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Paz-Cruz E, Ruiz-Pozo VA, Cadena-Ullauri S, Guevara-Ramirez P, Tamayo-Trujillo R, Ibarra-Castillo R, Laso-Bayas JL, Onofre-Ruiz P, Domenech N, Ibarra-Rodriguez AA, Zambrano AK. Associations of MYPN, TTN, SCN5A, MYO6 and ELN Mutations With Arrhythmias and Subsequent Sudden Cardiac Death: A Case Report of an Ecuadorian Individual. Cardiol Res 2023; 14:409-415. [PMID: 37936622 PMCID: PMC10627373 DOI: 10.14740/cr1552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 08/02/2023] [Indexed: 11/09/2023] Open
Abstract
Cardiac pathologies are among the most frequent causes of death worldwide. Regarding cardiovascular deaths, it is estimated that 5 million cases are caused by sudden cardiac death (SCD) annually. The primary cause of SCD is ventricular arrhythmias. Genomic studies have provided pathogenic, likely pathogenic, and variants of uncertain significance that may predispose individuals to cardiac causes of sudden death. In this study, we describe the case of a 43-year-old individual who experienced an episode of aborted SCD. An implantable cardioverter defibrillator was placed to prevent further SCD episodes. The diagnosis was ventricular fibrillation. Genomic analysis revealed some variants in the MYPN (pathogenic), GCKR (likely pathogenic), TTN (variant of uncertain significance), SCN5A (variant of uncertain significance), MYO6 (variant of uncertain significance), and ELN (variant of uncertain significance) genes, which could be associated with SCD episodes. In addition, a protein-protein interaction network was obtained, with proteins related to ventricular arrhythmia and the biological processes involved. Therefore, this study identified genetic variants that may be associated with and trigger SCD in the individual. Moreover, genetic variants of uncertain significance, which have not been reported, could contribute to the genetic basis of the disease.
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Affiliation(s)
- Elius Paz-Cruz
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
- These authors contributed equally to this work and share first authorship
| | - Viviana A Ruiz-Pozo
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
- These authors contributed equally to this work and share first authorship
| | - Santiago Cadena-Ullauri
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Patricia Guevara-Ramirez
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Rafael Tamayo-Trujillo
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | | | | | - Paul Onofre-Ruiz
- Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Nieves Domenech
- Instituto de Investigacion Biomedica de A Coruna (INIBIC) - CIBERCV, Complexo Hospitalario Universitario de A Coruna (CHUAC), Sergas, Universidad da Coruna (UDC), Spain
| | | | - Ana Karina Zambrano
- Centro de Investigacion Genetica y Genomica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
- These authors contributed equally to this work and share first authorship
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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] [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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Patt E, Singhania A, Roberts AE, Morton SU. The Genetics of Neurodevelopment in Congenital Heart Disease. Can J Cardiol 2023; 39:97-114. [PMID: 36183910 DOI: 10.1016/j.cjca.2022.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/23/2022] [Accepted: 09/25/2022] [Indexed: 02/07/2023] Open
Abstract
Congenital heart disease (CHD) is the most common birth anomaly, affecting almost 1% of infants. Neurodevelopmental delay is the most common extracardiac feature in people with CHD. Many factors may contribute to neurodevelopmental risk, including genetic factors, CHD physiology, and the prenatal/postnatal environment. Damaging variants are most highly enriched among individuals with extracardiac anomalies or neurodevelopmental delay in addition to CHD, indicating that genetic factors have an impact beyond cardiac tissues in people with CHD. Potential sources of genetic risk include large deletions or duplications that affect multiple genes, such as 22q11 deletion syndrome, single genes that alter both heart and brain development, such as CHD7, and common variants that affect neurodevelopmental resiliency, such as APOE. Increased use of genome-sequencing technologies in studies of neurodevelopmental outcomes in people with CHD will improve our ability to detect relevant genes and variants. Ultimately, such knowledge can lead to improved and more timely intervention of learning support for affected children.
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Affiliation(s)
- Eli Patt
- Harvard Medical School, Boston, Massachusetts, USA
| | - Asmita Singhania
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Amy E Roberts
- Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts, USA; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA; Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Sarah U Morton
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA; Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA.
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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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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] [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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Jiang CC, Lin LS, Long S, Ke XY, Fukunaga K, Lu YM, Han F. Signalling pathways in autism spectrum disorder: mechanisms and therapeutic implications. Signal Transduct Target Ther 2022; 7:229. [PMID: 35817793 PMCID: PMC9273593 DOI: 10.1038/s41392-022-01081-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/19/2022] [Accepted: 06/23/2022] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorder (ASD) is a prevalent and complex neurodevelopmental disorder which has strong genetic basis. Despite the rapidly rising incidence of autism, little is known about its aetiology, risk factors, and disease progression. There are currently neither validated biomarkers for diagnostic screening nor specific medication for autism. Over the last two decades, there have been remarkable advances in genetics, with hundreds of genes identified and validated as being associated with a high risk for autism. The convergence of neuroscience methods is becoming more widely recognized for its significance in elucidating the pathological mechanisms of autism. Efforts have been devoted to exploring the behavioural functions, key pathological mechanisms and potential treatments of autism. Here, as we highlight in this review, emerging evidence shows that signal transduction molecular events are involved in pathological processes such as transcription, translation, synaptic transmission, epigenetics and immunoinflammatory responses. This involvement has important implications for the discovery of precise molecular targets for autism. Moreover, we review recent insights into the mechanisms and clinical implications of signal transduction in autism from molecular, cellular, neural circuit, and neurobehavioural aspects. Finally, the challenges and future perspectives are discussed with regard to novel strategies predicated on the biological features of autism.
