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Mahesan A, Kamila G, Tiwari R, Das S, Sharma MC, Jauhari P, Chakrabarty B, Gulati S. Congenital Myasthenia Syndrome Due to a Novel DPAGT1 Gene Mutation - An Error of Glycosylation Masquerading as a Congenital Myopathy. Neurol India 2024; 72:175-177. [PMID: 38443029 DOI: 10.4103/neurol-india.neurol-india-d-23-00582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 12/25/2023] [Indexed: 03/07/2024]
Affiliation(s)
- Aakash Mahesan
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
| | - Gautam Kamila
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
| | - Richa Tiwari
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
| | - Sumanta Das
- Department of Pathology, AIIMS, New Delhi, India
| | | | - Prashant Jauhari
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
| | - Biswaroop Chakrabarty
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
| | - Sheffali Gulati
- Centre of Excellence and Advanced Research for Childhood Neurodevelopmental Disorders, Child Neurology Division, Department of Pediatrics, AIIMS, New Delhi, India
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Qaisar R. Targeting neuromuscular junction to treat neuromuscular disorders. Life Sci 2023; 333:122186. [PMID: 37858716 DOI: 10.1016/j.lfs.2023.122186] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/07/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023]
Abstract
The integrity and preservation of the neuromuscular junction (NMJ), the interface between the motor neuron and skeletal muscle, is critical for maintaining a healthy skeletal muscle. The structural and/or functional defects in the three cellular components of NMJ, namely the pre-synaptic terminal, synaptic cleft, and post-synaptic region, negatively affect skeletal muscle mass and/or strength. Therefore, NMJ repair appears to be an appropriate therapy for muscle disorders. Mouse models provide a detailed molecular characterization of various cellular components of NMJ with relevance to human diseases. This review discusses different molecular targets on the three cellular components of NMJ for treating muscle diseases. The potential effects of these therapies on NMJ morphology and motor performance, their therapeutic efficacy, and clinical relevance are discussed. Collectively, the available data supports targeting NMJ alone or as an adjunct therapy in treating muscle disorders. However, the potential impact of such interventions on human patients with muscle disorders requires further investigation.
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Affiliation(s)
- Rizwan Qaisar
- Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates; Space Medicine Research Group, Sharjah Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates; Cardiovascular Research Group, Sharjah Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates.
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Almatrafi AM, Alluqmani MM, Basit S. Homozygous Duplication in the CHRNE in a Family with Congenital Myasthenic Syndrome 4C: 18-Year Follow Up. Biomedicines 2023; 11:2983. [PMID: 38001983 PMCID: PMC10668953 DOI: 10.3390/biomedicines11112983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/29/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Congenital myasthenic syndromes (CMSs) are rare inherited diseases characterized by muscle weakness and fatigability on exertion resulting from defects in the neuromuscular junctions. Mutations in 32 genes have been reported as the underlying causes of CMS, with mutations in the cholinergic receptor nicotinic epsilon subunit (CHRNE) being the most common cause of the disease. Methodology and Materials: This study investigated a large consanguineous family with multiple individuals suffering from abnormal fatigue and muscle weakness in the ocular and limb regions. Moreover, the affected individuals were followed up for 18 years to observe the clinical course of the disease. RESULTS High-quality exome sequencing followed by bidirectional Sanger sequencing revealed a homozygous duplication variant (NM_000080.4: c.1220-8_1227dup) in the splice acceptor site of exon 11 of the CHRNE gene. This variant is predicted to cause frameshift and premature termination (p.Cys410ProfsTer51). Both parents had heterozygous duplication variants with no clinical symptoms. The personalized treatment of the affected individuals resulted in a marked improvement in the clinical symptoms. More than 80% of the disease symptoms in the affected individuals subsided after the use of pyridostigmine and salbutamol (4 mg). CONCLUSIONS This is the first report of long-term follow up of cases with homozygous insertion (c.1220-8_1227dup) in the CHRNE gene. Furthermore, this report expands the phenotypic symptoms associated with the CHRNE mutation.
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Affiliation(s)
- Ahmad M. Almatrafi
- Department of Biology, College of Science, Taibah University, Medina 42353, Saudi Arabia;
| | - Majed M. Alluqmani
- Department of Neurology, College of Medicine, Taibah University, Medina 42353, Saudi Arabia;
| | - Sulman Basit
- Department of Biochemistry and Molecular Medicine, College of Medicine, Taibah University, Medina 42353, Saudi Arabia
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Özsoy Ö, Cinleti T, Günay Ç, Sarıkaya Uzan G, Yeşilmen MC, Lochmüller H, Horvath R, Yiş U, Oktay Y, Hiz Kurul S. DPAGT1-CDG: Report of Two New Pediatric Patients and Brief Review of the Literature. Mol Syndromol 2023; 14:322-330. [PMID: 37766827 PMCID: PMC10521235 DOI: 10.1159/000529494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 01/27/2023] [Indexed: 09/29/2023] Open
Abstract
Introduction Congenital glycosylation disorders are multisystem diseases with heterogeneous clinical manifestations caused by defects in the synthesis of the glycan moiety of glycoproteins or glycolipids or the binding of glycans to proteins and lipids. DPAGT1 (UDP-GlcNAc: dolichol phosphate N-acetylglucosamine-1-phosphotransferase) is an initiating protein in the biosynthetic pathway of dolichol-linked oligosaccharides required for protein N-glycosylation. Pathogenic variants in DPAGT1 (UDP-GlcNAc: dolichol phosphate N-acetylglucosamine-1-phosphotransferase) gene cause a rare type of congenital glycosylation disorder called DPAGT1-CDG (formerly CDG-Ij) (OMIM #608093). It is a rare autosomal recessive disease or a milder version with congenital myasthenic syndrome known as DPAGT1-CMS. A severe disease course with hypotonia, cataracts, skeletal deformities, resistant epilepsy, intellectual disability, global developmental delay, premature death has been described in most patients with DPAGT1-CDG. Patient Presentation We describe two patients with variants in the DPAGT1 gene: an 8-month-old boy with a homozygous, missense DPAGT1:c.339T>G (p.Phe113Leu) novel variant and a 13-year-old female patient with compound heterozygous variants, DPAGT1:c.466C>T (p.Arg156Cys, R156C) and DPAGT1:c.161+5G>A. While the 8-month-old patient was diagnosed with congenital cataract at the age of 1 month, had dysmorphic findings, and epilepsy, clinical symptoms in the other patient appeared later but with more prominent muscle weakness, behavioral disorder, dysmorphic findings, and no epilepsy. Discussion Cholinesterase inhibitor therapy was found to be effective in patients against muscle weakness, supporting DPAGT1 deficiency as the underlying etiology. We started pyridostigmine treatment in our patient with more pronounced muscle weakness, and we saw its benefit. We aimed to present our patients diagnosed with DPAGT1-CDG due to different variants in the same gene and different clinical presentations, treatment and to compare them with other patients in the literature.
