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Hyperekplexia

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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
#1
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 disorder. We found that 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...
July 19, 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
#2
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...
July 7, 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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
https://www.readbyqxmd.com/read/28167838/glrb-allelic-variation-associated-with-agoraphobic-cognitions-increased-startle-response-and-fear-network-activation-a-potential-neurogenetic-pathway-to-panic-disorder
#12
J Deckert, H Weber, C Villmann, T B Lonsdorf, J Richter, M Andreatta, A Arias-Vasquez, L Hommers, L Kent, C Schartner, S Cichon, C Wolf, N Schaefer, C R von Collenberg, B Wachter, R Blum, D Schümann, R Scharfenort, J Schumacher, A J Forstner, C Baumann, M A Schiele, S Notzon, P Zwanzger, J G E Janzing, T Galesloot, L A Kiemeney, A Gajewska, E Glotzbach-Schoon, A Mühlberger, G Alpers, T Fydrich, L Fehm, A L Gerlach, T Kircher, T Lang, A Ströhle, V Arolt, H-U Wittchen, R Kalisch, C Büchel, A Hamm, M M Nöthen, M Romanos, K Domschke, P Pauli, A Reif
The molecular genetics of panic disorder (PD) with and without agoraphobia (AG) are still largely unknown and progress is hampered by small sample sizes. We therefore performed a genome-wide association study with a dimensional, PD/AG-related anxiety phenotype based on the Agoraphobia Cognition Questionnaire (ACQ) in a sample of 1370 healthy German volunteers of the CRC TRR58 MEGA study wave 1. A genome-wide significant association was found between ACQ and single non-coding nucleotide variants of the GLRB gene (rs78726293, P=3...
February 7, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/28122427/familiar-hyperekplexia-a-potential-cause-of-cautious-gait-a-new-korean-case-and-a-systematic-review-of-phenotypes
#13
Yoonju Lee, Nan Young Kim, Sangkyoon Hong, Su Jin Chung, Seong Ho Jeong, Phil Hyu Lee, Young H Sohn
Familial hyperekplexia, also called startle disease, is a rare neurological disorder characterized by excessive startle responses to noise or touch. It can be associated with serious injury from frequent falls, apnea spells, and aspiration pneumonia. Familial hyperekplexia has a heterogeneous genetic background with several identified causative genes; it demonstrates both dominant and recessive inheritance in the α1 subunit of the glycine receptor (GLRA1), the β subunit of the glycine receptor and the presynaptic sodium and chloride-dependent glycine transporter 2 genes...
January 2017: Journal of Movement Disorders
https://www.readbyqxmd.com/read/28090805/visually-evoked-startle-response-in-a-patient-with-epilepsy-a-case-report-and-review-of-the-literature
#14
Burcu Zeydan, Aysegul Gunduz, Veysi Demirbilek, Aysin Dervent
Both symptomatic and genetic, cases with hyperekplexia or startle seizures induced by acoustic stimuli, are previously reported. By contrast, startle response induced by visual stimuli is rare. While visual stimuli are more commonly associated with startle seizures, here we present an 11-year-old girl with epilepsy, motor-mental retardation, and spastic tetraparesis, who had repetitive startle responses by photic stimulation during the electroencephalogram recording, without any spike-and-wave discharges associated with the startles...
January 15, 2017: Neurocase
https://www.readbyqxmd.com/read/27843043/hyperekplexia-report-on-phenotype-and-genotype-of-16-jordanian-patients
#15
Amira Masri, Seo-Kyung Chung, Mark I Rees
BACKGROUND: Hyperekplexia, is a rare disorder characterized by excessive startle response to acoustic, visual, or other stimuli. It is inherited in autosomal recessive and dominant pattern. OBJECTIVE: To describe the clinical and genetic features of hyperekplexia in Jordanian patients. METHODS: This retrospective study includes all patients with proved genetic diagnosis of hyperekplexia who presented to our clinic at the Jordan University Hospital from January 2001 through July 2015...