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Affiliation(s)
- Chen-Chen Jiang
- International Joint Laboratory for Drug Target of Critical Illnesses; Key Laboratory of Cardiovascular & Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Li-Shan Lin
- Department of Physiology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, China
| | - Sen Long
- Department of Pharmacy, Hangzhou Seventh People's Hospital, Mental Health Center Zhejiang University School of Medicine, Hangzhou, 310013, China
| | - Xiao-Yan Ke
- Child Mental Health Research Center, Nanjing Brain Hospital, Nanjing Medical University, Nanjing, 210029, China
| | - Kohji Fukunaga
- Department of CNS Drug Innovation, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Ying-Mei Lu
- Department of Physiology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, China.
| | - Feng Han
- International Joint Laboratory for Drug Target of Critical Illnesses; Key Laboratory of Cardiovascular & Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China. .,Institute of Brain Science, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, 210029, China. .,Gusu School, Nanjing Medical University, Suzhou Municipal Hospital, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, 215002, China.
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De novo mutations in childhood cases of sudden unexplained death that disrupt intracellular Ca2+ regulation. Proc Natl Acad Sci U S A 2021; 118:2115140118. [PMID: 34930847 PMCID: PMC8719874 DOI: 10.1073/pnas.2115140118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2021] [Indexed: 01/04/2023] Open
Abstract
Approximately 400 United States children 1 y of age and older die suddenly from unexplained causes annually. We studied whole-exome sequence data from 124 “trios” (decedent child and living parents) to identify genetic risk factors. Nonsynonymous mutations, mostly de novo (present in child but absent in both biological parents), were highly enriched in genes associated with cardiac and seizure disorders relative to controls, and contributed to 9% of deaths. We found significant overtransmission of loss-of-function or pathogenic missense variants in cardiac and seizure disorder genes. Most pathogenic variants were de novo in origin, highlighting the importance of trio studies. Many of these pathogenic de novo mutations altered a protein network regulating calcium-related excitability at submembrane junctions in cardiomyocytes and neurons. Sudden unexplained death in childhood (SUDC) is an understudied problem. Whole-exome sequence data from 124 “trios” (decedent child, living parents) was used to test for excessive de novo mutations (DNMs) in genes involved in cardiac arrhythmias, epilepsy, and other disorders. Among decedents, nonsynonymous DNMs were enriched in genes associated with cardiac and seizure disorders relative to controls (odds ratio = 9.76, P = 2.15 × 10−4). We also found evidence for overtransmission of loss-of-function (LoF) or previously reported pathogenic variants in these same genes from heterozygous carrier parents (11 of 14 transmitted, P = 0.03). We identified a total of 11 SUDC proband genotypes (7 de novo, 1 transmitted parental mosaic, 2 transmitted parental heterozygous, and 1 compound heterozygous) as pathogenic and likely contributory to death, a genetic finding in 8.9% of our cohort. Two genes had recurrent missense DNMs, RYR2 and CACNA1C. Both RYR2 mutations are pathogenic (P = 1.7 × 10−7) and were previously studied in mouse models. Both CACNA1C mutations lie within a 104-nt exon (P = 1.0 × 10−7) and result in slowed L-type calcium channel inactivation and lower current density. In total, six pathogenic DNMs can alter calcium-related regulation of cardiomyocyte and neuronal excitability at a submembrane junction, suggesting a pathway conferring susceptibility to sudden death. There was a trend for excess LoF mutations in LoF intolerant genes, where ≥1 nonhealthy sample in denovo-db has a similar variant (odds ratio = 6.73, P = 0.02); additional uncharacterized genetic causes of sudden death in children might be discovered with larger cohorts.
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8
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Hermida A, Jedraszak G, Kubala M, Mathiron A, Berna P, Bennis Y, Hermida JS. Long-term follow-up of a patient with type 2 Timothy syndrome and the partial efficacy of mexiletine. Gene 2021; 777:145465. [PMID: 33524520 DOI: 10.1016/j.gene.2021.145465] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/23/2020] [Accepted: 01/22/2021] [Indexed: 11/15/2022]
Abstract
We report a detailed case of type 2 TS due to a p.(Gly402Ser) mutation in exon 8 of the CACNA1C gene. The patient shows a marked prolongation of repolarization with a mean QTc of 540 ms. He shows no structural heart disease, syndactyly, or cranio-facial abnormalities. However, he shows developmental delays, without autism, and dental abnormalities. The cardiac phenotype is very severe, with a resuscitated cardiac arrest at 2.5 years of age, followed by 26 appropriate shocks during nine years of follow-up. Adding mexiletine to nadolol resulted in a reduction of the QTc and a slight decrease in the number of appropriate shocks.
