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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...
November 11, 2016: Brain & Development
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
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
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
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
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
Mohammed Zain Seidahmed, Mustafa A Salih, Omer B Abdulbasit, Abdulmohsen Samadi, Khalid Al Hussien, Abeer M Miqdad, Maha S Biary, Anas M Alazami, Ibrahim A Alorainy, Mohammad M Kabiraj, Ranad Shaheen, Fowzan S Alkuraya
BACKGROUND: Asparagine synthetase deficiency (OMIM# 615574) is a very rare newly described neurometabolic disorder characterized by congenital microcephaly and severe global developmental delay, associated with intractable seizures or hyperekplexia. Brain MRI typically shows cerebral atrophy with simplified gyral pattern and delayed myelination. Only 12 cases have been described to date. The disease is caused by homozygous or compound heterozygous mutations in the ASNS gene on chromosome 7q21...
July 15, 2016: BMC Neurology
Gifty Bhat, Danielle LaGrave, Alison Millson, John Herriges, Allen N Lamb, Reuben Matalon
We report an 8-year-old female with autism spectrum disorder (ASD), intellectual disability and speech delay who was found to carry a de novo 82 kb deletion of chromosome Xq11.1-11.2 involving the ARHGEF9 gene on chromosomal microarray. So far, 11 patients with point mutations, disruptions due to chromosomal rearrangements and deletions involving ARHGEF9 have been reported in the literature. ARHGEF9-related disorders comprise a wide phenotypic spectrum, including behavior disorders, autism spectrum disorder, intellectual disability, hyperekplexia and infantile epileptic encephalopathy...
September 2016: European Journal of Medical Genetics
Yan Zhang, Anna Bode, Bindi Nguyen, Angelo Keramidas, Joseph W Lynch
Hyperekplexia is a rare human neuromotor disorder caused by mutations that impair the efficacy of glycinergic inhibitory neurotransmission. Loss-of-function mutations in the GLRA1 or GLRB genes, which encode the α1 and β glycine receptor (GlyR) subunits, are the major cause. Paradoxically, gain-of-function GLRA1 mutations also cause hyperekplexia, although the mechanism is unknown. Here we identify two new gain-of-function mutations (I43F and W170S) and characterize these along with known gain-of-function mutations (Q226E, V280M, and R414H) to identify how they cause hyperekplexia...
July 15, 2016: Journal of Biological Chemistry
Megan E Wilkins, Alex Caley, Marc C Gielen, Robert J Harvey, Trevor G Smart
KEY POINTS: Hyperekplexia or startle disease is a serious neurological condition affecting newborn children and usually involves dysfunctional glycinergic neurotransmission. Glycine receptors (GlyRs) are major mediators of inhibition in the spinal cord and brainstem. A missense mutation, replacing asparagine (N) with lysine (K), at position 46 in the GlyR α1 subunit induced hyperekplexia following a reduction in the potency of the transmitter glycine; this resulted from a rapid deactivation of the agonist current at mutant GlyRs...
July 1, 2016: Journal of Physiology
Anna Winczewska-Wiktor, Magdalena Badura-Stronka, Anna Monies-Nowicka, Michal Maciej Nowicki, Barbara Steinborn, Anna Latos-Bieleńska, Dorota Monies
BACKGROUND: In addition to its role in cell adhesion and gene expression in the canonical Wingless/integrated Wnt signaling pathway, β-catenin also regulates genes that underlie the transmission of nerve impulses. Mutations of CTNNB1 (β-catenin) have recently been described in patients with a wide range of neurodevelopmental disorders (intellectual disability, microcephaly and other syndromic features). We for the first time associate CTNNB1 mutation with hyperekplexia identifying it as an additional candidate for consideration in patients with startle syndrome...
2016: BMC Neurology
Y Kono, S Hülsmann
Glycinergic neurons provide an important mechanism to control excitation of motoneurons in the brainstem and a reduction or loss of glycinergic inhibition can be deleterious by leading to hyperexcitation such as in hyperekplexia or neurodegeneration and neuronal death as in amyotrophic lateral sclerosis (ALS). Second messenger systems that change cyclic AMP and lead to phosphorylation of the α3 subunit of the glycine receptor (GlyR α3) have been shown to be potent modulators of synaptic inhibition in the spinal cord and brain stem...