April 2017: Brain & Development
https://www.readbyqxmd.com/read/27773429/loss-of-glycine-transporter-1-causes-a-subtype-of-glycine-encephalopathy-with-arthrogryposis-and-mildly-elevated-cerebrospinal-fluid-glycine
#16
Alina Kurolap, Anja Armbruster, Tova Hershkovitz, Katharina Hauf, Adi Mory, Tamar Paperna, Ewald Hannappel, Galit Tal, Yusif Nijem, Ella Sella, Muhammad Mahajnah, Anat Ilivitzki, Dov Hershkovitz, Nina Ekhilevitch, Hanna Mandel, Volker Eulenburg, Hagit N Baris
Glycine is a major neurotransmitter that activates inhibitory glycine receptors and is a co-agonist for excitatory glutamatergic N-methyl-D-aspartate (NMDA) receptors. Two transporters, GLYT1 and GLYT2, regulate extracellular glycine concentrations within the CNS. Dysregulation of the extracellular glycine has been associated with hyperekplexia and nonketotic hyperglycinemia. Here, we report four individuals from two families who presented at birth with facial dysmorphism, encephalopathy, arthrogryposis, hypotonia progressing to hypertonicity with startle-like clonus, and respiratory failure...
November 3, 2016: American Journal of Human Genetics
https://www.readbyqxmd.com/read/27759100/the-astrocytic-transporter-slc7a10-asc-1-mediates-glycinergic-inhibition-of-spinal-cord-motor-neurons
#17
Jeffrey T Ehmsen, Yong Liu, Yue Wang, Nikhil Paladugu, Anna E Johnson, Jeffrey D Rothstein, Sascha du Lac, Mark P Mattson, Ahmet Höke
SLC7A10 (Asc-1) is a sodium-independent amino acid transporter known to facilitate transport of a number of amino acids including glycine, L-serine, L-alanine, and L-cysteine, as well as their D-enantiomers. It has been described as a neuronal transporter with a primary role related to modulation of excitatory glutamatergic neurotransmission. We find that SLC7A10 is substantially enriched in a subset of astrocytes of the caudal brain and spinal cord in a distribution corresponding with high densities of glycinergic inhibitory synapses...
October 19, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27758720/-autoimmune-encephalitis-due-to-mantle-cell-lymphoma
#18
A A H Bressers, N A Goto, S Piepers, J C Regelink
BACKGROUND: Autoimmune encephalitis is a rare condition characterized by subacute development of cognitive and psychiatric symptoms. A paraneoplastic syndrome involves autoimmune encephalitis caused by classic antibodies. Although this condition is often associated with cancer, no malignancy has yet been found in 70-90% of patients at the time of diagnosis. CASE DESCRIPTION: We saw a 58-year-old male patient with fatigue, diarrhoea and weight loss. He was also experiencing hyperekplexia, personality changes and an instable gait...
2016: Nederlands Tijdschrift Voor Geneeskunde
https://www.readbyqxmd.com/read/27713689/the-free-zinc-concentration-in-the-synaptic-cleft-of-artificial-glycinergic-synapses-rises-to-at-least-1-%C3%AE-m
#19
Yan Zhang, Angelo Keramidas, Joseph W Lynch
Zn(2+) is concentrated into presynaptic vesicles at many central synapses and is released into the synaptic cleft by nerve terminal stimulation. There is strong evidence that synaptically released Zn(2+) modulates glutamatergic neurotransmission, although there is debate concerning the peak concentration it reaches in the synaptic cleft. Glycine receptors (GlyRs), which mediate inhibitory neurotransmission in the spinal cord and brainstem, are potentiated by low nanomolar Zn(2+) and inhibited by micromolar Zn(2+)...
2016: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/27445686/defects-of-the-glycinergic-synapse-in-zebrafish
#20
REVIEW
Kazutoyo Ogino, Hiromi Hirata
Glycine mediates fast inhibitory synaptic transmission. Physiological importance of the glycinergic synapse is well established in the brainstem and the spinal cord. In humans, the loss of glycinergic function in the spinal cord and brainstem leads to hyperekplexia, which is characterized by an excess startle reflex to sudden acoustic or tactile stimulation. In addition, glycinergic synapses in this region are also involved in the regulation of respiration and locomotion, and in the nociceptive processing. The importance of the glycinergic synapse is conserved across vertebrate species...
2016: Frontiers in Molecular Neuroscience
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