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Affiliation(s)
- Alexis Hermida
- Cardiology, Arrhythmia, and Cardiac Stimulation Service, Amiens-Picardie University Hospital, Amiens, France.
| | - Guillaume Jedraszak
- Molecular Genetics Laboratory, Amiens-Picardie University Hospital, Amiens, France; EA4666 HEMATIM, University of Picardie-Jules Verne, Amiens, France
| | - Maciej Kubala
- Cardiology, Arrhythmia, and Cardiac Stimulation Service, Amiens-Picardie University Hospital, Amiens, France
| | - Amel Mathiron
- Pediatric Cardiology Department, Amiens-Picardie University Hospital, Amiens, France
| | - Pascal Berna
- Department of Thoracic Surgery Service, Amiens-Picardie University Hospital, Amiens, France
| | - Youssef Bennis
- Laboratory of Pharmacology and Toxicology, Amiens-Picardie University Hospital, Amiens, France
| | - Jean-Sylvain Hermida
- Cardiology, Arrhythmia, and Cardiac Stimulation Service, Amiens-Picardie University Hospital, Amiens, France
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Bauer R, Timothy KW, Golden A. Update on the Molecular Genetics of Timothy Syndrome. Front Pediatr 2021; 9:668546. [PMID: 34079780 PMCID: PMC8165229 DOI: 10.3389/fped.2021.668546] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
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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Neurological Disorders and Risk of Arrhythmia. Int J Mol Sci 2020; 22:ijms22010188. [PMID: 33375447 PMCID: PMC7795827 DOI: 10.3390/ijms22010188] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/19/2020] [Accepted: 12/24/2020] [Indexed: 01/08/2023] Open
Abstract
Neurological disorders including depression, anxiety, post-traumatic stress disorder (PTSD), schizophrenia, autism and epilepsy are associated with an increased incidence of cardiovascular disorders and susceptibility to heart failure. The underlying molecular mechanisms that link neurological disorders and adverse cardiac function are poorly understood. Further, a lack of progress is likely due to a paucity of studies that investigate the relationship between neurological disorders and cardiac electrical activity in health and disease. Therefore, there is an important need to understand the spatiotemporal behavior of neurocardiac mechanisms. This can be advanced through the identification and validation of neurological and cardiac signaling pathways that may be adversely regulated. In this review we highlight how dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS) activity and inflammation, predispose to psychiatric disorders and cardiac dysfunction. Moreover, antipsychotic and antidepressant medications increase the risk for adverse cardiac events, mostly through the block of the human ether-a-go-go-related gene (hERG), which plays a critical role in cardiac repolarization. Therefore, understanding how neurological disorders lead to adverse cardiac ion channel remodeling is likely to have significant implications for the development of effective therapeutic interventions and helps improve the rational development of targeted therapeutics with significant clinical implications.
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Marcantoni A, Calorio C, Hidisoglu E, Chiantia G, Carbone E. Cav1.2 channelopathies causing autism: new hallmarks on Timothy syndrome. Pflugers Arch 2020; 472:775-789. [PMID: 32621084 DOI: 10.1007/s00424-020-02430-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 02/07/2023]
Abstract
Cav1.2 L-type calcium channels play key roles in long-term synaptic plasticity, sensory transduction, muscle contraction, and hormone release. De novo mutations in the gene encoding Cav1.2 (CACNA1C) causes two forms of Timothy syndrome (TS1, TS2), characterized by a multisystem disorder inclusive of cardiac arrhythmias, long QT, autism, and adrenal gland dysfunction. In both TS1 and TS2, the missense mutation G406R is on the alternatively spliced exon 8 and 8A coding for the IS6-helix of Cav1.2 and is responsible for the penetrant form of autism in most TS individuals. The mutation causes specific gain-of-function changes to Cav1.2 channel gating: a "leftward shift" of voltage-dependent activation, reduced voltage-dependent inactivation, and a "leftward shift" of steady-state inactivation. How this occurs and how Cav1.2 gating changes alter neuronal firing and synaptic plasticity is still largely unexplained. Trying to better understanding the molecular basis of Cav1.2 gating dysfunctions leading to autism, here, we will present and discuss the properties of recently reported typical and atypical TS phenotypes and the effective gating changes exhibited by missense mutations associated with long QTs without extracardiac symptoms, unrelated to TS. We will also discuss new emerging views achieved from using iPSCs-derived neurons and the newly available autistic TS2-neo mouse model, both appearing promising for understanding neuronal mistuning in autistic TS patients. We will also analyze and describe recent proposals of molecular pathways that might explain mistuned Ca2+-mediated and Ca2+-independent excitation-transcription signals to the nucleus. Briefly, we will also discuss possible pharmacological approaches to treat autism associated with L-type channelopathies.
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Affiliation(s)
- Andrea Marcantoni
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, N.I.S. Centre, Corso Raffaello 30, 10125, Torino, Italy
| | - Chiara Calorio
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, N.I.S. Centre, Corso Raffaello 30, 10125, Torino, Italy
| | - Enis Hidisoglu
- Department of Biophysics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Giuseppe Chiantia
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, N.I.S. Centre, Corso Raffaello 30, 10125, Torino, Italy
| | - Emilio Carbone
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, N.I.S. Centre, Corso Raffaello 30, 10125, Torino, Italy.
