the full extent of the multisystem phenotype is not well described. In-depth, multisystem phenotyping is required to inform diagnosis and guide management. We report our findings following deep multimodal phenotyping across all systems in a large case series of 69 total patients, with comprehensive data for 52. As a national referral centre, we assessed point prevalence and showed it is higher than previously reported, at 0.105 per 100 000 population in England. While the classical phenotype of episodic weakness is recognized, we found that a quarter of our cohort have fixed myopathy and 13.5% required a wheelchair or gait aid. We identified frequent fat accumulation on MRI and tubular aggregates on muscle biopsy, emphasizing the active myopathic process underpinning the potential for severe neuromuscular disability. Long exercise testing was not reliable in predicting neuromuscular symptoms. A normal long exercise test was seen in five patients, of whom four had episodic weakness. Sixty-seven per cent of patients treated with acetazolamide reported a good neuromuscular response. Thirteen per cent of the cohort required cardiac defibrillator or pacemaker insertion. An additional 23% reported syncope. Baseline electrocardiograms were not helpful in stratifying cardiac risk, but Holter monitoring was. A subset of patients had no cardiac symptoms, but had abnormal Holter monitor recordings which prompted medication treatment. We describe the utility of loop recorders to guide management in two such asymptomatic patients. Micrognathia was the most commonly reported skeletal feature; however, 8% of patients did not have dysmorphic features and one-third of patients had only mild dysmorphic features. We describe novel phenotypic features including abnormal echocardiogram in nine patients, prominent pain, fatigue and fasciculations. Five patients exhibited executive dysfunction and slowed processing which may be linked to central expression of KCNJ2. We report eight new KCNJ2 variants with in vitro functional data. Our series illustrates that Andersen-Tawil syndrome is not benign. We report marked neuromuscular morbidity and cardiac risk with multisystem involvement. Our key recommendations include proactive genetic screening of all family members of a proband. This is required, given the risk of cardiac arrhythmias among asymptomatic individuals, and a significant subset of Andersen-Tawil syndrome patients have no (or few) dysmorphic features or negative long exercise test. We discuss recommendations for increased cardiac surveillance and neuropsychometry testing.
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Affiliation(s)
- Vinojini Vivekanandam
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Roope Männikkö
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Iwona Skorupinska
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Louise Germain
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Belinda Gray
- Cardiovascular Clinical Academic Group, St. George's, University of London and St. George's University Hospitals NHS Foundation Trust, London, UK
| | - Sarah Wedderburn
- West of Scotland Regional Genetics Service, Queen Elizabeth University Hospital, Glasgow, UK
| | - Damian Kozyra
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Richa Sud
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Natalie James
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Sarah Holmes
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | | | - Doreen Fialho
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Ashirwad Merve
- Department of Neuropathology, National Hospital for Neurology and Neurosurgery, London, UK
| | - Jatin Pattni
- Neuropsychology, National Hospital for Neurology and Neurosurgery, London, UK
| | - Maria Farrugia
- West of Scotland Regional Genetics Service, Queen Elizabeth University Hospital, Glasgow, UK
| | - Elijah R Behr
- Cardiovascular Clinical Academic Group, St. George's, University of London and St. George's University Hospitals NHS Foundation Trust, London, UK
| | - Chiara Marini-Bettolo
- John Walton Muscular Dystrophy Research Centre, Newcastle University and Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Michael G Hanna
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Emma Matthews
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
- Atkinson-Morley Neuromuscular Centre, Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
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7
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Treatment and Management of Disorders of Neuromuscular Hyperexcitability and Periodic Paralysis. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Žakelj N, Osredkar D, Šuštar N. Mind the Gap: Acetazolamide Prolonged Periods without Paralysis in a Girl with Andersen-Tawil Syndrome. Case Rep Neurol 2021; 13:515-520. [PMID: 34720956 PMCID: PMC8460927 DOI: 10.1159/000517899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/13/2021] [Indexed: 11/19/2022] Open
Abstract
We present a case report of a 13-year-old girl with Andersen-Tawil Syndrome (ATS), a rare genetic disorder which is characterized by dysmorphic features, ventricular arrhythmias, and frequent episodes of muscle paralysis that interfere with daily activities and social engagement. After the introduction of off-label treatment with acetazolamide periods without paralysis lengthened, our patient became more independent of the help of her parents and required a wheelchair less frequently, thus improving her social life. Based on our experience, we recommend a trial of acetazolamide in patients with ATS.
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Affiliation(s)
- Nina Žakelj
- Department of Pediatric Neurology, University Children's Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Damjan Osredkar
- Department of Pediatric Neurology, University Children's Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Faculty of Medicine, Centre for Developmental Neuroscience, University of Ljubljana, Ljubljana, Slovenia
| | - Nataša Šuštar
- Department of Pediatric Neurology, University Children's Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
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9
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Catheter ablation of frequent monomorphic ventricular arrhythmias in Andersen-Tawil syndrome: case report and focused literature review. J Interv Card Electrophysiol 2021; 66:729-736. [PMID: 34665385 DOI: 10.1007/s10840-021-01077-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/10/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND/PURPOSE Andersen-Tawil syndrome type 1 is a rare autosomal dominant disease caused by a KCNJ2 gene mutation and clinically characterized by dysmorphic features, periodic muscular paralysis, and frequent ventricular arrhythmias (VAs). Although polymorphic and bidirectional ventricular tachycardias are prevalent, PVCs are the most frequent VAs. In addition, a "dominant" morphology with RBBB pattern associated with either superior or inferior axis is seen in most of the patients. Due to the limited efficacy of most antiarrhythmic drugs, catheter ablation (CA) is an alternative in patients with monomorphic VAs. Based on our experience, we aimed to review the arrhythmogenic mechanisms and substrates for VAs, and we analyzed the potential reasons for CA failure in this group of patients. METHODS Case report and focused literature review. RESULTS Catheter ablation has been reported to be unsuccessful in all of the few cases published so far. Most of the information suggests that VAs are mainly originated from the left ventricle and probably in the Purkinje network. Although identifying well-established and accepted mapping criteria for successful ablation of a monomorphic ventricular arrhythmia, papillary muscles seem not to be the right target. CONCLUSIONS More research is needed to understand better the precise mechanism and site of origin of VAs in Andersen-Tawil syndrome patients with this particular "dominant" monomorphic ventricular pattern to establish the potential role of CA.
