1
|
Kramer NJ, Prakash G, Isaac RS, Choquet K, Soto I, Petrova B, Merens HE, Kanarek N, Churchman LS. Regulators of mitonuclear balance link mitochondrial metabolism to mtDNA expression. Nat Cell Biol 2023; 25:1575-1589. [PMID: 37770567 DOI: 10.1038/s41556-023-01244-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 08/29/2023] [Indexed: 09/30/2023]
Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells requiring coordinated gene expression across organelles. To identify genes involved in dual-origin protein complex synthesis, we performed fluorescence-activated cell-sorting-based genome-wide screens analysing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of Complex IV. We identified genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6. We found that PREPL specifically impacts Complex IV biogenesis by acting at the intersection of mitochondrial lipid metabolism and protein synthesis, whereas NME6, an uncharacterized nucleoside diphosphate kinase, controls OXPHOS biogenesis through multiple mechanisms reliant on its NDPK domain. Firstly, NME6 forms a complex with RCC1L, which together perform nucleoside diphosphate kinase activity to maintain local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Secondly, NME6 modulates the activity of mitoribosome regulatory complexes, altering mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression.
Collapse
Affiliation(s)
- Nicholas J Kramer
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Gyan Prakash
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - R Stefan Isaac
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Karine Choquet
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Iliana Soto
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Boryana Petrova
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Hope E Merens
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Naama Kanarek
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - L Stirling Churchman
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
2
|
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.
Collapse
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.)
| |
Collapse
|
3
|
Kramer NJ, Prakash G, Choquet K, Soto I, Petrova B, Merens HE, Kanarek N, Churchman LS. Genome-wide screens for mitonuclear co-regulators uncover links between compartmentalized metabolism and mitochondrial gene expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.11.528118. [PMID: 36798306 PMCID: PMC9934615 DOI: 10.1101/2023.02.11.528118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells, in which gene expression must be coordinated across organelles using distinct pools of ribosomes. How cells produce and maintain the accurate subunit stoichiometries for these OXPHOS complexes remains largely unknown. To identify genes involved in dual-origin protein complex synthesis, we performed FACS-based genome-wide screens analyzing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of cytochrome c oxidase (Complex IV). We identified novel genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6 . We found that PREPL specifically regulates Complex IV biogenesis by interacting with mitochondrial protein synthesis machinery, while NME6, an uncharacterized nucleoside diphosphate kinase (NDPK), controls OXPHOS complex biogenesis through multiple mechanisms reliant on its NDPK domain. First, NME6 maintains local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Second, through stabilizing interactions with RCC1L, NME6 modulates the activity of mitoribosome regulatory complexes, leading to disruptions in mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression. Finally, we present these screens as a resource, providing a catalog of genes involved in mitonuclear gene regulation and OXPHOS biogenesis.
Collapse
|
4
|
Pugliese A, Holland SH, Rodolico C, Lochmüller H, Spendiff S. Presynaptic Congenital Myasthenic Syndromes: Understanding Clinical Phenotypes through In vivo Models. J Neuromuscul Dis 2023; 10:731-759. [PMID: 37212067 PMCID: PMC10578258 DOI: 10.3233/jnd-221646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2023] [Indexed: 05/23/2023]
Abstract
Presynaptic congenital myasthenic syndromes (CMS) are a group of genetic disorders affecting the presynaptic side of the neuromuscular junctions (NMJ). They can result from a dysfunction in acetylcholine (ACh) synthesis or recycling, in its packaging into synaptic vesicles, or its subsequent release into the synaptic cleft. Other proteins involved in presynaptic endplate development and maintenance can also be impaired.Presynaptic CMS usually presents during the prenatal or neonatal period, with a severe phenotype including congenital arthrogryposis, developmental delay, and apnoeic crisis. However, milder phenotypes with proximal muscle weakness and good response to treatment have been described. Finally, many presynaptic genes are expressed in the brain, justifying the presence of additional central nervous system symptoms.Several animal models have been developed to study CMS, providing the opportunity to identify disease mechanisms and test treatment options. In this review, we describe presynaptic CMS phenotypes with a focus on in vivo models, to better understand CMS pathophysiology and define new causative genes.
Collapse
Affiliation(s)
- Alessia Pugliese
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Stephen H. Holland
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Sally Spendiff
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| |
Collapse
|
5
|
Younger DS. Neonatal and infantile hypotonia. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:401-423. [PMID: 37562880 DOI: 10.1016/b978-0-323-98818-6.00011-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
The underlying etiology of neonatal and infantile hypotonia can be divided into primary peripheral and central nervous system and acquired or genetic disorders. The approach to identifying the likeliest cause of hypotonia begins with a bedside assessment followed by a careful review of the birth history and early development and family pedigree and obtaining available genetic studies and age- and disease-appropriate laboratory investigations. Until about a decade ago, the main goal was to identify the clinical signs and a battery of basic investigations including electrophysiology to confirm or exclude a given neuromuscular disorder, however the availability of whole-exome sequencing and next generation sequencing and transcriptome sequencing has simplified the identification of specific underlying genetic defect and improved the accuracy of diagnosis in many related Mendelian disorders.
Collapse
Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
| |
Collapse
|
6
|
Rosier K, McDevitt MT, Smet J, Floyd BJ, Verschoore M, Marcaida MJ, Bingman CA, Lemmens I, Dal Peraro M, Tavernier J, Cravatt BF, Gounko NV, Vints K, Monnens Y, Bhalla K, Aerts L, Rashan EH, Vanlander AV, Van Coster R, Régal L, Pagliarini DJ, Creemers JW. Prolyl endopeptidase-like is a (thio)esterase involved in mitochondrial respiratory chain function. iScience 2021; 24:103460. [PMID: 34888501 PMCID: PMC8634043 DOI: 10.1016/j.isci.2021.103460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/27/2021] [Accepted: 11/11/2021] [Indexed: 11/25/2022] Open
Abstract
Deficiency of the serine hydrolase prolyl endopeptidase-like (PREPL) causes a recessive metabolic disorder characterized by neonatal hypotonia, feeding difficulties, and growth hormone deficiency. The pathophysiology of PREPL deficiency and the physiological substrates of PREPL remain largely unknown. In this study, we connect PREPL with mitochondrial gene expression and oxidative phosphorylation by analyzing its protein interactors. We demonstrate that the long PREPLL isoform localizes to mitochondria, whereas PREPLS remains cytosolic. Prepl KO mice showed reduced mitochondrial complex activities and disrupted mitochondrial gene expression. Furthermore, mitochondrial ultrastructure was abnormal in a PREPL-deficient patient and Prepl KO mice. In addition, we reveal that PREPL has (thio)esterase activity and inhibition of PREPL by Palmostatin M suggests a depalmitoylating function. We subsequently determined the crystal structure of PREPL, thereby providing insight into the mechanism of action. Taken together, PREPL is a (thio)esterase rather than a peptidase and PREPLL is involved in mitochondrial homeostasis.
