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Jiang C, Zhang Y. Current updates on arrhythmia within Timothy syndrome: genetics, mechanisms and therapeutics. Expert Rev Mol Med 2023; 25:e17. [PMID: 37132248 PMCID: PMC10407238 DOI: 10.1017/erm.2023.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 04/13/2023] [Accepted: 04/23/2023] [Indexed: 05/04/2023]
Abstract
Timothy syndrome (TS), characterised by multiple system malfunction especially the prolonged corrected QT interval and synchronised appearance of hand/foot syndactyly, is an extremely rare disease affecting early life with devastating arrhythmia. In this work, firstly, the various mutations in causative gene CACNA1C encoding cardiac L-type voltage-gated calcium channel (LTCC), regard with the genetic pathogeny and nomenclature of TS are reviewed. Secondly, the expression profile and function of CACNA1C gene encoding Cav1.2 proteins, and its gain-of-function mutation in TS leading to multiple organ disease phenotypes especially arrhythmia are discussed. More importantly, we focus on the altered molecular mechanism underlying arrhythmia in TS, and discuss about how LTCC malfunction in TS can cause disorganised calcium handling with excessive intracellular calcium and its triggered dysregulated excitation-transcription coupling. In addition, current therapeutics for TS cardiac phenotypes including LTCC blockers, beta-adrenergic blocking agents, sodium channel blocker, multichannel inhibitors and pacemakers are summarised. Eventually, the research strategy using patient-specific induced pluripotent stem cells is recommended as one of the promising future directions for developing therapeutic approaches. This review updates our understanding on the research progress and future avenues to study the genetics and molecular mechanism underlying the pathogenesis of devastating arrhythmia within TS, and provides novel insights for developing therapeutic measures.
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Affiliation(s)
- Congshan Jiang
- National Regional Children's Medical Centre (Northwest), Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, Xi'an Key Laboratory of Children's Health and Diseases, Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, China
| | - Yanmin Zhang
- National Regional Children's Medical Centre (Northwest), Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, Xi'an Key Laboratory of Children's Health and Diseases, Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, China
- Department of Cardiology, Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, China
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Abstract
The CACNA1C gene encodes the pore-forming subunit of the CaV1.2 L-type Ca2+ channel, a critical component of membrane physiology in multiple tissues, including the heart, brain, and immune system. As such, mutations altering the function of these channels have the potential to impact a wide array of cellular functions. The first mutations identified within CACNA1C were shown to cause a severe, multisystem disorder known as Timothy syndrome (TS), which is characterized by neurodevelopmental deficits, long-QT syndrome, life-threatening cardiac arrhythmias, craniofacial abnormalities, and immune deficits. Since this initial description, the number and variety of disease-associated mutations identified in CACNA1C have grown tremendously, expanding the range of phenotypes observed in affected patients. CACNA1C channelopathies are now known to encompass multisystem phenotypes as described in TS, as well as more selective phenotypes where patients may exhibit predominantly cardiac or neurological symptoms. Here, we review the impact of genetic mutations on CaV1.2 function and the resultant physiological consequences.
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Affiliation(s)
- Kevin G Herold
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - John W Hussey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ivy E Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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Ehtesham N, Mosallaei M, Beheshtian M, Khoshbakht S, Fadaee M, Vazehan R, Faraji Zonooz M, Karimzadeh P, Kahrizi K, Najmabadi H. Characterizing Genotypes and Phenotypes Associated with Dysfunction of Channel-Encoding Genes in a Cohort of Patients with Intellectual Disability. Arch Iran Med 2022; 25:788-797. [PMID: 37543906 PMCID: PMC10685845 DOI: 10.34172/aim.2022.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 12/20/2021] [Indexed: 08/08/2023]
Abstract
BACKGROUND Ion channel dysfunction in the brain can lead to impairment of neuronal membranes and generate several neurological diseases, especially neurodevelopmental disorders. METHODS In this study, we set out to delineate the genotype and phenotype spectrums of 14 Iranian patients from 7 families with intellectual disability (ID) and/or developmental delay (DD) in whom genetic mutations were identified by next-generation sequencing (NGS) in 7 channel-encoding genes: KCNJ10, KCNQ3, KCNK6, CACNA1C, CACNA1G, SCN8A, and GRIN2B. Moreover, the data of 340 previously fully reported ID and/or DD cases with a mutation in any of these seven genes were combined with our patients to clarify the genotype and phenotype spectrum in this group. RESULTS In total, the most common phenotypes in 354 cases with ID/DD in whom mutation in any of these 7 channel-encoding genes was identified were as follows: ID (77.4%), seizure (69.8%), DD (59.8%), behavioral abnormality (29.9%), hypotonia (21.7%), speech disorder (21.5%), gait disturbance (20.9%), and ataxia (20.3%). Electroencephalography abnormality (33.9%) was the major brain imaging abnormality. CONCLUSION The results of this study broaden the molecular spectrum of channel pathogenic variants associated with different clinical presentations in individuals with ID and/or DD.
