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Sodium channelopathies

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https://www.readbyqxmd.com/read/28757052/genetics-update-monogenetics-polygene-disorders-and-the-quest-for-modifying-genes
#1
REVIEW
Joseph D Symonds, Sameer M Zuberi
The genetic channelopathies are a broad collection of diseases. Many ion channel genes demonstrate wide phenotypic pleiotropy, but nonetheless concerted efforts have been made to characterise genotype-phenotype relationships. In this review we give an overview of the factors that influence genotype-phenotype relationships across this group of diseases as a whole, using specific individual channelopathies as examples. We suggest reasons for the limitations observed in these relationships. We discuss the role of ion channel variation in polygenic disease and highlight research that has contributed to unravelling the complex aetiological nature of these conditions...
July 27, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28756098/phenotypic-variability-in-lqt3-human-induced-pluripotent-stem-cell-derived-cardiomyocytes-and-their-response-to-antiarrhythmic-pharmacologic-therapy-an-in-silico-approach
#2
Michelangelo Paci, Elisa Passini, Stefano Severi, Jari Hyttinen, Blanca Rodriguez
BACKGROUND: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are in vitro models with the clear advantages of their human origin and suitability for human disease investigations. However, limitations include their incomplete characterization and variability reported in different cell lines and laboratories. OBJECTIVE: The purpose of this study was to investigate in silico ionic mechanisms potentially explaining the phenotypic variability of hiPSC-CMs in long QT syndrome type 3 (LQT3) and their response to antiarrhythmic drugs...
July 27, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28662944/skeletal-muscle-channelopathies-rare-disorders-with-common-pediatric-symptoms
#3
Emma Matthews, Arpana Silwal, Richa Sud, Michael G Hanna, Adnan Y Manzur, Francesco Muntoni, Pinki Munot
OBJECTIVE: To ascertain the presenting symptoms of children with skeletal muscle channelopathies to promote early diagnosis and treatment. STUDY DESIGN: Retrospective case review of 38 children with a skeletal muscle channelopathy attending the specialist pediatric neuromuscular service at Great Ormond Street Hospital over a 15-year period. RESULTS: Gait disorder and leg cramps are a frequent presentation of myotonic disorders (19 of 29). Strabismus or extraocular myotonia (9 of 19) and respiratory and/or bulbar symptoms (11 of 19) are common among those with sodium channelopathy...
June 26, 2017: Journal of Pediatrics
https://www.readbyqxmd.com/read/28637969/development-of-a-patient-derived-induced-pluripotent-stem-cell-model-for-the-investigation-of-scn5a-d1275n-related-cardiac-sodium-channelopathy
#4
Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi Harita, Yuta Yamamoto, Hirohiko Kohjitani, Sayako Hirose, Fumika Yokoi, Jiarong Chen, Osamu Baba, Takahiro Horie, Kazuhisa Chonabayashi, Seiko Ohno, Futoshi Toyoda, Yoshinori Yoshida, Koh Ono, Minoru Horie, Takeshi Kimura
BACKGROUND: TheSCN5Agene encodes the α subunit of the cardiac voltage-gated sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type...
June 20, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28597987/trafficking-and-localization-to-the-plasma-membrane-of-nav-1-5-promoted-by-the-%C3%AE-2-subunit-is-defective-due-to-a-%C3%AE-2-mutation-associated-with-brugada-syndrome
#5
Gemma Dulsat, Sonia Palomeras, Eric Cortada, Helena Riuró, Ramon Brugada, Marcel Vergés
BACKGROUND INFORMATION: Cardiac channelopathies arise by mutations in genes encoding ion channel subunits. One example is Brugada Syndrome (BrS), which causes arrhythmias and sudden death. BrS is often associated with mutations in SCN5A, encoding Nav 1.5, the α subunit of the major cardiac voltage-gated sodium channel. This channel forms a protein complex including one or two associated β subunits as well as other proteins. RESULTS: We analyzed regulation of Nav 1...