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12
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Han D, Xue X, Yan Y, Li G. Dysfunctional Cav1.2 channel in Timothy syndrome, from cell to bedside. Exp Biol Med (Maywood) 2019; 244:960-971. [PMID: 31324123 DOI: 10.1177/1535370219863149] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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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13
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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] [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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14
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Calorio C, Gavello D, Guarina L, Salio C, Sassoè-Pognetto M, Riganti C, Bianchi FT, Hofer NT, Tuluc P, Obermair GJ, Defilippi P, Balzac F, Turco E, Bett GC, Rasmusson RL, Carbone E. Impaired chromaffin cell excitability and exocytosis in autistic Timothy syndrome TS2-neo mouse rescued by L-type calcium channel blockers. J Physiol 2019; 597:1705-1733. [PMID: 30629744 DOI: 10.1113/jp277487] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/19/2018] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Tymothy syndrome (TS) is a multisystem disorder featuring cardiac arrhythmias, autism and adrenal gland dysfunction that originates from a de novo point mutation in the gene encoding the Cav1.2 (CACNA1C) L-type channel. To study the role of Cav1.2 channel signals in autism, the autistic TS2-neo mouse has been generated bearing the G406R point-mutation associated with TS type-2. Using heterozygous TS2-neo mice, we report that the G406R mutation reduces the rate of inactivation and shifts leftward the activation and inactivation of L-type channels, causing marked increase of resting Ca2+ influx ('window' Ca2+ current). The increased 'window current' causes marked reduction of NaV channel density, switches normal tonic firing to abnormal burst firing, reduces mitochondrial metabolism, induces cell swelling and decreases catecholamine release. Overnight incubations with nifedipine rescue NaV channel density, normal firing and the quantity of catecholamine released. We provide evidence that chromaffin cell malfunction derives from altered Cav1.2 channel gating. ABSTRACT L-type voltage-gated calcium (Cav1) channels have a key role in long-term synaptic plasticity, sensory transduction, muscle contraction and hormone release. A point mutation in the gene encoding Cav1.2 (CACNA1C) causes Tymothy syndrome (TS), a multisystem disorder featuring cardiac arrhythmias, autism spectrum disorder (ASD) and adrenal gland dysfunction. In the more severe type-2 form (TS2), the missense mutation G406R is on exon 8 coding for the IS6-helix of the Cav1.2 channel. The mutation causes reduced inactivation and induces autism. How this occurs and how Cav1.2 gating-changes alter cell excitability, neuronal firing and hormone release on a molecular basis is still largely unknown. Here, using the TS2-neo mouse model of TS we show that the G406R mutation altered excitability and reduced secretory activity in adrenal chromaffin cells (CCs). Specifically, the TS2 mutation reduced the rate of voltage-dependent inactivation and shifted leftward the activation and steady-state inactivation of L-type channels. This markedly increased the resting 'window' Ca2+ current that caused an increased percentage of CCs undergoing abnormal action potential (AP) burst firing, cell swelling, reduced mitochondrial metabolism and decreased catecholamine release. The increased 'window' Ca2+ current caused also decreased NaV channel density and increased steady-state inactivation, which contributed to the increased abnormal burst firing. Overnight incubation with the L-type channel blocker nifedipine rescued the normal AP firing of CCs, the density of functioning NaV channels and their steady-state inactivation. We provide evidence that CC malfunction derives from the altered Cav1.2 channel gating and that dihydropyridines are potential therapeutics for ASD.
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Affiliation(s)
- Chiara Calorio
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Daniela Gavello
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Laura Guarina
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Chiara Salio
- Department of Veterinary Sciences, University of Torino, Torino, Italy
| | - Marco Sassoè-Pognetto
- Department of Neuroscience Rita Levi Montalcini, University of Torino, Torino, Italy
| | - Chiara Riganti
- Department of Oncology, University of Torino, Torino, Italy
| | | | - Nadja T Hofer
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gerald J Obermair
- Department of Physiology & Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Paola Defilippi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Fiorella Balzac
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Emilia Turco
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Glenna C Bett
- Department of Physiology & Biophysics, State University of New York, Buffalo, NY, USA
| | - Randall L Rasmusson
- Department of Physiology & Biophysics, State University of New York, Buffalo, NY, USA
| | - Emilio Carbone
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
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15
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16
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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] [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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17
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Giudicessi JR, Ackerman MJ. Calcium Revisited: New Insights Into the Molecular Basis of Long-QT Syndrome. Circ Arrhythm Electrophysiol 2018; 9:CIRCEP.116.002480. [PMID: 27390209 DOI: 10.1161/circep.116.002480] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/27/2016] [Indexed: 12/12/2022]
Affiliation(s)
- John R Giudicessi
- From the Internal Medicine Residency and Clinician-Investigator Programs, Department of Medicine (J.R.G.) and Departments of Cardiovascular Diseases, Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (M.J.A.), Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- From the Internal Medicine Residency and Clinician-Investigator Programs, Department of Medicine (J.R.G.) and Departments of Cardiovascular Diseases, Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (M.J.A.), Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.
