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Dolu MH, Öz Tunçer G, Akça Ü, Aydın S, Bahadir O, Sezer Ö, Aksoy A, Taşdemir HA. Hyperekplexia: A Single-Center Experience. J Child Neurol 2024:8830738241263243. [PMID: 39051604 DOI: 10.1177/08830738241263243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
BACKGROUND Hyperekplexia is a rare neurogenetic disorder that is classically characterized by an exaggerated startle response to sudden unexpected stimuli. This study aimed to determine clinical and genetic characteristics of our patients with hyperekplexia. METHODS The age of onset and diagnosis, familial and perinatal history, clinical course, complications, metabolic screening tests, magnetic resonance imaging (MRI), medications, neuropsychometric evaluations, and gene mutations of patients diagnosed with hyperekplexia were reviewed retrospectively. RESULTS All hyperekplexia patients had displayed neonatal excessive startle response and muscle stiffness, which we accepted as the major form of the disorder. Sixteen patients had mutations in genes associated with hyperekplexia. The ages at clinical diagnosis and genetic confirmation ranged from newborn to 16 years old and from 2.5 to 19 years, respectively. Nine patients (56.25%) were initially misdiagnosed with epilepsy. Seven patients (43.75%) carried a diagnosis of intellectual disability, defined here as a total IQ <80. Delayed gross motor development was detected in 4 patients (25%), and speech delay was reported in 3 (18.75%). Mutations in GLRA1 (NM_000171.4) and SLC6A5 (NM_004211.5) were identified in 13 (81.25%) and 3 patients (18.75%), respectively. Fifteen of the 16 patients (93.75%) showed autosomal recessive inheritance. Only 1 patient (6.25%) showed autosomal dominant inheritance. CONCLUSION Although hyperekplexia is a potentially treatable disease, it can be complicated by delayed speech and/or motor acquisition and also by intellectual disability. This study shows that hyperekplexia is not always a benign condition and that all patients diagnosed with hyperekplexia should be evaluated for neuropsychiatric status and provided with genetic testing.
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Affiliation(s)
- Merve Hilal Dolu
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Gökçen Öz Tunçer
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Ünal Akça
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Seren Aydın
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Oğuzhan Bahadir
- Department of Medical Genetics, Samsun Education and Research Hospital, Samsun, Turkey
| | - Özlem Sezer
- Department of Medical Genetics, Samsun Education and Research Hospital, Samsun, Turkey
| | - Ayşe Aksoy
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Haydar Ali Taşdemir
- Department of Pediatric Neurology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
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Aglave NR, Sontakke RA, Bokade C, Jhunjhunwala K. Hyperekplexia: Unveiling a Rare Neurological Condition With a Treatable Solution. Cureus 2024; 16:e61770. [PMID: 38975479 PMCID: PMC11226931 DOI: 10.7759/cureus.61770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 06/03/2024] [Indexed: 07/09/2024] Open
Abstract
Hyperekplexia (HPX) is a rare hereditary disorder characterized by an exaggerated startle reflex and neonatal hypertonia. It exhibits both autosomal dominant and autosomal recessive inheritance patterns, depending on the gene involved. It could be a fatal neurogenetic disorder, but it is treatable. We reported a nine-month-old female child with mild gross motor delay, an exaggerated startle reflex, and multiple episodes of transient hypertonia. Neurological and electrophysiological investigations and clinical presentation suggested the diagnosis of hereditary HPX. The child showed a good response to oral clonazepam, with a reduced frequency of such episodes and attainment of age-specific milestones.
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Affiliation(s)
- Nisha R Aglave
- Pediatrics, Datta Meghe Medical College, Datta Meghe Institute of Higher Education and Research (DU), Nagpur, IND
| | - Rachana A Sontakke
- Pediatrics, Narendra Kumar Prasadrao (NKP) Salve Institute of Medical Sciences and Research Center and Lata Mangeshkar Hospital, Nagpur, IND
| | - Chandrakant Bokade
- Pediatrics, Datta Meghe Medical College, Datta Meghe Institute of Higher Education and Research (DU), Nagpur, IND
| | - Kush Jhunjhunwala
- Pediatrics, Datta Meghe Medical College, Datta Meghe Institute of Higher Education and Research (DU), Nagpur, IND
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Lim TT, Por CY, Beh YY, Schee JP, Tan AH. Treatment of startle and related disorders. Clin Park Relat Disord 2023; 9:100218. [PMID: 37808566 PMCID: PMC10556813 DOI: 10.1016/j.prdoa.2023.100218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/04/2023] [Accepted: 09/15/2023] [Indexed: 10/10/2023] Open
Affiliation(s)
| | - Chia Yin Por
- Department of Medicine, Penang General Hospital, Penang, Malaysia
| | - Yuan Ye Beh
- Department of Medicine, Penang General Hospital, Penang, Malaysia
| | - Jie Ping Schee
- Faculty of Medicine (Divisions of Neurology), University of Malaya, Malaysia
| | - Ai Huey Tan
- Faculty of Medicine (Divisions of Neurology), University of Malaya, Malaysia
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4
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Dudipala SC, Reddy RV, Shankar R. Hyperekplexia: A Treatable Seizure Mimicker in Infants. Cureus 2023; 15:e38082. [PMID: 37252475 PMCID: PMC10208903 DOI: 10.7759/cureus.38082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
Hyperekplexia (HK) or startle disease is an uncommon, early infantile onset, potentially treatable neurogenetic disorder. It is characterized by an exaggerated startle reflex in response to tactile or acoustic or visual stimuli followed by generalized hypertonia. It is caused by genetic mutations in a number of different genes such as GLRA1, SLC6A5, GLRB, GPHN, and ARHGEF9. HK is frequently misdiagnosed as a form of epilepsy and is advised for prolonged antiseizure medications. Here, we report a two-month-old female child with HK, who was treated for epilepsy. Next-generation sequencing revealed a pathogenic homozygous missense mutation of variant c.1259C>A in exon 9 of the GLRA1 gene that was compatible with the diagnosis of hyperekplexia-1.
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Affiliation(s)
- Sai Chandar Dudipala
- Pediatrics, Prathima Institute of Medical Sciences, Karimnagar, IND
- Pediatric Neurology, Star Women & Children Hospital, Karimnagar, IND
| | | | - Roop Shankar
- Pediatrics, Star Women & Children Hospital, Karimnagar, IND
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5
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Kaur M, Vyas R, Meshram T, Bhatia P. Hyperekplexia with congenital heart disease: anesthetic concerns and management. Anesth Pain Med (Seoul) 2022; 17:338-339. [PMID: 35918868 PMCID: PMC9346195 DOI: 10.17085/apm.22173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/08/2022] [Indexed: 11/17/2022] Open
Affiliation(s)
- Manbir Kaur
- Department of Anesthesia and Critical Care, All India Institute of Medical Sciences (AIIMS), Jodhpur, India
- Corresponding author: Manbir Kaur, M.D. Department of Anesthesia and Critical Care, 3rd floor, AICU, Emergency building, AIIMS Jodhpur 342005, Rajasthan, India Tel: 91-291-2831001, E-mail:
| | - Raksha Vyas
- Department of Anesthesia and Critical Care, All India Institute of Medical Sciences (AIIMS), Jodhpur, India
| | - Tanvi Meshram
- Department of Anesthesia and Critical Care, All India Institute of Medical Sciences (AIIMS), Jodhpur, India
| | - Pradeep Bhatia
- Department of Anesthesia and Critical Care, All India Institute of Medical Sciences (AIIMS), Jodhpur, India
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Hereditary Hyperekplexia: A New Family and a Systematic Review of GLRA1 Gene-Related Phenotypes. Pediatr Neurol 2022; 132:45-49. [PMID: 35636282 DOI: 10.1016/j.pediatrneurol.2022.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 05/05/2022] [Accepted: 05/07/2022] [Indexed: 11/20/2022]
Abstract
Hereditary hyperekplexia (HPX) is a genetic neurodevelopmental disorder recently defined by the triad of (1) neonatal hypertonia, (2) excessive startle reflexes, and (3) generalized stiffness following the startle. Defects in GLRA1 are the most common cause of HPX, inherited both in an autosomal dominant and autosomal recessive manner. GLRA1 mutations can also cause milder phenotypes in the startle syndromes spectrum, but the prevalence is uncertain and no clear genotype-phenotype correlation has emerged yet. Moreover, the prevalence of neurodevelopmental outcomes has not been clearly defined. Here we report a new family of patients with a typical HPX phenotype, linked to a novel GLRA1 mutation, inherited with a recessive pattern. We then perform a systematic review of the literature of GLRA1-related HPX, describing the main epidemiological features of 210 patients. We found that GLRA1-related phenotypes do not necessarily fulfill the current criteria for HPX, including also milder and later-onset phenotypes. Among clinical features of the disease, neurodevelopmental issues were reported in a third of the sample; interestingly, we found that these problems, particularly when severe, were more common in homozygous than in heterozygous patients. Additional clinical and preclinical studies are needed to define predictors of adverse neurodevelopmental outcomes and underlying mechanisms.