Collapse
Affiliation(s)
- Karen Rosier
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Molly T. McDevitt
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Joél Smet
- Department of Internal Medicine and Pediatrics, Division of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Brendan J. Floyd
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Maxime Verschoore
- Department of Internal Medicine and Pediatrics, Division of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Maria J. Marcaida
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Craig A. Bingman
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Irma Lemmens
- Center for Medical Biotechnology, VIB, Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Jan Tavernier
- Center for Medical Biotechnology, VIB, Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Benjamin F. Cravatt
- The Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Natalia V. Gounko
- VIB-KU Leuven Center for Brain & Disease Research, Electron Microscopy Platform & VIB-Bioimaging Core, Leuven, Belgium
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Katlijn Vints
- VIB-KU Leuven Center for Brain & Disease Research, Electron Microscopy Platform & VIB-Bioimaging Core, Leuven, Belgium
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Yenthe Monnens
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Kritika Bhalla
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Laetitia Aerts
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Edrees H. Rashan
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Arnaud V. Vanlander
- Department of Internal Medicine and Pediatrics, Division of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Rudy Van Coster
- Department of Internal Medicine and Pediatrics, Division of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Luc Régal
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
- Department of Pediatrics, Pediatric Neurology and Metabolism, UZ Brussel, Brussels, Belgium
| | - David J. Pagliarini
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Departments of Cell Biology and Physiology, Biochemistry and Molecular Biophysics, and Genetics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - John W.M. Creemers
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| |
Collapse
|
7
|
Ramdas S, Beeson D. Congenital myasthenic syndromes: where do we go from here? Neuromuscul Disord 2021; 31:943-954. [PMID: 34736634 DOI: 10.1016/j.nmd.2021.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022]
Abstract
Congenital myasthenia syndromes are rare but often treatable conditions affecting neuromuscular transmission. They result from loss or impaired function of one of a number of proteins secondary to a genetic defect. An estimate of the prevalence in the UK gave 9.2 cases per million, however, this is likely an underestimate since the adoption of next generation sequencing for diagnosis away from specialist centres is enhancing the 'pick up' rate. Next generation sequencing has helped identify a series of novel genes that harbour mutations causative for congenital myasthenic syndrome that include not only genes that encode proteins specifically expressed at the neuromuscular junction but also those that are ubiquitously expressed. The list of genes harbouring disease-causing mutations for congenital myasthenic syndrome continues to expand and is now over 30, but with many of the newly identified genes it is increasingly being recognised that abnormal neuromuscular transmission is only one component of a multifaceted phenotype in which muscle, the central nervous system, and other organs may also be affected. Treatment can be tailored to the underlying molecular mechanism for impaired neuromuscular transmission but treating the more complex multifaceted disorders and will require development of new therapies.
Collapse
Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular centre, Children's Hospital, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
| |
Collapse
|
8
|
Towheed A, Hietanen CL, Kamath VG, Singh LN, Ho A, Engelstad K, Cornett K, Montes J, De Vivo D. Hypotonia-cystinuria 2p21 deletion syndrome: Intrafamilial variability of clinical expression. Ann Clin Transl Neurol 2021; 8:2199-2204. [PMID: 34612606 PMCID: PMC8607452 DOI: 10.1002/acn3.51464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 11/23/2022] Open
Abstract
Two siblings presented similarly with congenital hypotonia, lactic acidosis, and failure to thrive. Later in childhood, the brother developed cystinuria and nephrolithiasis whereas the older sister suffered from cystinuria and chronic neurobehavioral disturbances. Biopsied muscle studies demonstrated deficient cytochrome c oxidase activities consistent with a mitochondrial disease. Whole exome sequencing (WES), however, revealed a homozygous 2p21 deletion involving two contiquous genes, SLC3A1 (deletion of exons 2‐10) and PREPL (deletion of exons 2‐14). The molecular findings were consistent with the hypotonia–cystinuria 2p21 deletion syndrome, presenting similarly in infancy with mitochondrial dysfunction but diverging later in childhood and displaying intrafamilial phenotypic variability.
Collapse
Affiliation(s)
- Atif Towheed
- Touro College of Osteopathic Medicine, Middletown, NY, 10940
| | | | | | - Larry N Singh
- Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, 19104
| | - Angela Ho
- Touro College of Osteopathic Medicine, Middletown, NY, 10940
| | - Kristin Engelstad
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032
| | - Kayla Cornett
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032
| | - Jacqueline Montes
- Department of Rehabilitation and Regenerative Medicine (Physical Therapy), Columbia University Irving Medical Center, New York, NY, 10032
| | - Darryl De Vivo
- Department of Neurology and Pediatrics, Columbia University Irving Medical Center, New York, NY, 10032
| |
Collapse
|
9
|
Prior DE, Ghosh PS. Congenital Myasthenic Syndrome From a Single Center: Phenotypic and Genotypic features. J Child Neurol 2021; 36:610-617. [PMID: 33471587 DOI: 10.1177/0883073820987755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Congenital myasthenic syndrome is a group of rare genetic disorders affecting transmission across the neuromuscular junction. Patients present with variable ocular, bulbar, respiratory, and extremity weakness that may respond to symptomatic therapies. METHODS We identified 18 patients with congenital myasthenic syndrome from a pediatric neuromuscular center over a decade. Through a retrospective chart review, we characterize demographic profile, clinical features, genetic variants, treatment, and follow-up of these patients. RESULTS Patients had the following genetic subtypes: CHRNE (6), CHAT (2), MUSK (2), DOK7 (2), COLQ (1), RAPSN (1), PREPL (1), GFPT1 (1), CHRBB1 (1), and CHRNA1 (1). The phenotype varied based on the genetic variants, though most patients have generalized fatigable weakness affecting ocular, bulbar, and extremity muscles. There was a significant delay in the diagnosis of this condition from the onset of symptoms. Although most patients improved with pyridostigmine, some subtypes showed worsening with pyridostigmine and others benefited from albuterol, ephedrine, or 3,4-diaminopyridine treatment. CONCLUSION Increasing recognition of this rare syndrome will lead to early diagnosis and prompt treatment. Prompt utilization of genetic testing will identify novel variants and the expanding phenotype of this condition.
Collapse
Affiliation(s)
- Devin E Prior
- Department of Neurology, 2094Mount Auburn Hospital, Cambridge, MA, USA.,Department of Neurology, 1862Boston Children's Hospital, Boston MA, USA
| | - Partha S Ghosh
- Department of Neurology, 1862Boston Children's Hospital, Boston MA, USA
| |
Collapse
|
10
|
Kim MJ, Yum MS, Seo GH, Lee Y, Jang HN, Ko TS, Lee BH. Clinical Application of Whole Exome Sequencing to Identify Rare but Remediable Neurologic Disorders. J Clin Med 2020; 9:jcm9113724. [PMID: 33233562 PMCID: PMC7699758 DOI: 10.3390/jcm9113724] [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: 10/26/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 12/17/2022] Open
Abstract
Background: The aim of this study was to describe the application of whole exome sequencing (WES) in the accurate genetic diagnosis and personalized treatment of extremely rare neurogenetic disorders. Methods: From 2017 to 2019, children with neurodevelopmental symptoms were evaluated using WES in the pediatric neurology clinic and medical genetics center. The clinical presentation, laboratory findings including the genetic results from WES, and diagnosis-based treatment and outcomes of the four patients are discussed. Results: A total of 376 children with neurodevelopmental symptom were evaluated by WES, and four patients (1.1%) were diagnosed with treatable neurologic disorders. Patient 1 (Pt 1) showed global muscle hypotonia, dysmorphic facial features, and multiple anomalies beginning in the perinatal period. Pt 1 was diagnosed with congenital myasthenic syndrome 22 of PREPL deficiency. Pt 2 presented with hypotonia and developmental arrest and was diagnosed with autosomal recessive dopa-responsive dystonia due to TH deficiency. Pt 3, who suffered from intractable epilepsy and progressive cognitive decline, was diagnosed with epileptic encephalopathy 47 with a heterozygous FGF12 mutation. Pt 4 presented with motor delay and episodic ataxia and was diagnosed with episodic ataxia type II (heterozygous CACNA1A mutation). The patients’ major neurologic symptoms were remarkably relieved with pyridostigmine (Pt 1), levodopa (Pt 2), sodium channel blocker (Pt 3), and acetazolamide (Pt 4), and most patients regained developmental milestones in the follow-up period (0.4 to 3 years). Conclusions: The early application of WES helps in the identification of extremely rare genetic diseases, for which effective treatment modalities exist. Ultimately, WES resulted in optimal clinical outcomes of affected patients.
