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Hyperekplexia

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https://www.readbyqxmd.com/read/29445326/structure-function-studies-of-the-%C3%AE-4-subunit-reveal-evolutionary-loss-of-a-glyr-subtype-involved-in-startle-and-escape-responses
#1
Sophie Leacock, Parnayan Syed, Victoria M James, Anna Bode, Koichi Kawakami, Angelo Keramidas, Maximiliano Suster, Joseph W Lynch, Robert J Harvey
Inhibitory glycine receptors (GlyRs) are pentameric ligand-gated anion channels with major roles in startle disease/hyperekplexia (GlyR α1), cortical neuronal migration/autism spectrum disorder (GlyR α2), and inflammatory pain sensitization/rhythmic breathing (GlyR α3). However, the role of the GlyR α4 subunit has remained enigmatic, because the corresponding human gene ( GLRA4 ) is thought to be a pseudogene due to an in-frame stop codon at position 390 within the fourth membrane-spanning domain (M4). Despite this, a recent genetic study has implicated GLRA4 in intellectual disability, behavioral problems and craniofacial anomalies...
2018: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/29440552/a-missense-mutation-a384p-associated-with-human-hyperekplexia-reveals-a-desensitization-site-of-glycine-receptors
#2
Chen-Hung Wang, Ciria C Hernandez, Junyi Wu, Ning Zhou, Hsin-Yu Hsu, Mei-Lin Shen, Yi-Ching Wang, Robert L Macdonald, Dong Chuan Wu
Hyperekplexia, an inherited neuronal disorder characterized by exaggerated startle responses with unexpected sensory stimuli, is caused by dysfunction of glycinergic inhibitory transmission. From analysis of newly identified human hyperekplexia mutations in the glycine receptor (GlyR) α1 subunit, we found that an alanine-to-proline missense mutation (A384P) resulted in substantially higher desensitization level and lower agonist sensitivity of homomeric α1 GlyRs when expressed in HEK cells. The incorporation of the β subunit fully reversed the reduction in agonist sensitivity and partially reversed the desensitization of α1 A384P The heteromeric α1 A384P β GlyRs showed enhanced desensitization but unchanged agonists-induced maximum responses, surface expression, main channel conductance, and voltage-dependence compared with that of the wild-type α1β (α1 WT β) GlyRs...
February 13, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29279279/characterization-of-a-novel-variant-in-siblings-with-asparagine-synthetase-deficiency
#3
Stephanie J Sacharow, Elizabeth E Dudenhausen, Carrie L Lomelino, Lance Rodan, Christelle Moufawad El Achkar, Heather E Olson, Casie A Genetti, Pankaj B Agrawal, Robert McKenna, Michael S Kilberg
Asparagine Synthetase Deficiency (ASD) is a recently described inborn error of metabolism caused by bi-allelic pathogenic variants in the asparagine synthetase (ASNS) gene. ASD typically presents congenitally with microcephaly and severe, often medically refractory, epilepsy. Development is generally severely affected at birth. Tone is abnormal with axial hypotonia and progressive appendicular spasticity. Hyperekplexia has been reported. Neuroimaging typically demonstrates gyral simplification, abnormal myelination, and progressive cerebral atrophy...
December 20, 2017: Molecular Genetics and Metabolism
https://www.readbyqxmd.com/read/29149236/mutations-affecting-glycinergic-neurotransmission-in-hyperekplexia-increase-pain-sensitivity
#4
Pascal Henri Vuilleumier, Raphael Fritsche, Jürg Schliessbach, Bernhard Schmitt, Lars Arendt-Nielsen, Hanns Ulrich Zeilhofer, Michele Curatolo
Inhibitory interneurons in the spinal cord use glycine and GABA for fast inhibitory neurotransmission. While there is abundant research on these inhibitory pain pathways in animal models, their relevance in humans remains unclear, largely due to the limited possibility to manipulate selectively these pathways in humans. Hyperekplexia is a rare human disease that is caused by loss-of-function mutations in genes encoding for glycine receptors and glycine transporters. In the present study, we tested whether hyperekplexia patients display altered pain perception or central pain modulation compared with healthy subjects...
