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Chawla T, Nashi S, Baskar D, Polavarapu K, Vengalil S, Bardhan M, Preethish-Kumar V, Sukrutha R, Unnikrishnan G, Huddar A, Padmanabha H, Anjanappa RM, Bevinahalli N, Nittur V, Rajanna M, Arunachal Udupi G, Nalini A. Phenotype-genotype spectrum of a cohort of congenital muscular dystrophies: a single-centre experience from India. Neurogenetics 2024; 25:435-469. [PMID: 39103709 DOI: 10.1007/s10048-024-00776-6] [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] [Received: 04/29/2024] [Accepted: 07/19/2024] [Indexed: 08/07/2024]
Abstract
Congenital Muscular Dystrophies (CMD) are phenotypically and genotypically heterogenous disorders with a prevalence of 0.68 to 2.5/100,000, contributing to significant morbidity and mortality. We aimed to study the phenotype-genotype spectrum of genetically confirmed cases of CMD. This was retrospective & descriptive study done at a quaternary care referral centre in south India. Genetically confirmed cases of CMDs seen between 2010 to 2020 were recruited. Detailed clinical history, including pedigree, MRI brain/muscle, next generation sequencing results of 61 CMD cases were collected. Collagen VI-related dystrophy (COL6-RD) (36%) was the most common subtype with variants frequently seen in COL6A1 gene. Other CMDs identified were LAMA2-RD (26%), alpha-dystroglycan-RD (19%), LMNA-RD (8%), CHKB-RD (7%) and SEPN1-RD (3%). Similar to previous cohorts, overall, missense variants were common in COL-6 RD. Variants in triple helical domain (THD) of COL6-RD were seen in 11/22 patients, 5 of whom were ambulatory contrary to previous literature citing severe disease with these variants. However, our follow-up period was shorter. In the LAMA2-RD, 2/16 patients were ambulatory & all 16 carried truncating variants. Among dystroglycanopathies, FKRP-RD was the commonest. Milder phenotype of FKRP- RD was observed with variant c.1343C > T, which was also a recurrent variant in our cohort. p.Arg249Trp variant in LMNA-CMD associated with early loss of ambulation was also identified in 1/5 of our patients who expired at age 2.8 years. The current retrospective series provides detailed clinical features and mutation patterns of genetically confirmed cases of CMD from a single center in India.
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Affiliation(s)
- Tanushree Chawla
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Saraswati Nashi
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Dipti Baskar
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - Seena Vengalil
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Mainak Bardhan
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Veeramani Preethish-Kumar
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Ramya Sukrutha
- Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Gopikrishnan Unnikrishnan
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Akshata Huddar
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Hansashree Padmanabha
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Ram Murthy Anjanappa
- Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Nandeesh Bevinahalli
- Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bengaluru, 560029, India
| | - Vidya Nittur
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Manoj Rajanna
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Gautham Arunachal Udupi
- Department of Human Genetics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India
| | - Atchayaram Nalini
- Department of Neurology, Neuroscience Faculty Center, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, 560029, India.
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Zhao X, Gao C, Li L, Jiang L, Wei Y, Che F, Liu Q. Clinical exome sequencing identifies novel compound heterozygous mutations of the POMT2 gene in patients with limb-girdle muscular dystrophy. Int J Dev Neurosci 2023; 83:23-30. [PMID: 36217604 DOI: 10.1002/jdn.10233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE Mutations in protein O-mannosyltransferase 2 (POMT2) (MIM#607439) have been identified in severe congenital muscular dystrophy such as Walker-Warburg syndrome (WWS) and milder limb-girdle muscular dystrophy type 2N (LGMD2N). The aim of this study is to investigate the genetic causes in patients with LGMD2N. METHODS Three patients diagnosed with mild limb-girdle muscular dystrophy were recruited. The genetically pathogenic variant was identified by clinical exome sequencing, and healthy controls were verified by Sanger sequencing. RESULTS Novel compound heterozygous mutations c.800A > G and c.1074_1075delinsAT of POMT2 were revealed in one affected individual by clinical exome sequencing. There was no report of these two variants and predicted to be highly damaging to the function of the POMT2. CONCLUSION The novel variants extend the spectrum of POMT2 mutations, which promotes the prognostic value of testing for POMT2 mutations in patients with LGMD2N.