June 9, 2017: Biology of the Cell
https://www.readbyqxmd.com/read/28571716/post-translational-dysfunctions-in-channelopathies-of-the-nervous-system
#6
REVIEW
Benedetta Terragni, Paolo Scalmani, Silvana Franceschetti, Sandrine Cestèle, Massimo Mantegazza
Channelopathies comprise various diseases caused by defects of ion channels. Modifications of their biophysical properties are common and have been widely studied. However, ion channels are heterogeneous multi-molecular complexes that are extensively modulated and undergo a maturation process comprising numerous steps of structural modifications and intracellular trafficking. Perturbations of these processes can give rise to aberrant channels that cause pathologies. Here we review channelopathies of the nervous system associated with dysfunctions at the post-translational level (folding, trafficking, degradation, subcellular localization, interactions with associated proteins and structural post-translational modifications)...
May 29, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28557061/classification-of-involuntary-movements-in-dogs-myoclonus-and-myotonia
#7
REVIEW
M Lowrie, L Garosi
Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one hand, a classification system is required that is clinically useful to aid in guiding diagnosis and treatment. On the other hand, there is need for a system that organizes current knowledge regarding biological mechanisms to guide scientific research. These 2 needs are distinct, making it challenging to develop a robust classification system suitable for all purposes...
July 2017: Journal of Veterinary Internal Medicine
https://www.readbyqxmd.com/read/28552867/an-unusual-case-of-sodium-channel-myotonia-with-transient-weakness-upon-initiating-movements-which-is-characteristic-in-becker-disease
#8
Junpei Yamamoto, Keiichi Hokkoku, Yuki Hatanaka, Shunichi Sakoda, Jun-Hui Yuan M D, Masahiro Sonoo
We reported a 32-year-old man who was a sporadic case of myotonic syndrome with muscle stiffness or transient weakness of limbs upon initiating movements after rest. On examination, he showed painless myotonia with warm-up phenomenon, Hercules-like hypertrophic musculature and myotonic discharges in EMG. The clinical findings resembled to those of Becker disease rather than Thomsen disease. But electrodiagnosis suggested sodium channel myotonia instead of chloride channelopathy. Genetic testing detected a novel missense mutation (p...
May 26, 2017: Rinshō Shinkeigaku, Clinical Neurology
https://www.readbyqxmd.com/read/28536668/brugada-syndrome-in-a-patient-with-vascular-ehlers-danlos-syndrome-sudden-death-risk-amplified
#9
Jason D'Souza, Divyanshu Malhotra, Aditya Goud, Chanukya Dahagam, George Everett
The vast majority of sudden cardiac arrests occur in patients with structural heart disease and in approximately 10% of the cases, it can occur in those with structurally normal hearts. Brugada syndrome is an autosomal dominant sodium channelopathy that has been implicated in sudden deaths. Given their low prevalence, our knowledge about Brugada syndrome is still evolving. Apart from schizophrenia, there have been no reports of associated medical conditions. We recently encountered a patient with vascular Ehlers-Danlos syndrome who was also found to have Brugada syndrome...
April 19, 2017: Curēus
https://www.readbyqxmd.com/read/28527083/shared-mechanisms-of-epilepsy-migraine-and-affective-disorders
#10
Davide Zarcone, Simona Corbetta
Since the nineteenth century several clinical features have been observed in common between migraine and epilepsy (such as episodic attacks, triggering factors, presence of aura, frequent familiarity), but only in recent years researchers have really engaged in finding a common pathogenic mechanism. From studies of disease incidence, we understand how either migraine among patients with epilepsy or epilepsy among migraine patients are more frequent than in the general population. This association may result from a direct causality, by the same environmental risk factors and/or by a common genetic susceptibility...
May 2017: Neurological Sciences
https://www.readbyqxmd.com/read/28470179/autoimmune-channelopathies-as-a-novel-mechanism-in-cardiac-arrhythmias
#11
REVIEW
Pietro Enea Lazzerini, Pier Leopoldo Capecchi, Franco Laghi-Pasini, Mohamed Boutjdir
Cardiac arrhythmias confer a considerable burden of morbidity and mortality in industrialized countries. Although coronary artery disease and heart failure are the prevalent causes of cardiac arrest, in 5-15% of patients, structural abnormalities at autopsy are absent. In a proportion of these patients, mutations in genes encoding cardiac ion channels are documented (inherited channelopathies), but, to date, the molecular autopsy is negative in nearly 70% of patients. Emerging evidence indicates that autoimmunity is involved in the pathogenesis of cardiac arrhythmias...