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18
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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: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [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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19
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Clinical Outcomes and Modes of Death in Timothy Syndrome. JACC Clin Electrophysiol 2018; 4:459-466. [DOI: 10.1016/j.jacep.2017.08.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 08/21/2017] [Accepted: 08/22/2017] [Indexed: 11/19/2022]
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20
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Ozawa J, Ohno S, Saito H, Saitoh A, Matsuura H, Horie M. A novel CACNA1C mutation identified in a patient with Timothy syndrome without syndactyly exerts both marked loss- and gain-of-function effects. HeartRhythm Case Rep 2018; 4:273-277. [PMID: 30023270 PMCID: PMC6050422 DOI: 10.1016/j.hrcr.2018.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Junichi Ozawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan.,Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan.,Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Otsu, Japan
| | - Hideki Saito
- Department of Cardiology, Seirei Hamamatsu General Hospital, Hamamatsu, Japan
| | - Akihiko Saitoh
- Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
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21
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Zhang Q, Chen J, Qin Y, Wang J, Zhou L. Mutations in voltage-gated L-type calcium channel: implications in cardiac arrhythmia. Channels (Austin) 2018; 12:201-218. [PMID: 30027834 PMCID: PMC6104696 DOI: 10.1080/19336950.2018.1499368] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/08/2018] [Accepted: 07/05/2018] [Indexed: 02/06/2023] Open
Abstract
The voltage-gated L-type calcium channel (LTCC) is essential for multiple cellular processes. In the heart, calcium influx through LTCC plays an important role in cardiac electrical excitation. Mutations in LTCC genes, including CACNA1C, CACNA1D, CACNB2 and CACNA2D, will induce the dysfunctions of calcium channels, which result in the abnormal excitations of cardiomyocytes, and finally lead to cardiac arrhythmias. Nevertheless, the newly found mutations in LTCC and their functions are continuously being elucidated. This review summarizes recent findings on the mutations of LTCC, which are associated with long QT syndromes, Timothy syndromes, Brugada syndromes, short QT syndromes, and some other cardiac arrhythmias. Indeed, we describe the gain/loss-of-functions of these mutations in LTCC, which can give an explanation for the phenotypes of cardiac arrhythmias. Moreover, we present several challenges in the field at present, and propose some diagnostic or therapeutic approaches to these mutation-associated cardiac diseases in the future.
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Affiliation(s)
- Qing Zhang
- Department of Cardiology, the Second Affiliated Hospital of Nantong University, Nantong First Hospital, Nantong, Jiangsu, China
- Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Junjie Chen
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yao Qin
- Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Juejin Wang
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Lei Zhou
- Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
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22
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Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J, Széll M, Forster T, Nagy I, Hegedűs Z. Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations. Am J Med Genet A 2017; 173:784-789. [PMID: 28211989 DOI: 10.1002/ajmg.a.38084] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/21/2016] [Indexed: 11/09/2022]
Abstract
Timothy syndrome 1 (TS1) is a rare genetic disorder characterized by multisystem abnormalities including QT prolongation, congenital heart defects, facial dysmorphism, episodic hypoglycemia, and neurological symptoms. A morphological hallmark of TS1 is syndactyly, present in all cases. TS1 is caused by the canonical p.Gly406Arg mutation in the alternatively spliced exon 8A in the CACNA1C gene, encoding for the main cardiac L-type calcium channel. A variant case of TS1 is reported. The proband had intermittent fetal bradycardia with heart rate of 72 bpm. On the first day of life bradycardia due to 2:1 atrioventricular (AV) block and marked QTc prolongation of 600 ms was noted. On medical therapy with propranolol and mexiletine 1:1 AV conduction returned with QTc prolongation of 470-580 ms. The patient lacked other extracardiac manifestations, most importantly syndactyly, neurological complications or autism. On genetic analysis, the canonical TS1 causing mutation, p.Gly406Arg in exon 8A of the CACNA1C gene was detected. The CACNA1C p.Gly406Arg variant was not present in the parents, but was detected in different DNA samples of the index patient. Our case highlight further phenotypic variability in TS. Most importantly, it underlines that the lack of syndactyly does not exclude the presence of a TS1 genotype. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Róbert Sepp
- Second Department of Internal Medicine and Cardiology Center, University of Szeged, Szeged, Hungary
| | - Lidia Hategan
- Second Department of Internal Medicine and Cardiology Center, University of Szeged, Szeged, Hungary
| | - Attila Bácsi
- Fejér County "Szent György" University Teaching Hospital, Székesfehérvár, Hungary
| | | | - László Környei
- "Gottsegen György" National Institute of Cardiology, Budapest, Hungary
| | - János Borbás
- Second Department of Internal Medicine and Cardiology Center, University of Szeged, Szeged, Hungary
| | - Márta Széll
- Department of Medical Genetics, University of Szeged, Szeged, Hungary
| | - Tamás Forster
- Second Department of Internal Medicine and Cardiology Center, University of Szeged, Szeged, Hungary
| | - István Nagy
- Seqomics Biotechnology Ltd., Mórahalom, Hungary.,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Zoltán Hegedűs
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Department of Biochemistry and Medical Chemistry, University of Pécs, Pécs, Hungary
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23
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The genetics underlying idiopathic ventricular fibrillation: A special role for catecholaminergic polymorphic ventricular tachycardia? Int J Cardiol 2017; 250:139-145. [PMID: 29032884 DOI: 10.1016/j.ijcard.2017.10.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/03/2017] [Accepted: 10/03/2017] [Indexed: 11/21/2022]
Abstract
BACKGROUND Ventricular fibrillation (VF) is a major cause of sudden cardiac death. In some cases clinical investigations fail to identify the underlying cause and the event is classified as idiopathic (IVF). Since mutations in arrhythmia-associated genes frequently determine arrhythmia susceptibility, screening for disease-predisposing variants could improve IVF diagnostics. METHODS AND RESULTS The study included 76 Finnish and Italian patients with a mean age of 31.2years at the time of the VF event, collected between the years 1996-2016 and diagnosed with idiopathic, out-of-hospital VF. Using whole-exome sequencing (WES) and next-generation sequencing (NGS) approaches, we aimed to identify genetic variants potentially contributing to the life-threatening arrhythmias of these patients. Combining the results from the two study populations, we identified pathogenic or likely pathogenic variants residing in the RYR2, CACNA1C and DSP genes in 7 patients (9%). Most of them (5, 71%) were found in the RYR2 gene, associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). These genetic findings prompted clinical investigations leading to disease reclassification. Additionally, in 9 patients (11.8%) we detected 10 novel or extremely rare (MAF<0.005%) variants that were classified as of unknown significance (VUS). CONCLUSION The results of our study suggest that a subset of patients originally diagnosed with IVF may carry clinically-relevant variants in genes associated with cardiac channelopathies and cardiomyopathies. Although misclassification of other cardiac channelopathies as IVF appears rare, our findings indicate that the possibility of CPVT as the underlying disease entity should be carefully evaluated in IVF patients.