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Affiliation(s)
- Xiangyu Zhao
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Chunhai Gao
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Lin Li
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Liangqian Jiang
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Yuda Wei
- Department of Clinical Laboratory, Linyi People's Hospital, Shandong University, Linyi, China
| | - Fengyuan Che
- Department of Central Laboratory, Linyi People's Hospital, Shandong University, Linyi, China.,Department of Neurology, Linyi People's Hospital, Shandong University, Linyi, China
| | - Qiji Liu
- Key Laboratory for Experimental Teratology of the Ministry of Education, Department of Medical Genetics, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
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A homozygous mutation in the POMT2 gene in four siblings with limb-girdle muscular dystrophy 2N. Turk Arch Pediatr 2021; 56:68-71. [PMID: 34013233 DOI: 10.14744/turkpediatriars.2020.37880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/09/2020] [Indexed: 11/20/2022]
Abstract
Mutations in protein O-mannosyltransferase 2 can cause a wide spectrum of clinical phenotypes from severe congenital muscular dystrophy such as Walker-Warburg syndrome to milder limb-girdle muscular dystrophy 2N. We aimed to describe the clinical and paraclinical features, laboratory tests, and molecular findings of four siblings with a homozygous mutation in the protein O-mannosyltransferase 2 gene. There were two sisters and two brothers, aged 4 to 17 years, with an age of onset symptoms at 3 to 12 years. The main neurologic findings were mild intellectual disability, hypoactive deep tendon reflexes, symmetrical weakness of the proximal lower and/or upper limbs, and difficulties in walking on heels and/or toes. The scoliosis found in two siblings has not been associated with protein O-mannosyltransferase 2 gene mutations related to limb-girdle muscular dystrophy 2N in previous reports. This report expands the phenotypic spectrum of protein O-mannosyltransferase 2 gene mutation-related limb-girdle muscular dystrophy 2N.
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Nguyen NL, Ngoc CTB, Vu CD, Nguyen TTH, Nguyen HH. Whole Exome Sequencing as a Diagnostic Tool for Unidentified Muscular Dystrophy in a Vietnamese Family. Diagnostics (Basel) 2020; 10:741. [PMID: 32987775 PMCID: PMC7598670 DOI: 10.3390/diagnostics10100741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 11/17/2022] Open
Abstract
Muscular dystrophies are a group of heterogeneous clinical and genetic disorders. Two siblings presented with characteristics like muscular dystrophy, abnormal white matter, and elevated serum creatine kinase level. The high throughput of whole exome sequencing (WES) makes it an efficient tool for obtaining a precise diagnosis without the need for immunohistochemistry. WES was performed in the two siblings and their parents, followed by prioritization of variants and validation by Sanger sequencing. Very rare variants with moderate to high predicted impact in genes associated with neuromuscular disorders were selected. We identified two pathogenic missense variants, c.778C>T (p.H260Y) and c.2987G>A (p.C996Y), in the LAMA2 gene (NM_000426.3), in the homozygous state in two siblings, and in the heterozygous state in their unaffected parents, which were confirmed by Sanger sequencing. Variant c.2987G>A has not been reported previously. These variants may lead to a change in the structure and function of laminin-α2, a member of the family of laminin-211, which is an extracellular matrix protein that functions to stabilize the basement membrane of muscle fibers during contractions. Overall, WES enabled an accurate diagnosis of both patients with LAMA2-related muscular dystrophy and expanded the spectrum of missense variants in LAMA2.
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Affiliation(s)
- Ngoc-Lan Nguyen
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Cau Giay, Hanoi 100000, Vietnam; (N.-L.N.); (T.T.H.N.)
- Institute of Genome Research, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Cau Giay, Hanoi 100000, Vietnam
| | - Can Thi Bich Ngoc
- Center for Rare Diseases and Newborn Screening, Department of Endocrinology, Metabolism and Genetics, Vietnam National Children’s Hospital, 18/879 La Thanh str., Dong Da, Hanoi 100000, Vietnam; (C.T.B.N.); (C.D.V.)
| | - Chi Dung Vu
- Center for Rare Diseases and Newborn Screening, Department of Endocrinology, Metabolism and Genetics, Vietnam National Children’s Hospital, 18/879 La Thanh str., Dong Da, Hanoi 100000, Vietnam; (C.T.B.N.); (C.D.V.)
| | - Thi Thu Huong Nguyen
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Cau Giay, Hanoi 100000, Vietnam; (N.-L.N.); (T.T.H.N.)
| | - Huy Hoang Nguyen
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Cau Giay, Hanoi 100000, Vietnam; (N.-L.N.); (T.T.H.N.)
- Institute of Genome Research, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Cau Giay, Hanoi 100000, Vietnam
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Mahjoub G, Faghihi MA, Taghdiri M. Reporting one very rare pathogenic variation c.1106G>A in POMT2 gene. Intractable Rare Dis Res 2020; 9:104-108. [PMID: 32494558 PMCID: PMC7263986 DOI: 10.5582/irdr.2020.03013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Dystroglycan (DG) is a major cell membrane glycoprotein, which is encoded by the DAG1 gene. α-DG is one of DG subunits, belongs to O-mannosylated protein of mammals and was identified in brain, peripheral nerves and muscle. Dystroglycanopathies are a group of heterogeneous congenital muscular dystrophies, which can result from defective α-DG mannosylation. First line of α-DG glycosylation is catalyzed by protein O-mannosyltransferase family (PMT). In this study, the mutation was identified in the POMT2 gene, which encodes O-mannosyltransferase 2 protein and its mutations can be contributed to dystroglycanopathies. A very rare missense mutation in the POMT2 gene (NM_013382: exon9: c. 1106G>A) was identified by next generation sequencing (NGS) and was subsequently confirmed using Sanger sequencing in both affected siblings. There was no report of this mutation in the literature, therefore, the significance was uncertain. Our findings confirmed the pathogenicity of mutation and expanded the mutation spectrum of POMT2, which will be helpful in further molecular evaluations of muscular diseases.