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10
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Maggi L, Bonanno S, Altamura C, Desaphy JF. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells 2021; 10:cells10061521. [PMID: 34208776 PMCID: PMC8234207 DOI: 10.3390/cells10061521] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle ion channelopathies (SMICs) are a large heterogeneous group of rare genetic disorders caused by mutations in genes encoding ion channel subunits in the skeletal muscle mainly characterized by myotonia or periodic paralysis, potentially resulting in long-term disabilities. However, with the development of new molecular technologies, new genes and new phenotypes, including progressive myopathies, have been recently discovered, markedly increasing the complexity in the field. In this regard, new advances in SMICs show a less conventional role of ion channels in muscle cell division, proliferation, differentiation, and survival. Hence, SMICs represent an expanding and exciting field. Here, we review current knowledge of SMICs, with a description of their clinical phenotypes, cellular and molecular pathomechanisms, and available treatments.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Correspondence:
| | - Silvia Bonanno
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
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Marked reduction in paralytic attacks in a patient with Andersen-Tawil syndrome switched from acetazolamide to dichlorphenamide. Neuromuscul Disord 2021; 31:656-659. [PMID: 34078557 DOI: 10.1016/j.nmd.2021.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/19/2021] [Accepted: 04/11/2021] [Indexed: 11/20/2022]
Abstract
Andersen-Tawil syndrome is a rare, autosomal dominant, multisystem disorder for which the majority of cases are caused by pathogenic variants in the KCNJ2 gene. The syndrome is characterized by the clinical triad of episodic paralysis, cardiac conduction abnormalities, and dysmorphic facial and skeletal features. Treatment of Andersen-Tawil syndrome is primarily focused on management of cardiac arrhythmias and preventive management of paralytic attacks. Dichlorphenamide is approved by the US Food and Drug Administration for use in primary periodic paralysis based on several randomized, controlled trials but has not been studied in patients with Andersen-Tawil syndrome. Here, we report a case of the syndrome caused by a de novo pathogenic variant in the KCNJ2 gene (c.95_98del). The paralytic attack rate for this patient was better controlled with dichlorphenamide compared with acetazolamide, further supporting the use of dichlorphenamide in patients with Andersen-Tawil syndrome.
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12
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Fadilah A, Mordekar SR, Matthai S. Mutation in KCNJ2 Gene in a Boy with Atypical Features of Andersen–Tawil Syndrome, ADHD, and ASD: An Expanding Phenotype. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0040-1701503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
AbstractAndersen–Tawil syndrome, a potassium ion channelopathy, is caused by mutations in the KCNJ2 gene, and accounts for approximately 10% of channelopathies. Phenotype is variable. An 11-year-old boy presented with periodic paralysis without localizing neurological signs, associated in only two of three occasions with hypokalemia, on a background of a diagnosis of attention deficit hyperactivity disorder and autism spectrum disorder. There was a history of syncope and palpitations. This was a matter of diagnostic uncertainty due to the difficulty in interpreting his neurological signs, and inconsistency of abnormal potassium levels. In children/young people with recurrent episodes of weakness without localizing signs on physical examination, and syncope, the possibility of a channelopathy should be considered, even in the absence of serum electrolyte abnormalities. There is a possible link between KCNJ2 mutations and difficulties in attention and a specific neurocognitive profile.
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Affiliation(s)
- Ala Fadilah
- Department of Paediatric Neurology, Ryegate Children's Centre, Sheffield Children's Hospital, Sheffield, United Kingdom
| | - Santosh R. Mordekar
- Department of Paediatric Neurology, Ryegate Children's Centre, Sheffield Children's Hospital, Sheffield, United Kingdom
| | - Sona Matthai
- Department of General Paediatrics, Sheffield Children's Hospital, Sheffield, United Kingdom
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13
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Dolci C, Sansone VA, Gibelli D, Cappella A, Sforza C. Distinctive facial features in Andersen-Tawil syndrome: A three-dimensional stereophotogrammetric analysis. Am J Med Genet A 2020; 185:781-789. [PMID: 33369085 DOI: 10.1002/ajmg.a.62040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/19/2020] [Accepted: 12/14/2020] [Indexed: 01/28/2023]
Abstract
Andersen-Tawil syndrome (ATS) is a rare potassium channelopathy causing periodic paralysis, cardiac arrhythmias, and dysmorphic features. A detailed analysis of the face could facilitate diagnosis of ATS, as approximately 30% of patients do not show variants in KCNJ2 gene, and diagnosis is established by clinical findings. We aimed to characterize the face in ATS through a quantitative approach, as facial anomalies may be unnoticed on visual inspection. Facial images of 12 subjects with genetically confirmed ATS (six males, six females, age 5-67 years) were acquired through stereophotogrammetry. Using 38 soft-tissue landmarks, linear distances, angles, and ratios were calculated and expressed as z-score values, with reference to 477 healthy subjects matched for sex and age. All patients showed decreased lower facial height with shortening of philtrum (mean z-score ± SD: -1.5 ± 0.9), smaller mid and lower facial depths (-1.9 ± 0.7; -2.3 ± 0.9), short palpebral fissures (right -1.2 ± 0.4; left -1.6 ± 0.6), smaller mandibular ramus length (-2.1 ± 0.4), and increased nasal width/length ratio (1.4 ± 0.5) with smaller nostril axis length (right -1.8 ± 0.8, left -1.6 ± 0.7). Hypertelorism and low-set ears were detected in two-thirds of patients. The study quantified facial dysmorphysm in ATS, extending information about known features, and detecting unrecorded philtrum and nostril characteristics, which may be distinctive traits of the disorder.
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Affiliation(s)
- Claudia Dolci
- Functional Anatomy Research Center (FARC), Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico (LAFAS), Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Valeria A Sansone
- NEuroMuscularOmnicenter, NEMO Clinical Center, Neurorehabilitation Unit, Università degli Studi di Milano, Milan, Italy
| | - Daniele Gibelli
- Functional Anatomy Research Center (FARC), Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico (LAFAS), Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Annalisa Cappella
- Functional Anatomy Research Center (FARC), Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico (LAFAS), Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Chiarella Sforza
- Functional Anatomy Research Center (FARC), Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico (LAFAS), Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
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Inagaki M, Tatsumi T, Yomogita H, Hirose A, Kubo T, Sekiguchi M, Miyasaka N. Obstetric management of a patient with Andersen-Tawil syndrome: A case report. J Obstet Gynaecol Res 2020; 47:446-451. [PMID: 33205612 DOI: 10.1111/jog.14553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 11/27/2022]
Abstract
Andersen-Tawil syndrome (ATS) is a rare hereditary long QT syndrome type 7 caused by a missense mutation in the KCNJ2 gene. ATS is characterized by ventricular arrhythmia, periodic limb paralysis and minor external malformations. Although only three reports of pregnant women with Andersen-Tawil syndrome have been reported to date, no exacerbation of ventricular arrhythmia was observed from pre-partum to delivery in all cases compared to that before pregnancy, and it was suggested that the risk of arrhythmic events from pre-partum to delivery is not high. Unlike these previous reports, we herein present a case of Andersen-Tawil syndrome in which ventricular arrhythmias increased and sustained ventricular tachycardia was developed during labor progression. We also advise caution that pregnant patients with Andersen-Tawil syndrome may have varying times of exacerbation of the arrhythmia, and ventricular arrhythmias may be associated with painful uterine contractions.