Collapse
Affiliation(s)
- Min-Jee Kim
- Department of Pediatrics, Asan Medical Center Children’s Hospital, Ulsan University College of Medicine 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, Korea; (M.-J.K.); (H.N.J.); (T.-S.K.)
| | - Mi-Sun Yum
- Department of Pediatrics, Asan Medical Center Children’s Hospital, Ulsan University College of Medicine 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, Korea; (M.-J.K.); (H.N.J.); (T.-S.K.)
- Correspondence: ; Tel.: +82-2-3010-3386; Fax: +82-2-3010-3356
| | - Go Hun Seo
- 3billion Inc., Seoul 06193, Korea; (G.H.S.); (B.H.L.)
| | - Yena Lee
- Department of Genetics, Asan Medical Center, Ulsan University College of Medicine, 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, Korea;
| | - Han Na Jang
- Department of Pediatrics, Asan Medical Center Children’s Hospital, Ulsan University College of Medicine 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, Korea; (M.-J.K.); (H.N.J.); (T.-S.K.)
| | - Tae-Sung Ko
- Department of Pediatrics, Asan Medical Center Children’s Hospital, Ulsan University College of Medicine 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, Korea; (M.-J.K.); (H.N.J.); (T.-S.K.)
| | - Beom Hee Lee
- 3billion Inc., Seoul 06193, Korea; (G.H.S.); (B.H.L.)
| |
Collapse
|
11
|
Shchagina O, Bessonova L, Bychkov I, Beskorovainaya T, Poliakov A. A Family Case of Congenital Myasthenic Syndrome-22 Induced by Different Combinations of Molecular Causes in Siblings. Genes (Basel) 2020; 11:genes11070821. [PMID: 32707643 PMCID: PMC7397044 DOI: 10.3390/genes11070821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 11/16/2022] Open
Abstract
Congenital myasthenic syndrome-22 (CMS22, OMIM 616224) is a very rare recessive hereditary disorder. At the moment, ten CMS22 patients are described, with the disorder caused by nine different Loss-of-Function mutations and 14 gross deletions in the PREPL gene. The materials for our study were DNA samples of five family members: two patients with myasthenia, their healthy sibling and parents. Clinical exome analysis was carried out for one patient, then the whole family was checked for target variants with Sanger sequencing, quantitative multiplex ligation-dependent probe amplification, and chromosome 2 microsatellite markers study. To determine the functional significance of the splicing variant, we applied the minigene assay. The cause of the proband's disorder is a compound heterozygous state of two previously non-described pathogenic PREPL variants: a c.1528C>T (p.(Arg510Ter)) nonsense mutation and a c.2094G>T pseudo-missense variant, which, simultaneously with a p.(Lys698Asn) amino acid substitution, affects splicing, leading to exon 14 skipping in mRNA. The second patient's disorder was caused by a homozygous nonsense c.1528C>T (p.(Arg510Ter)) mutation due to maternal uniparental disomy (UPD) of chromosome 2. In this study, we describe a unique case, in which two siblings with a rare disorder have different pathologic genotypes.
Collapse
|
12
|
Prolyl Endopeptidase-Like Facilitates the α-Synuclein Aggregation Seeding, and This Effect Is Reverted by Serine Peptidase Inhibitor PMSF. Biomolecules 2020; 10:biom10060962. [PMID: 32630529 PMCID: PMC7355856 DOI: 10.3390/biom10060962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/16/2020] [Accepted: 06/23/2020] [Indexed: 12/18/2022] Open
Abstract
The aggregation of α-synuclein (α-Syn) is a characteristic of Parkinson’s disease (PD). α-Syn oligomerization/aggregation is accelerated by the serine peptidase, prolyl oligopeptidase (POP). Factors that affect POP conformation, including most of its inhibitors and an impairing mutation in its active site, influence the acceleration of α-Syn aggregation resulting from the interaction of these proteins. It is noteworthy, however, that α-Syn is not cleaved by POP. Prolyl endopeptidase-like (PREPL) protein is structurally related to the serine peptidases belonging to the POP family. Based on the α-Syn–POP studies and knowing that PREPL may contribute to the regulation of synaptic vesicle exocytosis, when this protein can encounter α-Syn, we investigated the α-Syn–PREPL interaction. The binding of these two human proteins was observed with an apparent affinity constant of about 5.7 μM and, as in the α-Syn assays with POP, the presence of PREPL accelerated the oligomerization/aggregation events, with no α-Syn cleavage. Furthermore, despite this lack of hydrolytic cleavage, the serine peptidase active site inhibitor phenylmethylsulfonyl fluoride (PMSF) abolished the enhancement of the α-Syn aggregation by PREPL. Therefore, given the attention to POP inhibitors as potential drugs to treat synucleinopathies, the present data point to PREPL as another potential target to be explored for this purpose.
Collapse
|
13
|
Xiao T, Wu LW. [Advances in the diagnosis and treatment of congenital myasthenic syndrome]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2020; 22:672-676. [PMID: 32571471 PMCID: PMC7390217 DOI: 10.7499/j.issn.1008-8830.1912095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
Congenital myasthenic syndrome (CMS) is a group of clinical and genetic heterogeneous diseases caused by impaired neuromuscular transmission due to genetic defects. At present, it has been reported that more than 30 genes can cause CMS. All CMS subtypes have the clinical features of fatigue and muscle weakness, but age of onset, symptoms, and treatment response vary with the molecular mechanisms underlying genetic defects. Pharmacotherapy and symptomatic/supportive treatment are the main methods for the treatment of CMS, and antisense oligonucleotide technology has been proven to be beneficial for CHRNA 1-related CMS in animals. Since CMS is a group of increasingly recognized clinical and genetic heterogeneous diseases, an understanding of the latest knowledge and research advances in its clinical features, genetic research, and treatment helps to give early diagnosis and treatment as well as gain a deeper understanding of the pathogenesis of CMS, so as to make new breakthroughs in the treatment of CMS.
Collapse
Affiliation(s)
- Ting Xiao
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China.
| | | |
Collapse
|
14
|
Xiao T, Wu LW. [Advances in the diagnosis and treatment of congenital myasthenic syndrome]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2020; 22:672-676. [PMID: 32571471 PMCID: PMC7390217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/24/2020] [Indexed: 11/12/2023]
Abstract
Congenital myasthenic syndrome (CMS) is a group of clinical and genetic heterogeneous diseases caused by impaired neuromuscular transmission due to genetic defects. At present, it has been reported that more than 30 genes can cause CMS. All CMS subtypes have the clinical features of fatigue and muscle weakness, but age of onset, symptoms, and treatment response vary with the molecular mechanisms underlying genetic defects. Pharmacotherapy and symptomatic/supportive treatment are the main methods for the treatment of CMS, and antisense oligonucleotide technology has been proven to be beneficial for CHRNA 1-related CMS in animals. Since CMS is a group of increasingly recognized clinical and genetic heterogeneous diseases, an understanding of the latest knowledge and research advances in its clinical features, genetic research, and treatment helps to give early diagnosis and treatment as well as gain a deeper understanding of the pathogenesis of CMS, so as to make new breakthroughs in the treatment of CMS.