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Affiliation(s)
- Naeim Ehtesham
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Meysam Mosallaei
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Maryam Beheshtian
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Shahrouz Khoshbakht
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mahsa Fadaee
- Kariminejad – Najmabadi Pathology & Genetics Center, Tehran, Iran
| | - Raheleh Vazehan
- Kariminejad – Najmabadi Pathology & Genetics Center, Tehran, Iran
| | | | - Parvaneh Karimzadeh
- Department of Pediatric Neurology, School of Medicine, Pediatric Neurology Research Center, Mofid Children’s Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
- Kariminejad – Najmabadi Pathology & Genetics Center, Tehran, Iran
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Borbás J, Vámos M, Hategan L, Hanák L, Farkas N, Szakács Z, Csupor D, Tél B, Kupó P, Csányi B, Nagy V, Komócsi A, Habon T, Hegyi P, Sepp R. Geno- and phenotypic characteristics and clinical outcomes of CACNA1C gene mutation associated Timothy syndrome, “cardiac only” Timothy syndrome and isolated long QT syndrome 8: A systematic review. Front Cardiovasc Med 2022; 9:1021009. [DOI: 10.3389/fcvm.2022.1021009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/02/2022] [Indexed: 11/30/2022] Open
Abstract
BackgroundMutations in the CACNA1C gene–encoding for the major Ca2+ channel of the heart–may exhibit a variety of clinical manifestations. These include typical or atypical Timothy syndromes (TS) which are associated with multiple organ manifestations, and cardiac involvement in form of malignant arrhythmias, QTc prolongation, or AV block. “Cardiac only” Timothy syndrome (COTS) shows no extracardiac manifestation, whereas some CACNA1C gene mutations are associated with QTc prolongation alone (isolated long QT syndrome 8, LQT8).MethodsA systematic search of the literature reporting cases of CACNA1C gene mutation associated syndromes, including TS, COTS and isolated LQT8 via major databases published from 2004 through 2019 was performed. Detailed patient-level phenotypic and genotypic characteristics, as well as long-term outcome measures were collected and compared between pre-specified patient groups, defined both on phenotype and genotype.ResultsA total of 59 TS, 6 COTS, and 20 isolated LQT8 index cases were identified. Apart of syndactyly or baldness, there were no major differences regarding clinical manifestations or outcome measures between TS subtypes, either defining TS subtypes on the genotype or based on the phenotype. Both subtypes were characterized by an extreme degree of QTc prolongation (median ≥600 ms) which were reflected in high major adverse cardiac event rate. On the other hand, there were marked differences between TS, COTS, and isolated LQT8. Timothy syndrome was characterized by a much earlier disease onset, much more pronounced QTc prolongation and much higher mortality rate than COTS or isolated LQT8. Similar differences were observed comparing CACNA1C exon 8/8A vs. non-exon 8/8A mutation carriers. TS showed a high degree of genetic homogeneity, as the p.Gly406Arg mutation either in exon 8 or exon 8A alone was responsible for 70% of the cases.ConclusionsClinical phenotypes associated with mutations in the CACNA1C gene show important clinical differences. Timothy syndrome is associated with the most severe clinical phenotype and with the highest risk of morbidity and mortality. However, distinguishing TS subtypes, in any form, are not supported by our data.Systematic review registration[https://www.crd.york.ac.uk/prospero/], identifier [CRD42020184737].