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Affiliation(s)
- Özlem Özsoy
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Tayfun Cinleti
- Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Çağatay Günay
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Gamze Sarıkaya Uzan
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Mehmet Can Yeşilmen
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Hanns Lochmüller
- CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Division of Neurology, Department of Medicine, The Ottawa Hospital, and Brain and Mind Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Uluç Yiş
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Yavuz Oktay
- Izmir Biomedicine and Genome Center, Dokuz Eylül University Health Campus, İzmir, Turkey
- Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, İzmir, Turkey
- Department of Medical Biology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Semra Hiz Kurul
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
- Izmir Biomedicine and Genome Center, Dokuz Eylül University Health Campus, İzmir, Turkey
- Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, İzmir, Turkey
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Cheli M, Brugnoni R, Gibertini S, Mantegazza R, Maggi L. Novel DPAGT1 Gene Mutation in Two Twins with Congenital Myasthenic Syndrome and a Review of the Literature. J Neuromuscul Dis 2023; 10:449-458. [PMID: 37005892 DOI: 10.3233/jnd-221675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Congenital myasthenic syndromes (CMS) are rare diseases caused by mutation in genes coding for proteins involved in neuromuscular junction structure and function. DPAGT1 gene mutations are a rare cause of CMS whose clinical evolution and pathophysiological mechanisms have not been clarified completely. We present the case of two twins displaying an infancy-onset predominant limb-girdle phenotype and carrying a novel DPAGT1 mutation associated with unusual histological and clinical findings. CMS can mimic paediatric and adult limb-girdle phenotype, hence neurophysiology plays a fundamental role in the differential diagnosis.
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Affiliation(s)
- Marta Cheli
- Neuroimmunology and Neuromuscular Disease Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Disease Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Sara Gibertini
- Neuroimmunology and Neuromuscular Disease Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Renato Mantegazza
- Neuroimmunology and Neuromuscular Disease Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disease Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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Hyde LF, Kong Y, Zhao L, Rao SR, Wang J, Stone L, Njaa A, Collin GB, Krebs MP, Chang B, Fliesler SJ, Nishina PM, Naggert JK. A Dpagt1 Missense Variant Causes Degenerative Retinopathy without Myasthenic Syndrome in Mice. Int J Mol Sci 2022; 23:12005. [PMID: 36233305 PMCID: PMC9570038 DOI: 10.3390/ijms231912005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/29/2022] [Accepted: 10/04/2022] [Indexed: 01/12/2023] Open
Abstract
Congenital disorders of glycosylation (CDG) are a heterogenous group of primarily autosomal recessive mendelian diseases caused by disruptions in the synthesis of lipid-linked oligosaccharides and their transfer to proteins. CDGs usually affect multiple organ systems and vary in presentation, even within families. There is currently no cure, and treatment is aimed at ameliorating symptoms and improving quality of life. Here, we describe a chemically induced mouse mutant, tvrm76, with early-onset photoreceptor degeneration. The recessive mutation was mapped to Chromosome 9 and associated with a missense mutation in the Dpagt1 gene encoding UDP-N-acetyl-D-glucosamine:dolichyl-phosphate N-acetyl-D-glucosaminephosphotransferase (EC 2.7.8.15). The mutation is predicted to cause a substitution of aspartic acid with glycine at residue 166 of DPAGT1. This represents the first viable animal model of a Dpagt1 mutation and a novel phenotype for a CDG. The increased expression of Ddit3, and elevated levels of HSPA5 (BiP) suggest the presence of early-onset endoplasmic reticulum (ER) stress. These changes were associated with the induction of photoreceptor apoptosis in tvrm76 retinas. Mutations in human DPAGT1 cause myasthenic syndrome-13 and severe forms of a congenital disorder of glycosylation Type Ij. In contrast, Dpagt1tvrm76 homozygous mice present with congenital photoreceptor degeneration without overt muscle or muscular junction involvement. Our results suggest the possibility of DPAGT1 mutations in human patients that present primarily with retinitis pigmentosa, with little or no muscle disease. Variants in DPAGT1 should be considered when evaluating cases of non-syndromic retinal degeneration.