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Affiliation(s)
- Ghazale Mahjoub
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Faghihi
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, USA
| | - Maryam Taghdiri
- Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran
- Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Address correspondence to:Maryam Taghdiri, Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran and Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran. E-mail:
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7
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Finsterer J. Phenotypic heterogeneity of POMT2
gene variants. Am J Med Genet A 2018; 176:743-745. [DOI: 10.1002/ajmg.a.38588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/03/2017] [Accepted: 12/01/2017] [Indexed: 11/06/2022]
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Nabhan MM, ElKhateeb N, Braun DA, Eun S, Saleem SN, YungGee H, Hildebrandt F, Soliman NA. Cystic kidneys in fetal Walker-Warburg syndrome with POMT2 mutation: Intrafamilial phenotypic variability in four siblings and review of literature. Am J Med Genet A 2017; 173:2697-2702. [PMID: 28815891 DOI: 10.1002/ajmg.a.38393] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 07/11/2017] [Accepted: 07/18/2017] [Indexed: 11/11/2022]
Abstract
Walker-Warburg syndrome (WWS) is a severe form of congenital muscular dystrophy secondary to α-dystroglycanopathy with muscle, brain, and eye abnormalities often leading to death in the first weeks of life. It is transmitted in an autosomal recessive pattern, and has been linked to at least 15 different genes; including protein O-mannosyltransferase 1 (POMT1), protein O-mannosyltransferase 2 (POMT2), protein O-mannose beta-1,2-N acetylglucosaminyltransferase (POMGNT1), fukutin (FKTN), isoprenoid synthase domain-containing protein (ISPD), and other genes. We report on a consanguineous family with four consecutive siblings affected by this condition with lethal outcome in three (still birth), and termination of the fourth pregnancy based on antenatal MRI identification of brain and kidney anomalies that heralded proper and deep clinical phenotyping. The diagnosis of WWS was suggested based on the unique collective phenotype comprising brain anomalies in the form of lissencephaly, subcortical/subependymal heterotopia, and cerebellar hypoplasia shared by all four siblings; microphthalmia in one sibling; and large cystic kidneys in the fetus and another sibling. Other unshared neurological abnormalities included hydrocephalus and Dandy-Walker malformation. Whole exome sequencing of the fetus revealed a highly conserved missense mutation in POMT2 that is known to cause WWS with brain and eye anomalies.In conclusion, the heterogeneous clinical presentation in the four affected conceptions with POMT2 mutation expands the current clinical spectrum of POMT2-associated WWS to include large cystic kidneys; and confirms intra-familial variability in terms of brain, kidney, and eye anomalies.
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Affiliation(s)
- Marwa M Nabhan
- Department of Pediatrics, Centre of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - Nour ElKhateeb
- Department of Pediatrics, Centre of Pediatric Neurology & Metabolic diseases, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Daniela A Braun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sungho Eun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sahar N Saleem
- Department of Radiology, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Heon YungGee
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.,Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Neveen A Soliman
- Department of Pediatrics, Centre of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
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Larsen ISB, Narimatsu Y, Joshi HJ, Yang Z, Harrison OJ, Brasch J, Shapiro L, Honig B, Vakhrushev SY, Clausen H, Halim A. Mammalian O-mannosylation of cadherins and plexins is independent of protein O-mannosyltransferases 1 and 2. J Biol Chem 2017; 292:11586-11598. [PMID: 28512129 DOI: 10.1074/jbc.m117.794487] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Indexed: 11/06/2022] Open
Abstract
Protein O-mannosylation is found in yeast and metazoans, and a family of conserved orthologous protein O-mannosyltransferases is believed to initiate this important post-translational modification. We recently discovered that the cadherin superfamily carries O-linked mannose (O-Man) glycans at highly conserved residues in specific extracellular cadherin domains, and it was suggested that the function of E-cadherin was dependent on the O-Man glycans. Deficiencies in enzymes catalyzing O-Man biosynthesis, including the two human protein O-mannosyltransferases, POMT1 and POMT2, underlie a subgroup of congenital muscular dystrophies designated α-dystroglycanopathies, because deficient O-Man glycosylation of α-dystroglycan disrupts laminin interaction with α-dystroglycan and the extracellular matrix. To explore the functions of O-Man glycans on cadherins and protocadherins, we used a combinatorial gene-editing strategy in multiple cell lines to evaluate the role of the two POMTs initiating O-Man glycosylation and the major enzyme elongating O-Man glycans, the protein O-mannose β-1,2-N-acetylglucosaminyltransferase, POMGnT1. Surprisingly, O-mannosylation of cadherins and protocadherins does not require POMT1 and/or POMT2 in contrast to α-dystroglycan, and moreover, the O-Man glycans on cadherins are not elongated. Thus, the classical and evolutionarily conserved POMT O-mannosylation pathway is essentially dedicated to α-dystroglycan and a few other proteins, whereas a novel O-mannosylation process in mammalian cells is predicted to serve the large cadherin superfamily and other proteins.