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Westphal DS, Hauser M, Beckmann BM, Wolf CM, Hessling G, Oberhoffer-Fritz R, Wacker-Gussmann A. Fetal Bradycardia Caused by Monogenic Disorders-A Review of the Literature. J Clin Med 2022; 11:jcm11236880. [PMID: 36498454 PMCID: PMC9741304 DOI: 10.3390/jcm11236880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/03/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022] Open
Abstract
Introduction: The standard obstetric definition of fetal bradycardia is a sustained fetal heart rate < 110 bpm over at least 10 min. Fetal bradycardia can be the first and only prenatal presentation of a heart disease. We present an overview on different genetic disorders that should be taken into consideration in case of diagnosed fetal bradycardia. Methods: A literature review was conducted using a PubMed- and OMIM-based search for monogenetic disorders causing fetal bradycardia in September 2022. Results: The review on the literature identified nine monogenic diseases that could lead to fetal bradycardia. Four of these disorders can be associated with extracardiac findings. Discussion: Genetic testing should be considered in cases with fetal bradycardia, especially in cases of additional extracardiac findings. Broad sequencing techniques and improved prenatal phenotyping could help to establish a diagnosis in an increasing number of cases.
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Affiliation(s)
- Dominik S. Westphal
- Department of Internal Medicine I, Klinikum Rechts der Isar, School of Medicine and Health, Technical University Munich, 81675 Munich, Germany
- Institute of Human Genetics, Klinikum Rechts der Isar, School of Medicine and Health, Technical University Munich, 81675 Munich, Germany
- Correspondence:
| | | | - Britt-Maria Beckmann
- Institute of Legal Medicine, University Hospital Frankfurt, Goethe University, 60596 Frankfurt, Germany
| | - Cordula M. Wolf
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802 Munich, Germany
- Department of Congenital Heart Defects and Pediatric Cardiology, German Heart Center Munich, School of Medicine and Health, Technical University Munich, 80636 Munich, Germany
| | - Gabriele Hessling
- Department of Congenital Heart Defects and Pediatric Cardiology, German Heart Center Munich, School of Medicine and Health, Technical University Munich, 80636 Munich, Germany
| | - Renate Oberhoffer-Fritz
- Department of Congenital Heart Defects and Pediatric Cardiology, German Heart Center Munich, School of Medicine and Health, Technical University Munich, 80636 Munich, Germany
- Institute of Preventive Pediatrics, TUM Department of Sport and Health Sciences, Technical University Munich, 80992 Munich, Germany
| | - Annette Wacker-Gussmann
- Department of Congenital Heart Defects and Pediatric Cardiology, German Heart Center Munich, School of Medicine and Health, Technical University Munich, 80636 Munich, Germany
- Institute of Preventive Pediatrics, TUM Department of Sport and Health Sciences, Technical University Munich, 80992 Munich, Germany
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Melgar Quicaño LA, Chipa Ccasani F. [Congenital long QT syndrome]. Arch Peru Cardiol Cir Cardiovasc 2021; 2:49-57. [PMID: 37727265 PMCID: PMC10506569 DOI: 10.47487/apcyccv.v2i1.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 09/21/2023]
Abstract
Congenital long QT syndrome (LQTS) represents a group of heart diseases of genetic origin characterized by prolongation of the QT interval and an abnormal T wave on the electrocardiogram (ECG). They can have a dominant or recessive expression, the latter associated with sensorineural deafness. In both cases, its clinical presentation is associated with recurrent syncope and sudden death as a consequence of ventricular tachycardia, specifically Torsades de Pointes. Currently they are classified according to the specific genetic defect, being able to compromise around 16 genes and almost 2000 mutations. It should be suspected in individuals with related symptoms, electrocardiographic findings, and family history. Management is based on the reduction or elimination of symptoms, and concomitantly the prevention of sudden death (SD), in those children with congenital deafness, the management requires the application of the otolaryngologist specialist's own measures. The cardiovascular management implies the modification of lifestyles, mainly the prohibition of competitive sports, including swimming, avoiding exposure to loud sounds or triggers. The medications used include beta-blockers, and more rarely flecainide, ranozaline, and verapamil; invasive management consists of the implantation of a cardioverter defibrillator or even left sympathetic denervation, each with its own risks and benefits. In any of the cases, we must avoid the circumstances that increase the QT interval, as well as carry out the appropriate analysis of the benefits and risks of each possible invasive measure.