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Affiliation(s)
- Mai Inagaki
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takayuki Tatsumi
- Department of Pediatrics, Perinatal and Maternal Medicine (Ibaraki), Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroshi Yomogita
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Asuka Hirose
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takuyuki Kubo
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masaki Sekiguchi
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Naoyuki Miyasaka
- Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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15
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Abstract
Andersen-Tawil syndrome (ATS) is a very rare orphan genetic multisystem channelopathy without structural heart disease (with rare exceptions). ATS type 1 is inherited in an autosomal dominant fashion and is caused by mutations in the KCNJ2 gene, which encodes the α subunit of the K+ channel protein Kir2.1 (in ≈ 50-60% of cases). ATS type 2 is in turn linked to a rare mutation in the KCNJ5-GIRK4 gene that encodes the G protein-sensitive-activated inwardly rectifying K+ channel Kir3.4 (15%), which carries the acetylcholine-induced potassium current. About 30% of cases are de novo/sporadic, suggesting that additional as-yet unidentified genes also cause the disorder. A triad of periodic muscle paralysis, repolarization changes in the electrocardiogram, and structural body changes characterize ATS. The typical muscular change is episodic flaccid muscle weakness. Prolongation of the QU/QUc intervals and normal or minimally prolonged QT/QTc intervals with a tendency to ventricular arrhythmias are typical repolarization changes. Bidirectional ventricular tachycardia is the hallmark ventricular arrhythmia, but also premature ventricular contractions, and rarely, polymorphic ventricular tachycardia of torsade de pointes type may be present. Patients with ATS have characteristic physical developmental dysmorphisms that affect the face, skull, limbs, thorax, and stature. Mild learning difficulties and a distinct neurocognitive phenotype (deficits in executive function and abstract reasoning) have been described. About 60% of affected individuals have all features of the major triad. The purpose of this review is to present historical aspects, nomenclature (observations/criticisms), epidemiology, genetics, electrocardiography, arrhythmias, electrophysiological mechanisms, diagnostic criteria/clues of periodic paralysis, prognosis, and management of ATS.
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Vivekanandam V, Männikkö R, Matthews E, Hanna MG. Improving genetic diagnostics of skeletal muscle channelopathies. Expert Rev Mol Diagn 2020; 20:725-736. [PMID: 32657178 DOI: 10.1080/14737159.2020.1782195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Skeletal muscle channelopathies are rare inherited conditions that cause significant morbidity and impact on quality of life. Some subsets have a mortality risk. Improved genetic methodology and understanding of phenotypes have improved diagnostic accuracy and yield. AREAS COVERED We discuss diagnostic advances since the advent of next-generation sequencing and the role of whole exome and genome sequencing. Advances in genotype-phenotype-functional correlations have improved understanding of inheritance and phenotypes. We outline new phenotypes, particularly in the pediatric setting and consider co-existing mutations that may act as genetic modifiers. We also discuss four newly identified genes associated with skeletal muscle channelopathies. EXPERT OPINION Next-generation sequencing using gene panels has improved diagnostic rates, identified new mutations, and discovered patients with co-existing pathogenic mutations ('double trouble'). This field has previously focussed on single genes, but we are now beginning to understand interactions between co-existing mutations, genetic modifiers, and their role in pathomechanisms. New genetic observations in pediatric presentations of channelopathies broadens our understanding of the conditions. Genetic and mechanistic advances have increased the potential to develop treatments.
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Affiliation(s)
- Vinojini Vivekanandam
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Roope Männikkö
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Michael G Hanna
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
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17
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Sansone VA. Episodic Muscle Disorders. Continuum (Minneap Minn) 2019; 25:1696-1711. [PMID: 31794467 DOI: 10.1212/con.0000000000000802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE OF REVIEW This article reviews the episodic muscle disorders, including benign cramp-fasciculation syndrome, the periodic paralyses, and the nondystrophic myotonias. The core diagnostic criteria for a diagnosis of primary periodic paralysis, including clues to distinguish between the hypokalemic and hyperkalemic forms, and the distinctive elements that characterize Andersen-Tawil syndrome are discussed. Management of patients with these disorders is also discussed. RECENT FINDINGS Childhood presentations of periodic paralysis have recently been described, including atypical findings. Carbonic anhydrase inhibitors, such as dichlorphenamide, have recently been approved by the US Food and Drug Administration (FDA) for the treatment of both hypokalemic and hyperkalemic forms of periodic paralysis. Muscle MRI may be a useful outcome measure in pharmacologic trials in periodic paralysis. Genetic research continues to identify additional gene mutations responsible for periodic paralysis. SUMMARY This article will help neurologists diagnose and manage episodic muscle disorders and, in particular, the periodic paralyses and the nondystrophic myotonias.
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Wallace E, Howard L, Liu M, O'Brien T, Ward D, Shen S, Prendiville T. Long QT Syndrome: Genetics and Future Perspective. Pediatr Cardiol 2019; 40:1419-1430. [PMID: 31440766 PMCID: PMC6785594 DOI: 10.1007/s00246-019-02151-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 07/10/2019] [Indexed: 01/19/2023]
Abstract
Long QT syndrome (LQTS) is an inherited primary arrhythmia syndrome that may present with malignant arrhythmia and, rarely, risk of sudden death. The clinical symptoms include palpitations, syncope, and anoxic seizures secondary to ventricular arrhythmia, classically torsade de pointes. This predisposition to malignant arrhythmia is from a cardiac ion channelopathy that results in delayed repolarization of the cardiomyocyte action potential. The QT interval on the surface electrocardiogram is a summation of the individual cellular ventricular action potential durations, and hence is a surrogate marker of the abnormal cellular membrane repolarization. Severely affected phenotypes administered current standard of care therapies may not be fully protected from the occurrence of cardiac arrhythmias. There are 17 different subtypes of LQTS associated with monogenic mutations of 15 autosomal dominant genes. It is now possible to model the various LQTS phenotypes through the generation of patient-specific induced pluripotent stem cell-derived cardiomyocytes. RNA interference can silence or suppress the expression of mutant genes. Thus, RNA interference can be a potential therapeutic intervention that may be employed in LQTS to knock out mutant mRNAs which code for the defective proteins. CRISPR/Cas9 is a genome editing technology that offers great potential in elucidating gene function and a potential therapeutic strategy for monogenic disease. Further studies are required to determine whether CRISPR/Cas9 can be employed as an efficacious and safe rescue of the LQTS phenotype. Current progress has raised opportunities to generate in vitro human cardiomyocyte models for drug screening and to explore gene therapy through genome editing.