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Zhan FX, Wang SG, Cao L. Advances in hyperekplexia and other startle syndromes. Neurol Sci 2021; 42:4095-4107. [PMID: 34379238 DOI: 10.1007/s10072-021-05493-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/14/2021] [Indexed: 02/03/2023]
Abstract
Startle, a basic alerting reaction common to all mammals, is described as a sudden involuntary movement of the body evoked by all kinds of sudden and unexpected stimulus. Startle syndromes are heterogeneous groups of disorders with abnormal and exaggerated responses to startling events, including hyperekplexia, stimulus-induced disorders, and neuropsychiatric startle syndromes. Hyperekplexia can be attributed to a genetic, idiopathic, or symptomatic cause. Excluding secondary factors, hereditary hyperekplexia, a rare neurogenetic disorder with highly genetic heterogeneity, is characterized by neonatal hypertonia, exaggerated startle response provoked by the sudden external stimuli, and followed by a short period of general stiffness. It mainly arises from defects of inhibitory glycinergic neurotransmission. GLRA1 is the major pathogenic gene of hereditary hyperekplexia, along with many other genes involved in the function of glycinergic inhibitory synapses. While about 40% of patients remain negative genetic findings. Clonazepam, which can specifically upgrade the GABARA1 chloride channels, is the main and most effective administration for hereditary hyperekplexia patients. In this review, with the aim at enhancing the recognition and prompting potential treatment for hyperekplexia, we focused on discussing the advances in hereditary hyperekplexia genetics and the expound progress in pathogenic mechanisms of the glycinergic-synapse-related pathway and then followed by a brief overview of other common startle syndromes.
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Affiliation(s)
- Fei-Xia Zhan
- Department of Neurology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai, 200233, China
| | - Shi-Ge Wang
- Department of Neurology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai, 200233, China
| | - Li Cao
- Department of Neurology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai, 200233, China.
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Abstract
Movement disorders presenting in childhood include tics, dystonia, chorea, tremor, stereotypy, myoclonus, and parkinsonism, each of which can be part of various clinical syndromes with distinct etiologies. Some of these conditions are benign and require only reassurance; others are bothersome and require treatment, or may be clues that herald underlying pathology. Answers lie in the inherent characteristics of the movements themselves, together with the clinical context provided in the history obtained by the examiner. The aim of this review is to present an overview of the categories of involuntary movements, along with examples of common acquired and genetic causes, and an approach to history-taking, examination, and treatment.
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Affiliation(s)
- Joanna Blackburn
- Division of Child Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern Feinberg School of Medicine, Chicago, IL, United States
| | - Mered Parnes
- Pediatric Movement Disorders Clinic, Section of Pediatric Neurology and Developmental Neuroscience, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, United States.
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Saini AG, Pandey S. Hyperekplexia and other startle syndromes. J Neurol Sci 2020; 416:117051. [PMID: 32721683 DOI: 10.1016/j.jns.2020.117051] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/01/2020] [Accepted: 07/16/2020] [Indexed: 11/18/2022]
Abstract
Abnormal startle syndromes are classified into hyperekplexia, stimulus-induced, and neuropsychiatric startle syndromes. Hyperekplexia is attributed to a genetic, idiopathic, or symptomatic cause. Hereditary hyperekplexia is a treatable neurogenetic disorder. In patients with a hyperactive startle response, the first step is to characterize the extent and associations of 'response.' Secondary or symptomatic causes are particularly important in children, as they provide useful clinical clues to an underlying neurodevelopmental or neurodegenerative disorders. Particular attention should be given to any neonate or infant with generalized or episodic stiffness, drug-refractory seizures, recurrent apnea, stimulus-sensitive behavioral states, or sudden infant death syndrome. Eliciting a non-habituating head-retraction reflex to repeated nose tapping should be a part of routine examination of all new-borns. Vigevano maneuver should be taught to all families and health-care workers as an emergency rescue measure. The onset of excessive startle after infancy should direct investigations for an acquired cause such as brainstem injury, antibodies against glycine receptors, and neurodegeneration. Finally, one should not forget to evaluate unexplained cases of abnormal gait and frequent falls in adults for underlying undiagnosed startle syndromes. Oral clonazepam is an effective therapy besides behavioral and safety interventions for hereditary cases. The outcomes in genetic cases are good overall.
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Affiliation(s)
- Arushi Gahlot Saini
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Sanjay Pandey
- Department of Neurology, Govind Ballabh Pant Institute of Postgraduate medical education and research, JLN Marg, New Delhi 110002, India.
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10
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Hakeem H, Khurshid R, Siddiqui F, Bhatti DE. Approach to exaggerated startle reflex: a case of hyperekplexia minor. BMJ Case Rep 2020; 13:13/4/e232370. [PMID: 32332042 DOI: 10.1136/bcr-2019-232370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A broad set of conditions may present with an exaggerated startle reflex in clinics. This, combined with the overall rarity of these disorders, may pose diagnostic uncertainty in the mind of the treating physician. Herein, we report a case of a patient who presented to us with the complaint of exaggerated startle reflex and outline a simple approach towards characterisation of these disorders.
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Affiliation(s)
- Haris Hakeem
- Neurology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Ramsha Khurshid
- Neurophysiology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Fowzia Siddiqui
- Neurology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Danish Ejaz Bhatti
- Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA
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11
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Zhan F, Zhang C, Wang S, Zhu Z, Chen G, Zhao M, Cao L. Excessive Startle with Novel GLRA1 Mutations in 4 Chinese Patients and a Literature Review of GLRA1-Related Hyperekplexia. J Clin Neurol 2020; 16:230-236. [PMID: 32319239 PMCID: PMC7174104 DOI: 10.3988/jcn.2020.16.2.230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 11/17/2022] Open
Abstract
Background and Purpose Hyperekplexia (HPX), a rare neurogenetic disorder, is classically characterized by neonatal hypertonia, exaggerated startle response provoked by the sudden external stimuli and followed by a shortly general stiffness. Glycine receptor alpha 1 (GLRA1) is the major pathogenic gene of the disease. We described the clinical manifestations of genetically confirmed HPX patients and made a literature review of GLRA1-related HPX to improve the early recognition and prompt the management of the disorder. Methods Extensive clinical evaluations were analyzed in 4 Chinese HPX patients from two unrelated families. Next generation sequencing was conducted in the probands. Sanger sequence and segregation analysis were applied to confirm the findings. Results All four patients including 3 males and 1 female presented with excessive startle reflex, a cautious gait and recurrent falls. Moreover, startle episodes were dramatically improved with the treatment of clonazepam in all cases. Exome sequencing revealed 2 homozygous GLRA1 mutations in the patients. The mutation c.1286T>A p.I429N has been previously reported, while c.754delC p.L252* is novel. Conclusions HPX is a treatable disease, and clonazepam is the drug of choice. By studying and reviewing the disorder, we summarized the phenotype, expanded the genotype spectrum, and discussed the possible pathogenic mechanisms to enhance the understanding and recognition of the disease. Early awareness of the disease is crucial to the prompt and proper administration, as well as the genetic counseling.