November 15, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/29062233/sporadic-hyperekplexia-due-to-self-limiting-brainstem-encephalopathy
#5
Dilek Yilmaz, Bülent Cengiz
Hyperekplexia is a rare movement disorder characterized by pathologically exaggerated response to unexpected stimuli. It is differentiated from the normal startle reflex by its lower threshold, higher intensity, and resistance to habituation. Many of the acquired hyperekplexias result from brainstem involvement such as encephalitis, infarct, hemorrhage, pontocerebellar hypoplasia and medullary compression. This case report depicts a rare manifestation of hyperekplexia. The unusual aspect of this case was the vocalization that was reproduced in response to startling stimuli...
2017: Neuropsychiatric Disease and Treatment
https://www.readbyqxmd.com/read/29053777/movement-disorders-with-neuronal-antibodies-syndromic-approach-genetic-parallels-and-pathophysiology
#6
Bettina Balint, Angela Vincent, Hans-Michael Meinck, Sarosh R Irani, Kailash P Bhatia
Movement disorders are a prominent and common feature in many autoantibody-associated neurological diseases, a group of potentially treatable conditions that can mimic infectious, metabolic or neurodegenerative disease. Certain movement disorders are likely to associate with certain autoantibodies; for example, the characteristic dyskinesias, chorea and dystonia associated with NMDAR antibodies, stiff person spectrum disorders with GAD, glycine receptor, amphiphysin or DPPX antibodies, specific paroxysmal dystonias with LGI1 antibodies, and cerebellar ataxia with various anti-neuronal antibodies...
September 25, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28985719/a-novel-compound-mutation-in-glra1-cause-hyperekplexia-in-a-chinese-boy-a-case-report-and-review-of-the-literature
#7
Zhiliang Yang, Guilian Sun, Fang Yao, Dongying Tao, Binlu Zhu
BACKGROUND: The pathogenesis of hereditary hyperekplexia is thought to involve abnormalities in the glycinergic neurotransmission system, the most of mutations reported in GLRA1. This gene encodes the glycine receptor α1 subunit, which has an extracellular domain (ECD) and a transmembrane domain (TMD) with 4 α-helices (TM1-TM4). CASE PRESENTATION: We investigated the genetic cause of hyperekplexia in a Chinese family with one affected member. Whole-exome sequencing of the 5 candidate genes was performed on the proband patient, and direct sequencing was performed to validate and confirm the detected mutation in other family members...
October 6, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/28927557/cacna1a-related-early-onset-encephalopathy-with-myoclonic-epilepsy-a-case-report
#8
Takuya Hayashida, Yoshiaki Saito, Atsushi Ishii, Hiroyuki Yamada, Ayako Itakura, Toshinori Minato, Tetsuhiro Fukuyama, Yoshihiro Maegaki, Shinichi Hirose
We report a one-year-old boy with early-onset myoclonic epilepsy, developmental arrest, and hyperekplexia during early infancy. He presented with refractory myoclonic/tonic seizures since birth. Electroencephalography revealed multifocal spikes, and rhythmic activities that occurred simultaneous with aggravation of myoclonus accompanied by tonic upper limb elevation. Brain magnetic resonance imaging revealed progressive cerebral atrophy with periventricular signal change and thin corpus callosum at one year of age...
September 16, 2017: Brain & Development
https://www.readbyqxmd.com/read/28879899/hyperekplexia-a-forgotten-diagnosis-clinched-by-next-generation-sequencing
#9
Meenakshi Lallar, Anukool Srivastava, Shubha R Phadke
Hyperekplexia is a rare early neonatal onset, potentially treatable, neurological disorder, characterized by a triad of immediate neonatal-onset stiffness, an exaggerated startle reflex in response to tactile or auditory stimuli followed by short periodical generalized stiffness. It is a monogenic genetically heterogeneous condition which can be potentially life threatening due to apneic episodes and is usually misdiagnosed as seizures. Here, we report two female siblings with hyperekplexia who were being treated by multiple antiepileptic medications for seizure-like episodes...