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Affiliation(s)
- Eimear Wallace
- Regenerative Medicine Institute, School of Medicine, National University of Ireland (NUI) Galway, Galway, Ireland
| | - Linda Howard
- Regenerative Medicine Institute, School of Medicine, National University of Ireland (NUI) Galway, Galway, Ireland
| | - Min Liu
- Regenerative Medicine Institute, School of Medicine, National University of Ireland (NUI) Galway, Galway, Ireland
| | - Timothy O'Brien
- Regenerative Medicine Institute, School of Medicine, National University of Ireland (NUI) Galway, Galway, Ireland
| | - Deirdre Ward
- Department of Cardiology, Tallaght University Hospital, Dublin, Ireland
| | - Sanbing Shen
- Regenerative Medicine Institute, School of Medicine, National University of Ireland (NUI) Galway, Galway, Ireland
| | - Terence Prendiville
- Department of Paediatric Cardiology, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.
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19
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Bissay V, Van Malderen SCH. What the internist should know about hereditary muscle channelopathies. Acta Clin Belg 2018; 73:1-6. [PMID: 29088983 DOI: 10.1080/17843286.2017.1396674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES Non-dystrophic myotonia, periodic paralysis and, to a certain extent, myotonic dystrophies are rare hereditary skeletal muscle channelopathies, charactarized by myotonia or episodic muscle weakness. This review highlights the diagnostic challenges and treatment options. RESULTS Some of these rare skeletal muscle disorders are associated with a broad range of systemic and nonspecific muscle symptoms. Consequently, patients are often referred to the internist before seeing a neurologist. This article provides clinical clues to better diagnose an tackle these unique disorders. CONCLUSION A increased knowledge will reduce the diagnostic delay, improve monitoring and treatment, and might even prevent potentially life-threatening conditions as seen in DM.
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Affiliation(s)
- Véronique Bissay
- Department of Neurology, Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Sophie C. H. Van Malderen
- Department of Cardiology, AZ Nikolaas, Sint-Niklaas, Belgium
- Department of Cardiology, ZNA Middelheim Hospital, Antwerpen, Belgium
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20
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Statland JM, Fontaine B, Hanna MG, Johnson NE, Kissel JT, Sansone VA, Shieh PB, Tawil RN, Trivedi J, Cannon SC, Griggs RC. Review of the Diagnosis and Treatment of Periodic Paralysis. Muscle Nerve 2017; 57:522-530. [PMID: 29125635 PMCID: PMC5867231 DOI: 10.1002/mus.26009] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/24/2017] [Accepted: 11/07/2017] [Indexed: 01/16/2023]
Abstract
Periodic paralyses (PPs) are rare neuromuscular disorders caused by mutations in skeletal muscle sodium, calcium, and potassium channel genes. PPs include hypokalemic paralysis, hyperkalemic paralysis, and Andersen‐Tawil syndrome. Common features of PP include autosomal dominant inheritance, onset typically in the first or second decades, episodic attacks of flaccid weakness, which are often triggered by diet or rest after exercise. Diagnosis is based on the characteristic clinic presentation then confirmed by genetic testing. In the absence of an identified genetic mutation, documented low or high potassium levels during attacks or a decrement on long exercise testing support diagnosis. The treatment approach should include both management of acute attacks and prevention of attacks. Treatments include behavioral interventions directed at avoidance of triggers, modification of potassium levels, diuretics, and carbonic anhydrase inhibitors. Muscle Nerve57: 522–530, 2018
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas, 66160, USA
| | - Bertrand Fontaine
- Sorbonne-Université, INSERM, AP-HP, Reference Center for Channelopathies, Department of Neuology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Michael G Hanna
- MRC Center for Neuromuscular Diseases, University College of London Institute of Neurology, London, England
| | - Nicholas E Johnson
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - John T Kissel
- Department of Neurology, The Ohio State University, Columbus, Ohio, USA
| | - Valeria A Sansone
- The NEMO Center, Neurorehabilitation Unit, University of Milan, Italy
| | - Perry B Shieh
- Department of Neurology, University of California at Los Angeles School of Medicine, Los Angeles, California, USA
| | - Rabi N Tawil
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Jaya Trivedi
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Stephen C Cannon
- Department of Physiology, University of California at Los Angeles School of Medicine, Los Angeles, California, USA
| | - Robert C Griggs
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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21
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El-Sherif N, Turitto G, Boutjdir M. Congenital Long QT syndrome and torsade de pointes. Ann Noninvasive Electrocardiol 2017; 22. [PMID: 28670758 DOI: 10.1111/anec.12481] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/19/2017] [Indexed: 12/19/2022] Open
Abstract
Since its initial description by Jervell and Lange-Nielsen in 1957, the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. A prolonged QT interval in the surface electrocardiogram is the sine qua non of the LQTS and is a surrogate measure of the ventricular action potential duration (APD). Congenital as well as acquired alterations in certain cardiac ion channels can affect their currents in such a way as to increase the APD and hence the QT interval. The inhomogeneous lengthening of the APD across the ventricular wall results in dispersion of APD. This together with the tendency of prolonged APD to be associated with oscillations at the plateau level, termed early afterdepolarizations (EADs), provides the substrate of ventricular tachyarrhythmia associated with LQTS, usually referred to as torsade de pointes (TdP) VT. This review will discuss the genetic, molecular, and phenotype characteristics of congenital LQTS as well as current management strategies and future directions in the field.