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Affiliation(s)
| | - Yang Kong
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
| | - Lihong Zhao
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Research Service, VA Western New York Healthcare System, Buffalo, NY 14215, USA
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Lisa Stone
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Andrew Njaa
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - Mark P Krebs
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Research Service, VA Western New York Healthcare System, Buffalo, NY 14215, USA
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Estephan EP, Zambon AA, Thompson R, Polavarapu K, Jomaa D, Töpf A, Helito PVP, Heise CO, Moreno CAM, Silva AMS, Kouyoumdjian JA, Morita MDP, Reed UC, Lochmüller H, Zanoteli E. Congenital myasthenic syndrome: Correlation between clinical features and molecular diagnosis. Eur J Neurol 2021; 29:833-842. [PMID: 34749429 DOI: 10.1111/ene.15173] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/01/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis. METHODS Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis. RESULTS Seventy-nine patients (68 families) were included in the cohort: 48 in group A, 23 in group B and 8 in group C. Fifty-one were considered confirmed CMS (30 CHRNE, 5 RAPSN, 4 COL13A1, 3 DOK7, 3 COLQ, 2 GFPT1, 1 CHAT, 1 SCN4A, 1 GMPPB, 1 CHRNA1), 7 probable CMS, 5 non-CMS and 16 unsolved. The chance of a confirmed molecular diagnosis of CMS was significantly higher for group A and lower for group C. Some individual clinical features, alterations on biopsy and electrophysiology enhanced specificity for CMS. Muscle imaging showed at least mild alterations in the majority of confirmed cases, with preferential involvement of soleus, especially in CHRNE CMS. CONCLUSIONS Stricter clinical criteria increase the chance of confirming a CMS diagnosis, but may lose sensitivity, especially for some specific genes.
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Affiliation(s)
- Eduardo P Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - Antonio A Zambon
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Danny Jomaa
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Queen's University School of Medicine, Kingston, ON, Canada
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, University of Newcastle, Newcastle upon Tyne, UK
| | - Paulo V P Helito
- Department of Radiology, Hospital das Clínicas (HCFMUSP), Instituto de Ortopedia (IOT), Sao Paulo, Brazil
| | - Carlos O Heise
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Cristiane A M Moreno
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - André M S Silva
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Joao A Kouyoumdjian
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Maria da Penha Morita
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Umbertina C Reed
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada.,Department of Medicine, Ottawa Research Institute, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, University Medical Center Freiburg, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
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Etzel JD, Neely KA, Ely AL. Congenital glycosylation disorder: a novel presentation of coexisting anterior and posterior segment pathology and its implications in pediatric cataract management. J AAPOS 2019; 23:297-300. [PMID: 31153949 DOI: 10.1016/j.jaapos.2019.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/17/2019] [Accepted: 05/24/2019] [Indexed: 10/26/2022]
Abstract
We report a case exhibiting the coexistence of anterior and posterior segment pathology in the same eye secondary to a congenital disorder of glycosylation resulting from a DPAGT1 gene mutation. This case details a novel gene mutation in a male infant found to have bilateral congenital cataracts, removed at 6 and 7 weeks of life, only to uncover bilateral retinal and optic atrophy. Our report highlights issues of surgical timing for syndrome-related pediatric cataracts, given the risks related to secondary glaucoma versus deprivation amblyopia, in an infant born with both cataracts and vision-limiting posterior segment pathology.
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Affiliation(s)
- Justin D Etzel
- Department of Ophthalmology, Krieger Eye Institute at Sinai Hospital, Baltimore, Maryland
| | - Kimberly A Neely
- Department of Ophthalmology, Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Amanda L Ely
- Department of Ophthalmology, Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania.
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Abstract
Introduction: The present status of amifampridine (AFP) for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) is reviewed. Areas covered: All relevant literature identified through a PubMed search under treatment of LEMS, aminopyridine, and amifampridine are reviewed. An expert opinion on AFP was formulated. Expert opinion: AFPs, 3,4-DAP and 3,4-DAPP, are the most studied drugs in neuromuscular diseases. Randomized and non-randomized studies showed the most effective drug as symptomatic medication for LEMS. AFPs are safe and tolerable. Thus, AFPs should be the drug of choice for the symptomatic treatment in LEMS. As long as the daily dose is less than 80 mg a day, there is no concern for the serious side-reaction, seizure. Because of short-acting drug effects, it should be given three or four times a day. Peri-oral and finger paresthesia, the most common side-reaction, is accepted as a sign of drug-intake by many patients. Gastro-intestinal side reactions, the next common side-reaction of AFPs, are tolerable. AFPs are also the drug of choice and life-saving for LEMS crisis. For the long-term usage, it is proven to be safe and AFPs can be supplemented with liberal amount of pyridostigmine to sustain a symptomatic improvement without any undue side-reaction.