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Affiliation(s)
- Ida Signe Bohse Larsen
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Yoshiki Narimatsu
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Hiren Jitendra Joshi
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Zhang Yang
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | | | - Julia Brasch
- the Department of Biochemistry and Molecular Biophysics
| | - Lawrence Shapiro
- the Department of Biochemistry and Molecular Biophysics.,Zuckerman Mind Brain Behavior Institute, Department of Systems Biology, and
| | - Barry Honig
- the Department of Biochemistry and Molecular Biophysics.,Zuckerman Mind Brain Behavior Institute, Department of Systems Biology, and.,Howard Hughes Medical Institute Columbia University, New York, New York 10032
| | - Sergey Y Vakhrushev
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Henrik Clausen
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Adnan Halim
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
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11
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Praissman JL, Wells L. Mammalian O-mannosylation pathway: glycan structures, enzymes, and protein substrates. Biochemistry 2014; 53:3066-78. [PMID: 24786756 PMCID: PMC4033628 DOI: 10.1021/bi500153y] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The
mammalian O-mannosylation pathway for protein post-translational
modification is intricately involved in modulating cell–matrix
interactions in the musculature and nervous system. Defects in enzymes
of this biosynthetic pathway are causative for multiple forms of congenital
muscular dystophy. The application of advanced genetic and biochemical
technologies has resulted in remarkable progress in this field over
the past few years, culminating with the publication of three landmark
papers in 2013 alone. In this review, we will highlight recent progress
focusing on the dramatic expansion of the set of genes known to be
involved in O-mannosylation and disease processes, the concurrent
acceleration of the rate of O-mannosylation pathway protein functional
assignments, the tremendous increase in the number of proteins now
known to be modified by O-mannosylation, and the recent progress in
protein O-mannose glycan quantification and site assignment. Also,
we attempt to highlight key outstanding questions raised by this abundance
of new information.
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Affiliation(s)
- Jeremy L Praissman
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, The University of Georgia , Athens, Georgia 30602, United States
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A fourth case of POMT2-related limb girdle muscle dystrophy with mild reduction of α-dystroglycan glycosylation. Eur J Paediatr Neurol 2014; 18:404-8. [PMID: 24183756 DOI: 10.1016/j.ejpn.2013.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/17/2013] [Accepted: 10/17/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND POMT2 mutations have been identified in Walker-Warburg syndrome or muscle-eye-brain-like, but rarely in limb girdle muscular dystrophy (LGMD). RESULTS Two POMT2 mutations, one null and one missense, were found in a patient with LGMD and mild mental impairment, no brain or ocular involvement, minor histopathological features, and slight reduction of α-dystroglycan (α-DG) glycosylation and α-DG laminin binding. CONCLUSIONS Our case, the fourth LGMD POMT2-mutated reported to date, provides further evidence of correlation between level of α-DG glycosylation and phenotype severity.
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Wells L. The o-mannosylation pathway: glycosyltransferases and proteins implicated in congenital muscular dystrophy. J Biol Chem 2013; 288:6930-5. [PMID: 23329833 DOI: 10.1074/jbc.r112.438978] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Several forms of congenital muscular dystrophy, referred to as dystroglycanopathies, result from defects in the protein O-mannosylation biosynthetic pathway. In this minireview, I discuss 12 proteins involved in the pathway and how they play a role in the building of glycan structures (most notably on the protein α-dystroglycan) that allow for binding to multiple proteins of the extracellular matrix.
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Affiliation(s)
- Lance Wells
- Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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14
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Gomez Toledo A, Raducu M, Cruces J, Nilsson J, Halim A, Larson G, Rüetschi U, Grahn A. O-Mannose and O-N-acetyl galactosamine glycosylation of mammalian α-dystroglycan is conserved in a region-specific manner. Glycobiology 2012; 22:1413-23. [PMID: 22781125 DOI: 10.1093/glycob/cws109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Defects in the O-linked glycosylation of the peripheral membrane protein α-dystroglycan (α-DG) are the main cause of several forms of congenital muscular dystrophies and thus the characterization of the glycosylation of α-DG is of great medical importance. A detailed investigation of the glycosylation pattern of the native α-DG protein is essential for the understanding of the biological processes related to human disease in which the protein is involved. To date, several studies have reported novel O-glycans and attachment sites on the mucin-like domain of mammalian α-DG with both similar and contradicting glycosylation patterns, indicating the species-specific O-glycosylation of mammalian α-DG. By applying a standardized purification scheme and subsequent glycoproteomic analysis of native α-DG from rabbit and human skeletal muscle biopsies and from cultured mouse C2C12 myotubes, we show that the O-glycosylation patterns of the mucin-like domain of native α-DG are conserved among mammalians in a region-specific manner.