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Affiliation(s)
- Feixia Zhan
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chao Zhang
- Department of Neurology, Suzhou Hospital Affiliated to Anhui Medical University, Suzhou, China
| | - Shige Wang
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zeyu Zhu
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guang Chen
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mingliang Zhao
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Cao
- Department of Neurology, RuiJin Hospital & RuiJin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Hegazy NH, Breitinger HG, Breitinger U. Kavalactones from Kava (Piper methysticum) root extract as modulators of recombinant human glycine receptors. Biol Chem 2020; 400:1205-1215. [PMID: 31141476 DOI: 10.1515/hsz-2019-0112] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/17/2019] [Indexed: 02/07/2023]
Abstract
Roots of kava (Piper methysticum) plant are used in almost all Pacific Ocean cultures to prepare a drink with sedative, anesthetic and euphoric properties. One of the main active ingredients of the extract are kava lactones. Here, kava root CO2 extract and three kavalactones, DL-kavain, dihydrokavain and yangonin (isolated from whole extract by column chromatography) were tested for their inhibitory action on recombinant homomeric human α1 glycine receptors expressed in HEK293 cells. Kava CO2 root extract, as well as the individual components DL-kavain, dihydrokavain and yangonin inhibited glycine receptor activity in a dose-dependent manner. DL-kavain was the most potent inhibitor (IC50 = 0.077 ± 0.002 mm), followed by yangonin (IC50 = 0.31 ± 0.04 mm) and dihydrokavain (IC50 = 3.23 ± 0.10 mm) which were 4- and 40-fold less active than DL-kavain, respectively. Application of kava root extract did not reduce maximum currents, but increased EC50 of glycine. Simultaneous application of kava extract and strychnine showed additive inhibition, suggesting that binding of kavalactones and strychnine on the receptor is mutually exclusive. Overall, kavalactones exert a moderate inhibitory effect on the human α1 glycine receptor with DL-kavain being the most potent constituent.
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Affiliation(s)
- Nada Hany Hegazy
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Hans-Georg Breitinger
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
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Zou G, Xia J, Han Q, Liu D, Xiong W. The synthetic cannabinoid dehydroxylcannabidiol restores the function of a major GABA A receptor isoform in a cell model of hyperekplexia. J Biol Chem 2020; 295:138-145. [PMID: 31757808 PMCID: PMC6952599 DOI: 10.1074/jbc.ra119.011221] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/21/2019] [Indexed: 11/06/2022] Open
Abstract
The functions of the glycine receptor (GlyR) and GABAA receptor (GABAAR) are both impaired in hyperekplexia, a neurological disorder usually caused by GlyR mutations. Although emerging evidence indicates that cannabinoids can directly restore normal GlyR function, whether they affect GABAAR in hyperekplexia remains unknown. Here we show that dehydroxylcannabidiol (DH-CBD), a synthetic nonpsychoactive cannabinoid, restores the GABA- and glycine-activated currents (IGABA and IGly , respectively) in HEK293 cells coexpressing a major GABAAR isoform (α1β2γ2) and GlyRα1 carrying a human hyperekplexia-associated mutation (GlyRα1R271Q). Using coimmunoprecipitation and FRET assays, we found that DH-CBD disrupts the protein interaction between GABAAR and GlyRα1R271Q Furthermore, a point mutation of GlyRα1, changing Ser-296 to Ala-296, which is critical for cannabinoid binding on GlyR, significantly blocked DH-CBD-induced restoration of IGABA and IGly currents. This S296A substitution also considerably attenuated DH-CBD-induced disruption of the interaction between GlyRα1R271Q and GABAAR. These findings suggest that, because it restores the functions of both GlyRα1 and GABAAR, DH-CBD may represent a potentially valuable candidate drug to manage hyperekplexia.
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Affiliation(s)
- Guichang Zou
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of the University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Jing Xia
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of the University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Qianqian Han
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Dan Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Wei Xiong
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of the University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
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A Preschooler Girl With Hyperekplexia Treated With Escitalopram. Clin Neuropharmacol 2019; 42:217. [PMID: 31725477 DOI: 10.1097/wnf.0000000000000365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Vuilleumier PH, Fritsche R, Schliessbach J, Schmitt B, Arendt-Nielsen L, Zeilhofer HU, Curatolo M. Mutations affecting glycinergic neurotransmission in hyperekplexia increase pain sensitivity. Brain 2019; 141:63-71. [PMID: 29149236 DOI: 10.1093/brain/awx289] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 09/19/2017] [Indexed: 11/14/2022] Open
Abstract
See Dickenson (doi:10.1093/brain/awx334) for a scientific commentary on this article.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. Seven patients with genetically and clinically confirmed hyperekplexia were compared to 14 healthy age- and sex-matched controls. The following quantitative sensory tests were performed: pressure pain detection threshold (primary outcome), ice water tolerance, single and repeated electrical pain detection thresholds, nociceptive withdrawal reflex threshold, and conditioned pain modulation. Statistical analysis was performed using linear mixed models. Hyperekplexia patients displayed lower pain thresholds than healthy controls for all of the quantitative sensory tests [mean (standard deviation)]: pressure pain detection threshold [273 (170) versus 475 (115) kPa, P = 0.003], ice water tolerance [49.2 (36.5) versus 85.7 (35.0) s, P = 0.015], electrical single pain detection threshold [5.42 (2.64) versus 7.47 (2.62) mA, P = 0.012], electrical repeated pain detection threshold [3.76 (1.41) versus 5.8 (1.73) mA, P = 0.003], and nociceptive withdrawal reflex [7.42 (3.63) versus 14.1 (6.9) mA, P = 0.015]. Conditioned pain modulation was significantly reduced in hyperekplexia [increase to baseline: 53.2 (63.7) versus 105 (57) kPa, P = 0.030]. Our data demonstrate increased pain sensitivity and impaired central pain modulation in hyperekplexia patients, supporting the importance of glycinergic neurotransmission for central pain modulation in humans.
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Affiliation(s)
- Pascal Henri Vuilleumier
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, University of Bern, Switzerland
| | - Raphael Fritsche
- Department of Ophthalmology, Canton Hospital of Lucerne, Switzerland
| | - Jürg Schliessbach
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, University of Bern, Switzerland
| | - Bernhard Schmitt
- Department of Child Neurology, Children's Hospital, University of Zurich, Switzerland
| | - Lars Arendt-Nielsen
- Center for Sensory-Motor Interaction, School of Medicine, University of Aalborg, Denmark
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, and Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
| | - Michele Curatolo
- Center for Sensory-Motor Interaction, School of Medicine, University of Aalborg, Denmark.,Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, USA
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Current Overview of Neonatal Convulsions. MEDICAL BULLETIN OF SISLI ETFAL HOSPITAL 2019; 53:1-6. [PMID: 33536818 PMCID: PMC7847733 DOI: 10.14744/semb.2018.22844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 12/06/2018] [Indexed: 11/30/2022]
Abstract
Neonatal convulsions are one of the most common emergency neurological events in the early period after birth. The frequency has been reported to be 1.5 to 3 in 1000 live births. It has been established that the convulsion threshold is lower in infants due to immature neonatal neurons and differences in neurotransmitters. Hypoxic ischemic encephalopathy is the most common etiology in neonatal convulsions. Other causes vary, and may be related to the level of development of the country. Convulsions are classified into 4 different types according to the clinical findings. The most common is the subtle (undefined) type of seizure; the other types are defined as clonic, tonic, and myoclonic seizures. Non-epileptic paroxysmal movements frequently seen in the neonatal period, should not be confused with seizures. The most common non-epileptic paroxysmal movements are jitteriness, benign neonatal sleep myoclonus, and hyperekplexia. A newborn that experiences convulsions should be hospitalized and monitored with continuous video electroencephalogram, if possible. If an initial rapid evaluation detects an acute metabolic disorder, treatment is provided, and, if warranted, it will be followed by a plan for further treatment with anticonvulsant drugs. Phenobarbital is still currently recommended as first-line therapy, though there are studies of other anticonvulsant drugs. Levetiracetam and phenytoin are commonly used as second-step anticonvulsant drugs. The aim of treatment should be not only to stop acute symptomatic seizures, but also to reduce the risk of brain damage and to minimize the possible negative effects of epilepsy and neurological deficits.