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Affiliation(s)
- Shin J Oh
- Department of Neurology, University of Alabama , Birmingham , AL , USA
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Nicolau S, Kao JC, Liewluck T. Trouble at the junction: When myopathy and myasthenia overlap. Muscle Nerve 2019; 60:648-657. [PMID: 31449669 DOI: 10.1002/mus.26676] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
Abstract
Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Justin C Kao
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
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Issop Y, Hathazi D, Khan MM, Rudolf R, Weis J, Spendiff S, Slater CR, Roos A, Lochmüller H. GFPT1 deficiency in muscle leads to myasthenia and myopathy in mice. Hum Mol Genet 2019; 27:3218-3232. [PMID: 29905857 PMCID: PMC6121184 DOI: 10.1093/hmg/ddy225] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 06/05/2018] [Indexed: 11/13/2022] Open
Abstract
Glutamine-fructose-6-phosphate transaminase 1 (GFPT1) is the rate-limiting enzyme in the hexosamine biosynthetic pathway which yields precursors required for protein and lipid glycosylation. Mutations in GFPT1 and other genes downstream of this pathway cause congenital myasthenic syndrome (CMS) characterized by fatigable muscle weakness owing to impaired neurotransmission. The precise pathomechanisms at the neuromuscular junction (NMJ) owing to a deficiency in GFPT1 is yet to be discovered. One of the challenges we face is the viability of Gfpt1−/− knockout mice. In this study, we use Cre/LoxP technology to generate a muscle-specific GFPT1 knockout mouse model, Gfpt1tm1d/tm1d, characteristic of the human CMS phenotype. Our data suggest a critical role for muscle derived GFPT1 in the development of the NMJ, neurotransmission, skeletal muscle integrity and highlight that a deficiency in skeletal muscle alone is sufficient to cause morphological postsynaptic NMJ changes that are accompanied by presynaptic alterations despite the conservation of neuronal GFPT1 expression. In addition to the conventional morphological NMJ changes and fatigable muscle weakness, Gfpt1tm1d/tm1d mice display a progressive myopathic phenotype with the presence of tubular aggregates in muscle, characteristic of the GFPT1-CMS phenotype. We further identify an upregulation of skeletal muscle proteins glypican-1, farnesyltransferase/geranylgeranyltransferase type-1 subunit α and muscle-specific kinase, which are known to be involved in the differentiation and maintenance of the NMJ. The Gfpt1tm1d/tm1d model allows for further investigation of pathophysiological consequences on genes and pathways downstream of GFPT1 likely to involve misglycosylation or hypoglycosylation of NMJs and muscle targets.
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Affiliation(s)
- Yasmin Issop
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle, UK
| | - Denisa Hathazi
- Leibniz-Institut für Analytische Wissenschaften-ISAS e.V, Dortmund, Germany
| | - Muzamil Majid Khan
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Rüdiger Rudolf
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.,Interdisciplinary Center for Neurosciences, University of Heidelberg, Heidelberg, Germany.,Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Sally Spendiff
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle, UK
| | - Clarke R Slater
- Institute of Neuroscience, Newcastle University, Newcastle, UK
| | - Andreas Roos
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle, UK.,Leibniz-Institut für Analytische Wissenschaften-ISAS e.V, Dortmund, Germany
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle, UK.,Department of Neuropediatrics and Muscle Disorders,Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
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13
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Abstract
OBJECTIVES Congenital myasthenic syndromes (CMSs) are a genotypically and phenotypically heterogeneous group of neuromuscular disorders, which have in common an impaired neuromuscular transmission. Since the field of CMSs is steadily expanding, the present review aimed at summarizing and discussing current knowledge and recent advances concerning the etiology, clinical presentation, diagnosis, and treatment of CMSs. METHODS Systematic literature review. RESULTS Currently, mutations in 32 genes are made responsible for autosomal dominant or autosomal recessive CMSs. These mutations concern 8 presynaptic, 4 synaptic, 15 post-synaptic, and 5 glycosilation proteins. These proteins function as ion-channels, enzymes, or structural, signalling, sensor, or transporter proteins. The most common causative genes are CHAT, COLQ, RAPSN, CHRNE, DOK7, and GFPT1. Phenotypically, these mutations manifest as abnormal fatigability or permanent or fluctuating weakness of extra-ocular, facial, bulbar, axial, respiratory, or limb muscles, hypotonia, or developmental delay. Cognitive disability, dysmorphism, neuropathy, or epilepsy are rare. Low- or high-frequency repetitive nerve stimulation may show an abnormal increment or decrement, and SF-EMG an increased jitter or blockings. Most CMSs respond favourably to acetylcholine-esterase inhibitors, 3,4-diamino-pyridine, salbutamol, albuterol, ephedrine, fluoxetine, or atracurium. CONCLUSIONS CMSs are an increasingly recognised group of genetically transmitted defects, which usually respond favorably to drugs enhancing the neuromuscular transmission. CMSs need to be differentiated from neuromuscular disorders due to muscle or nerve dysfunction.