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Affiliation(s)
- Nabil El-Sherif
- Downstate Medical Center, State University of New York, Brooklyn, NY, USA.,VA NY Harbor Healthcare System, Brooklyn, NY, USA
| | - Gioia Turitto
- NewYork-Presbyterian Brooklyn Methodist Hospital, New York, NY, USA
| | - Mohamed Boutjdir
- Downstate Medical Center, State University of New York, Brooklyn, NY, USA.,VA NY Harbor Healthcare System, Brooklyn, NY, USA.,NYU School of Medicine, New York, NY, USA
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22
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Intrafamilial phenotypic variability in Andersen–Tawil syndrome: A diagnostic challenge in a potentially treatable condition. Neuromuscul Disord 2017; 27:294-297. [DOI: 10.1016/j.nmd.2016.11.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 11/12/2016] [Indexed: 11/18/2022]
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23
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Li J, Xiao S, Xie X, Zhou H, Pang C, Li S, Zhang H, Logothetis DE, Zhan Y, An H. Three pairs of weak interactions precisely regulate the G-loop gate of Kir2.1 channel. Proteins 2016; 84:1929-1937. [PMID: 27699887 DOI: 10.1002/prot.25176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/30/2016] [Accepted: 09/19/2016] [Indexed: 11/08/2022]
Abstract
Kir2.1 (also known as IRK1) plays key roles in regulation of resting membrane potential and cell excitability. To achieve its physiological roles, Kir2.1 performs a series of conformational transition, named as gating. However, the structural basis of gating is still obscure. Here, we combined site-directed mutation, two-electrode voltage clamp with molecular dynamics simulations and determined that H221 regulates the gating process of Kir2.1 by involving a weak interaction network. Our data show that the H221R mutant accelerates the rundown kinetics and decelerates the reactivation kinetics of Kir2.1. Compared with the WT channel, the H221R mutation strengthens the interaction between the CD- and G-loops (E303-R221) which stabilizes the close state of the G-loop gate and weakens the interactions between C-linker and CD-loop (R221-R189) and the adjacent G-loops (E303-R312) which destabilizes the open state of G-loop gate. Our data indicate that the three pairs of interactions (E303-H221, H221-R189 and E303-R312) precisely regulate the G-loop gate by controlling the conformation of G-loop. Proteins 2016; 84:1929-1937. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Junwei Li
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China.,Department of Electrical Engineering and Computer Science, Hebei University of Technology, Langfang, 065000, China
| | - Shaoying Xiao
- Department of Urban Planning, School of Architecture and Art Design, Hebei University of Technology, Tianjin, 300401, China
| | - Xiaoxiao Xie
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Hui Zhou
- Department of Mathematics and Physics, North China Electric Power University, Baoding, 071003, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Shanshan Li
- Department of Mechatronics Engineering, Hebei University of Technology, Tianjin, 300130, China
| | - Hailin Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of Pharmacology and Toxicology for New Drug, Hebei Province, Department of Pharmacology, Hebei Medical University, Shijiazhuang, 050017, China
| | - Diomedes E Logothetis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - Yong Zhan
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
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24
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Mizusawa Y. Recent advances in genetic testing and counseling for inherited arrhythmias. J Arrhythm 2016; 32:389-397. [PMID: 27761163 PMCID: PMC5063262 DOI: 10.1016/j.joa.2015.12.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 12/01/2015] [Accepted: 12/17/2015] [Indexed: 12/19/2022] Open
Abstract
Inherited arrhythmias, such as cardiomyopathies and cardiac ion channelopathies, along with coronary heart disease (CHD) are three most common disorders that predispose adults to sudden cardiac death. In the last three decades, causal genes in inherited arrhythmias have been successfully identified. At the same time, it has become evident that the genetic architectures are more complex than previously known. Recent advancements in DNA sequencing technology (next generation sequencing) have enabled us to study such complex genetic traits. This article discusses indications for genetic testing of patients with inherited arrhythmias. Further, it describes the benefits and challenges that we face in the era of next generation sequencing. Finally, it briefly discusses genetic counseling, in which a multidisciplinary approach is required due to the increased complexity of the genetic information related to inherited arrhythmias.
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Key Words
- ARVD/C, arrhythmogenic right ventricular dysplasia/cardiomyopathy
- BrS, Brugada syndrome
- CHD, coronary heart disease
- CPVT, catecholaminergic polymorphic ventricular tachycardia
- Cardiac ion channelopathies
- Cardiomyopathies
- DCM, dilated cardiomyopathy
- GWAS, genome wide association study
- Genetic counseling
- Genetic testing
- HCM, hypertrophic cardiomyopathy
- HF, heart failure
- ICD, implantable cardioverter defibrillator
- Inherited arrhythmias
- LQTS, long QT syndrome
- NGS, next generation sequencing
- SCD, sudden cardiac death
- VA, ventricular arrhythmia
- VF, ventricular fibrillation
- WES, whole exome sequencing
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Affiliation(s)
- Yuka Mizusawa
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Room K2-115, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
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25
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Spillane J, Kullmann DM, Hanna MG. Genetic neurological channelopathies: molecular genetics and clinical phenotypes. J Neurol Neurosurg Psychiatry 2016; 87:37-48. [PMID: 26558925 PMCID: PMC4717447 DOI: 10.1136/jnnp-2015-311233] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/13/2015] [Indexed: 01/08/2023]
Abstract
Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.
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Affiliation(s)
- J Spillane
- Royal Free Hospital Foundation Trust London, London, UK MRC Centre for Neuromuscular Disease, UCL, London, UK
| | - D M Kullmann
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
| | - M G Hanna
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
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26
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Abstract
In the last decade, there have been considerable advances in the understanding of the pathophysiology of malignant ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Over 80% of SCD occurs in patients with organic heart disease. However, approximately 10%-15% of SCD occurs in the presence of structurally normal heart, and the majority of these patients are young. In this group of patients, changes in genes encoding cardiac ion channels produce modifications of the function of the channel resulting in an electrophysiological substrate of VT and SCD. Collectively, these disorders are referred to as cardiac ion channelopathies. The four major syndromes in this group are: the long QT syndrome (LQTS), the Brugada syndrome (BrS), the short QT syndrome (SQTS), and the catecholaminergic polymorphic ventricular tachycardia (CPVT). Each of these syndromes includes multiple subtypes with different and sometimes complex cardiac ion channel genetic abnormalities. Many are associated with other somatic and neurological abnormalities besides the risk of VT and SCD. The current management of cardiac ion channelopathies can be summarized as follows: (1) in symptomatic patients, the implantable cardioverter defibrillator (ICD) is the only viable option; (2) in asymptomatic patients, risk stratification is necessary, followed by either the ICD, pharmacotherapy, or a combination of both. A genotype-specific approach to pharmacotherapy requires a thorough understanding of the molecular-cellular basis of arrhythmogenesis in cardiac ion channelopathies as well as the specific drug profile.