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Clinical features and genetic analysis of two siblings with startle disease in an Italian family: a case report. BMC MEDICAL GENETICS 2019; 20:40. [PMID: 30866851 PMCID: PMC6417078 DOI: 10.1186/s12881-019-0779-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 03/06/2019] [Indexed: 12/03/2022]
Abstract
Background Hyperekplexia also known as Startle disease is a rare neuromotor hereditary disorder characterized by exaggerated startle responses to unexpected auditory, tactile, and visual stimuli and generalized muscle stiffness, which both gradually subside during the first months of life. Although the diagnosis of Hyperekplexia is based on clinical findings, pathogenic variants in five genes have been reported to cause Hyperekplexia, of which GLRA1 accounts for about 80% of cases. Dominant and recessive mutations have been identified in GLRA1 gene as pathogenic variants in many individuals with the familial form of Hyperekplexia and occasionally in simplex cases. Case presentation In the present study, we describe clinical and genetic features of two Italian siblings, one with the major and one with the minor form of the disease. DNA samples from the probands and their parents were performed by NGS approach and validated by Sanger sequencing. The analysis of the GLRA1 gene revealed, in both probands, compound heterozygous mutations: c.895C > T or p.R299X inherited from the mother and c.587C > A or p.D98E inherited from the father. Conclusions Until now, these two identified mutations in GLRA1 have not been reported before as compound mutations. What clearly emerges within our study is the clinical heterogeneity in the same family. In fact, even though in the same pedigree, the affected mother showed only mild startle responses to unexpected noise stimuli, which might be explained by variable expressivity, while the father, showed no clear signs of symptomatology, which might be explained by non-penetrance. Finally, the two brothers have different form of the disease, even if the compound heterozygous mutations in GLRA1 are the same, showing that the same mutation in GLRA1 could have different phenotypic expressions and suggesting an underling mechanism of variable expressivity.
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Thau E, Whyte H. A newborn infant with hypertonic episodes. Paediatr Child Health 2019; 24:3-4. [DOI: 10.1093/pch/pxy041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Elana Thau
- The Hospital For Sick Children - Paediatric Emergency Medicine, Toronto, Ontario
| | - Hilary Whyte
- The Hospital For Sick Children – Neonatology, Toronto, Ontario
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Involvement of glycine receptor α1 subunits in cannabinoid-induced analgesia. Neuropharmacology 2018; 133:224-232. [PMID: 29407767 DOI: 10.1016/j.neuropharm.2018.01.041] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 01/24/2018] [Accepted: 01/29/2018] [Indexed: 12/12/2022]
Abstract
Some cannabinoids have been shown to suppress chronic pain by targeting glycine receptors (GlyRs). Although cannabinoid potentiation of α3 GlyRs is thought to contribute to cannabinoid-induced analgesia, the role of cannabinoid potentiation of α1 GlyRs in cannabinoid suppression of chronic pain remains unclear. Here we report that dehydroxylcannabidiol (DH-CBD), a nonpsychoactive cannabinoid, significantly suppresses chronic inflammatory pain caused by noxious heat stimulation. This effect may involve spinal α1 GlyRs since the expression level of α1 subunits in the spinal cord is positively correlated with CFA-induced inflammatory pain and the GlyRs antagonist strychnine blocks the DH-CBD-induced analgesia. A point-mutation of S296A in TM3 of α1 GlyRs significantly inhibits DH-CBD potentiation of glycine currents (IGly) in HEK-293 cells and neurons in lamina I-II of spinal cord slices. To explore the in vivo consequence of DH-CBD potentiation of α1 GlyRs, we generated a GlyRα1S296A knock-in mouse line. We observed that DH-CBD-induced potentiation of IGly and analgesia for inflammatory pain was absent in GlyRα1S296A knock-in mice. These findings suggest that spinal α1 GlyR is a potential target for cannabinoid analgesia in chronic inflammatory pain.
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Yang Z, Sun G, Yao F, Tao D, Zhu B. A novel compound mutation in GLRA1 cause hyperekplexia in a Chinese boy- a case report and review of the literature. BMC MEDICAL GENETICS 2017; 18:110. [PMID: 28985719 PMCID: PMC5631533 DOI: 10.1186/s12881-017-0476-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/03/2017] [Indexed: 11/10/2022]
Abstract
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. We also review and analyse all reported GLRA1 mutations. The proband had a compound heterozygous GLRA1 mutation that comprised 2 novel GLRA1 missense mutations, C.569C > T (p.T190 M) from the mother and C.1270G > A (p.D424N) from the father. SIFT, Polyphen-2 and MutationTaster analysis identified the mutations as disease-causing, but the parents had no signs of hyperekplexia. The p.T190 M mutation is located in the ECD, while p.D424N is located in TM4. Conclusions Our findings contribute to a growing list GLRA1 mutations associated with hyperekplexia and provide new insights into correlations between phenotype and GLRA1 mutations. Some recessive mutations can induce hyperekplexia in combination with other recessive GLRA1 mutations. Mutations in the ECD, TM1, TM1-TM2 loop, TM3, TM3-TM4 loop and TM4 are more often recessive and part of a compound mutation, while those in TM2 and the TM2-TM3 loop are more likely to be dominant hereditary mutations. Electronic supplementary material The online version of this article (10.1186/s12881-017-0476-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhiliang Yang
- Department of Pediatrics, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China.
| | - Guilian Sun
- Department of Pediatrics, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Fang Yao
- Department of Pediatrics, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Dongying Tao
- Department of Pediatrics, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Binlu Zhu
- Department of Pediatrics, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
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Russo SP, Fossati B, Toffetti M, Lanzone J, Cardani R, Meola G. Clinical Reasoning: A 35-year-old woman with hyperstartling, stiffness, and accidental falls: A startling diagnosis. Neurology 2017; 88:e38-e41. [PMID: 28138086 DOI: 10.1212/wnl.0000000000003567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Silvia Paola Russo
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy.
| | - Barbara Fossati
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy
| | - Mauro Toffetti
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy
| | - Jacopo Lanzone
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy
| | - Rosanna Cardani
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy
| | - Giovanni Meola
- From the Departments of Biomedical Sciences for Health (S.P.R., M.T., J.L., G.M.) and Neurology (S.P.R., M.T., J.L., G.M.), University of Milan; and the Departments of Neurology (B.F., G.M.) and Muscle Histopathology and Molecular Biology (R.C.), IRCCS Policlinico S. Donato, S. Donato Milanese, Milan, Italy
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Lee Y, Kim NY, Hong S, Chung SJ, Jeong SH, Lee PH, Sohn YH. Familiar Hyperekplexia, a Potential Cause of Cautious Gait: A New Korean Case and a Systematic Review of Phenotypes. J Mov Disord 2016; 10:53-58. [PMID: 28122427 PMCID: PMC5288664 DOI: 10.14802/jmd.16044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/03/2016] [Accepted: 11/04/2016] [Indexed: 11/24/2022] Open
Abstract
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. Clonazepam is an effective medical treatment for hyperekplexia. Here, we report genetically confirmed familial hyperekplexia patients presenting early adult cautious gait. Additionally, we review clinical features, mode of inheritance, ethnicity and the types and locations of mutations of previously reported hyperekplexia cases with a GLRA1 gene mutation.