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Affiliation(s)
- Alejandro Gomez Toledo
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden
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Barkovich AJ, Guerrini R, Kuzniecky RI, Jackson GD, Dobyns WB. A developmental and genetic classification for malformations of cortical development: update 2012. Brain 2012; 135:1348-69. [PMID: 22427329 PMCID: PMC3338922 DOI: 10.1093/brain/aws019] [Citation(s) in RCA: 698] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Malformations of cerebral cortical development include a wide range of developmental disorders that are common causes of neurodevelopmental delay and epilepsy. In addition, study of these disorders contributes greatly to the understanding of normal brain development and its perturbations. The rapid recent evolution of molecular biology, genetics and imaging has resulted in an explosive increase in our knowledge of cerebral cortex development and in the number and types of malformations of cortical development that have been reported. These advances continue to modify our perception of these malformations. This review addresses recent changes in our perception of these disorders and proposes a modified classification based upon updates in our knowledge of cerebral cortical development.
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Affiliation(s)
- A James Barkovich
- Neuroradiology, University of California at San Francisco, 505 Parnassus Avenue, San Francisco, CA 94913-0628, USA.
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16
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Abstract
Glycosylation is an essential process by which sugars are attached to proteins and lipids. Complete lack of glycosylation is not compatible with life. Because of the widespread function of glycosylation, inherited disorders of glycosylation are multisystemic. Since the identification of the first defect on N-linked glycosylation in the 1980s, there are over 40 different congenital protein hypoglycosylation diseases. This review will include defects of N-linked glycosylation, O-linked glycosylation and disorders of combined N- and O-linked glycosylation.
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Affiliation(s)
- Susan E Sparks
- Department of Pediatrics, Levine Children's Hospital at Carolinas Medical Center, Charlotte, NC, USA; Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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18
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Nilsson J, Nilsson J, Larson G, Grahn A. Characterization of site-specific O-glycan structures within the mucin-like domain of alpha-dystroglycan from human skeletal muscle. Glycobiology 2010; 20:1160-9. [PMID: 20507882 DOI: 10.1093/glycob/cwq082] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The glycosylation of the extracellular protein alpha-dystroglycan is important for its ligand-binding activity, and altered or blocked glycosylation is associated with several forms of congenital muscular dystrophies. By immunoprecipitation and sialic acid capture-and-release enrichment strategies, we isolated tryptic glycopeptides of alpha-dystroglycan from human skeletal muscle. Nano-liquid chromatography tandem mass spectrometry was used to identify both glycopeptides and peptides corresponding to the mucin-like and C-terminal domain of alpha-dystroglycan. The O-glycans found had either Hex-O-Thr or HexNAc-O-Ser/Thr anchored structures, which were often elongated and frequently, but not always, terminated with sialic acid. The HexNAc-O-Ser/Thr, but not Hex-O-Thr glycopeptides, displayed heterogeneity regarding glycan core structures and level of glycosylation site occupancy. We demonstrate for the first time glycan attachment sites of the NeuAcHexHexNAcHex-O structure corresponding to the anticipated Neu5Acalpha3Galbeta4GlcNAcbeta2Man-O-glycan (sLacNAc-Man), within the mucin-like domain of human alpha-dystroglycan from human skeletal muscle. Twenty-five glycopeptides were characterized from human alpha-dystroglycan, which provide insight to the complex in vivo O-glycosylation of alpha-dystroglycan.
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Affiliation(s)
- Johanna Nilsson
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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19
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Reed UC. Congenital muscular dystrophy. Part II: a review of pathogenesis and therapeutic perspectives. ARQUIVOS DE NEURO-PSIQUIATRIA 2010; 67:343-62. [PMID: 19547838 DOI: 10.1590/s0004-282x2009000200035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/14/2009] [Indexed: 11/22/2022]
Abstract
The congenital muscular dystrophies (CMDs) are a group of genetically and clinically heterogeneous hereditary myopathies with preferentially autosomal recessive inheritance, that are characterized by congenital hypotonia, delayed motor development and early onset of progressive muscle weakness associated with dystrophic pattern on muscle biopsy. The clinical course is broadly variable and can comprise the involvement of the brain and eyes. From 1994, a great development in the knowledge of the molecular basis has occurred and the classification of CMDs has to be continuously up dated. In the last number of this journal, we presented the main clinical and diagnostic data concerning the different subtypes of CMD. In this second part of the review, we analyse the main reports from the literature concerning the pathogenesis and the therapeutic perspectives of the most common subtypes of CMD: MDC1A with merosin deficiency, collagen VI related CMDs (Ullrich and Bethlem), CMDs with abnormal glycosylation of alpha-dystroglycan (Fukuyama CMD, Muscle-eye-brain disease, Walker Warburg syndrome, MDC1C, MDC1D), and rigid spine syndrome, another much rare subtype of CMDs not related with the dystrophin/glycoproteins/extracellular matrix complex.