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Affiliation(s)
| | - Fredy Chipa Ccasani
- Instituto Nacional de Salud del Niño, San Borja. Lima, PerúInstituto Nacional de Salud del NiñoLimaPerú
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Abstract
Timothy Syndrome (TS) (OMIM #601005) is a rare autosomal dominant syndrome caused by variants in CACNA1C, which encodes the α1C subunit of the voltage-gated calcium channel Cav1.2. TS is classically caused by only a few different genetic changes and characterized by prolonged QT interval, syndactyly, and neurodevelopmental delay; however, the number of identified TS-causing variants is growing, and the resulting symptom profiles are incredibly complex and variable. Here, we aim to review the genetic and clinical findings of all published case reports of TS to date. We discuss multiple possible mechanisms for the variability seen in clinical features across these cases, including mosaicism, genetic background, isoform complexity of CACNA1C and differential expression of transcripts, and biophysical changes in mutant CACNA1C channels. Finally, we propose future research directions such as variant validation, in vivo modeling, and natural history characterization.
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Affiliation(s)
- Rosemary Bauer
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | | | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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8
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Cheng L, Li X, Zhao L, Wang Z, Zhang J, Liang Z, Wu Y. Reevaluating the Mutation Classification in Genetic Studies of Bradycardia Using ACMG/AMP Variant Classification Framework. Int J Genomics 2020; 2020:2415850. [PMID: 32211440 DOI: 10.1155/2020/2415850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/08/2020] [Indexed: 11/17/2022] Open
Abstract
PURPOSE Next-generation sequencing (NGS) has become more accessible, leading to an increasing number of genetic studies of familial bradycardia being reported. However, most of the variants lack full evaluation. The relationship between genetic factors and bradycardia should be summarized and reevaluated. METHODS We summarized genetic studies published in the PubMed database from 2008/1/1 to 2019/9/1 and used the ACMG/AMP classification framework to analyze related sequence variants. RESULTS We identified 88 articles, 99 sequence variants, and 34 genes after searching the PubMed database and classified ABCC9, ACTN2, CACNA1C, DES, HCN4, KCNQ1, KCNH2, LMNA, MECP2, LAMP2, NPPA, SCN5A, and TRPM4 as high-priority genes causing familial bradycardia. Most mutated genes have been reported as having multiple clinical manifestations. CONCLUSIONS For patients with familial CCD, 13 high-priority genes are recommended for evaluation. For genetic studies, variants should be carefully evaluated using the ACMG/AMP variant classification framework before publication.
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Abstract
Timothy syndrome is a rare disorder caused by CACNA1C gene mutations and characterized by multi-organ system dysfunctions, including ventricular arrhythmias, syndactyly, dysmorphic facial features, intermittent hypoglycemia, immunodeficiency, developmental delay, and autism. Because of the low morbidity and high mortality at a young age, it remains a huge challenge to establish a diagnosis and treatment system to manage Timothy syndrome patients. Here, we aim to provide a detailed review of Timothy syndrome, discuss the mechanisms underlying dysfunctional Cav1.2 due to CACNA1C mutations, and provide some new emerging evidences in treating Timothy syndrome from cell to bedside, promoting the management of this rare disease. Impact statement The knowledge of Timothy syndrome (TS) caused by dysfunctional Cav1.2 channel due to CACNA1C mutations is rapidly evolving as novel technologies of electrophysiology are introduced and our understanding of the mechanisms of TS develops. In this review, we focus on the TS-related dysfunctional Cav1.2 and the underlying mechanisms. We update TS-related CACNA1C mutations in a precise way over the past 20 years and summarize all reported TS patients based on their clinical presentations and molecular mechanisms, respectively. We hope this review will provide a new comprehensive way to better understand the electrophysiological mechanisms underlying TS from cell to bedside, promoting the management of TS in practice.