Collapse
Affiliation(s)
- Ting Xiao
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China.
| | | |
Collapse
|
15
|
Yang Q, Hua R, Qian J, Yi S, Shen F, Zhang Q, Li M, Yi S, Luo J, Fan X. PREPL Deficiency: A Homozygous Splice Site PREPL Mutation in a Patient With Congenital Myasthenic Syndrome and Absence of Ovaries and Hypoplasia of Uterus. Front Genet 2020; 11:198. [PMID: 32218803 PMCID: PMC7078161 DOI: 10.3389/fgene.2020.00198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 02/20/2020] [Indexed: 11/13/2022] Open
Abstract
Prolyl endopeptidase-like (PREPL) deficiency (MIM 616224) is a very rare congenital disorder characterized by neonatal hypotonia and feeding difficulties, ptosis, neuromuscular symptoms, cognitive impairments, growth hormone deficiency, short stature, and hypergonadotropic hypogonadism. This syndrome is an autosomal recessive disease resulting from mutations in the PREPL gene. Previous reports have associated PREPL deficiency with only one nucleotide substitution, the deletion of four nucleotides, and eight small microdeletions in the PREPL gene In this study, we used whole exome sequencing (WES) to identify a novel homozygous splicing mutation (c.616 + 1G > T) in a 14-year-old Chinese girl with PREPL deficiency. Sequencing of the RT-PCR products from the patient’s blood sample revealed that the c.616 + 1G > T variant disrupted normal splicing in intron 4 leading to an aberrant inclusion of 43 nucleotides in intron, a frameshift, and premature termination codon. Our patient exhibited several of the common phenotypes, including severe neonatal hypotonia, growth impairment and cognitive problems. However, we also observed several unusual phenotypic characteristics: absence of the ovaries, hypoplasia of the uterus, microcephaly and a short neck in patient is alsoobserved. These results provide further evidence for the involvement of PREPL development of the ovaries and uterus. Our findings may provide further insight into the relationship between the genotype and phenotype in collagen-associated diseases and improve the clinical diagnosis of Prolyl endopeptidase-like deficiency.
Collapse
Affiliation(s)
- Qi Yang
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Rong Hua
- The Guangxi Zhang Autonomous Region Reproductive Hospital, Nanning, China
| | - Jiale Qian
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Shang Yi
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Fei Shen
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Qiang Zhang
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Mengting Li
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Sheng Yi
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Jingsi Luo
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| | - Xin Fan
- Genetic and Metabolic Central Laboratory, Guangxi Maternal and Child Health Hospital, Nanning, China
| |
Collapse
|
16
|
Zhang P, Wu B, Lu Y, Ni Q, Liu R, Zhou W, Wang H. First maternal uniparental disomy for chromosome 2 with PREPL novel frameshift mutation of congenital myasthenic syndrome 22 in an infant. Mol Genet Genomic Med 2020; 8:e1144. [PMID: 31985178 PMCID: PMC7057094 DOI: 10.1002/mgg3.1144] [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: 11/07/2019] [Accepted: 01/07/2020] [Indexed: 11/11/2022] Open
Abstract
Background Congenital myasthenic syndrome 22 (CMS22) is a rare autosomal recessive disorder due to isolated PREPL deficiency and characterized by neonatal hypotonia, muscular weakness, and feeding difficulties. Eight such cases have already been reported, while maternal uniparental disomy with a PREPL pathogenic mutation has never been involved. Methods Trio whole‐exome sequencing (WES), comparative genomic hybridization microarray (arry‐CGH), and Sanger sequencing were performed on a 6‐month‐old girl with severe neonatal hypotonia and feeding difficulties. Also, the phenotype and genotype of reported CMS22 patients were reviewed. Results In this female infant, we identified a novel homozygous frameshift mutation in PREPL (c.1282_1285delTTTG, p.Phe428Argfs*18) by trio‐WES. Sanger sequencing confirmed that her mother was heterozygous and her father was normal. Trio‐WES data showed that 96.70% (1668/1725) variants on chromosome 2 were homozygous and maternally inherited, suggesting maternal uniparental disomy of chromosome 2 [UPD(2)mat]. Array‐CGH did not show copy number variants (CNVs) but revealed complete UPD(2). Conclusion To date, nine patients with CMS22 have been reported including our patient, and we report the youngest and the first UPD(2)mat with PREPL novel homozygous pathogenic mutation case, which expand the mutation spectrum of PREPL gene.
Collapse
Affiliation(s)
- Ping Zhang
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Bingbing Wu
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Yulan Lu
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Qi Ni
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Renchao Liu
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Wenhao Zhou
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China.,Department of Neonates, Key Laboratory of Neonatal Diseases, Ministry of Health, Children's Hospital of Fudan University, Shanghai, China
| | - Huijun Wang
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China.,Key Laboratory of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| |
Collapse
|
17
|
Yahyaoui R, Pérez-Frías J. Amino Acid Transport Defects in Human Inherited Metabolic Disorders. Int J Mol Sci 2019; 21:ijms21010119. [PMID: 31878022 PMCID: PMC6981491 DOI: 10.3390/ijms21010119] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/12/2019] [Accepted: 12/18/2019] [Indexed: 02/07/2023] Open
Abstract
Amino acid transporters play very important roles in nutrient uptake, neurotransmitter recycling, protein synthesis, gene expression, cell redox balance, cell signaling, and regulation of cell volume. With regard to transporters that are closely connected to metabolism, amino acid transporter-associated diseases are linked to metabolic disorders, particularly when they involve different organs, cell types, or cell compartments. To date, 65 different human solute carrier (SLC) families and more than 400 transporter genes have been identified, including 11 that are known to include amino acid transporters. This review intends to summarize and update all the conditions in which a strong association has been found between an amino acid transporter and an inherited metabolic disorder. Many of these inherited disorders have been identified in recent years. In this work, the physiological functions of amino acid transporters will be described by the inherited diseases that arise from transporter impairment. The pathogenesis, clinical phenotype, laboratory findings, diagnosis, genetics, and treatment of these disorders are also briefly described. Appropriate clinical and diagnostic characterization of the underlying molecular defect may give patients the opportunity to avail themselves of appropriate therapeutic options in the future.
Collapse
Affiliation(s)
- Raquel Yahyaoui
- Laboratory of Metabolic Disorders and Newborn Screening Center of Eastern Andalusia, Málaga Regional University Hospital, 29011 Málaga, Spain
- Grupo Endocrinología y Nutrición, Diabetes y Obesidad, Instituto de Investigación Biomédica de Málaga-IBIMA, 29010 Málaga, Spain
- Correspondence:
| | - Javier Pérez-Frías
- Grupo Multidisciplinar de Investigación Pediátrica, Instituto de Investigación Biomédica de Málaga-IBIMA, 29010 Málaga, Spain;
- Departamento de Farmacología y Pediatría, Facultad de Medicina, Universidad de Málaga, 29010 Málaga, Spain
| |
Collapse
|
18
|
Tucker EJ, Jaillard S, Grover SR, van den Bergen J, Robevska G, Bell KM, Sadedin S, Hanna C, Dulon J, Touraine P, Sinclair AH. TP63-truncating variants cause isolated premature ovarian insufficiency. Hum Mutat 2019; 40:886-892. [PMID: 30924587 DOI: 10.1002/humu.23744] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/05/2019] [Accepted: 03/13/2019] [Indexed: 12/21/2022]
Abstract
Premature ovarian insufficiency involves amenorrhea and elevated follicle-stimulating hormone before age 40, and its genetic basis is poorly understood. Here, we study 13 premature ovarian insufficiency (POI) patients using whole-exome sequencing. We identify PREPL and TP63 causative variants, and variants in other potentially novel POI genes. PREPL deficiency is a known cause of syndromic POI, matching the patients' phenotype. A role for TP63 in ovarian biology has previously been proposed but variants have been described in multiorgan syndromes, and not isolated POI. One patient with isolated POI harbored a de novo nonsense TP63 variant in the terminal exon and an unrelated patient had a different nonsense variant in the same exon. These variants interfere with the repression domain while leaving the activation domain intact. We expand the phenotypic spectrum of TP63-related disorders, provide a new genotype:phenotype correlation for TP63 and identify a new genetic cause of isolated POI.