September 2017: Neurology India
https://www.readbyqxmd.com/read/28724750/disruption-of-a-structurally-important-extracellular-element-in-the-glycine-receptor-leads-to-decreased-synaptic-integration-and-signaling-resulting-in-severe-startle-disease
#10
Natascha Schaefer, Alexandra Berger, Johannes van Brederode, Fang Zheng, Yan Zhang, Sophie Leacock, Laura Littau, Sibylle Jablonka, Sony Malhotra, Maya Topf, Friederike Winter, Daria Davydova, Joseph W Lynch, Christopher J Paige, Christian Alzheimer, Robert J Harvey, Carmen Villmann
Functional impairments or trafficking defects of inhibitory glycine receptors (GlyRs) have been linked to human hyperekplexia/startle disease and autism spectrum disorders. We found that a lack of synaptic integration of GlyRs, together with disrupted receptor function, is responsible for a lethal startle phenotype in a novel spontaneous mouse mutant shaky, caused by a missense mutation, Q177K, located in the extracellular β8-β9 loop of the GlyR α1 subunit. Recently, structural data provided evidence that the flexibility of the β8-β9 loop is crucial for conformational transitions during opening and closing of the ion channel and represents a novel allosteric binding site in Cys-loop receptors...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28687938/a-scoring-system-predicting-the-clinical-course-of-clpb-defect-based-on-the-foetal-and-neonatal-presentation-of-31-patients
#11
Ewa Pronicka, Mariola Ropacka-Lesiak, Joanna Trubicka, Magdalena Pajdowska, Markus Linke, Elsebet Ostergaard, Carol Saunders, Sandra Horsch, Clara van Karnebeek, Joy Yaplito-Lee, Felix Distelmaier, Katrin Õunap, Shamima Rahman, Martin Castelle, John Kelleher, Safa Baris, Katarzyna Iwanicka-Pronicka, Colin G Steward, Elżbieta Ciara, Saskia B Wortmann
Recently, CLPB deficiency has been shown to cause a genetic syndrome with cataracts, neutropenia, and 3-methylglutaconic aciduria. Surprisingly, the neurological presentation ranges from completely unaffected to patients with virtual absence of development. Muscular hypo- and hypertonia, movement disorder and progressive brain atrophy are frequently reported. We present the foetal, peri- and neonatal features of 31 patients, of which five are previously unreported, using a newly developed clinical severity scoring system rating the clinical, metabolic, imaging and other findings weighted by the age of onset...
November 2017: Journal of Inherited Metabolic Disease
https://www.readbyqxmd.com/read/28620718/the-phenotypic-spectrum-of-arhgef9-includes-intellectual-disability-focal-epilepsy-and-febrile-seizures
#12
Karl Martin Klein, Manuela Pendziwiat, Anda Eilam, Ronit Gilad, Ilan Blatt, Felix Rosenow, Moien Kanaan, Ingo Helbig, Zaid Afawi
Mutations or structural genomic alterations of the X-chromosomal gene ARHGEF9 have been described in male and female patients with intellectual disability. Hyperekplexia and epilepsy were observed to a variable degree, but incompletely described. Here, we expand the phenotypic spectrum of ARHGEF9 by describing a large Ethiopian-Jewish family with epilepsy and intellectual disability. The four affected male siblings, their unaffected parents and two unaffected female siblings were recruited and phenotyped. Parametric linkage analysis was performed using SNP microarrays...
July 2017: Journal of Neurology
https://www.readbyqxmd.com/read/28566967/clinical-and-electrophysiological-findings-in-two-siblings-with-familial-hyperekplexia
#13
Yeşim Gülen Abanoz, Yasin Abanoz, Ayşegül Gündüz, Nurten Uzun, Meral E Kiziltan
No abstract text is available yet for this article.
March 2017: Noro Psikiyatri Arsivi
https://www.readbyqxmd.com/read/28553377/sporadic-hyperekplexia-plus-syndrome
#14
Sadanandavalli Retnaswami Chandra, Chetan Vekhande, Lakshminarayanapuram Gopal Viswanathan, Pooja Mailankody, Karru Venkata Ravi Teja
A disorder of infants and children with pathological startle response, features of other system involvement, falls, and stiffness with retained consciousness. It should be differentiated from conditions such as myoclonic epilepsy, psychogenic movement disorder, Isaac syndrome, Schwartz-Jampel syndrome, Gilles de la Tourette, and culture-specific startle syndromes such as jumping Frenchman of Maine. A 5-year-old child symptomatic with repeated falls spontaneously as well as by sound and activities since neonatal period...