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Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
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14
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Rodríguez Cruz PM, Palace J, Beeson D. The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes. Int J Mol Sci 2018; 19:ijms19061677. [PMID: 29874875 PMCID: PMC6032286 DOI: 10.3390/ijms19061677] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
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15
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Bogdanova‐Mihaylova P, Murphy RPJ, Alexander MD, McHugh JC, Foley AR, Brett F, Murphy SM. Congenital myasthenic syndrome due to
DPAGT
1
mutations mimicking congenital myopathy in an Irish family. Eur J Neurol 2018; 25:e22-e23. [DOI: 10.1111/ene.13532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 11/20/2017] [Indexed: 11/30/2022]
Affiliation(s)
- P. Bogdanova‐Mihaylova
- Department of Neurology Adelaide and Meath Hospitals incorporating the National Children's Hospital Dublin
| | - R. P. J. Murphy
- Department of Neurology Adelaide and Meath Hospitals incorporating the National Children's Hospital Dublin
| | - M. D. Alexander
- Department of Clinical Neurophysiology Adelaide and Meath Hospitals incorporating the National Children's Hospital Dublin
- Academic Unit of Neurology Trinity College Dublin Dublin Ireland
| | - J. C. McHugh
- Department of Clinical Neurophysiology Adelaide and Meath Hospitals incorporating the National Children's Hospital Dublin
- Academic Unit of Neurology Trinity College Dublin Dublin Ireland
| | - A. Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda MDUSA
| | - F. Brett
- Histopathology Department Beaumont Hospital Dublin Ireland
| | - S. M. Murphy
- Department of Neurology Adelaide and Meath Hospitals incorporating the National Children's Hospital Dublin
- Academic Unit of Neurology Trinity College Dublin Dublin Ireland
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16
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Beeson D, Cossins J, Rodriguez-Cruz P, Maxwell S, Liu WW, Palace J. Myasthenic syndromes due to defects in COL13A1 and in the N-linked glycosylation pathway. Ann N Y Acad Sci 2018; 1413:163-169. [DOI: 10.1111/nyas.13576] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 11/09/2017] [Accepted: 11/14/2017] [Indexed: 12/11/2022]
Affiliation(s)
- David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neuroscience; Weatherall Institute of Molecular Medicine; The John Radcliffe Oxford UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neuroscience; Weatherall Institute of Molecular Medicine; The John Radcliffe Oxford UK
| | - Pedro Rodriguez-Cruz
- Neurosciences Group, Nuffield Department of Clinical Neuroscience; Weatherall Institute of Molecular Medicine; The John Radcliffe Oxford UK
| | - Susan Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neuroscience; Weatherall Institute of Molecular Medicine; The John Radcliffe Oxford UK
| | - Wei-Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neuroscience; Weatherall Institute of Molecular Medicine; The John Radcliffe Oxford UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neuroscience; Level 3 The West Wing; The John Radcliffe Oxford UK
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17
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Péanne R, de Lonlay P, Foulquier F, Kornak U, Lefeber DJ, Morava E, Pérez B, Seta N, Thiel C, Van Schaftingen E, Matthijs G, Jaeken J. Congenital disorders of glycosylation (CDG): Quo vadis? Eur J Med Genet 2017; 61:643-663. [PMID: 29079546 DOI: 10.1016/j.ejmg.2017.10.012] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/05/2017] [Accepted: 10/22/2017] [Indexed: 12/12/2022]
Abstract
The survey summarizes in its first part the current status of knowledge on the Congenital Disorders of Glycosylation (CDG) with regard to their phenotypic spectrum, diagnostic and therapeutic strategies, and pathophysiology. It documents the clinical and basic research activities, and efforts to involve patients and their families. In the second part, it tries to look into the future of CDG. More specific biomarkers are needed for fast CDG diagnosis and treatment monitoring. Whole genome sequencing will play an increasingly important role in the molecular diagnosis of unsolved CDG. Epigenetic defects are expected to join the rapidly expanding genetic and allelic heterogeneity of the CDG family. Novel treatments are urgently needed particularly for PMM2-CDG, the most prevalent CDG. Patient services such as apps should be developed e.g. to document the natural history and monitor treatment. Networking (EURO-CDG, the European Reference Networks (MetabERN)) is an efficient tool to disseminate knowledge and boost collaboration at all levels. The final goal is of course to improve the quality of life of the patients and their families.
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Affiliation(s)
- Romain Péanne
- Center for Human Genetics, KU Leuven, Leuven, Belgium; LIA GLYCOLAB4CDG France/Belgium (International Associated Laboratory "Laboratory for the Research on Congenital Disorders of Glycosylation - from cellular mechanisms to cure", France
| | - Pascale de Lonlay
- APHP, Hôpital Necker Enfants Malades, Service et Centre de Référence des Maladies Métaboliques, Université Paris Descartes, Institut Imagine, Paris, France
| | - François Foulquier
- Université de Lille, Unité de Glycobiologie Structurale et Fonctionnelle, Villeneuve D'ascq, France; LIA GLYCOLAB4CDG France/Belgium (International Associated Laboratory "Laboratory for the Research on Congenital Disorders of Glycosylation - from cellular mechanisms to cure", Belgium
| | - Uwe Kornak
- Institut für Medizinische Genetik und Humangenetik, and Berlin-Brandenburg Centre for Regenerative Therapies, Charité University, Berlin, Germany
| | - Dirk J Lefeber
- Department of Neurology, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eva Morava
- Center for Metabolic Diseases, KU Leuven, Leuven, Belgium
| | - Belén Pérez
- Centro de Diagnostico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Nathalie Seta
- AP-HP, Hôpital Bichat, Biochemistry Laboratory, Paris, France
| | - Christian Thiel
- Stoffwechselzentrum, Universitäts-Kinderklinik, Heidelberg, Germany
| | - Emile Van Schaftingen
- Laboratory of Biochemistry, de Duve Institute, University of Louvain, Brussels, Belgium
| | - Gert Matthijs
- Center for Human Genetics, KU Leuven, Leuven, Belgium; LIA GLYCOLAB4CDG France/Belgium (International Associated Laboratory "Laboratory for the Research on Congenital Disorders of Glycosylation - from cellular mechanisms to cure", France.
| | - Jaak Jaeken
- Center for Metabolic Diseases, KU Leuven, Leuven, Belgium
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18
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Al-Muhaizea MA, Al-Mobarak SB. COLQ-mutant Congenital Myasthenic Syndrome with Microcephaly: A Unique Case with Literature Review. Transl Neurosci 2017; 8:65-69. [PMID: 28744372 PMCID: PMC5518714 DOI: 10.1515/tnsci-2017-0011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/15/2017] [Indexed: 11/15/2022] Open
Abstract
Congenital Myasthenic Syndrome (CMS) is a group of inherited neuromuscular junction disorders caused by defects in several genes. Clinical features include delayed motor milestones, recurrent respiratory illnesses and variable fatigable weakness. The central nervous system involvement is typically not part of the CMS. We report here a Saudi girl with genetically proven Collagen Like Tail Subunit Of Asymmetric Acetylcholinesterase (COLQ) mutation type CMS who has global developmental delay, microcephaly and respiratory failure. We have reviewed the literature regarding COLQ-type CMS and to the best of our knowledge this is the first ever reported association of congenital myasthenia syndrome with microcephaly.