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Affiliation(s)
- Yoonju Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Nan Young Kim
- Hallym Institute of Translational Genomics and Bioinformatics, Hallym University College of Medicine, Anyang, Korea
| | - Sangkyoon Hong
- Hallym Institute of Translational Genomics and Bioinformatics, Hallym University College of Medicine, Anyang, Korea
| | - Su Jin Chung
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Seong Ho Jeong
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Phil Hyu Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Young H Sohn
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
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23
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Facini C, Spagnoli C, Pisani F. Epileptic and non-epileptic paroxysmal motor phenomena in newborns. J Matern Fetal Neonatal Med 2016; 29:3652-9. [DOI: 10.3109/14767058.2016.1140735] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Carlotta Facini
- Child Neuropsychiatry Unit, Neuroscience Department, University of Parma, Parma, Italy
| | - Carlotta Spagnoli
- Child Neuropsychiatry Unit, Neuroscience Department, University of Parma, Parma, Italy
| | - Francesco Pisani
- Child Neuropsychiatry Unit, Neuroscience Department, University of Parma, Parma, Italy
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24
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Spillane J, Kullmann DM, Hanna MG. Genetic neurological channelopathies: molecular genetics and clinical phenotypes. J Neurol Neurosurg Psychiatry 2016; 87:37-48. [PMID: 26558925 PMCID: PMC4717447 DOI: 10.1136/jnnp-2015-311233] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/13/2015] [Indexed: 01/08/2023]
Abstract
Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.
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Affiliation(s)
- J Spillane
- Royal Free Hospital Foundation Trust London, London, UK MRC Centre for Neuromuscular Disease, UCL, London, UK
| | - D M Kullmann
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
| | - M G Hanna
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
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25
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Paroxysmal nonepileptic motor phenomena in newborn. Brain Dev 2015; 37:833-9. [PMID: 25687201 DOI: 10.1016/j.braindev.2015.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 01/18/2015] [Accepted: 01/19/2015] [Indexed: 01/28/2023]
Abstract
INTRODUCTION Understanding the pathophysiological meaning of paroxysmal nonepileptic motor phenomena in newborns represents a challenge for the clinicians of the Neonatal Intensive Care Unit. METHODS This paper provides an extensive review of the most frequent paroxysmal nonepileptic motor phenomena in newborns, in order to improve the knowledge about this sub-topic of the neonatal pathology and to guide the diagnostic-therapeutic approach. RESULTS The correct identification of an epileptic form, among different motor phenomena, which may clinically mimic seizures, is essential for a correct management, avoiding overtreatment. However, it is likewise important to know and to be able to identify other rare neurological conditions, such as hyperekplexia, spinal muscular atrophy, acute bilirubin encephalopathy, that could make a first appearance with paroxysmal motor manifestations, needing specific diagnostic work-up and treatment. CONCLUSIONS These clinical events should not be underestimated because, even if many times they are physiological and age-related, sometimes they could be the visible signs of an underlying epileptic or nonepileptic neurological disease.
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26
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Chau A, Roitfarb M, Carabuena JM, Camann W. Anesthetic Management of a Parturient with Hyperekplexia. ACTA ACUST UNITED AC 2015; 4:103-6. [DOI: 10.1213/xaa.0000000000000135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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GAD65/GAD67 double knockout mice exhibit intermediate severity in both cleft palate and omphalocele compared with GAD67 knockout and VGAT knockout mice. Neuroscience 2015; 288:86-93. [DOI: 10.1016/j.neuroscience.2014.12.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/11/2014] [Accepted: 12/13/2014] [Indexed: 12/24/2022]
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Abstract
Hyperekplexia is a rare disorder caused by autosomal dominant or recessive modes of inheritance and characterized by episodes of exaggerated startle. Five causative genes have been identified to date. The syndrome has been recognized for decades and due to its rarity, the literature contains mostly descriptive reports, many early studies lacking molecular genetic diagnoses. A spectrum of clinical severity exists. Severe cases can lead to neonatal cardiac arrest and death during an episode, an outcome prevented by early diagnosis and clinical vigilance. Large treatment studies are not feasible, so therapeutic measures continue to be empiric. A marked response to clonazepam is often reported but refractory cases exist. Herein we report the clinical course and treatment response of a severely affected infant homozygous for an SLC6A5 nonsense mutation and review the literature summarizing the history and genetic understanding of the disease as well as the described comorbidities and treatment options.
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29
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Wilson GN. Exome analysis of connective tissue dysplasia: death and rebirth of clinical genetics? Am J Med Genet A 2014; 164A:1209-12. [PMID: 24664531 DOI: 10.1002/ajmg.a.36463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/06/2013] [Indexed: 11/08/2022]
Abstract
Exome results are reported for two patients with connective tissue dysplasia, one refining a clinical diagnosis of Ehlers-Danlos to Marfan syndrome, the other suggesting arthrogryposis derived from maternofetal Stickler syndrome. Patient 1 had mutations in transthyretin (TTR), fibrillin (FBN1), and a calcium channel (CACNA1A) gene suggesting diagnoses of transthyretin amyloidosis, Marfan syndrome, and familial hemiplegic migraines, respectively. Patient 2 presented with arthrogryposis that was correlated with his mother's habitus and arthritis once COL2A1 mutations suggestive of Stickler syndrome were defined. Although DNA results often defy prediction by the best of clinicians, these patients illustrate needs for ongoing clinical scholarship (e.g., to delineate guidelines for management of mutations like that for hyperekplexia in Patient 2) and for interpretation of polygenic change that is optimized by clinical genetic/syndromology experience (e.g., suggesting acetazolamide therapy for Patient 1 and explaining arthrogryposis in Patient 2).
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Affiliation(s)
- Golder N Wilson
- Departments of Pediatrics, Obstetrics and Gynecology, Texas Tech University Health Science Centers, Amarillo and Lubbock (Pediatrics), KinderGenome Pediatric Genetics, Dallas, Texas
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30
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Bode A, Lynch JW. The impact of human hyperekplexia mutations on glycine receptor structure and function. Mol Brain 2014; 7:2. [PMID: 24405574 PMCID: PMC3895786 DOI: 10.1186/1756-6606-7-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/07/2014] [Indexed: 01/11/2023] Open
Abstract
Hyperekplexia is a rare neurological disorder characterized by neonatal hypertonia, exaggerated startle responses to unexpected stimuli and a variable incidence of apnoea, intellectual disability and delays in speech acquisition. The majority of motor defects are successfully treated by clonazepam. Hyperekplexia is caused by hereditary mutations that disrupt the functioning of inhibitory glycinergic synapses in neuromotor pathways of the spinal cord and brainstem. The human glycine receptor α1 and β subunits, which predominate at these synapses, are the major targets of mutations. International genetic screening programs, that together have analysed several hundred probands, have recently generated a clear picture of genotype-phenotype correlations and the prevalence of different categories of hyperekplexia mutations. Focusing largely on this new information, this review seeks to summarise the effects of mutations on glycine receptor structure and function and how these functional alterations lead to hyperekplexia.
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Affiliation(s)
| | - Joseph W Lynch
- Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Queensland 4072, Australia.