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20
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Jimenez-Mallebrera C, Torelli S, Feng L, Kim J, Godfrey C, Clement E, Mein R, Abbs S, Brown SC, Campbell KP, Kröger S, Talim B, Topaloglu H, Quinlivan R, Roper H, Childs AM, Kinali M, Sewry CA, Muntoni F. A comparative study of alpha-dystroglycan glycosylation in dystroglycanopathies suggests that the hypoglycosylation of alpha-dystroglycan does not consistently correlate with clinical severity. Brain Pathol 2009; 19:596-611. [PMID: 18691338 PMCID: PMC2860390 DOI: 10.1111/j.1750-3639.2008.00198.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Accepted: 06/13/2008] [Indexed: 11/25/2022] Open
Abstract
Hypoglycosylation of alpha-dystroglycan underpins a subgroup of muscular dystrophies ranging from congenital onset of weakness, severe brain malformations and death in the perinatal period to mild weakness in adulthood without brain involvement. Mutations in six genes have been identified in a proportion of patients. POMT1, POMT2 and POMGnT1 encode for glycosyltransferases involved in the mannosylation of alpha-dystroglycan but the function of fukutin, FKRP and LARGE is less clear. The pathological hallmark is reduced immunolabeling of skeletal muscle with antibodies recognizing glycosylated epitopes on alpha-dystroglycan. If the common pathway of these conditions is the hypoglycosyation of alpha-dystroglycan, one would expect a correlation between clinical severity and the extent of hypoglycosylation. By studying 24 patients with mutations in these genes, we found a good correlation between reduced alpha-dystroglycan staining and clinical course in patients with mutations in POMT1, POMT2 and POMGnT1. However, this was not always the case in patients with defects in fukutin and FKRP, as we identified patients with mild limb-girdle phenotypes without brain involvement with profound depletion of alpha-dystroglycan. These data indicate that it is not always possible to correlate clinical course and alpha-dystroglycan labeling and suggest that there might be differences in alpha-dystroglycan processing in these disorders.
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Affiliation(s)
- Cecilia Jimenez-Mallebrera
- Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital for Children, UCL, London, UK.
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21
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Hewitt JE. Abnormal glycosylation of dystroglycan in human genetic disease. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1792:853-861. [PMID: 19539754 DOI: 10.1016/j.bbadis.2009.06.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/05/2009] [Accepted: 06/10/2009] [Indexed: 10/20/2022]
Abstract
The dystroglycanopathies are a group of inherited muscular dystrophies that have a common underlying mechanism, hypoglycosylation of the extracellular receptor alpha-dystroglycan. Many of these disorders are also associated with defects in the central nervous system and the eye. Defects in alpha-dystroglycan may also play a role in cancer progression. This review discusses the six dystroglycanopathy genes identified so far, their known or proposed roles in dystroglycan glycosylation and their relevance to human disease, and some of animal models now available for the study of the dystroglycanopathies.
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Affiliation(s)
- Jane E Hewitt
- Institute of Genetics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
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22
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MURAKAMI T, HAYASHI YK, OGAWA M, NOGUCHI S, CAMPBELL KP, TOGAWA M, INOUE T, OKA A, OHNO K, NONAKA I, NISHINO I. A novel POMT2 mutation causes mild congenital muscular dystrophy with normal brain MRI. Brain Dev 2009; 31:465-8. [PMID: 18804929 PMCID: PMC2702532 DOI: 10.1016/j.braindev.2008.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 07/18/2008] [Accepted: 08/06/2008] [Indexed: 10/21/2022]
Abstract
We report a patient harboring a novel homozygous mutation of c.604T>G (p.F202V) in POMT2. He showed delayed psychomotor development but acquired the ability to walk at the age of 3 years and 10 months. His brain MRI was normal. No ocular abnormalities were seen. Biopsied skeletal muscle revealed markedly decreased but still detectable glycosylated forms of alpha-dystroglycan (alpha-DG). Our results indicate that mutations in POMT2 can cause a wide spectrum of clinical phenotypes as observed in other genes associated with alpha-dystroglycanopathy. Presence of small amounts of partly glycosylated alpha-DG may have a role in reducing the clinical symptoms of alpha-dystroglycanopathy.