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19
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Mutations in GFPT1-related congenital myasthenic syndromes are associated with synaptic morphological defects and underlie a tubular aggregate myopathy with synaptopathy. J Neurol 2017; 264:1791-1803. [DOI: 10.1007/s00415-017-8569-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/03/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022]
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20
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DPAGT1-CDG: Functional analysis of disease-causing pathogenic mutations and role of endoplasmic reticulum stress. PLoS One 2017; 12:e0179456. [PMID: 28662078 PMCID: PMC5491010 DOI: 10.1371/journal.pone.0179456] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/29/2017] [Indexed: 11/23/2022] Open
Abstract
Pathogenic mutations in DPAGT1 are manifested as two possible phenotypes: congenital disorder of glycosylation DPAGT1-CDG (also known as CDG-Ij), and limb-girdle congenital myasthenic syndrome (CMS) with tubular aggregates. UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosamine phosphotransferase (GPT), the protein encoded by DPAGT1, is an endoplasmic reticulum (ER)-resident protein involved in an initial step in the N-glycosylation pathway. The aim of the present study was to examine the effect of six variants in DPAGT1 detected in patients with DPAGT1-CDG, and the role of endoplasmic reticulum stress, as part of the search for therapeutic strategies to use against DPAGT1-CDG. The effect of the six mutations, i.e., c.358C>A (p.Leu120Met), c.791T>G (p.Val264Gly), c.901C>T (p.Arg301Cys), c.902G>A (p.Arg301His), c.1154T>G (p.Leu385Arg), and of the novel mutation c.329T>C (p.Phe110Ser), were examined via the analysis of DPAGT1 transcriptional profiles and GTP levels in patient-derived fibroblasts. In addition, the transient expression of different mutations was analysed in COS-7 cells. The results obtained, together with those of bioinformatic studies, revealed these mutations to affect the splicing process, the stability of GTP, or the ability of this protein to correctly localise in the ER membrane. The unfolded protein response (UPR; the response to ER stress) was found not to be active in patient-derived fibroblasts, unlike that seen in cells from patients with PMM2-CDG or DPM1-CDG. Even so, the fibroblasts of patients with DPAGT1-CDG seemed to be more sensitive to the stressor tunicamycin. The present work improves our knowledge of DPAGT1-CDG and provides bases for developing tailored splicing and folding therapies.
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21
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Brady S, Healy EG, Gang Q, Parton M, Quinlivan R, Jacob S, Curtis E, Al-Sarraj S, Sewry CA, Hanna MG, Houlden H, Beeson D, Holton JL. Tubular Aggregates and Cylindrical Spirals Have Distinct Immunohistochemical Signatures. J Neuropathol Exp Neurol 2016; 75:1171-1178. [DOI: 10.1093/jnen/nlw096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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22
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Rodríguez Cruz PM, Belaya K, Basiri K, Sedghi M, Farrugia ME, Holton JL, Liu WW, Maxwell S, Petty R, Walls TJ, Kennett R, Pitt M, Sarkozy A, Parton M, Lochmüller H, Muntoni F, Palace J, Beeson D. Clinical features of the myasthenic syndrome arising from mutations in GMPPB. J Neurol Neurosurg Psychiatry 2016; 87:802-9. [PMID: 27147698 PMCID: PMC6047737 DOI: 10.1136/jnnp-2016-313163] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/31/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND Congenital myasthenic syndrome (CMS) due to mutations in GMPPB has recently been reported confirming the importance of glycosylation for the integrity of neuromuscular transmission. METHODS Review of case notes of patients with mutations in GMPPB to identify the associated clinical, neurophysiological, pathological and laboratory features. In addition, serum creatine kinase (CK) levels within the Oxford CMS cohort were retrospectively analysed to assess its usefulness in the differential diagnosis of this new entity. RESULTS All patients had prominent limb-girdle weakness with minimal or absent craniobulbar manifestations. Presentation was delayed beyond infancy with proximal muscle weakness and most patients recall poor performance in sports during childhood. Neurophysiology showed abnormal neuromuscular transmission only in the affected muscles and myopathic changes. Muscle biopsy showed dystrophic features and reduced α-dystroglycan glycosylation. In addition, myopathic changes were present on muscle MRI. CK was significantly increased in serum compared to other CMS subtypes. Patients were responsive to pyridostigimine alone or combined with 3,4-diaminopyridine and/or salbutamol. CONCLUSIONS Patients with GMPPB-CMS have phenotypic features aligned with CMS subtypes harbouring mutations within the early stages of the glycosylation pathway. Additional features shared with the dystroglycanopathies include myopathic features, raised CK levels and variable mild cognitive delay. This syndrome underlines that CMS can occur in the absence of classic myasthenic manifestations such as ptosis and ophthalmoplegia or facial weakness, and links myasthenic disorders with dystroglycanopathies. This report should facilitate the recognition of this disorder, which is likely to be underdiagnosed and can benefit from symptomatic treatment.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Katsiaryna Belaya
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Keivan Basiri
- Neurology Department, Neuroscience Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maryam Sedghi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maria Elena Farrugia
- Department of Neurology, Institute of Neurological Sciences, The Queen Elizabeth University Hospital, Glasgow, UK
| | - Janice L Holton