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31
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Presynaptic glycine receptors as a potential therapeutic target for hyperekplexia disease. Nat Neurosci 2014; 17:232-9. [PMID: 24390226 DOI: 10.1038/nn.3615] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 12/03/2013] [Indexed: 11/08/2022]
Abstract
Although postsynaptic glycine receptors (GlyRs) as αβ heteromers attract considerable research attention, little is known about the role of presynaptic GlyRs, likely α homomers, in diseases. Here, we demonstrate that dehydroxylcannabidiol (DH-CBD), a nonpsychoactive cannabinoid, can rescue GlyR functional deficiency and exaggerated acoustic and tactile startle responses in mice bearing point mutations in α1 GlyRs that are responsible for a hereditary startle-hyperekplexia disease. The GlyRs expressed as α1 homomers either in HEK-293 cells or at presynaptic terminals of the calyceal synapses in the auditory brainstem are more vulnerable than heteromers to hyperekplexia mutation-induced impairment. Homomeric mutants are more sensitive to DH-CBD than are heteromers, suggesting presynaptic GlyRs as a primary target. Consistent with this idea, DH-CBD selectively rescues impaired presynaptic GlyR activity and diminished glycine release in the brainstem and spinal cord of hyperekplexic mutant mice. Thus, presynaptic α1 GlyRs emerge as a potential therapeutic target for dominant hyperekplexia disease and other diseases with GlyR deficiency.
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Hussain S, Prasad M, Rittey C, Desurkar A. A Startling Case of Neonatal Hyperekplexia Responsive to Levetiracetam: A New Alternative in Management? J Child Neurol 2013; 28:1513-1516. [PMID: 23034981 DOI: 10.1177/0883073812460094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The authors report a case of hyperekplexia presenting in the neonatal period resistant to clonazepam that responded subsequently to levetiracetam. Hyperekplexia is often misdiagnosed as epilepsy and can be difficult to manage with a particular concern over neonatal apnea and an increased risk of sudden infant death syndrome. The mainstay of therapy to date has been with clonazepam. The authors describe the salient features of their case, clinical diagnosis, and issues pertaining to management. The authors believe this is the first reported case of the use of levetiracetam for effectively treating hyperekplexia within the neonatal and infant period.
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Affiliation(s)
- Shanawaz Hussain
- 1Department of Pediatric Neurology, Sheffield Children's Hospital, Sheffield, UK
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Thomas RH, Chung SK, Wood SE, Cushion TD, Drew CJG, Hammond CL, Vanbellinghen JF, Mullins JGL, Rees MI. Genotype-phenotype correlations in hyperekplexia: apnoeas, learning difficulties and speech delay. Brain 2013; 136:3085-95. [DOI: 10.1093/brain/awt207] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Verrotti A, Matricardi S, Capovilla G, D’Egidio C, Cusmai R, Romeo A, Pruna D, Pavone P, Cappanera S, Granata T, Gobbi G, Striano P, Grosso S, Parisi P, Franzoni E, Striano S, Spalice A, Marino R, Vigevano F, Coppola G. Reflex myoclonic epilepsy in infancy: A multicenter clinical study. Epilepsy Res 2013; 103:237-44. [PMID: 22819072 DOI: 10.1016/j.eplepsyres.2012.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 06/26/2012] [Accepted: 07/03/2012] [Indexed: 11/25/2022]
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35
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Lee CG, Kwon MJ, Yu HJ, Nam SH, Lee J, Ki CS, Lee M. Clinical features and genetic analysis of children with hyperekplexia in Korea. J Child Neurol 2013; 28:90-4. [PMID: 22532536 DOI: 10.1177/0883073812441058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Hyperekplexia is a rare inherited neurologic disorder that is characterized by hypertonia and an exaggerated startle response to sudden external stimuli. Until now, 5 genes are known to be associated with hyperekplexia: GLRA1, SLC6A5, GLRB, GPHN, and ARHGEF9. In this report, we performed a clinical and genetic analysis of 4 Korean children with hyperekplexia. Two patients had typical clinical manifestations of hyperekplexia that initially were misdiagnosed as epilepsy. Direct sequencing of the GLRB and GLRA1 genes revealed 2 novel mutations, GLRB c.298-1G>A and c.1028C>T (p.S343F), in patient 1 and 1 novel mutation, GLRA1 c.895C>T (p.R299X), in patient 2. The other 2 familial cases, patients 3 and 4, exhibited startle responses, which appeared at the age of 1 year, and had global developmental delay. Those patients showed negative results for the 5 genes.
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Affiliation(s)
- Cha Gon Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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de la Roche J, Leuwer M, Krampfl K, Haeseler G, Dengler R, Buchholz V, Ahrens J. 4-Chloropropofol enhances chloride currents in human hyperekplexic and artificial mutated glycine receptors. BMC Neurol 2012; 12:104. [PMID: 23006332 PMCID: PMC3517478 DOI: 10.1186/1471-2377-12-104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 09/19/2012] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND The mammalian neurological disorder hereditary hyperekplexia can be attributed to various mutations of strychnine sensitive glycine receptors. The clinical symptoms of "startle disease" predominantly occur in the newborn leading to convulsive hypertonia and an exaggerated startle response to unexpected mild stimuli. Amongst others, point mutations R271Q and R271L in the α1-subunit of strychnine sensitive glycine receptors show reduced glycine sensitivity and cause the clinical symptoms of hyperekplexia.Halogenation has been shown to be a crucial structural determinant for the potency of a phenolic compound to positively modulate glycine receptor function.The aim of this in vitro study was to characterize the effects of 4-chloropropofol (4-chloro-2,6-dimethylphenol) at four glycine receptor mutations. METHODS Glycine receptor subunits were expressed in HEK 293 cells and experiments were performed using the whole-cell patch-clamp technique. RESULTS 4-chloropropofol exerted a positive allosteric modulatory effect in a low sub-nanomolar concentration range at the wild type receptor (EC50 value of 0.08 ± 0.02 nM) and in a micromolar concentration range at the mutations (1.3 ± 0.6 μM, 0.1 ± 0.2 μM, 6.0 ± 2.3 μM and 55 ± 28 μM for R271Q, L, K and S267I, respectively). CONCLUSIONS 4-chloropropofol might be an effective compound for the activation of mutated glycine receptors in experimental models of startle disease.
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Affiliation(s)
- Jeanne de la Roche
- Clinic for Anesthesia and Critical Care Medicine, OE 8050, Hannover Medical School, Carl-Neuberg-Str, 1, 30625, Hannover, Germany.
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Shan Q, Han L, Lynch JW. Function of hyperekplexia-causing α1R271Q/L glycine receptors is restored by shifting the affected residue out of the allosteric signalling pathway. Br J Pharmacol 2012; 165:2113-23. [PMID: 21955162 DOI: 10.1111/j.1476-5381.2011.01701.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Glycine receptor α1 subunit R271Q and R271L (α1R271Q/L) mutations cause the neuromotor disorder, hereditary hyperekplexia. Studies suggest that the 271 residue is located within the allosteric signalling pathway linking the agonist binding site to the channel gate. The present study aimed to investigate a possible mechanism for restoring the function of the α1R271Q/L glycine receptor. EXPERIMENTAL APPROACH A 12-amino-acid segment incorporating the 271 residue on the glycine receptor α1271Q/L subunit was replaced by the homologous segment from the glycine receptor β subunit (α1(Ch) 271Q/L). The function of the α1(Ch) 271Q/L glycine receptor was examined by whole-cell patch-clamp recording and voltage-clamp fluorometry techniques. KEY RESULTS The function of the α1(Ch) 271Q/L glycine receptor was restored to the level of the wild-type (WT) α1 glycine receptor. Moreover, in the α1(Ch) glycine receptor, in contrast to the α1 glycine receptor, the channel function was not sensitive to various substitutions of the 271 residue, and the conformational change in the vicinity of the 271 residue was uncoupled from the channel gating. CONCLUSIONS AND IMPLICATIONS The 271 residue is shifted out of the allosteric signalling pathway in the α1(Ch) glycine receptor. We propose that this mechanism provides a novel drug design strategy not only for glycine receptor α1R271Q/L-caused hereditary hyperekplexia, but also for any pathological condition that is caused by missense mutation- or covalent modification-induced disorders involving residues in allosteric signalling pathways. Such a strategy makes it possible to design an ideal drug, which only corrects the function of the mutant or modified protein without affecting the WT or naive protein.
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Affiliation(s)
- Qiang Shan
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia.