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24
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Bai J, Wang K, Liu Y, Li Y, Liang C, Luo G, Dong S, Yuan Y, Zhang H. Computational Cardiac Modeling Reveals Mechanisms of Ventricular Arrhythmogenesis in Long QT Syndrome Type 8: CACNA1C R858H Mutation Linked to Ventricular Fibrillation. Front Physiol 2017; 8:771. [PMID: 29046645 PMCID: PMC5632762 DOI: 10.3389/fphys.2017.00771] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/21/2017] [Indexed: 01/05/2023] Open
Abstract
Functional analysis of the L-type calcium channel has shown that the CACNA1C R858H mutation associated with severe QT interval prolongation may lead to ventricular fibrillation (VF). This study investigated multiple potential mechanisms by which the CACNA1C R858H mutation facilitates and perpetuates VF. The Ten Tusscher-Panfilov (TP06) human ventricular cell models incorporating the experimental data on the kinetic properties of L-type calcium channels were integrated into one-dimensional (1D) fiber, 2D sheet, and 3D ventricular models to investigate the pro-arrhythmic effects of CACNA1C mutations by quantifying changes in intracellular calcium handling, action potential profiles, action potential duration restitution (APDR) curves, dispersion of repolarization (DOR), QT interval and spiral wave dynamics. R858H “mutant” L-type calcium current (ICaL) augmented sarcoplasmic reticulum calcium content, leading to the development of afterdepolarizations at the single cell level and focal activities at the tissue level. It also produced inhomogeneous APD prolongation, causing QT prolongation and repolarization dispersion amplification, rendering R858H “mutant” tissue more vulnerable to the induction of reentry compared with other conditions. In conclusion, altered ICaL due to the CACNA1C R858H mutation increases arrhythmia risk due to afterdepolarizations and increased tissue vulnerability to unidirectional conduction block. However, the observed reentry is not due to afterdepolarizations (not present in our model), but rather to a novel blocking mechanism.
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Affiliation(s)
- Jieyun Bai
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yashu Liu
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yacong Li
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Cuiping Liang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Gongning Luo
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Suyu Dong
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Yongfeng Yuan
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Henggui Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China.,Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom.,Space Institute of Southern China, Shenzhen, China
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25
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Dewar LJ, Alcaide M, Fornika D, D’Amato L, Shafaatalab S, Stevens CM, Balachandra T, Phillips SM, Sanatani S, Morin RD, Tibbits GF. Investigating the Genetic Causes of Sudden Unexpected Death in Children Through Targeted Next-Generation Sequencing Analysis. ACTA ACUST UNITED AC 2017; 10:CIRCGENETICS.116.001738. [DOI: 10.1161/circgenetics.116.001738] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 04/25/2017] [Indexed: 12/27/2022]
Abstract
Background—
Inherited arrhythmia syndromes are responsible for a significant portion of autopsy-negative sudden unexpected death (SUD) cases, but molecular autopsy used to identify potentially causal variants is not routinely included in SUD investigations. We collaborated with a medical examiner's office to assist in finding a diagnosis for their autopsy-negative child SUD cases.
Methods and Results—
191 child SUD cases (<5 years of age) were selected for analyses. Our next generation sequencing panel incorporated 38 inherited arrhythmia syndrome candidate genes and another 33 genes not previously investigated for variants that may underlie SUDY pathophysiology. Overall, we identified 11 potentially causal disease-associated variants in 12 cases, for an overall yield of 6.3%. We also identified 31 variants of uncertain significance in 36 cases and 16 novel variants predicted to be pathogenic in silico in 15 cases. The disease-associated variants were reported to the medical examiner to notify surviving relatives and recommend clinical assessment.