Collapse
Affiliation(s)
- Elena J Tucker
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Sylvie Jaillard
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,CHU Rennes, Service de Cytogénétique et Biologie Cellulaire, F-35033, Rennes, France.,INSERM U1085-IRSET, Université de Rennes1, Frances Pathologies Gynécologiques Rares, F-35042, Rennes, Paris, France
| | - Sonia R Grover
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Department of Paediatric and Adolescent Gynaecology, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Jocelyn van den Bergen
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Gorjana Robevska
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Katrina M Bell
- Bioinformatics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Simon Sadedin
- Bioinformatics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Chloe Hanna
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatric and Adolescent Gynaecology, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Jérôme Dulon
- Department of Endocrinology and Reproductive Medicine, AP-HP, Sorbonne University Medicine, Centre de Référence desMaladies Endocriniennes Rares de laCroissance et du Développement, Centre des Pathologies Gynécologiques Rares, Paris, France
| | - Philippe Touraine
- Department of Endocrinology and Reproductive Medicine, AP-HP, Sorbonne University Medicine, Centre de Référence desMaladies Endocriniennes Rares de laCroissance et du Développement, Centre des Pathologies Gynécologiques Rares, Paris, France
| | - Andrew H Sinclair
- Reproductive Development, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| |
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
| |
Collapse
|
20
|
Targeted therapies for congenital myasthenic syndromes: systematic review and steps towards a treatabolome. Emerg Top Life Sci 2019; 3:19-37. [PMID: 30931400 PMCID: PMC6436731 DOI: 10.1042/etls20180100] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite recent scientific advances, most rare genetic diseases — including most neuromuscular diseases — do not currently have curative gene-based therapies available. However, in some cases, such as vitamin, cofactor or enzyme deficiencies, channelopathies and disorders of the neuromuscular junction, a confirmed genetic diagnosis provides guidance on treatment, with drugs available that may significantly alter the disease course, improve functional ability and extend life expectancy. Nevertheless, many treatable patients remain undiagnosed or do not receive treatment even after genetic diagnosis. The growth of computer-aided genetic analysis systems that enable clinicians to diagnose their undiagnosed patients has not yet been matched by genetics-based decision-support systems for treatment guidance. Generating a ‘treatabolome’ of treatable variants and the evidence for the treatment has the potential to increase treatment rates for treatable conditions. Here, we use the congenital myasthenic syndromes (CMS), a group of clinically and genetically heterogeneous but frequently treatable neuromuscular conditions, to illustrate the steps in the creation of a treatabolome for rare inherited diseases. We perform a systematic review of the evidence for pharmacological treatment of each CMS type, gathering evidence from 207 studies of over 1000 patients and stratifying by genetic defect, as treatment varies depending on the underlying cause. We assess the strength and quality of the evidence and create a dataset that provides the foundation for a computer-aided system to enable clinicians to gain easier access to information about treatable variants and the evidence they need to consider.
Collapse
|
21
|
Kılıç M, Ceylan AC, Örün UA, Kılıç E. First cardiac manifestation of hypotonia-cystinuria syndrome. Metab Brain Dis 2018; 33:1375-1379. [PMID: 29627929 DOI: 10.1007/s11011-018-0226-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/27/2018] [Indexed: 02/03/2023]
Abstract
Hypotonia-cystinuria syndrome is a very rare autosomal recessive contiguous gene deletion syndrome of PREPL and SLC3A1 at 2p21 with neuromuscular and neuroendocrinologic presentation. We report a two-year-six-month-old affected female infant and her five-month-old affected brother with a novel homozygous deletion in SLC3A1 and PREPL gene. Both of siblings had mild facial dysmorphism, hypotonia, feeding problems, failure to thrive, developmental delay. She also had dilated cardiomyopathy which differ from other reported patients. Therefore cardiomyopathy may also be considered one of the features of hypotonia-cystinuria syndrome. With this case report, we present cardiac manifestation of hypotonia-cystinuria syndrome for the first time. Because of two siblings had hyperechogenic bowel in prenatal sonography, it might be a prenatal marker for HCS.
Collapse
Affiliation(s)
- Mustafa Kılıç
- Sami Ulus Children Hospital, Metabolism Unit, Babur cad, No: 44, 06080, Altındağ, Ankara, Turkey.
| | - Ahmet Cevdet Ceylan
- Atatürk Training and Research Hospital, Department of Genetics, Yıldırım Beyazıt University, Ankara, Turkey
| | - Utku Arman Örün
- Pediatric Cardiology Unit, Sami Ulus Children Hospital, Ankara, Turkey
| | - Esra Kılıç
- Pediatric Hematology-Oncology Training and Research Hospital, Pediatric Genetic Unit, Ankara, Turkey
| |
Collapse
|
22
|
Farmakidis C, Pasnoor M, Barohn RJ, Dimachkie MM. Congenital Myasthenic Syndromes: a Clinical and Treatment Approach. Curr Treat Options Neurol 2018; 20:36. [DOI: 10.1007/s11940-018-0520-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
23
|
Abstract
PURPOSE OF REVIEW Summarize features of the currently recognized congenital myasthenic syndromes (CMS) with emphasis on novel findings identified in the past 6 years. RECENT FINDINGS Since the last review of the CMS in this journal in 2012, several novel CMS were identified. The identified disease proteins are SNAP25B, synaptotagmin 2, Munc13-1, synaptobrevin-1, GFPT1, DPAGT1, ALG2, ALG14, Agrin, GMPPB, LRP4, myosin 9A, collagen 13A1, the mitochondrial citrate carrier, PREPL, LAMA5, the vesicular ACh transporter, and the high-affinity presynaptic choline transporter. Exome sequencing has provided a powerful tool for identifying novel CMS. Identifying the disease genes is essential for determining optimal therapy. The landscape of the CMS is still unfolding.
Collapse
Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| |
Collapse
|
24
|
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.
Collapse
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.
| |
Collapse
|
25
|
Silva S, Miyake N, Tapia C, Matsumoto N. The second point mutation in PREPL: a case report and literature review. J Hum Genet 2018; 63:677-681. [PMID: 29483676 DOI: 10.1038/s10038-018-0426-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/29/2018] [Accepted: 01/31/2018] [Indexed: 12/13/2022]
Abstract
Prolyl endopeptidase-like (PREPL) deficiency (MIM# 616224) is a rare autosomal recessive inherited congenital myasthenic syndrome characterized by neonatal hypotonia, feeding problems, mild dysmorphism, and neuromuscular symptoms, followed by hyperphagia and obesity in later childhood. Some patients also exhibit growth deficits, sexual hormone deficiency, and cognitive impairments. This syndrome is caused by biallelic mutations in PREPL. To date, only one nucleotide deletion and seven small microdeletions in PREPL have been reported. Here we report a female patient with a novel homozygous frameshift mutation in PREPL (NM_006036.4, c.342delA:p.Val115Leufs*39). Her clinical features are similar to those of previously reported cases. The mutation is the first homozygous point mutation reported in humans.
Collapse
Affiliation(s)
- Sebastian Silva
- Servicio de Pediatría, Hospital de Puerto Montt, 5507798, Puerto Montt, Chile
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan.
| | - Carolina Tapia
- Instituto de Rehabilitación Teletón, 5502446, Puerto Montt, Chile
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan.
| |
Collapse
|
26
|
Engel AG, Shen XM, Selcen D. The unfolding landscape of the congenital myasthenic syndromes. Ann N Y Acad Sci 2018; 1413:25-34. [PMID: 29355968 DOI: 10.1111/nyas.13539] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/28/2017] [Accepted: 10/02/2017] [Indexed: 12/14/2022]
Abstract
Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is impaired by one or more specific mechanisms. Since the advent of next-generation sequencing methods, the discovery of novel CMS targets and phenotypes has proceeded at an accelerated rate. Here, we review the current classification of CMS and describe our findings in five of these targets identified and investigated in our laboratory in the past 5 years. Defects in LRP4 hinder synaptic development and maintenance; the defects in PREPL are predicted to diminish filling of the synaptic vesicle with acetylcholine; and defects in SNAP25, Munc13-1, and synaptotbrevin-1 impede synaptic vesicle exocytosis.