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Nussinov R. Allosteric modulators can restore function in an amino acid neurotransmitter receptor by slightly altering intra-molecular communication pathways. Br J Pharmacol 2012; 165:2110-2. [PMID: 22122331 PMCID: PMC3413848 DOI: 10.1111/j.1476-5381.2011.01793.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 11/08/2011] [Accepted: 11/16/2011] [Indexed: 11/30/2022] Open
Abstract
Mutations, even if not directly in the ligand binding sites of proteins, can lead to disease. In cell surface receptors, this can happen if they uncouple conformational changes that take place upon agonist (or antagonist) binding to the extracellular domain and the intracellular response. Uncoupling can take place by disrupting a major allosteric propagation pathway between the extra- and intracellular domains. Here I provide a mechanistic explanation: I first describe how propagation takes place; second, what can happen in the presence of a disease-related mutation which is distant from the binding site; and finally, how drugs may overcome this disruption and rescue function. The mutations in the glycine receptor α1 subunit (α1R271Q/L) which cause the neuromotor disorder hyperekplexia are on example of such allosteric mutations. In this issue of the BJP, Shan et al. show that normal function was restored to these mutant receptors by substitution of the segment which contained the mutated position, by a homologous one. An allosteric drug could mimic the effects of such substitution. Within this framework, I highlight the advantages of allosteric drugs and the challenges in their design.
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Affiliation(s)
- Ruth Nussinov
- Basic Research Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology ProgramNCI-Frederick, Frederick, MD, USA
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv UniversityTel Aviv, Israel
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Al-Futaisi AM, Al-Kindi MN, Al-Mawali AM, Koul RL, Al-Adawi S, Al-Yahyaee SA. Novel mutation of GLRA1 in Omani families with hyperekplexia and mild mental retardation. Pediatr Neurol 2012; 46:89-93. [PMID: 22264702 DOI: 10.1016/j.pediatrneurol.2011.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 11/22/2011] [Indexed: 11/24/2022]
Abstract
Hyperekplexia is characterized by neonatal hypertonia and exaggerated startle reflex in response to loud noise or tactile stimuli. Mutations in patients with hyperekplexia were evident in several genes encoding proteins involved in glycinergic neurotransmission, i.e., glycine receptor α and β subunits, collybistin, gephyrin, and glycine transporter 2. We clinically and genetically characterized two large, unrelated consanguineous families with hyperekplexia. Affected members of the two families manifested hyperekplexia with mild mental retardation. Patients exhibited a novel homozygote c.593G>C missense mutation in GLRA1, resulting in amino acid substitution p.W170S in the corresponding mature glycine receptor α1 subunit. This mutation was absent in 400 randomly selected chromosomes in the same population. In conclusion, a novel p.W170S mutation in the extracellular ligand binding domain of glycine receptor α1 subunit was detected in patients with hyperekplexia and mild mental retardation.
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Affiliation(s)
- Amna Mohammed Al-Futaisi
- Department of Child Health, Sultan Qaboos University Hospital, Sultan Qaboos University, Muscat, Oman
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Dreissen YE, Bakker MJ, Koelman JH, Tijssen MA. Exaggerated startle reactions. Clin Neurophysiol 2012; 123:34-44. [DOI: 10.1016/j.clinph.2011.09.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 08/31/2011] [Accepted: 09/03/2011] [Indexed: 11/15/2022]
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Abstract
Startle refers to a sudden involuntary movement of the body in response to a surprising and unexpected stimulus. It is a fast twitch of facial and body muscles evoked by a sudden and intense tactile, visual, or acoustic stimulus. While startle can be considered to be a protective function against injury, startle syndromes are abnormal responses to startling events, consisting of three heterogeneous groups of disorders. The first is hyperekplexia, characterized by brisk and generalized startle in response to trivial stimulation. The major form of hereditary hyperekplexia has a genetic basis, frequently due to mutations in the α1 subunit of the glycine receptor (GLRA1) on chromosome 5q. In the second group, normal startle induces complex but stereotyped motor and/or behavioral abnormalities lasting several seconds, termed as startle epilepsy. It usually occurs in the setting of severe brain damage, particularly perinatal hypoxia. The third group is characterized by nonhabituating hyperstartling, provoked by loud noises, sudden commands, or gestures. The intensity of startle response tends to increase with frequency of stimulation, which often leads to injury. Interestingly, its occurrence is restricted to certain social or ethnic groups in different parts of the world, such as jumping Frenchmen of Maine among Franco-Canadian lumberjack communities, and Latah in Southeast Asia. So far, no neurological abnormalities have been reported in association with these neuropsychiatric startle syndromes. In this chapter, the authors discuss the clinical presentation, physiology, and the neuronal basis of the normal human startle as well as different groups of abnormal startle syndromes. The aim is to provide an overview of hyperstartling with some diagnostic hints and the distinguishing features among these syndromes.
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Affiliation(s)
- Roongroj Bhidayasiri
- Chulalongkorn Comprehensive Movement Disorders Center, Chulalongkorn University Hospital, Bangkok, Thailand
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Saito K, Kakizaki T, Hayashi R, Nishimaru H, Furukawa T, Nakazato Y, Takamori S, Ebihara S, Uematsu M, Mishina M, Miyazaki JI, Yokoyama M, Konishi S, Inoue K, Fukuda A, Fukumoto M, Nakamura K, Obata K, Yanagawa Y. The physiological roles of vesicular GABA transporter during embryonic development: a study using knockout mice. Mol Brain 2010; 3:40. [PMID: 21190592 PMCID: PMC3023674 DOI: 10.1186/1756-6606-3-40] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 12/30/2010] [Indexed: 11/16/2022] Open
Abstract
Background The vesicular GABA transporter (VGAT) loads GABA and glycine from the neuronal cytoplasm into synaptic vesicles. To address functional importance of VGAT during embryonic development, we generated global VGAT knockout mice and analyzed them. Results VGAT knockouts at embryonic day (E) 18.5 exhibited substantial increases in overall GABA and glycine, but not glutamate, contents in the forebrain. Electrophysiological recordings from E17.5-18.5 spinal cord motoneurons demonstrated that VGAT knockouts presented no spontaneous inhibitory postsynaptic currents mediated by GABA and glycine. Histological examination of E18.5 knockout fetuses revealed reductions in the trapezius muscle, hepatic congestion and little alveolar spaces in the lung, indicating that the development of skeletal muscle, liver and lung in these mice was severely affected. Conclusion VGAT is fundamental for the GABA- and/or glycine-mediated transmission that supports embryonic development. VGAT knockout mice will be useful for further investigating the roles of VGAT in normal physiology and pathophysiologic processes.
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Affiliation(s)
- Kenzi Saito
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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Pérez-Sánchez S, Fernández-Recio M, López-Domínguez J, Sánchez-Sánchez V, Álvarez-López M, Izquierdo-Ayuso G. Ictus isquémico talámico: una etiología infrecuente del síndrome de sobresalto. Neurologia 2010; 25:138-40. [DOI: 10.1016/s0213-4853(10)70041-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Pérez-Sánchez S, Fernández-Recio M, López-Domínguez J, Sánchez-Sánchez V, Álvarez-López M, Izquierdo-Ayuso G. Thalamic ischaemic stroke: An uncommon aetiology of “startle syndrome”. NEUROLOGÍA (ENGLISH EDITION) 2010. [DOI: 10.1016/s2173-5808(10)70027-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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Jurkat-Rott K, Lerche H, Weber Y, Lehmann-Horn F. Hereditary channelopathies in neurology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 686:305-34. [PMID: 20824453 DOI: 10.1007/978-90-481-9485-8_18] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ion channelopathies are caused by malfunction or altered regulation of ion channel proteins due to hereditary or acquired protein changes. In neurology, main phenotypes include certain forms of epilepsy, ataxia, migraine, neuropathic pain, myotonia, and muscle weakness including myasthenia and periodic paralyses. The total prevalence of monogenic channelopathies in neurology is about 35:100,000. Susceptibility-related mutations further increase the relevance of channel genes in medicine considerably. As many disease mechanisms have been elucidated by functional characterization on the molecular level, the channelopathies are regarded as model disorders for pathogenesis and treatment of non-monogenic forms of epilepsy and migraine. As more than 35% of marketed drugs target ion channels, there is a high chance to identify compounds that counteract the effects of the mutations.