Conclusions—
We have identified variants that may assist in the diagnosis of at least 6.3% of autopsy-negative child SUD cases and reduce risk of future SUD in surviving relatives. We recommend a cautious approach to variant interpretation. We also suggest inclusion of cardiomyopathy genes as well as other candidate SUD genes in molecular autopsy analyses.
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Affiliation(s)
- Laura J. Dewar
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Miguel Alcaide
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Daniel Fornika
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Luisa D’Amato
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Sanam Shafaatalab
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Charles M. Stevens
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Thambirajah Balachandra
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Susan M. Phillips
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Shubhayan Sanatani
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Ryan D. Morin
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
| | - Glen F. Tibbits
- From the Departments of Biomedical Physiology and Kinesiology (L.J.D., S.S., C.M.S., G.F.T.) and Molecular Biology and Biochemistry (M.A., D.F., L.D., C.M.S., R.D.M., G.F.T.), Simon Fraser University, Burnaby, British Columbia, Canada; BC Children’s Hospital Research Institute, Vancouver, Canada (L.J.D., S.S., C.M.S., G.F.T.); Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada (T.B., S.M.P.); and Division of Pediatric Cardiology, Department of Pediatrics, British
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26
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Bai J, Wang K, Li Q, Yuan Y, Zhang H. Pro-arrhythmogenic effects of CACNA1C G1911R mutation in human ventricular tachycardia: insights from cardiac multi-scale models. Sci Rep 2016; 6:31262. [PMID: 27502440 PMCID: PMC4977499 DOI: 10.1038/srep31262] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 07/14/2016] [Indexed: 01/11/2023] Open
Abstract
Mutations in the CACNA1C gene are associated with ventricular tachycardia (VT). Although the CACNA1C mutations were well identified in patients with cardiac arrhythmias, mechanisms by which cardiac arrhythmias are generated in such genetic mutation conditions remain unclear. In this study, we identified a novel mechanism of VT resulted from enhanced repolarization dispersion which is a key factor for arrhythmias in the CACNA1C G1911R mutation using multi-scale computational models of the human ventricle. The increased calcium influx in the mutation prolonged action potential duration (APD), produced steepened action potential duration restitution (APDR) curves as well as augmented membrane potential differences among different cell types during repolarization, increasing transmural dispersion of repolarization (DOR) and the spatial and temporal heterogeneity of cardiac electrical activities. Consequentially, the vulnerability to unidirectional conduction block in response to a premature stimulus increased at tissue level in the G1911R mutation. The increased functional repolarization dispersion anchored reentrant excitation waves in tissue and organ models, facilitating the initiation and maintenance of VT due to less meandering rotor tip. Thus, the increased repolarization dispersion caused by the G1911R mutation is a primary factor that may primarily contribute to the genesis of cardiac arrhythmias in Timothy Syndrome.
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Affiliation(s)
- Jieyun Bai
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, 150001, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, 150001, China
| | - Qince Li
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, 150001, China
| | - Yongfeng Yuan
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, 150001, China
| | - Henggui Zhang
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, 150001, China
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
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27
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Mullins C, Fishell G, Tsien RW. Unifying Views of Autism Spectrum Disorders: A Consideration of Autoregulatory Feedback Loops. Neuron 2016; 89:1131-1156. [PMID: 26985722 DOI: 10.1016/j.neuron.2016.02.017] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2016] [Indexed: 12/31/2022]
Abstract
Understanding the mechanisms underlying autism spectrum disorders (ASDs) is a challenging goal. Here we review recent progress on several fronts, including genetics, proteomics, biochemistry, and electrophysiology, that raise motivation for forming a viable pathophysiological hypothesis. In place of a traditionally unidirectional progression, we put forward a framework that extends homeostatic hypotheses by explicitly emphasizing autoregulatory feedback loops and known synaptic biology. The regulated biological feature can be neuronal electrical activity, the collective strength of synapses onto a dendritic branch, the local concentration of a signaling molecule, or the relative strengths of synaptic excitation and inhibition. The sensor of the biological variable (which we have termed the homeostat) engages mechanisms that operate as negative feedback elements to keep the biological variable tightly confined. We categorize known ASD-associated gene products according to their roles in such feedback loops and provide detailed commentary for exemplar genes within each module.
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Affiliation(s)
- Caitlin Mullins
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA
| | - Gord Fishell
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA
| | - Richard W Tsien
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA.
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28
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Philipp LR, Rodriguez FH. Cardiac arrest refractory to standard intervention in atypical Timothy syndrome (LQT8 type 2). Proc AMIA Symp 2016; 29:160-2. [PMID: 27034553 DOI: 10.1080/08998280.2016.11929398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Timothy syndrome (TS) is a rare, multisystem disorder most commonly associated with profound QTc prolongation and cutaneous dysmorphia arising from mutations of the L-type calcium channel. We present a case of a 12-day-old newborn who presented with respiratory distress and cyanosis. Diagnostic workup was notable for multiple cardiac abnormalities, and genetic analysis was consistent with an exon 8 mutation of the CACNA1C gene, which is diagnostic for TS type 2 (atypical TS). This patient presented with a novel constellation of symptoms, without dysmorphic features, and with a more moderate QTc interval. The heterogeneity of phenotypes suggests that this disorder may be characterized by variable expressivity or a spectrum of disease rather than a clearly defined syndrome.