April 21, 2016: Neuroscience
Hagit Sason, Jean Marie Billard, Garrick Paul Smith, Hazem Safory, Samah Neame, Eitan Kaplan, Dina Rosenberg, Salman Zubedat, Veronika N Foltyn, Claus Tornby Christoffersen, Christoffer Bundgaard, Christian Thomsen, Avi Avital, Kenneth Vielsted Christensen, Herman Wolosker
d-Serine is a co-agonist of NMDA receptors (NMDARs) whose activity is potentially regulated by Asc-1 (SLC7A10), a transporter that displays high affinity for d-serine and glycine. Asc-1 operates as a facilitative transporter and as an antiporter, though the preferred direction of d-serine transport is uncertain. We developed a selective Asc-1 blocker, Lu AE00527, that blocks d-serine release mediated by all the transport modes of Asc-1 in primary cultures and neocortical slices. Furthermore, d-serine release is reduced in slices from Asc-1 knockout (KO) mice, indicating that d-serine efflux is the preferred direction of Asc-1...
January 20, 2016: Cerebral Cortex
Ibrahim Aliyu, Zainab Ibrahim
Hyperekplexia is a rare movement disorder, which is mostly of genetic origin; though acquired cases are rarely reported. This disorder is characterized by excessive startling response to external stimuli; this can be disenabling, affecting quality-of-life. Furthermore, it can easily be mistaken for an epileptic disorder. Therefore, the case of a 10-year-old boy who presented with excessive startling shortly after been treated for cerebral malaria is reported; the patient responded to carbamazepine and was discharged home afterward...
October 2015: Indian Journal of Psychological Medicine
Hülya Maraş-Genç, Emek Uyur-Yalçın, Rasim Özgür Rosti, Joseph G Gleeson, Bülent Kara
The pontocerebellar hypoplasias (PCHs) are a heterogeneous group of autosomal recessive disorders characterized by hypoplasia of the ventral pons and cerebellum, with variable cerebral involvement and severe psychomotor retardation. Eight different subtypes (PCH1-8) have been reported up to now. PCH2 is the most common type, generally caused by homozygous mutations in the TSEN54 gene and characterized by cerebellar hypoplasia that affects the hemispheres more severely than the vermis, progressive cerebral atrophy, microcephaly, dyskinesia, seizures and death in early childhood...
May 2015: Turkish Journal of Pediatrics
J M Capo-Chichi, S Boissel, E Brustein, F F Hamdan, M E Samuels, P Drapeau, J L Michaud
No abstract text is available yet for this article.
December 2015: International Journal of Developmental Neuroscience
Juan Du, Wei Lü, Shenping Wu, Yifan Cheng, Eric Gouaux
The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders, including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of glycine receptors has been hindered by a lack of high-resolution structures. Here we report electron cryo-microscopy structures of the zebrafish α1 GlyR with strychnine, glycine, or glycine and ivermectin (glycine/ivermectin). Strychnine arrests the receptor in an antagonist-bound closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state...
October 8, 2015: Nature
Verónica Martínez-Rivera, Jacinto Martínez-Antón
No abstract text is available yet for this article.
August 16, 2015: Revista de Neurologia
Anthony Chau, Marni Roitfarb, Jean Marie Carabuena, William Camann
Hyperekplexia is a hereditary disorder characterized by exaggerated startle reflex in response to unexpected acoustic, tactile, and other stimuli. Neonates with hyperekplexia may present with hypertonia, developmental delays, apnea, and sudden death. The diagnosis is based on published clinical criteria. In some cases, a mutation encoding the postsynaptic inhibitory glycine receptors (GLRA1, GLRB) or presynaptic glycine transporter (SLC6A5) resulting in abnormal glycinergic neurotransmission is present. We report the case of a 38-year-old gravida 6 para 1 (G6P1) parturient with hyperekplexia who underwent successful vaginal delivery managed by the anesthesiology and neonatology service teams from initial antenatal consultation to labor and delivery to hospital discharge...
April 15, 2015: A & A Case Reports
Hazem Safory, Samah Neame, Yoav Shulman, Salman Zubedat, Inna Radzishevsky, Dina Rosenberg, Hagit Sason, Simone Engelender, Avi Avital, Swen Hülsmann, Jackie Schiller, Herman Wolosker
Asc-1 (SLC7A10) is an amino acid transporter whose deletion causes neurological abnormalities and early postnatal death in mice. Using metabolomics and behavioral and electrophysiological methods, we demonstrate that Asc-1 knockout mice display a marked decrease in glycine levels in the brain and spinal cord along with impairment of glycinergic inhibitory transmission, and a hyperekplexia-like phenotype that is rescued by replenishing brain glycine. Asc-1 works as a glycine and L-serine transporter, and its transport activity is required for the subsequent conversion of L-serine into glycine in vivo...
May 2015: EMBO Reports
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