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27
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Fadahunsi O, Shaikh B, Rettew A, Bennett K, Scollan D. Atrial pacing for the management of ventricular arrhythmias in Andersen-Tawil syndrome. HeartRhythm Case Rep 2015; 1:352-355. [PMID: 28491582 PMCID: PMC5419674 DOI: 10.1016/j.hrcr.2015.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Opeyemi Fadahunsi
- Department of Medicine, Reading Health System, West Reading, Pennsylvania
| | - Bilal Shaikh
- Department of Medicine, Reading Health System, West Reading, Pennsylvania
| | - Andrew Rettew
- Department of Medicine, Reading Health System, West Reading, Pennsylvania
| | - Kyle Bennett
- Department of Medicine, Reading Health System, West Reading, Pennsylvania
| | - David Scollan
- Cardiology Associates of West Reading, West Reading, Pennsylvania
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28
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Jhansi Rani P, Yashodhara P, Sundarachary NV, Veeramma U, Elahi SM, Amalakanti S, Lalitha A. Vanishing Weakness and Persistent Cardiac Dysrhythmia: Are We Dealing with Andersen Tawil Syndrome? Indian J Pediatr 2015; 82:642-4. [PMID: 25616308 DOI: 10.1007/s12098-014-1677-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 12/22/2014] [Indexed: 10/24/2022]
Abstract
Andersen Tawil Syndrome (ATS) is a very rare type of periodic paralysis; the authors present a case report from South India with features that have not been reported earlier. This case suggests many unexplored hypotheses for the disease and argues the need for physician sensitization of this entity.
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Affiliation(s)
- P Jhansi Rani
- Department of Pediatrics, Guntur Medical College, Guntur, Andhra Pradesh, India
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29
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Márquez MF, Totomoch-Serra A, Vargas-Alarcón G, Cruz-Robles D, Pellizzon OA, Cárdenas M. [Andersen-Tawil syndrome: a review of its clinical and genetic diagnosis with emphasis on cardiac manifestations]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2014; 84:278-85. [PMID: 25270337 DOI: 10.1016/j.acmx.2013.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 12/12/2013] [Accepted: 12/12/2013] [Indexed: 10/24/2022] Open
Abstract
The Andersen-Tawil syndrome is a cardiac ion channel disease that is inherited in an autosomal dominant way and is classified as type 7 of the congenital long QT syndromes. Affected gene is KCNJ2, which forms the inward rectifier potassium channel designated Kir2.1. This protein is involved in stabilizing the resting membrane potential and controls the duration of the action potential in skeletal muscle and heart. It also participates in the terminal repolarization phase of the action potential in ventricular myocytes and is a major component responsible for the correction in the potassium current during phase 3 of the action potential repolarization. Kir 2.1 channel has a predominant role in skeletal muscle, heart and brain. Alterations in this channel produce flaccid paralysis, arrhythmias, impaired skeletal development primarily in extremities and facial area. In this review we address the disease from the point of view of clinical and molecular diagnosis with emphasis on cardiac manifestations.
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Affiliation(s)
- Manlio F Márquez
- Departamento de Electrofisiología, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México.
| | - Armando Totomoch-Serra
- Departamento de Biología Molecular, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México; Maestría en Investigación Clínica Experimental en Salud, Universidad Nacional Autónoma de México, México D.F., México
| | - Gilberto Vargas-Alarcón
- Departamento de Biología Molecular, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México
| | - David Cruz-Robles
- Departamento de Biología Molecular, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México
| | - Oscar A Pellizzon
- Centro de Arritmias Cardíacas, Hospital Universitario del Centenario, Rosario (Santa Fe), Argentina
| | - Manuel Cárdenas
- Departamento de Electrofisiología, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México
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Nagamine S, Sakoda S, Koide R, Kawata A, Yuan J, Takashima H, Nakano I. A case of Andersen-Tawil syndrome presenting periodic paralysis exacerbated by acetazolamide. J Neurol Sci 2014; 347:385-6. [PMID: 25284084 DOI: 10.1016/j.jns.2014.09.040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/23/2014] [Accepted: 09/22/2014] [Indexed: 01/22/2023]
Affiliation(s)
- Satoshi Nagamine
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan.
| | - Shunichi Sakoda
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Reiji Koide
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan
| | - Akihiro Kawata
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan
| | - Junhui Yuan
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Imaharu Nakano
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan
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Fernlund E, Lundin C, Hertervig E, Kongstad O, Alders M, Platonov P. Novel mutation in the KCNJ2 gene is associated with a malignant arrhythmic phenotype of Andersen-Tawil syndrome. Ann Noninvasive Electrocardiol 2014; 18:471-8. [PMID: 24047492 DOI: 10.1111/anec.12074] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Andersen-Tawil syndrome (ATS) is a rare inherited multisystem disorder associated with mutations in KCNJ2 and low prevalence of life-threatening ventricular arrhythmias. Our aim was to describe the clinical course of ATS in a family, in which the proband survived aborted cardiac arrest (ACA) and genetic screening revealed a previously unknown mutation (c.271_282del12[p.Ala91_Leu94del]) in the KCNJ2 gene. METHODS A cascade family screening was performed in a 5-generation family after identification of the KCNJ2 mutation in the proband. Subsequently, 10 of 21 screened individuals appeared to be mutation carriers (median age 38 [range 10-75] years, 3 female). Mutation carriers underwent clinical examination including biochemistry panel, cardiac ultrasound, Holter ECG, and exercise stress test. RESULTS (1) At baseline, 2 patients had survived ACA, 3 had syncope or presyncopal attacks, and 2 reported palpitations. Exercise-induced nonsustained bidirectional ventricular tachycardia was documented in 4 patients, 2 received implantable cardioverter-defibrillators (ICD) for primary prevention and 2 for secondary prevention. (2) During follow-up, 1 primary prevention and 1 secondary prevention patient received in total 4 adequate ICD shocks. Life-threatening ventricular arrhythmias were documented during childhood in 5 of 10 mutation carriers. (3) All mutation carriers presented with characteristic mild dysmorphic features. Only 1 patient suffered from periodic paralysis. All had normal serum potassium level at repeated assessments and none had any other extracardiac disease manifestation. CONCLUSION Our findings suggest that the novel KCNJ2 mutation is associated with a predominantly cardiac phenotype of Andersen-Tawil syndrome with high propensity to life-threatening ventricular arrhythmias presenting from childhood and young adulthood.
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Affiliation(s)
- E Fernlund
- Childrens Heart Center, Lund University and Skane University Hospital, Lund, Sweden
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Druggability of the inward rectifier family: a hope for rare channelopathies? Future Med Chem 2014; 6:971-3. [PMID: 24547691 DOI: 10.4155/fmc.14.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Pyo JY, Joh DH, Park JS, Lee SJ, Lee H, Kim W, Joung B. Ventricular tachyarrhythmias in a patient with Andersen-Tawil syndrome. Korean Circ J 2013; 43:62-5. [PMID: 23407770 PMCID: PMC3569570 DOI: 10.4070/kcj.2013.43.1.62] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 07/10/2012] [Accepted: 07/20/2012] [Indexed: 01/25/2023] Open
Abstract
Andersen-Tawil syndrome (ATS), a rare autosomal dominant disorder, is characterized by periodic paralysis, dysmorphic features and cardiac arrhythmias. This syndrome is caused by mutations of KCNJ2 gene, which encodes inward rectifying potassium channel. Here, we report an 18-year-old girl who was presented with life-threatening cardiac arrhythmia and acute respiratory distress. She was diagnosed with ATS, based on dysmorphic features, ventricular arrhythmia, and periodic paralysis. This is the first case to be reported in Korea who experienced a fatal cardiac arrest and respiratory failure caused by ATS.