- Department of Molecular Neurosciences, UCL Institute of Neurology, London, UK MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Wei Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Susan Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Richard Petty
- Department of Neurology, Institute of Neurological Sciences, The Queen Elizabeth University Hospital, Glasgow, UK
| | - Timothy J Walls
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Robin Kennett
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Matthew Pitt
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Anna Sarkozy
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Matt Parton
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Hanns Lochmüller
- Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre & MRC Centre for Neuromuscular Diseases, UCL Institute of Child Health, London, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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23
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Ohno K, Ohkawara B, Ito M. Recent advances in congenital myasthenic syndromes. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/cen3.12316] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Bisei Ohkawara
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Mikako Ito
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
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Bartus RT, Bétourné A, Basile A, Peterson BL, Glass J, Boulis NM. β2-Adrenoceptor agonists as novel, safe and potentially effective therapies for Amyotrophic lateral sclerosis (ALS). Neurobiol Dis 2015; 85:11-24. [PMID: 26459114 DOI: 10.1016/j.nbd.2015.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/25/2015] [Accepted: 10/08/2015] [Indexed: 02/04/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a chronic and progressive neuromuscular disease for which no cure exists and better treatment options are desperately needed. We hypothesize that currently approved β2-adrenoceptor agonists may effectively treat the symptoms and possibly slow the progression of ALS. Although β2-agonists are primarily used to treat asthma, pharmacologic data from animal models of neuromuscular diseases suggest that these agents may have pharmacologic effects of benefit in treating ALS. These include inhibiting protein degradation, stimulating protein synthesis, inducing neurotrophic factor synthesis and release, positively modulating microglial and systemic immune function, maintaining the structural and functional integrity of motor endplates, and improving energy metabolism. Moreover, stimulation of β2-adrenoceptors can activate a range of downstream signaling events in many different cell types that could account for the diverse array of effects of these agents. The evidence supporting the possible therapeutic benefits of β2-agonists is briefly reviewed, followed by a more detailed review of clinical trials testing the efficacy of β-agonists in a variety of human neuromuscular maladies. The weight of evidence of the potential benefits from treating these diseases supports the hypothesis that β2-agonists may be efficacious in ALS. Finally, ways to monitor and manage the side effects that may arise with chronic administration of β2-agonists are evaluated. In sum, effective, safe and orally-active β2-agonists may provide a novel and convenient means to reduce the symptoms of ALS and possibly delay disease progression, affording a unique opportunity to repurpose these approved drugs for treating ALS, and rapidly transforming the management of this serious, unmet medical need.
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Affiliation(s)
| | | | | | | | - Jonathan Glass
- Dept Neurology and Emory ALS Center, Emory University School of Medicine, Atlanta, GA, United States
| | - Nicholas M Boulis
- Dept Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States
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25
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Jaeken J, Lefeber D, Matthijs G. Clinical utility gene card for: DPAGT1 defective congenital disorder of glycosylation. Eur J Hum Genet 2015; 23:ejhg2015177. [PMID: 26242989 DOI: 10.1038/ejhg.2015.177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/30/2015] [Indexed: 12/25/2022] Open
Affiliation(s)
- Jaak Jaeken
- Department of Development and Regeneration, Centre for Metabolic Disease, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium
| | - Dirk Lefeber
- Department of Neurology, Translational Metabolic Laboratory, Radboudumc, Nijmegen, The Netherlands
| | - Gert Matthijs
- Department of Human Genetics, Centre for Human Genetics, KU Leuven, Leuven, Belgium
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26
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Klein A, Robb S, Rushing E, Liu WW, Belaya K, Beeson D. Congenital myasthenic syndrome caused by mutations in DPAGT. Neuromuscul Disord 2014; 25:253-6. [PMID: 25500013 DOI: 10.1016/j.nmd.2014.11.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/19/2014] [Accepted: 11/20/2014] [Indexed: 11/28/2022]
Abstract
Congenital myasthenic syndromes with prominent limb girdle involvement are an important differential diagnosis for congenital myopathies because of the therapeutic considerations. We present a case where accurate diagnosis was delayed for many years. Fluctuations of weakness were misinterpreted as effects of alternative treatments. Weakness was generalised, most prominently in the arms. Fatigability was more prominent in less affected muscles revealed by a positive Simpson test. Stimulation single fibre electromyography confirmed the suspected neuromuscular transmission defect. The marked response to pyridostigmine and cognitive impairment pointed to a myasthenic syndrome due to impaired glycosylation. Two mutations in trans were found in DPAGT1, the gene coding for dolichyl-phosphate N-acetylglucosaminephosphotransferase, one novel, the other previously reported in a rare form of congenital disorder of glycosylation. Gene expression studies revealed that both mutations reduce DPAGT1 expression. Phenotypic features not previously described for DPAGT1 CMS included restricted ocular abduction and long finger flexor contractures.