Collapse
Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| |
Collapse
|
27
|
Engel AG. Genetic basis and phenotypic features of congenital myasthenic syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:565-589. [PMID: 29478601 DOI: 10.1016/b978-0-444-64076-5.00037-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
The congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. The disease proteins reside in the nerve terminal, the synaptic basal lamina, or in the postsynaptic region, or at multiple sites at the neuromuscular junction as well as in other tissues. Targeted mutation analysis by Sanger or exome sequencing has been facilitated by characteristic phenotypic features of some CMS. No fewer than 20 disease genes have been recognized to date. In one-half of the currently identified probands, the disease stems from mutations in genes encoding subunits of the muscle form of the acetylcholine receptor (CHRNA1, CHRNB, CHRNAD1, and CHRNE). In 10-14% of the probands the disease is caused by mutations in RAPSN, DOK 7, or COLQ, and in 5% by mutations in CHAT. Other less frequently identified disease genes include LAMB2, AGRN, LRP4, MUSK, GFPT1, DPAGT1, ALG2, and ALG 14 as well as SCN4A, PREPL, PLEC1, DNM2, and MTM1. Identification of the genetic basis of each CMS is important not only for genetic counseling and disease prevention but also for therapy, because therapeutic agents that benefit one type of CMS can be harmful in another.
Collapse
Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, United States.
| |
Collapse
|
28
|
Régal L, Mårtensson E, Maystadt I, Voermans N, Lederer D, Burlina A, Juan Fita MJ, Hoogeboom AJM, Olsson Engman M, Hollemans T, Schouten M, Meulemans S, Jonson T, François I, Gil Ortega D, Kamsteeg EJ, Creemers JWM. PREPL deficiency: delineation of the phenotype and development of a functional blood assay. Genet Med 2017; 20:109-118. [PMID: 28726805 DOI: 10.1038/gim.2017.74] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/17/2017] [Indexed: 12/13/2022] Open
Abstract
PurposePREPL deficiency causes neonatal hypotonia, ptosis, neonatal feeding difficulties, childhood obesity, xerostomia, and growth hormone deficiency. Different recessive contiguous gene deletion syndromes involving PREPL and a variable combination of SLC3A1 (hypotonia-cystinuria syndrome), CAMKMT (atypical hypotonia-cystinuria syndrome), and PPM1B (2p21 deletion syndrome) have been described. In isolated PREPL deficiency, previously described only once, the absence of cystinuria complicates the diagnosis. Therefore, we developed a PREPL blood assay and further delineated the phenotype.MethodsClinical features of new subjects with PREPL deficiency were recorded. The presence of PREPL in lymphocytes and its reactivity with an activity-based probe were evaluated by western blot.ResultsFive subjects with isolated PREPL deficiency, three with hypotonia-cystinuria syndrome, and two with atypical hypotonia-cystinuria syndrome had nine novel alleles. Their IQs ranged from 64 to 112. Adult neuromuscular signs included ptosis, nasal dysarthria, facial weakness, and variable proximal and neck flexor weakness. Autonomic features are prevalent. PREPL protein and reactivity were absent in lymphocytes from subjects with PREPL deficiency, but normal in the clinically similar Prader-Willi syndrome.ConclusionPREPL deficiency causes neuromuscular, autonomic, cognitive, endocrine, and dysmorphic clinical features. PREPL is not deficient in Prader-Willi syndrome. The novel blood test should facilitate the confirmation of PREPL deficiency.
Collapse
Affiliation(s)
- Luc Régal
- Laboratory of Biochemical Neuroendocrinology, Department of Human Genetics, University of Leuven, Leuven, Belgium.,Pediatric Neurology and Metabolism, Department of Pediatrics, UZ Brussel, Brussels, Belgium
| | - Emma Mårtensson
- Department of Clinical Genetics, Region Skåne and Lund University, Lund, Sweden
| | - Isabelle Maystadt
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Nicol Voermans
- Department of Neurology, RadboudUMC Nijmegen, Nijmegen, The Netherlands
| | - Damien Lederer
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Pediatrics, University Hospital Padova, Padova, Italy
| | - María Jesús Juan Fita
- Unidad de Metabolopatías, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
| | - A Jeannette M Hoogeboom
- Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | - Tess Hollemans
- Pediatric Neurology and Metabolism, Department of Pediatrics, UZ Brussel, Brussels, Belgium
| | - Meyke Schouten
- Department of Clinical Genetics, RadboudUMC Nijmegen, Nijmegen, The Netherlands
| | - Sandra Meulemans
- Laboratory of Biochemical Neuroendocrinology, Department of Human Genetics, University of Leuven, Leuven, Belgium
| | - Tord Jonson
- Department of Clinical Genetics, Region Skåne and Lund University, Lund, Sweden
| | - Inge François
- Department of Pediatric Endocrinology, UZ Leuven, Leuven, Belgium
| | - David Gil Ortega
- Unidad de Metabolopatías, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Erik-Jan Kamsteeg
- Department of Clinical Genetics, RadboudUMC Nijmegen, Nijmegen, The Netherlands
| | - John W M Creemers
- Laboratory of Biochemical Neuroendocrinology, Department of Human Genetics, University of Leuven, Leuven, Belgium
| |
Collapse
|
29
|
γ2 and γ1AP-1 complexes: Different essential functions and regulatory mechanisms in clathrin-dependent protein sorting. Eur J Cell Biol 2017; 96:356-368. [PMID: 28372831 DOI: 10.1016/j.ejcb.2017.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/24/2017] [Accepted: 03/24/2017] [Indexed: 11/20/2022] Open
Abstract
γ2 adaptin is homologous to γ1, but is only expressed in vertebrates while γ1 is found in all eukaryotes. We know little about γ2 functions and their relation to γ1. γ1 is an adaptin of the heterotetrameric AP-1 complexes, which sort proteins in and do form clathrin-coated transport vesicles and they also regulate maturation of early endosomes. γ1 knockout mice develop only to blastocysts and thus γ2 does not compensate γ1-deficiency in development. γ2 has not been classified as a clathrin-coated vesicle adaptor protein in proteome analyses and functions for monomeric γ2 in endosomal protein sorting have been proposed, but adaptin interaction studies suggested formation of heterotetrameric AP-1/γ2 complexes. We detected γ2 at the trans-Golgi network, on peripheral vesicles and identified γ2 clathrin-coated vesicles in mice. Ubiquitous σ1A and tissue-specific σ1B adaptins bind γ2 and γ1. σ1B knockout in mice does not effect γ1/σ1A AP-1 levels, but γ2/σ1A AP-1 levels are increased in brain and adipocytes. Also γ2 is essential in development. In zebrafish AP-1/γ2 and AP-1/γ1 fulfill different, essential functions in brain and the vascular system.