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Affiliation(s)
- Jung Yoon Pyo
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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Lestner JM, Ellis R, Canham N. Delineating the 17q24.2–q24.3 microdeletion syndrome phenotype. Eur J Med Genet 2012; 55:700-4. [DOI: 10.1016/j.ejmg.2012.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 07/04/2012] [Accepted: 08/07/2012] [Indexed: 12/28/2022]
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Andersen-Tawil Syndrome Associated with Aborted Sudden Cardiac Death: Atrial Pacing Was Effective for Ventricular Arrhythmias. Am J Med Sci 2012; 344:248-50. [DOI: 10.1097/maj.0b013e3182560209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brenyo AJ, Huang DT, Aktas MK. Congenital long and short QT syndromes. Cardiology 2012; 122:237-47. [PMID: 22906875 DOI: 10.1159/000339537] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 05/08/2012] [Indexed: 11/19/2022]
Abstract
Congenital long and short QT syndromes are familial arrhythmias characterized by derangement of repolarization and a high risk of sudden cardiac death due to ventricular tachyarrhythmias. With growing understanding of these syndromes in both the medical and lay communities, diagnostic and therapeutic difficulties are increasingly faced by health care providers. Modern genomics has determined the mechanism of arrhythmia induction in these patients, resulting in specific medical therapies and improved risk stratification. This paper reviews the common presentations, genetic etiology, basic evaluation, risk stratification, and therapeutic approach for both syndromes. Particular attention is paid to the effect of the individual syndrome on the cardiac action potential and its correlate the surface 12 lead ECG. In conclusion, patients with long and short QT syndromes are at risk for sudden death, with accurate diagnosis, risk stratification, and resulting appropriate therapy favorably altering their outcome.
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Affiliation(s)
- Andrew J Brenyo
- Department of Cardiovascular Diseases, University of Rochester Medical Center, Strong Memorial Hospital, Rochester, NY 14642, USA.
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Tan SV, Z'Graggen WJ, BoËrio D, Rayan DLR, Howard R, Hanna MG, Bostock H. Membrane dysfunction in Andersen-Tawil syndrome assessed by velocity recovery cycles. Muscle Nerve 2012; 46:193-203. [DOI: 10.1002/mus.23293] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Sansone VA, Ricci C, Montanari M, Apolone G, Rose M, Meola G. Measuring quality of life impairment in skeletal muscle channelopathies. Eur J Neurol 2012; 19:1470-6. [PMID: 22607270 PMCID: PMC3492909 DOI: 10.1111/j.1468-1331.2012.03751.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 04/02/2012] [Indexed: 01/31/2023]
Abstract
Background and purpose Fatigue and pain have been previously shown to be important determinants for decreasing quality of life (QoL) in one report in patients with non-dystrophic myotonia. The aims of our study were to assess QoL in skeletal muscle channelopathies (SMC) using INQoL (individualized QoL) and SF-36 questionnaires. Methods We administered INQoL and SF-36 to 66 Italian patients with SMC (26: periodic paralysis, 36: myotonia congenita and 4: Andersen-Tawil) and compared the results in 422 patients with myotonic dystrophies (DM1: 382; and DM2: 40). Results (i) INQoL index in SMC is similar to that in DMs (P = 0.79). (ii) Patients with myotonia congenita have the worst perception of QoL. (iii) Myotonia has the most detrimental effect on patients with myotonia congenita, followed by patients with DM2 and then by patients with DM1 and hyperkalemic periodic paralysis. (iv) Pain is a significant complaint in patients with myotonia congenita, hypokalemic periodic paralysis and DM2 but not in DM1. (v) Fatigue has a similar detrimental effect on all patient groups except for patients with hyperkalemic periodic paralysis in whom muscle weakness and myotonia more than fatigue affect QoL perception. (vi) Muscle symptoms considered in INQoL correlate with physical symptoms assessed by SF-36 (R from −0.34 to −0.76). Conclusions QoL perception in patients with SMC is similar to that of patients with DMs, chronic multisystem disabling conditions. Our results provide information to target treatment and health care of these patients. The sensitivity of INQoL to changes in QoL in the SMC needs to be further explored in longitudinal studies.
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Affiliation(s)
- V A Sansone
- Department of Neurology, University of Milan, IRCCS Policlinico San Donato, Milan, Italy.
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Monteforte N, Napolitano C, Priori SG. Genetics and arrhythmias: diagnostic and prognostic applications. Rev Esp Cardiol 2012; 65:278-86. [PMID: 22245453 DOI: 10.1016/j.recesp.2011.10.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/09/2011] [Indexed: 10/14/2022]
Abstract
This review article discusses the genetic bases of cardiac arrest with a specific focus on cardiac channelopathies and right ventricular cardiomyopathy. We review the appropriate use of genetic testing in those patients suspected to have inherited cardiac arrhythmias, highlighting the importance of most genotype-phenotype correlations for risk stratification. The article also presents the most recent views on diagnostic criteria and flowcharts for treatment of patients with inherited arrhythmogenic diseases.
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Affiliation(s)
- Nicola Monteforte
- Medicina Molecolare, IRCCS Fondazione Salvatore Maugeri, Pavía, Italy
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Fowler SJ, Bloise R. Genetic Testing for Cardiac Arrhythmias: Ready for Prime Time? Card Electrophysiol Clin 2010; 2:611-621. [PMID: 28770723 DOI: 10.1016/j.ccep.2010.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Despite the heterogeneity of substrates and clinical expressivity, genetic testing has a direct impact on clinical practice: it allows a specific diagnosis, including silent carriers (ie, asymptomatic diagnosis) and, in select diseases, the identification of a mutation has major impact for risk stratification and treatment of patients. This article addresses the role of genetic testing for each of the most epidemiologically relevant inherited arrhythmogenic diseases, specifically long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy.