September 2017: Nature Reviews. Cardiology
https://www.readbyqxmd.com/read/28430892/anti-arrhythmic-potential-of-the-late-sodium-current-inhibitor-gs-458967-in-murine-scn5a-1798insd-and-human-scn5a-1795insd-ipsc-derived-cardiomyocytes
#12
Vincent Portero, Simona Casini, Maaike Hoekstra, Arie O Verkerk, Isabella Mengarelli, Luiz Belardinelli, Sridharan Rajamani, Arthur A M Wilde, Connie R Bezzina, Marieke W Veldkamp, Carol Ann Remme
Aims: Selective inhibition of cardiac late sodium current (INaL) is an emerging target in the treatment of ventricular arrhythmias. We investigated the electrophysiological effects of GS-458967 (GS967), a potent, selective inhibitor of INaL, in an overlap syndrome model of both gain and loss of sodium channel function, comprising cardiomyocytes derived from both human SCN5A-1795insD+/- induced pluripotent stem cells (hiPSC-CMs) and mice carrying the homologous mutation Scn5a-1798insD+/-...
June 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28325641/spectrum-of-nondystrophic-skeletal-muscle-channelopathies-in-children
#13
Fouad Al-Ghamdi, Basil T Darras, Partha S Ghosh
BACKGROUND: The nondystrophic skeletal muscle channelopathies are a group of disorders caused by mutations of various voltage-gated ion channel genes, including nondystrophic myotonia and periodic paralysis. METHODS: We identified patients with a diagnosis of muscle channelopathy from our neuromuscular database in a tertiary care pediatric center from 2005 to 2015. We then performed a retrospective review of their medical records for demographic characteristics, clinical features, investigations, treatment, and follow-up...
May 2017: Pediatric Neurology
https://www.readbyqxmd.com/read/28290897/-the-brugada-syndrome-as-a-cause-of-sudden-death-diagnostics-and-clinical-manifestations-in-children
#14
I M Miklashevich, M A Shkolnikova
The Brugada syndrome is a hereditary potentially arrhythmogenic disease related to the category of channelopathies. It is manifested as syncopal states and sudden death in young people in the absence of structural cardiac disease. The basis of the disease is genetically determined abnormality of function of ionic channels of cardiomyocytes (sodium, potassium, calcium) phenotypically manifesting as sustained or transitory segment-ST elevation and high risk of polymorphic ventricular tachycardia, fibrillation, and sudden death...
October 2016: Kardiologiia
https://www.readbyqxmd.com/read/28286482/restoration-of-epithelial-sodium-channel-function-by-synthetic-peptides-in-pseudohypoaldosteronism-type-1b-mutants
#15
Anita Willam, Mohammed Aufy, Susan Tzotzos, Heinrich Evanzin, Sabine Chytracek, Sabrina Geppert, Bernhard Fischer, Hendrik Fischer, Helmut Pietschmann, Istvan Czikora, Rudolf Lucas, Rosa Lemmens-Gruber, Waheed Shabbir
The synthetically produced cyclic peptides solnatide (a.k.a. TIP or AP301) and its congener AP318, whose molecular structures mimic the lectin-like domain of human tumor necrosis factor (TNF), have been shown to activate the epithelial sodium channel (ENaC) in various cell- and animal-based studies. Loss-of-ENaC-function leads to a rare, life-threatening, salt-wasting syndrome, pseudohypoaldosteronism type 1B (PHA1B), which presents with failure to thrive, dehydration, low blood pressure, anorexia and vomiting; hyperkalemia, hyponatremia and metabolic acidosis suggest hypoaldosteronism, but plasma aldosterone and renin activity are high...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28185290/computational-analysis-of-the-human-sinus-node-action-potential-model-development-and-effects-of-mutations
#16
Alan Fabbri, Matteo Fantini, Ronald Wilders, Stefano Severi
KEY POINTS: We constructed a comprehensive mathematical model of the spontaneous electrical activity of a human sinoatrial node (SAN) pacemaker cell, starting from the recent Severi-DiFrancesco model of rabbit SAN cells. Our model is based on electrophysiological data from isolated human SAN pacemaker cells and closely matches the action potentials and calcium transient that were recorded experimentally. Simulated ion channelopathies explain the clinically observed changes in heart rate in corresponding mutation carriers, providing an independent qualitative validation of the model...