Collapse
|
30
|
Dib K, Tikhonova IG, Ivetic A, Schu P. The cytoplasmic tail of L-selectin interacts with the adaptor-protein complex AP-1 subunit μ1A via a novel basic binding motif. J Biol Chem 2017; 292:6703-6714. [PMID: 28235798 DOI: 10.1074/jbc.m116.768598] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/30/2017] [Indexed: 01/02/2023] Open
Abstract
L-selectin regulates leukocyte adhesion and rolling along the endothelium. Proteins binding to the cytoplasmic tail of L-selectin regulate L-selectin functions. We used L-selectin cytoplasmic tail peptide pulldown assays combined with high sensitivity liquid chromatography/mass spectrometry to identify novel L-selectin tail-binding proteins. Incubation of the L-selectin tail with cell extracts from phorbol 12-myristate 13-acetate-stimulated Raw 264.7 macrophages resulted in the binding of μ1A of the clathrin-coated vesicle AP-1 complex. Furthermore, full-length GST-μ1A and the GST-μ1A C-terminal domain, but not the GST-μ1A N-terminal domain, bind to L-selectin tail peptide, and the intracellular pool of L-selectin colocalizes with AP-1 at the trans-Golgi network. We identified a novel basic protein motif consisting of a cluster of three dibasic residues (356RR357, 359KK360, and 362KK363) in the membrane-proximal domain of the L-selectin tail as well as a doublet of aspartic acid residues (369DD370) in the membrane-distal end of the L-selectin tail involved in μ1A binding. Stimulation of Raw 264.7 macrophages with PMA augmented the amount of μ1A associated with anti-L-selectin immunoprecipitates. However, full-length GST-μ1A did not bind to the phospho-L-selectin tail or phospho-mimetic S364D L-selectin tail. Accordingly, we propose that phosphorylation of μ1A is required for interaction with the L-selectin tail and that L-selectin tail phosphorylation may regulate this interaction in vivo Molecular docking of the L-selectin tail to μ1A was used to identify the μ1A surface domain binding the L-selectin tail and to explain how phosphorylation of the L-selectin tail abrogates μ1A interaction. Our findings indicate that L-selectin is transported constitutively by the AP-1 complex, leading to the formation of a trans-Golgi network reserve pool and that phosphorylation of the L-selectin tail blocks AP-1-dependent retrograde transport of L-selectin.
Collapse
Affiliation(s)
- Karim Dib
- From the Max Planck Institute for Biochemistry, Department of Molecular Medicine, 82152 Martinsried, Germany, .,the Center for Experimental Medicine, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, United Kingdom
| | - Irina G Tikhonova
- the School of Pharmacy, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, United Kingdom
| | - Aleksandar Ivetic
- the BHF Center for Research Excellence, Cardiovascular Division, Faculty of Life Sciences and Medicine, King's College London, London SE5 9NU, United Kingdom, and
| | - Peter Schu
- University Medical Center Göttingen, Department of Cellular Biochemistry, Georg-August University Göttingen, D-37073 Göttingen, Germany
| |
Collapse
|
31
|
Lam CW, Wong KS, Leung HW, Law CY. Limb girdle myasthenia with digenic RAPSN and a novel disease gene AK9 mutations. Eur J Hum Genet 2016; 25:192-199. [PMID: 27966543 DOI: 10.1038/ejhg.2016.162] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 10/04/2016] [Accepted: 10/18/2016] [Indexed: 12/19/2022] Open
Abstract
Though dysfunction of neuromuscular junction (NMJ) is associated with congenital myasthenic syndrome (CMS), the proteins involved in neuromuscular transmission have not been completely identified. In this study, we aimed to identify a novel CMS gene in a consanguineous family with limb-girdle type CMS. Homozygosity mapping of the novel CMS gene was performed using high-density single-nucleotide polymorphism microarrays. The variants in CMS gene were identified by whole-exome sequencing (WES) and Sanger sequencing. A 20 MB-region of homozygosity (ROH) was mapped on chromosome 6q15-21. This was the only ROH that present in all clinically affected siblings and absent in all clinically unaffected siblings. WES showed a novel variant of AK9 gene located in this ROH. This variant was a start-gain mutation and introduced a cryptic 5'-UTR signal in intron 5 of the AK9 gene. The normal splicing signal would be interfered by the cryptic translation signal leading to defective splicing. Another 25 MB-ROH was found on chromosome 11p13-q12 in all siblings. WES showed a homozygous RAPSN pathogenic variant in this ROH. Since RAPSN-associated limb-girdle type CMS was only manifested in AK9 homozygous variant carriers, the disease phenotype was of digenic inheritance, and was determined by the novel disease modifier AK9 which provides NTPs for N-glycosylation. This is the first time that this specific genotype-phenotype correlation is reported. Importantly, the AK9-associated nucleotide deficiency may replete by dietary supplements. Since AK9 is a disease modifier, enhancing N-glycosylation by increasing dietary nucleotides may be a new therapeutic option for CMS patients.
Collapse
Affiliation(s)
- Ching-Wan Lam
- Department of Pathology, The University of Hong Kong, Hong Kong, China
| | - Ka-Sing Wong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Ho-Wan Leung
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Chun-Yiu Law
- Department of Pathology, The University of Hong Kong, Hong Kong, China
| |
Collapse
|
32
|
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
| |
Collapse
|
33
|
Candiello E, Kratzke M, Wenzel D, Cassel D, Schu P. AP-1/σ1A and AP-1/σ1B adaptor-proteins differentially regulate neuronal early endosome maturation via the Rab5/Vps34-pathway. Sci Rep 2016; 6:29950. [PMID: 27411398 PMCID: PMC4944158 DOI: 10.1038/srep29950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/24/2016] [Indexed: 12/26/2022] Open
Abstract
The σ1 subunit of the AP-1 clathrin-coated-vesicle adaptor-protein
complex is expressed as three isoforms. Tissues express σ1A and one of
the σ1B and σ1C isoforms. Brain is the tissue with the
highest σ1A and σ1B expression. σ1B-deficiency
leads to severe mental retardation, accumulation of early endosomes in synapses and
fewer synaptic vesicles, whose recycling is slowed down. AP-1/σ1A and
AP-1/σ1B regulate maturation of these early endosomes into
multivesicular body late endosomes, thereby controlling synaptic vesicle protein
transport into a degradative pathway. σ1A binds ArfGAP1, and with higher
affinity brain-specific ArfGAP1, which bind Rabex-5.
AP-1/σ1A-ArfGAP1-Rabex-5 complex formation leads to more endosomal
Rabex-5 and enhanced, Rab5GTP-stimulated Vps34 PI3-kinase activity,
which is essential for multivesicular body endosome formation. Formation of
AP-1/σ1A-ArfGAP1-Rabex-5 complexes is prevented by σ1B
binding of Rabex-5 and the amount of endosomal Rabex-5 is reduced. AP-1 complexes
differentially regulate endosome maturation and coordinate protein recycling and
degradation, revealing a novel molecular mechanism by which they regulate protein
transport besides their established function in clathrin-coated-vesicle
formation.
Collapse
Affiliation(s)
- Ermes Candiello
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Manuel Kratzke
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Dirk Wenzel
- Electron microscopy, Max-Planck-Institut for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Dan Cassel
- Israel Institute of Technology, Department Biology, Haifa 32000, Israel
| | - Peter Schu
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
| |
Collapse
|
34
|
Legati A, Reyes A, Nasca A, Invernizzi F, Lamantea E, Tiranti V, Garavaglia B, Lamperti C, Ardissone A, Moroni I, Robinson A, Ghezzi D, Zeviani M. New genes and pathomechanisms in mitochondrial disorders unraveled by NGS technologies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1326-1335. [PMID: 26968897 DOI: 10.1016/j.bbabio.2016.02.022] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 02/17/2016] [Accepted: 02/27/2016] [Indexed: 12/13/2022]
Abstract
Next Generation Sequencing (NGS) technologies are revolutionizing the diagnostic screening for rare disease entities, including primary mitochondrial disorders, particularly those caused by nuclear gene defects. NGS approaches are able to identify the causative gene defects in small families and even single individuals, unsuitable for investigation by traditional linkage analysis. These technologies are contributing to fill the gap between mitochondrial disease cases defined on the basis of clinical, neuroimaging and biochemical readouts, which still outnumber by approximately 50% the cases for which a molecular-genetic diagnosis is attained. We have been using a combined, two-step strategy, based on targeted genes panel as a first NGS screening, followed by whole exome sequencing (WES) in still unsolved cases, to analyze a large cohort of subjects, that failed to show mutations in mtDNA and in ad hoc sets of specific nuclear genes, sequenced by the Sanger's method. Not only this approach has allowed us to reach molecular diagnosis in a significant fraction (20%) of these difficult cases, but it has also revealed unexpected and conceptually new findings. These include the possibility of marked variable penetrance of recessive mutations, the identification of large-scale DNA rearrangements, which explain spuriously heterozygous cases, and the association of mutations in known genes with unusual, previously unreported clinical phenotypes. Importantly, WES on selected cases has unraveled the presence of pathogenic mutations in genes encoding non-mitochondrial proteins (e.g. the transcription factor E4F1), an observation that further expands the intricate genetics of mitochondrial disease and suggests a new area of investigation in mitochondrial medicine. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
Collapse
Affiliation(s)
- Andrea Legati
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Aurelio Reyes
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK
| | - Alessia Nasca
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Federica Invernizzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Eleonora Lamantea
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Valeria Tiranti
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Barbara Garavaglia
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Costanza Lamperti
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Anna Ardissone
- Unit of Child Neurology, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20133 Milan, Italy
| | - Isabella Moroni
- Unit of Child Neurology, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20133 Milan, Italy
| | - Alan Robinson
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK
| | - Daniele Ghezzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy.