January 2017: Journal of Pediatric Neurosciences
https://www.readbyqxmd.com/read/28528670/glycine-receptor-drug-discovery
#15
Joseph W Lynch, Yan Zhang, Sahil Talwar, Argel Estrada-Mondragon
Postsynaptic glycine receptor (GlyR) chloride channels mediate inhibitory neurotransmission in the spinal cord and brain stem, although presynaptic and extrasynaptic GlyRs are expressed more widely throughout the brain. In humans, GlyRs are assembled as homo- or heteromeric pentamers of α1-3 and β subunits. GlyR malfunctions have been linked to a range of neurological disorders including hyperekplexia, temporal lobe epilepsy, autism, breathing disorders, and chronic inflammatory pain. Although it is possible that GlyRs may eventually be clinically targeted for a variety of neurological disorders, most research to date has focused on developing GlyR-targeted treatments for chronic pain...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28429370/the-role-of-charged-residues-in-independent-glycine-receptor-folding-domains-for-intermolecular-interactions-and-ion-channel-function
#16
Georg Langlhofer, Carmen Villmann
Glycine receptor (GlyR) truncations in the intracellular TM3-4 loop, documented in patients suffering from hyperekplexia and in the mouse mutant oscillator, lead to non-functionality of GlyRs. The missing part that contains the TM3-4 loop, TM4 and C-terminal sequences is essential for pentameric receptor arrangements. In vitro co-expressions of GlyRα1-truncated N-domains and C-domains were able to restore ion channel function. An ionic interaction between both domains was hypothesized as the underlying mechanism...
July 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/28348128/teaching-video-neuroimages-hyperekplexia-a-syndrome-of-pathologic-startle-responses
#17
Louise-Laure Mariani, Elodie Hainque, Marie Mongin, Emmanuelle Apartis, Emmanuel Roze
No abstract text is available yet for this article.
March 28, 2017: Neurology
https://www.readbyqxmd.com/read/28258082/dppx-antibody-associated-encephalitis-main-syndrome-and-antibody-effects
#18
Makoto Hara, Helena Ariño, Mar Petit-Pedrol, Lidia Sabater, Maarten J Titulaer, Eugenia Martinez-Hernandez, Marco W J Schreurs, Myrna R Rosenfeld, Francesc Graus, Josep Dalmau
OBJECTIVE: To report the main syndrome of dipeptidyl-peptidase-like protein 6 (DPPX) antibody-associated encephalitis, immunoglobulin G (IgG) subclass, and the antibody effects on DPPX/Kv4.2 potassium channels. METHODS: A retrospective analysis of new patients and cases reported since 2013 was performed. IgG subclass and effects of antibodies on cultured neurons were determined with described techniques. RESULTS: Nine new patients were identified (median age 57 years, range 36-69 years)...
April 4, 2017: Neurology
https://www.readbyqxmd.com/read/28174298/the-startle-disease-mutation-e103k-impairs-activation-of-human-homomeric-%C3%AE-1-glycine-receptors-by-disrupting-an-intersubunit-salt-bridge-across-the-agonist-binding-site
#19
Fatemah Safar, Elliot Hurdiss, Marios Erotocritou, Timo Greiner, Remigijus Lape, Mark W Irvine, Guangyu Fang, David Jane, Rilei Yu, Marc A Dämgen, Philip C Biggin, Lucia G Sivilotti
Glycine receptors (GlyR) belong to the pentameric ligand-gated ion channel (pLGIC) superfamily and mediate fast inhibitory transmission in the vertebrate CNS. Disruption of glycinergic transmission by inherited mutations produces startle disease in man. Many startle mutations are in GlyRs and provide useful clues to the function of the channel domains. E103K is one of few startle mutations found in the extracellular agonist binding site of the channel, in loop A of the principal side of the subunit interface...
March 24, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28173650/-clinical-and-genetic-analysis-of-hyperekplexia-in-a-chinese-child-and-literature-review
#20
REVIEW
H Li, Z X Yang, J Xue, P Qian, X Y Liu
Objective: To investigate the clinical and genetic features of a Chinese child with hyperekplexia and review the related literature. Method: The clinical and genetic data of one patient with hyperekplexia, who had visited the department of Pediatrics, Peking University First Hospital in July 2012, were analyzed. "Hyperekplexia" "startle disease" "GLRB" were used as key words to search at CNKI, Wanfang and PubMed from the database from creation to August 2016. Result: The one-year-old female patient showed exaggerated startle reflexes and generalized stiffness in response to external sudden, unexpected stimuli at 2 hours after birth, which existed every day...
February 2, 2017: Zhonghua Er Ke za Zhi. Chinese Journal of Pediatrics
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