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Affiliation(s)
- Steven J Fowler
- Cardiovascular Genetics Program, Leon H. Charney Division of Cardiology, NYU Langone Medical Center, New York, USA; Clinical Cardiac Electrophysiology, Leon H. Charney Division of Cardiology, NYU Langone Medical Center, New York, USA
| | - Raffaella Bloise
- Molecular Cardiology, IRCCS Fondazione Salvatore Maugeri, Pavia, Italy; Department of Cardiology, University of Pavia, Pavia, Italy
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Aziz EF, Javed F, Pratap B, Herzog E. Strategies for the prevention and treatment of sudden cardiac death. Open Access Emerg Med 2010; 2010:99-114. [PMID: 22102788 PMCID: PMC3219585 DOI: 10.2147/oaem.s6869] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Cardiovascular diseases account for 40% of all deaths in the West. Sudden cardiac death (SCD) is a major health problem affecting over 300,000 patients annually in the United States alone. Presence of coronary artery disease (CAD), usually in the setting of diminished left ventricular ejection fraction, is still the single major risk factor for SCD. Additionally, acute myocardial ischemia, structural cardiac defects, anomalous coronary arteries, cardiomyopathies, genetic mutations, and ventricular arrhythmias are all attributed to SCD, demonstrating the perplexity of this condition. With the recent advancements in cardiovascular medicine, the incidence of SCD is expected to increase steeply as the prevalence of CAD and heart failure is uprising in general population. Considering SCD, the major challenge confronting contemporary cardiology, multiple strategies for prevention against SCD have been developed. β-blockers have been shown to reduce the risk of SCD, whereas implantable cardioverter-defibrillator devices are found to be effective at terminating the malignant arrhythmias. In recent years, multiple clinical trials were carried out to identify patients who may benefit from preventive intervention, including medical therapy and automatic cardioverter-defibrillator implantations. This review article provides insight into the advanced strategies for the prevention and treatment of SCD based on the data available in medical literature to date.
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Affiliation(s)
- Emad F Aziz
- The Advanced Cardiac Admission Program, St Luke's-Roosevelt Hospital Center, University Hospital of Columbia University, College of Physicians and Surgeons, New York, NY, USA
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de Boer TP, Houtman MJC, Compier M, van der Heyden MAG. The mammalian K(IR)2.x inward rectifier ion channel family: expression pattern and pathophysiology. Acta Physiol (Oxf) 2010; 199:243-56. [PMID: 20331539 DOI: 10.1111/j.1748-1716.2010.02108.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Inward rectifier currents based on K(IR)2.x subunits are regarded as essential components for establishing a stable and negative resting membrane potential in many excitable cell types. Pharmacological inhibition, null mutation in mice and dominant positive and negative mutations in patients reveal some of the important functions of these channels in their native tissues. Here we review the complex mammalian expression pattern of K(IR)2.x subunits and relate these to the outcomes of functional inhibition of the resultant channels. Correlations between expression and function in muscle and bone tissue are observed, while we recognize a discrepancy between neuronal expression and function.
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Affiliation(s)
- T P de Boer
- Department of Medical Physiology, UMCU, Utrecht, the Netherlands
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Nagashima M, Higaki T, Seike Y, Yokoyama Y. Cardiac Surgery for a Patient With Andersen-Tawil Syndrome. Ann Thorac Surg 2010; 90:285-7. [DOI: 10.1016/j.athoracsur.2009.12.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 12/09/2009] [Accepted: 12/15/2009] [Indexed: 11/24/2022]
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Nynke Hofman, Laura T van Lochem, Arthur AM Wilde. Genetic basis of malignant channelopathies and ventricular fibrillation in the structurally normal heart. Future Cardiol 2010; 6:395-408. [DOI: 10.2217/fca.10.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Sudden cardiac death occurs in a minority of patients in the absence of structural or functional abnormalities. In this category, pure electrical heart diseases are responsible for a large number of these unexpected deaths. These conditions include the long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome (collectively referred to as channelopathies) and idiopathic ventricular fibrillation. This article reviews the current molecular understanding of the electrical diseases of the heart associated with sudden cardiac death, and provides a summary of the causal genes and a flowchart with an overview of the genotype–phenotype correlation of the most common arrhythmia syndromes.
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Lim BC, Kim GB, Bae EJ, Noh CI, Hwang H, Kim KJ, Hwang YS, Ko TS, Chae JH. Andersen cardiodysrhythmic periodic paralysis with KCNJ2 mutations: a novel mutation in the pore selectivity filter residue. J Child Neurol 2010; 25:490-3. [PMID: 20382953 DOI: 10.1177/0883073809357937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Andersen cardiodysrhythmic periodic paralysis or Andersen-Tawil syndrome includes the distinct clinical features of periodic paralysis, cardiac arrhythmia, and facial and skeletal dysmorphisms and exhibits autosomal dominant inheritance. Mutations in the KCNJ2 gene, which encodes the human inward rectifier potassium channel Kir2.1, have been identified in the majority of cases. Despite well-established clinical and molecular characteristics, treatment is still case oriented, and timely diagnosis could be delayed because of the low incidence and phenotypic heterogeneity of this disease. This article describes the clinical and molecular features of 3 cases of Andersen-Tawil syndrome in 2 families. One of the mutations (G144D) was located in the pore selectivity filter residue (which is mutated recurrently) and was considered novel. Intermittent muscle weakness in childhood warrants careful evaluation of cardiac dysrhythmia and skeletal anomalies.
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Affiliation(s)
- Byung Chan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea
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Abstract
PURPOSE OF REVIEW In this article, we will review the appropriate use of genetic testing in those patients suspected to have inherited arrhythmogenic diseases, with specific focus on the indications for testing and the expected probability of positive genotyping. RECENT FINDINGS Important advances have been made in the identification of new genes, associated mutations, and polymorphisms that modulate susceptibility of acquired arrhythmias. We will examine the most recent advances relevant to the rational application of genetic analysis, guided by genotype-phenotype correlations derived from disease and patient-specific evaluation, as well as discussing novel technologies and recently published cost-effectiveness data. SUMMARY Genetic analysis can be performed to identify the molecular substrate in those patients suspected to be affected by an inherited arrhythmogenic disease; however, the clinical usefulness of this information is often not straightforward. We hope to emphasize the concept that there is a significant difference in the impact of genetic testing within the various arrhythmogenic disorders, and the benefit of accessing genetic testing is not the same in all patients. The resultant integration between the expected yield of genetic screening and cost may allow the formation of criteria to prioritize access for those who could derive the most clinical benefit.
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1081] [Impact Index Per Article: 77.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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A novel neuropsychiatric phenotype of KCNJ2 mutation in one Taiwanese family with Andersen–Tawil syndrome. J Hum Genet 2010; 55:186-8. [DOI: 10.1038/jhg.2010.2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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