| | - Massimo Zeviani
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK.
| |
Collapse
|
35
|
Arredondo J, Lara M, Gospe SM, Mazia CG, Vaccarezza M, Garcia-Erro M, Bowe CM, Chang CH, Mezei MM, Maselli RA. Choline Acetyltransferase Mutations Causing Congenital Myasthenic Syndrome: Molecular Findings and Genotype-Phenotype Correlations. Hum Mutat 2015; 36:881-93. [PMID: 26080897 DOI: 10.1002/humu.22823] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/06/2015] [Indexed: 11/08/2022]
Abstract
Choline acetyltransferase catalyzes the synthesis of acetylcholine at cholinergic nerves. Mutations in human CHAT cause a congenital myasthenic syndrome due to impaired synthesis of ACh; this severe variant of the disease is frequently associated with unexpected episodes of potentially fatal apnea. The severity of this condition varies remarkably, and the molecular factors determining this variability are poorly understood. Furthermore, genotype-phenotype correlations have been difficult to establish in patients with biallelic mutations. We analyzed the protein expression of phosphorylated ChAT of seven CHAT mutations, p.Val136Met, p.Arg207His, p.Arg186Trp, p.Val194Leu, p.Pro211Ala, p.Arg566Cys, and p.Ser694Cys, in HEK-293 cells to phosphorylated ChAT, determined their enzyme kinetics and thermal stability, and examined their structural changes. Three mutations, p.Arg207His, p.Arg186Trp, and p.Arg566Cys, are novel, and p.Val136Met and p.Arg207His are homozygous in three families and associated with severe disease. The characterization of mutants showed a decrease in the overall catalytic efficiency of ChAT; in particular, those located near the active-site tunnel produced the most seriously disruptive phenotypic effects. On the other hand, p.Val136Met, which is located far from both active and substrate-binding sites, produced the most drastic reduction of ChAT expression. Overall, CHAT mutations producing low enzyme expression and severe kinetic effects are associated with the most severe phenotypes.
Collapse
Affiliation(s)
- Juan Arredondo
- Department of Neurology, University of California Davis, Davis, California
| | - Marian Lara
- Department of Neurology, University of California Davis, Davis, California
| | - Sídney M Gospe
- Departments of Neurology and Pediatrics, University of Washington, and Seattle Children's Hospital, Seattle, Washington
| | - Claudio G Mazia
- Department of Neurology, Instituto de Investigaciones Médicas A Lanari-UBA, Buenos Aires, Argentina
| | - Maria Vaccarezza
- Servicio de Neurología Pediátrica, Hospital Italiano, Buenos Aires, Argentina
| | - Marcela Garcia-Erro
- Sector Enfermedades Neuromusculares Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina
| | - Constance M Bowe
- Department of Neurology, University of California Davis, Davis, California
| | - Celia H Chang
- Department of Neurology, University of California Davis, Davis, California
| | - Michelle M Mezei
- Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Ricardo A Maselli
- Department of Neurology, University of California Davis, Davis, California
| |
Collapse
|
36
|
Evangelista T, Hanna M, Lochmüller H. Congenital Myasthenic Syndromes with Predominant Limb Girdle Weakness. J Neuromuscul Dis 2015; 2:S21-S29. [PMID: 26870666 PMCID: PMC4746746 DOI: 10.3233/jnd-150098] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Congenital myasthenic syndromes are a heterogeneous group of genetically determined disorders characterized by impaired neuromuscular transmission. They usually present from birth to childhood and are characterised by exercise induced weakness and fatigability. Genotype-phenotype correlations are difficult. However, in some patients particular phenotypic aspects may point towards a specific genetic defect. The absence of ptosis and ophthalmoparesis in patients with limb-girdle weakness makes the diagnosis of a neuromuscular transmission defect particularly challenging (LG-CMS). This is illustrated by a well-documented case published by Walton in 1956. The diagnosis of LG-CMS is secured by demonstrating a neuromuscular transmission defect with single fibre EMG or repetitive nerve stimulation, in the absence of auto-antibodies. Ultimately, a genetic test is required to identify the underlying cause and assure counselling and optimization of treatment. LG-CMS are inherited in autosomal recessive traits, and are often associated with mutations in DOK7 and GFPT1, and less frequently with mutations in COLQ, ALG2, ALG14 and DPAGT. Genetic characterization of CMS is of the upmost importance when choosing the adequate treatment. Some of the currently used drugs can either ameliorate or aggravate the symptoms depending on the underlying genetic defect. The drug most frequently used for the treatment of CMS is pyridostigmine an acetylcholinesterase inhibitor. However, pyridostigmine is not effective or is even detrimental in DOK7- and COLQ-related LG-CMS, while beta-adrenergic agonists (ephedrine, salbutamol) show some sustained benefit. Standard clinical trials may be difficult, but standardized follow-up of patients and international collaboration may help to improve the standards of care of these conditions.
Collapse
Affiliation(s)
- Teresinha Evangelista
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, UK
| | - Mike Hanna
- UCL MRC Centre for Neuromuscular Disease, Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, UK
| |
Collapse
|
37
|
Engel AG, Shen XM, Selcen D, Sine SM. Congenital myasthenic syndromes: pathogenesis, diagnosis, and treatment. Lancet Neurol 2015; 14:420-34. [PMID: 25792100 PMCID: PMC4520251 DOI: 10.1016/s1474-4422(14)70201-7] [Citation(s) in RCA: 333] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The congenital myasthenic syndromes (CMS) are a diverse group of genetic disorders caused by abnormal signal transmission at the motor endplate, a special synaptic contact between motor axons and each skeletal muscle fibre. Most CMS stem from molecular defects in the muscle nicotinic acetylcholine receptor, but they can also be caused by mutations in presynaptic proteins, mutations in proteins associated with the synaptic basal lamina, defects in endplate development and maintenance, or defects in protein glycosylation. The specific diagnosis of some CMS can sometimes be reached by phenotypic clues pointing to the mutated gene. In the absence of such clues, exome sequencing is a useful technique for finding the disease gene. Greater understanding of the mechanisms of CMS have been obtained from structural and electrophysiological studies of the endplate, and from biochemical studies. Present therapies for the CMS include cholinergic agonists, long-lived open-channel blockers of the acetylcholine receptor ion channel, and adrenergic agonists. Although most CMS are treatable, caution should be exercised as some drugs that are beneficial in one syndrome can be detrimental in another.
Collapse
Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| |
Collapse
|
38
|
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.
Collapse
|
39
|
|
40
|
Eymard B, Hantaï D, Fournier E, Nicole S, Sternberg D, Richard P, Fardeau M. Syndromes myasthéniques congénitaux — L’expérience française. BULLETIN DE L ACADEMIE NATIONALE DE MEDECINE 2014. [DOI: 10.1016/s0001-4079(19)31341-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|