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Affiliation(s)
- Terumi MURAKAMI
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Pediatrics, Tokyo Women’s Medical University, Tokyo, Japan
| | - Yukiko K. HAYASHI
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Megumu OGAWA
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Satoru NOGUCHI
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kevin P. CAMPBELL
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Internal Medicine, and Neurology, University of Iowa Carver College of Medicine, Iowa City, Iowa, U.S.A
| | - Masami TOGAWA
- Department of Child Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, Tottori, Japan
| | - Takehiko INOUE
- Department of Child Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, Tottori, Japan
| | - Akira OKA
- Department of Child Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, Tottori, Japan
| | - Kousaku OHNO
- Department of Child Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, Tottori, Japan
| | - Ikuya NONAKA
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo NISHINO
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
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23
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Mercuri E, Messina S, Bruno C, Mora M, Pegoraro E, Comi GP, D'Amico A, Aiello C, Biancheri R, Berardinelli A, Boffi P, Cassandrini D, Laverda A, Moggio M, Morandi L, Moroni I, Pane M, Pezzani R, Pichiecchio A, Pini A, Minetti C, Mongini T, Mottarelli E, Ricci E, Ruggieri A, Saredi S, Scuderi C, Tessa A, Toscano A, Tortorella G, Trevisan CP, Uggetti C, Vasco G, Santorelli FM, Bertini E. Congenital muscular dystrophies with defective glycosylation of dystroglycan: a population study. Neurology 2009; 72:1802-9. [PMID: 19299310 DOI: 10.1212/01.wnl.0000346518.68110.60] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Congenital muscular dystrophies (CMD) with reduced glycosylation of alpha-dystroglycan (alpha-DG) are a heterogeneous group of conditions associated with mutations in six genes encoding proven or putative glycosyltransferases. OBJECTIVES The aim of the study was to establish the prevalence of mutations in the six genes in the Italian population and the spectrum of clinical and brain MRI findings. METHODS As part of a multicentric study involving all the tertiary neuromuscular centers in Italy, FKRP, POMT1, POMT2, POMGnT1, fukutin, and LARGE were screened in 81 patients with CMD and alpha-DG reduction on muscle biopsy (n = 76) or with a phenotype suggestive of alpha-dystroglycanopathy but in whom a muscle biopsy was not available for alpha-DG immunostaining (n = 5). RESULTS Homozygous and compound heterozygous mutations were detected in a total of 43/81 patients (53%), and included seven novel variants. Mutations in POMT1 were the most prevalent in our cohort (21%), followed by POMT2 (11%), POMGnT1 (10%), and FKRP (9%). One patient carried two heterozygous mutations in fukutin and one case harbored a new homozygous variant in LARGE. No clear-cut genotype-phenotype correlation could be observed with each gene, resulting in a wide spectrum of clinical phenotypes. The more severe phenotypes, however, appeared to be consistently associated with mutations predicted to result in a severe disruption of the respective genes. CONCLUSIONS Our data broaden the clinical spectrum associated with mutations in glycosyltransferases and provide data on their prevalence in the Italian population.
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Affiliation(s)
- E Mercuri
- Department of Child Neurology, Policlinico Gemelli, Largo Gemelli, 00168 Rome, Italy.
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24
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Abstract
Protein O-mannosylation is an essential modification in fungi and animals. Different from most other types of O-glycosylation, protein O-mannosylation is initiated in the endoplasmic reticulum by the transfer of mannose from dolichol monophosphate-activated mannose to serine and threonine residues of secretory proteins. In recent years, it has emerged that even bacteria are capable of O-mannosylation and that the biosynthetic pathway of O-mannosyl glycans is conserved between pro- and eukaryotes. In this review, we summarize the observations that have opened up the field and highlight characteristics of O-mannosylation in the different domains/kingdoms of life.
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Affiliation(s)
- Mark Lommel
- Department V Cell Chemistry, Heidelberg Institute for Plant Sciences, University of Heidelberg, Heidelberg, Germany
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25
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Muntoni F, Guicheney P, Voit T. 158th ENMC international workshop on congenital muscular dystrophy (Xth international CMD workshop) 8th-10th February 2008 Naarden, The Netherlands. Neuromuscul Disord 2009; 19:229-34. [PMID: 19097897 DOI: 10.1016/j.nmd.2008.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Indexed: 10/21/2022]
Affiliation(s)
- F Muntoni
- Dubowitz Neuromuscular Centre, Institute of Child Health & Great Ormond Street Hospital, 30 Guilford Street, London WC1N 1EH, UK.