April 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28183995/structure-of-a-eukaryotic-voltage-gated-sodium-channel-at-near-atomic-resolution
#17
Huaizong Shen, Qiang Zhou, Xiaojing Pan, Zhangqiang Li, Jianping Wu, Nieng Yan
Voltage-gated sodium (Nav) channels are responsible for the initiation and propagation of action potentials. They are associated with a variety of channelopathies and are targeted by multiple pharmaceutical drugs and natural toxins. Here, we report the cryogenic electron microscopy structure of a putative Nav channel from American cockroach (designated NavPaS) at 3.8 angstrom resolution. The voltage-sensing domains (VSDs) of the four repeats exhibit distinct conformations. The entrance to the asymmetric selectivity filter vestibule is guarded by heavily glycosylated and disulfide bond-stabilized extracellular loops...
March 3, 2017: Science
https://www.readbyqxmd.com/read/28150151/structure-based-assessment-of-disease-related-mutations-in-human-voltage-gated-sodium-channels
#18
REVIEW
Weiyun Huang, Minhao Liu, S Frank Yan, Nieng Yan
Voltage-gated sodium (Nav) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Nav channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Nav channels, with Nav1.1 and Nav1.5 each harboring more than 400 mutations. Nav channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Nav channels are required to understand their function and disease mechanisms...
June 2017: Protein & Cell
https://www.readbyqxmd.com/read/28090678/the-epileptic-and-nonepileptic-spectrum-of-paroxysmal-dyskinesias-channelopathies-synaptopathies-and-transportopathies
#19
REVIEW
Roberto Erro, Kailash P Bhatia, Alberto J Espay, Pasquale Striano
Historically, the syndrome of primary paroxysmal dyskinesias was considered a group of disorders as a result of ion channel dysfunction. This proposition was primarily based on the discovery of mutations in ion channels, which caused other episodic neurological disorders such as epilepsy and migraine and also supported by the frequent association between paroxysmal dyskinesias and epilepsy. However, the discovery of the genes responsible for the 3 classic forms of paroxysmal dyskinesias disproved this ion channel theory...
March 2017: Movement Disorders: Official Journal of the Movement Disorder Society
https://www.readbyqxmd.com/read/28024841/a-novel-ile1455thr-variant-in-the-skeletal-muscle-sodium-channel-alpha-subunit-in-a-patient-with-a-severe-adult-onset-proximal-myopathy-with-electrical-myotonia-and-a-patient-with-mild-paramyotonia-phenotype
#20
Marcin Bednarz, Bas C Stunnenberg, Benno Kusters, Erik-Jan Kamsteeg, Christiaan G Saris, James Groome, Vern Winston, Giovanni Meola, Karin Jurkat-Rott, Nicol C Voermans
In sodium channelopathies, a severe fixed myopathy caused by a dominant mutation is rare. We describe two unrelated patients with a novel variant, p.Ile1455Thr, with phenotypes of paramyotonia in one case and fixed proximal myopathy with latent myotonia in another. In-vitro whole cell patch-clamp studies show that the mutation slows inactivation and accelerates recovery, in line with other paramyotonia variants with destabilized fast inactivation as pathomechanism. Additionally, p.IleI1455 causes a loss-of-function by reduced membrane insertion, right-shift of activation, and slowed kinetics...
February 2017: Neuromuscular Disorders: NMD
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