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Affiliation(s)
- Andrea Klein
- Department of Paediatric Neurology, University Children's Hospital Zürich, Zürich, Switzerland.
| | - Stephanie Robb
- Dubowitz Neuromuscular Centre, Institute of Child Health, Great Ormond Street Hospital, London, United Kingdom
| | - Elisabeth Rushing
- Department of Neuropathology, University Hospital Zürich, Zürich, Switzerland
| | - Wei-Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Kasiaryna Belaya
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
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Inherited disorders of the neuromuscular junction: an update. J Neurol 2014; 261:2234-43. [PMID: 25305004 DOI: 10.1007/s00415-014-7520-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 10/24/2022]
Abstract
Congenital myasthenic syndromes (CMSs) are a group of heterogeneous inherited disorders caused by mutations in genes affecting the function and structure of the neuromuscular junction. This review updates the reader on established and novel subtypes of congenital myasthenia, and the treatment strategies for these increasingly heterogeneous disorders. The discovery of mutations associated with the N-glycosylation pathway and in the family of serine peptidases has shown that causative genes encoding ubiquitously expressed molecules can produce defects at the human neuromuscular junction. By contrast, mutations in lipoprotein-like receptor 4 (LRP4), a long-time candidate gene for congenital myasthenia, and a novel phenotype of myasthenia with distal weakness and atrophy due to mutations in AGRN have now been described. In addition, a pathogenic splicing mutation in a nonfunctional exon of CHRNA1 has been reported emphasizing the importance of analysing nonfunctional exons in genetic analysis. The benefit of salbutamol and ephedrine alone or combined with pyridostigmine or 3,4-DAP is increasingly being reported for particular subtypes of CMS.
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Selcen D, Shen XM, Brengman J, Li Y, Stans AA, Wieben E, Engel AG. DPAGT1 myasthenia and myopathy: genetic, phenotypic, and expression studies. Neurology 2014; 82:1822-30. [PMID: 24759841 DOI: 10.1212/wnl.0000000000000435] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To investigate patients with DPAGT1 (UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase 1)-associated myasthenic syndrome. METHODS We performed exome and Sanger sequencing, determined glycoprotein expression in patient muscles, assessed pathogenicity of the mutant proteins by examining their expression and enzymatic activity in transfected cells, evaluated structural changes in muscle and the neuromuscular junction, and examined electrophysiologic aspects of neuromuscular transmission in vitro. RESULTS Patients 1 and 2, 16 and 14 years of age, had progressive fatigable weakness since infancy and are intellectually disabled. Patient 3, a less severely affected brother of patient 1, also has autistic features. Each patient harbors 2 novel heteroallelic mutations in DPAGT1, an enzyme subserving protein N-glycosylation. Patients 1 and 3 harbor Met1Leu, which reduces protein expression, and His375Tyr, which decreases enzyme activity. Patient 2 carries Val264Met, which abolishes enzyme activity, and a synonymous Leu120Leu mutation that markedly augments exon skipping, resulting in some skipped and infrequent nonskipped alleles. Therefore, the nonskipped allele rescues the phenotype. Intracellular microelectrode studies indicate combined pre- and postsynaptic defects of neuromuscular transmission with evidence for somatic mosaicism in patient 2. Structural studies reveal hypoplastic endplates, fiber-type disproportion, tubular aggregates, and degeneration of muscle fiber organelles resulting in autophagocytosis. CONCLUSIONS DPAGT1 myasthenia affects multiple parameters of neuromuscular transmission, causes fiber-type disproportion and an autophagic myopathy, and can be associated with intellectual disability. We speculate that hypoglycosylation of synapse-specific proteins causes defects in central as well as motor synapses.
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Affiliation(s)
- Duygu Selcen
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN.
| | - Xin-Ming Shen
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
| | - Joan Brengman
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
| | - Ying Li
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
| | - Anthony A Stans
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
| | - Eric Wieben
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
| | - Andrew G Engel
- From the Departments of Neurology and Neuromuscular Research Laboratory (D.S., X.-M.S., J.B., A.G.E.), Biomedical Informatics and Statistics (Y.L.), Orthopedic Surgery (A.A.S.), and Biochemistry and Molecular Biology (E.W.), Mayo Clinic, Rochester, MN
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Wolthuis DFGJ, Janssen MC, Cassiman D, Lefeber DJ, Morava E, Morava-Kozicz E. Defining the phenotype and diagnostic considerations in adults with congenital disorders of N-linked glycosylation. Expert Rev Mol Diagn 2014; 14:217-24. [PMID: 24524732 DOI: 10.1586/14737159.2014.890052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Congenital disorders of N-glycosylation (CDG) form a rapidly growing group of more than 20 inborn errors of metabolism. Most patients are identified at the pediatric age with multisystem disease. There is no systematic review on the long-term outcome and clinical presentation in adult patients. Here, we review the adult phenotype in 78 CDG patients diagnosed with 18 different forms of N-glycosylation defects. Characteristics include intellectual disability, speech disorder and abnormal gait. After puberty, symptoms might remain non-progressive and patients may lead a socially functional life. Thrombosis and progressive symptoms, such as peripheral neuropathy, scoliosis and visual demise are specifically common in PMM2-CDG. Especially in adult patients, diagnostic glycosylation screening can be mildly abnormal or near-normal, hampering diagnosis. Features of adult CDG patients significantly differ from the pediatric phenotype. Non-syndromal intellectual disability, or congenital malformations in different types of CDG and decreasing sensitivity of screening might be responsible for the CDG cases remaining undiagnosed until adulthood.
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Affiliation(s)
- David F G J Wolthuis
- Hayward Genetics Center, Tulane University Medical School, New Orleans, LA, 70112, USA
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Ohno K. Glycosylation defects as an emerging novel cause leading to a limb-girdle type of congenital myasthenic syndromes. J Neurol Neurosurg Psychiatry 2013; 84:1064. [PMID: 23457230 DOI: 10.1136/jnnp-2013-304931] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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