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Affiliation(s)
- Lucas R Philipp
- Emory University School of Medicine (Philipp, Rodriguez) and Sibley Heart Center Cardiology (Rodriguez), Atlanta, Georgia
| | - Fred H Rodriguez
- Emory University School of Medicine (Philipp, Rodriguez) and Sibley Heart Center Cardiology (Rodriguez), Atlanta, Georgia
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29
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Boczek NJ, Ye D, Jin F, Tester DJ, Huseby A, Bos JM, Johnson AJ, Kanter R, Ackerman MJ. Identification and Functional Characterization of a Novel CACNA1C-Mediated Cardiac Disorder Characterized by Prolonged QT Intervals With Hypertrophic Cardiomyopathy, Congenital Heart Defects, and Sudden Cardiac Death. Circ Arrhythm Electrophysiol 2015; 8:1122-32. [PMID: 26253506 PMCID: PMC5094060 DOI: 10.1161/circep.115.002745] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 07/23/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND A portion of sudden cardiac deaths can be attributed to structural heart diseases, such as hypertrophic cardiomyopathy (HCM) or cardiac channelopathies such as long-QT syndrome (LQTS); however, the underlying molecular mechanisms are distinct. Here, we identify a novel CACNA1C missense mutation with mixed loss-of-function/gain-of-function responsible for a complex phenotype of LQTS, HCM, sudden cardiac death, and congenital heart defects. METHODS AND RESULTS Whole exome sequencing in combination with Ingenuity variant analysis was completed on 3 affected individuals and 1 unaffected individual from a large pedigree with concomitant LQTS, HCM, and congenital heart defects and identified a novel CACNA1C mutation, p.Arg518Cys, as the most likely candidate mutation. Mutational analysis of exon 12 of CACNA1C was completed on 5 additional patients with a similar phenotype of LQTS plus a personal or family history of HCM-like phenotypes and identified 2 additional pedigrees with mutations at the same position, p.Arg518Cys/His. Whole cell patch clamp technique was used to assess the electrophysiological effects of the identified mutations in CaV1.2 and revealed a complex phenotype, including loss of current density and inactivation in combination with increased window and late current. CONCLUSIONS Through whole exome sequencing and expanded cohort screening, we identified a novel genetic substrate p.Arg518Cys/His-CACNA1C, in patients with a complex phenotype including LQTS, HCM, and congenital heart defects annotated as cardiac-only Timothy syndrome. Our electrophysiological studies, identification of mutations at the same amino acid position in multiple pedigrees, and cosegregation with disease in these pedigrees provide evidence that p.Arg518Cys/His is the pathogenic substrate for the observed phenotype.
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Affiliation(s)
- Nicole J Boczek
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - Dan Ye
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - Fang Jin
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - David J Tester
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - April Huseby
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - J Martijn Bos
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - Aaron J Johnson
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - Ronald Kanter
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.)
| | - Michael J Ackerman
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (N.J.B., D.Y., D.J.T., J.M.B., M.J.A.), Division of Immunology and Neurology (F.J., A.H., A.J.J.), and Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology) (M.J.A.), Mayo Clinic, Rochester, MN; Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.K.).
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30
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Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 704] [Impact Index Per Article: 78.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
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31
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Diep V, Seaver LH. Long QT syndrome with craniofacial, digital, and neurologic features: Is it useful to distinguish between Timothy syndrome types 1 and 2? Am J Med Genet A 2015; 167A:2780-5. [PMID: 26227324 DOI: 10.1002/ajmg.a.37258] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/28/2015] [Indexed: 11/10/2022]
Abstract
Timothy syndrome (TS) is a rare genetic condition that associates long QT syndrome, structural heart defects, dysmorphic facial features, syndactyly, seizures, developmental delay, and autism. Timothy syndrome type 1 is caused by a recurrent de novo mutation (p.Gly406Arg) in exon 8A of the L-type calcium channel gene CACNA1C. Timothy syndrome type 2 was originally reported to be associated with a more severe cardiac phenotype but without syndactyly. Timothy syndrome type 2 is caused by mutation in an alternatively spliced exon 8 of the CACNA1C gene. Other mutations in CACNA1C are also reported with long QT syndrome with and without syndromic features overlapping that described in Timothy syndrome. The purpose of this report is to describe the presentation, physical features and natural history of a 4-year-old girl with Timothy syndrome type 2 due to the recurrent p.Gly406Arg mutation in exon 8 of CACNA1C. She has similar facial features to Timothy syndrome type 1 without syndactyly. She is developmentally delayed without autism. She recently had her first episode of torsade de pointes associated with febrile illness and hypoglycemia. The findings in this case provide further information about the phenotype and natural history of CACNA1C exon 8 mutation and together with previously reported cases of Timothy syndrome question whether the clinical and molecular distinction between Timothy syndromes types 1 and 2 remains clinically useful.
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Affiliation(s)
- Vinson Diep
- University of Hawai'i John A. Burns School of Medicine, Honolulu, Hawaii
| | - Laurie H Seaver
- Department of Pediatrics, University of Hawaii', John A. Burns School of Medicine, Honolulu, Hawaii.,Kapiolani Medical Specialists, Honolulu, Hawaii
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