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Pearl PL. New treatment paradigms in neonatal metabolic epilepsies. J Inherit Metab Dis 2009; 32:204-13. [PMID: 19234868 DOI: 10.1007/s10545-009-1045-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 12/23/2008] [Accepted: 01/06/2009] [Indexed: 10/21/2022]
Abstract
Neonatal seizures represent a major challenge among the epilepsies vis-à-vis seizure classification, electroclinical correlation, inherent excitability of neocortex, ontogenic characteristics of neurotransmitter receptors, and responsiveness to standard antiepileptic drugs. Each of these factors renders neonatal seizures more difficult to treat, and therapy has been a vexing area for recent advances in this seizure category. Conversely, specific metabolic disorders have very special therapeutic considerations in the clinical setting of neonatal seizures which require a high index of clinical suspicion and rapid intervention for a successful outcome. The prototype is pyridoxine dependency, although pyridoxal 5'-phosphate dependency is a recently recognized but treatable neonatal epilepsy that deserves earmarked distinction. Clinicians must remain vigilant for these possibilities, including atypical cases where apparent seizure-free intervals may occur. Folinic acid-dependent seizures are allelic with pyridoxine dependency. Serine-dependent seizures and glucose transporter deficiency may present with neonatal seizures and have specific therapy. A vital potassium channel regulated by serum ATP/ADP ratios in the pancreas and brain may be mutated with a resultant neuroendocrinopathy characterized by development delay, epilepsy, and neonatal diabetes (DEND). This requires oral hypoglycaemic therapy, and not insulin, for neurological responsiveness. The startle syndrome of hyperekplexia, which mimics neonatal epilepsy, has been associated with laryngospasm and sudden death but is treated with benzodiazepines.
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Affiliation(s)
- P L Pearl
- Department of Neurology, Neuroscience Center of Excellence and Clinical Research Institute, Children's National Medical Center, George Washington University School of Medicine, Washington, DC, USA.
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Hermanns H, Muth-Selbach U, Williams R, Krug S, Lipfert P, Werdehausen R, Braun S, Bauer I. Differential effects of spinally applied glycine transporter inhibitors on nociception in a rat model of neuropathic pain. Neurosci Lett 2008; 445:214-9. [PMID: 18793697 DOI: 10.1016/j.neulet.2008.09.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 09/06/2008] [Accepted: 09/08/2008] [Indexed: 10/21/2022]
Abstract
Changes in glycinergic neurotransmission in the spinal cord dorsal horn are critically involved in the development of pathological pain. Since the concentration of glycine in the synaptic cleft is controlled by specialized proteins, the glycine transporters GlyT1 and GlyT2, manipulation of this system might have significant effects on nociception. In the present study, we investigated the effects of the spinally applied glycine transporter inhibitors ALX 5407 (GlyT1) and ALX 1393 (GlyT2) on nociceptive behavior in the chronic constriction injury model of neuropathic pain in male Wistar rats. After implementation of neuropathy, the animals were injected with three dosages of ALX 5407 and ALX 1393 (10, 50 and 100 microg) via an intrathecal catheter (n = 8 each). Subsequently, nociceptive behavior was evaluated regarding thermal hyperalgesia (Hargreaves method) and mechanical sensitization (von Frey filaments) over 240 min after application. Inhibition of GlyT1 by ALX 5407 had differential dose-dependent effects. While the highest and the lowest concentrations were antinociceptive, the medium dose evoked pronociceptive effects. The GlyT2 inhibitor ALX 1393 was only effective in the highest concentration at which it exerted significant antinociception. However, in the same dose, ALX 1393 caused remarkable side effects such as respiratory depression and motor deficits in three animals. Our findings indicate that inhibition of glycine transporters is capable of evoking significant effects on nociceptive behavior in neuropathic pain. Whether glycine transporter inhibitors have the capability to gain clinical relevance as analgesic compounds on the long run has to be elucidated in further investigations.
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Affiliation(s)
- Henning Hermanns
- Department of Anesthesiology, University Hospital Düsseldorf, Düsseldorf, Germany.
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Kang HC, Jeong You S, Jae Chey M, Sam Baik J, Kim JW, Ki CS. Identification of a de novo Lys304Gln mutation in the glycine receptor alpha-1 subunit gene in a Korean infant with hyperekplexia. Mov Disord 2008; 23:610-3. [PMID: 18175347 DOI: 10.1002/mds.21909] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Startle disease or hyperekplexia (STHE; MIM 149400) is a rare disorder that is characterized by marked muscular hypertonia in infancy and an exaggerated startle response to unexpected acoustic or tactile stimuli. Mutations in the gene encoding the alpha-1 subunit of the inhibitory glycine receptor (GLRA1) were reported as causes of STHE. Recently, we encountered a Korean male infant with generalized stiffness that was observed from the first 3 days of life. The abnormal startle response was evident from the fourth week of life, and he showed marked improvement in the startle response and muscle hypertonia after being administered phenobarbital and clonazepam. Direct sequencing analysis of the infant and his parents revealed a de novo variation (c.910A>C) in the GLRA1 gene, resulting in a novel Lys304Gln missense mutation.
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Affiliation(s)
- Hoon-Chul Kang
- Department of Pediatrics, Epilepsy Center, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea
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Garg R, Ramachandran R, Sharma P. Anaesthetic implications of hyperekplexia--'startle disease'. Anaesth Intensive Care 2008; 36:254-6. [PMID: 18361020 DOI: 10.1177/0310057x0803600217] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This report describes anaesthesia for consanguineous siblings with the rare genetic condition hyperekplexia. This condition is also known as 'stiff baby syndrome' or 'startle disease'. Hyperekplexia can present in major and minor forms and is caused by a mutation in chromosome 5 which results in a defect in the alpha-1 subunit of the inhibitory glycine receptors in the caudal pontine reticular formation leading to neuronal hyperexcitability. The patients present with a potentially life-threatening exaggerated startle reflex. Life-threatening spasms may be terminated by forced flexion of the head and legs towards the trunk. Anaesthesia management should avoid stimuli which trigger the reflex. Clonazepam and diazepam are used to prevent and control the spasms. Propofol and other agents with the ability to potentiate both GABA-ergic and glycinergic transmission may be appropriate choices for anaesthesia. Reaction to neuromuscular blockers may be unpredictable. Both our patients had relatively prolonged but otherwise uneventful recovery.
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Affiliation(s)
- R Garg
- Department ofAnaesthesia, All India Institute of Medical Sciences, Delhi, India
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Bernard G, Shevell MI. Channelopathies: a review. Pediatr Neurol 2008; 38:73-85. [PMID: 18206787 DOI: 10.1016/j.pediatrneurol.2007.09.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 07/05/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
Abstract
Channelopathies are a recently delineated, emerging group of neurologic disorders united by genetically determined defects in ion-channel function. These disorders are characterized by a prominent genetic and phenotypic heterogeneity that can make them challenging and bewildering to understand. This systematic review attempts to categorize these disorders according to their predominant clinical manifestations (i.e., myotonia, weakness, migraine, ataxia, epilepsy, and movement disorders) within the context of what is presently known about the molecular basis of recognized clinical syndromes. Areas of both genetic and phenotypic overlap are highlighted. The review is intended to assist clinicians in enhancing their diagnostic acumen and in targeting specific genetic tests.
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Affiliation(s)
- Genevieve Bernard
- Department of Neurology/Neurosurgery, McGill University, Montreal Children's Hospital-McGill University Health Center, Montreal, Quebec, Canada
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