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Affiliation(s)
- Dan Han
- 1 Department of Cardiology, the First Affiliated Hospital of Xi'an Jiaotong University, Shaanxi 710061, P. R. China.,2 Department of Cardiovascular Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Shaanxi 710061, P.R. China*These authors contributed equally to this work and should be considered to share first authorship
| | - Xiaolin Xue
- 1 Department of Cardiology, the First Affiliated Hospital of Xi'an Jiaotong University, Shaanxi 710061, P. R. China
| | - Yang Yan
- 2 Department of Cardiovascular Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Shaanxi 710061, P.R. China*These authors contributed equally to this work and should be considered to share first authorship
| | - Guoliang Li
- 1 Department of Cardiology, the First Affiliated Hospital of Xi'an Jiaotong University, Shaanxi 710061, P. R. China
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Colson C, Mittre H, Busson A, Leenhardt A, Denjoy I, Fressard V, Troadec Y. Unusual clinical description of adult with Timothy syndrome, carrier of a new heterozygote mutation of CACNA1C. Eur J Med Genet 2019; 62:103648. [PMID: 30998997 DOI: 10.1016/j.ejmg.2019.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/11/2019] [Accepted: 04/02/2019] [Indexed: 11/19/2022]
Abstract
CANAC1C encodes for the main cardiac L-type calcium channel and mutations on it lead to a prolonged QT interval in Timothy Syndrome (TS). We provide a new de novo constitutional heterozygote missense variation in CACNA1C in a living adult woman, also carrier of the known c.2146-1G>C heterozygous variation of PKP2 inherited from her father. To our knowledge, this patient is the first to have the two variations in these genes. Theses clinical and molecular findings expand the clinical and molecular spectrum of TS and show the interest of next generation sequencing or whole exome sequencing in rare disorders, atypical or novel phenotype.
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Affiliation(s)
- Cindy Colson
- Service Génétique, Génétique Clinique, CHU, Caen, France; Normandy University, UNICAEN, BIOTARGEN, Caen, France.
| | - Hervé Mittre
- Service Génétique, Génétique Moléculaire, CHU, Caen, France
| | - Adeline Busson
- Service de Génétique Clinique, Hôpital Erasme, Bruxelles, Belgium
| | - Antoine Leenhardt
- Service de cardiologie, Hôpital Xavier Bichat-Claude Bernard, Paris, France
| | - Isabelle Denjoy
- Service de cardiologie, Hôpital Xavier Bichat-Claude Bernard, Paris, France
| | - Véronique Fressard
- Centre de génétique moléculaire et chromosomique, UF cardiogénétique et myogénétique moléculaire et cellulaire, Hôpital Pitié-Salpétrière, Paris, France
| | - Yann Troadec
- Service Génétique, Génétique Clinique, CHU, Caen, France; Normandy University, UNICAEN, BIOTARGEN, Caen, France
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Bozarth X, Dines JN, Cong Q, Mirzaa GM, Foss K, Lawrence Merritt J, Thies J, Mefford HC, Novotny E. Expanding clinical phenotype in CACNA1C related disorders: From neonatal onset severe epileptic encephalopathy to late-onset epilepsy. Am J Med Genet A 2018; 176:2733-2739. [PMID: 30513141 DOI: 10.1002/ajmg.a.40657] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 02/01/2023]
Abstract
CACNA1C (NM_000719.6) encodes an L-type calcium voltage-gated calcium channel (Cav 1.2), and pathogenic variants have been associated with two distinct clinical entities: Timothy syndrome and Brugada syndrome. Thus far, CACNA1C has not been reported as a gene associated with epileptic encephalopathy and is less commonly associated with epilepsy. We report three individuals from two families with variants in CACNA1C. Patient 1 presented with neonatal onset epileptic encephalopathy (NOEE) and was found to have a de novo missense variant in CACNA1C (c.4087G>A (p.V1363M)) on exome sequencing. In Family 2, Patient 2 presented with congenital cardiac anomalies and cardiomyopathy and was found to have a paternally inherited splice site variant, c.3717+1_3717+2insA, on a cardiomyopathy panel. Her father, Patient 3, presented with learning difficulties, late-onset epilepsy, and congenital cardiac anomalies. Family 2 highlights variable expressivity seen within a family. This case series expands the clinical and molecular phenotype of CACNA1C-related disorders and highlights the need to include CACNA1C on epilepsy gene panels.
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Affiliation(s)
- Xiuhua Bozarth
- Division of Pediatric Neurology, Department of Neurology, University of Washington, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Jennifer N Dines
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington.,Division of Medical Genetics, Department of Internal Medicine, University of Washington, Seattle, Washington
| | - Qian Cong
- Department of Biochemistry and Institution for Protein Design, University of Washington, Seattle, Washington
| | - Ghayda M Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington
| | - Kimberly Foss
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, Washington
| | - J Lawrence Merritt
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington
| | - Jenny Thies
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, Washington
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington
| | - Edward Novotny
- Division of Pediatric Neurology, Department of Neurology, University of Washington, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
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13
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Gardner RJM, Crozier IG, Binfield AL, Love DR, Lehnert K, Gibson K, Lintott CJ, Snell RG, Jacobsen JC, Jones PP, Waddell-Smith KE, Kennedy MA, Skinner JR. Penetrance and expressivity of the R858H CACNA1C variant in a five-generation pedigree segregating an arrhythmogenic channelopathy. Mol Genet Genomic Med 2018; 7:e00476. [PMID: 30345660 PMCID: PMC6382452 DOI: 10.1002/mgg3.476] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Isolated cardiac arrhythmia due to a variant in CACNA1C is of recent knowledge. Most reports have been of singleton cases or of quite small families, and estimates of penetrance and expressivity have been difficult to obtain. We here describe a large pedigree, from which such estimates have been calculated. METHODS We studied a five-generation family, in which a CACNA1C variant c.2573G>A p.Arg858His co-segregates with syncope and cardiac arrest, documenting electrocardiographic data and cardiac symptomatology. The reported patients/families from the literature with CACNA1C gene variants were reviewed, and genotype-phenotype correlations are drawn. RESULTS The range of phenotype in the studied family is wide, from no apparent effect, through an asymptomatic QT interval prolongation on electrocardiography, to episodes of presyncope and syncope, ventricular fibrillation, and sudden death. QT prolongation showed inconsistent correlation with functional cardiology. Based upon analysis of 28 heterozygous family members, estimates of penetrance and expressivity are derived. CONCLUSIONS These estimates of penetrance and expressivity, for this specific variant, may be useful in clinical practice. Review of the literature indicates that individual CACNA1C variants have their own particular genotype-phenotype correlations. We suggest that, at least in respect of the particular variant reported here, "arrhythmogenic channelopathy" may be a more fitting nomenclature than long QT syndrome.
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Affiliation(s)
- R J McKinlay Gardner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand.,Clinical Genetics Group, Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand
| | - Ian G Crozier
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Christchurch Hospital, Christchurch, New Zealand
| | - Alex L Binfield
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Paediatrics, Christchurch Hospital, Christchurch, New Zealand.,Department of Paediatrics, University of Otago, Christchurch, New Zealand
| | - Donald R Love
- Cardiac Inherited Disease Group, Auckland, New Zealand.,LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Klaus Lehnert
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Kate Gibson
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Caroline J Lintott
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Russell G Snell
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jessie C Jacobsen
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Peter P Jones
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Physiology and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Kathryn E Waddell-Smith
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
| | - Martin A Kennedy
- Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - Jonathan R Skinner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
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Kosaki R, Ono H, Terashima H, Kosaki K. Timothy syndrome-like condition with syndactyly but without prolongation of the QT interval. Am J Med Genet A 2018; 176:1657-1661. [PMID: 29736926 DOI: 10.1002/ajmg.a.38833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 03/18/2018] [Accepted: 04/17/2018] [Indexed: 01/03/2023]
Abstract
Timothy syndrome is characterized by a unique combination of a prolongation of the corrected QT interval of the electrocardiogram and bilateral cutaneous syndactyly of the fingers and the toes and is caused by heterozygous mutations in CACNA1C, a gene encoding a calcium channel. After the discovery of the CACNA1C gene as the causative gene for Timothy syndrome, patients with CACNA1C mutations with QT prolongation but without syndactyly were described. Here, we report a 5-year-old female patient with cutaneous syndactyly, developmental delay, and pulmonary hypertension. Exome analysis showed a previously undescribed de novo heterozygous mutation in the CACNA1C gene, p.Arg1024Gly. To our knowledge, this patient is the first to exhibit syndactyly and to carry a CACNA1C mutation but to not have QT prolongation, which has long been considered an obligatory feature of Timothy syndrome.
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Affiliation(s)
- Rika Kosaki
- Division of Medical Genetics, National Center for Child Health and Development, Tokyo, Japan
| | - Hiroshi Ono
- Division of Cardiology, National Center for Child Health and Development, Tokyo, Japan
| | - Hiroshi Terashima
- Division of Neulorogy, National Center for Child Health and Development, Tokyo, Japan
| | - Kenjiro Kosaki
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
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