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26
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Reed UC. Congenital muscular dystrophy. Part I: a review of phenotypical and diagnostic aspects. ARQUIVOS DE NEURO-PSIQUIATRIA 2009; 67:144-168. [PMID: 19330236 DOI: 10.1590/s0004-282x2009000100038] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 12/17/2008] [Indexed: 12/30/2022]
Abstract
The congenital muscular dystrophies (CMDs) are a group of genetically and clinically heterogeneous hereditary myopathies with preferentially autosomal recessive inheritance, that are characterized by congenital hypotonia, delayed motor development and early onset of progressive muscle weakness associated with dystrophic pattern on muscle biopsy. The clinical course is broadly variable and can comprise the involvement of the brain and eyes. From 1994, a great development in the knowledge of the molecular basis has occurred and the classification of CMDs has to be continuously up dated. We initially present the main clinical and diagnostic data concerning the CMDs related to changes in the complex dystrophin-associated glycoproteins-extracellular matrix: CMD with merosin deficiency (CMD1A), collagen VI related CMDs (Ullrich CMD and Bethlem myopathy), CMDs with abnormal glycosylation of alpha-dystroglycan (Fukuyama CMD, Muscle-eye-brain disease, Walker-Warburg syndrome, CMD1C, CMD1D), and the much rarer CMD with integrin deficiency. Finally, we present other forms of CMDs not related with the dystrophin/glycoproteins/extracellular matrix complex (rigid spine syndrome, CMD1B, CMD with lamin A/C deficiency), and some apparently specific clinical forms not yet associated with a known molecular mechanism. The second part of this review concerning the pathogenesis and therapeutic perspectives of the different subtypes of CMD will be described in a next number.
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Affiliation(s)
- Umbertina Conti Reed
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil.
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27
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Yanagisawa A, Bouchet C, Quijano-Roy S, Vuillaumier-Barrot S, Clarke N, Odent S, Rodriguez D, Romero NB, Osawa M, Endo T, Taratuto AL, Seta N, Guicheney P. POMT2 intragenic deletions and splicing abnormalities causing congenital muscular dystrophy with mental retardation. Eur J Med Genet 2008; 52:201-6. [PMID: 19138766 DOI: 10.1016/j.ejmg.2008.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 12/17/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Alpha-dystroglycanopathies are a group of congenital muscular dystrophies (CMDs) with autosomal recessive inheritance characterized by abnormal glycosylation of alpha-dystroglycan. Although six genetic causes have been identified (FKTN, POMGNT1, POMT1, POMT2, FKRP, and LARGE) many alpha-dystroglycanopathy patients remain without a genetic diagnosis after standard exon sequencing. To date POMT2 mutations have been identified in CMD cases with a wide range of clinical severities from Walker-Warburg syndrome to limb girdle muscular dystrophy without structural brain or ocular involvement. METHODS We analyzed POMT2 in six CMD patients, who had severe diffuse muscle weakness, generalized joint contractures, microcephaly, severe mental retardation and elevated CK levels. Eye involvement was absent or limited to myopia or strabismus. We sequenced the coding regions of POMT2 using genomic DNA and cDNA generated from blood lymphocytes or B lymphoblastoid cell lines. Quantitative PCR analysis of genomic DNA was used to identify and determine the breakpoints of large deletions. RESULTS We report five novel mutations in POMT2, four of which were outside of coding exons, two large genomic deletions and two intronic single base substitutions that induced aberrant mRNA splicing. CONCLUSIONS Large scale DNA rearrangements (such as large deletions) and cryptic splice mutations, that can be missed on standard sequencing of genomic DNA, may be relatively common in POMT2. Additional techniques, such as sequencing of cDNA are needed to identify all mutations. These results also confirm that POMT2 mutations are an important cause of the less severe alpha-dystroglycanopathy phenotypes.
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Affiliation(s)
- Akiko Yanagisawa
- Inserm, U582, Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, UPMC University Paris 06, UMR_S582, IFR14, Paris, France
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28
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Clement E, Mercuri E, Godfrey C, Smith J, Robb S, Kinali M, Straub V, Bushby K, Manzur A, Talim B, Cowan F, Quinlivan R, Klein A, Longman C, McWilliam R, Topaloglu H, Mein R, Abbs S, North K, Barkovich AJ, Rutherford M, Muntoni F. Brain involvement in muscular dystrophies with defective dystroglycan glycosylation. Ann Neurol 2008; 64:573-82. [PMID: 19067344 DOI: 10.1002/ana.21482] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To assess the range and severity of brain involvement, as assessed by magnetic resonance imaging, in 27 patients with mutations in POMT1 (4), POMT2 (9), POMGnT1 (7), Fukutin (4), or LARGE (3), responsible for muscular dystrophies with abnormal glycosylation of dystroglycan (dystroglycanopathies). METHODS Blinded review of magnetic resonance imaging brain scans from 27 patients with mutations in 1 of these 5 genes. RESULTS Brain magnetic resonance images were normal in 3 of 27 patients; in another 5, only nonspecific abnormalities (ventricular dilatation, periventricular white matter abnormalities, or both) were seen. The remaining 19 patients had a spectrum of structural defects, ranging from complete lissencephaly in patients with Walker-Warburg syndrome to isolated cerebellar involvement. Cerebellar cysts and/or dysplasia and hypoplasia were the predominant features in four patients. Polymicrogyria (11/27) was more severe in the frontoparietal regions in 6, and had an occipitofrontal gradient in 2. Pontine clefts, with an unusual appearance to the corticospinal tracts, were seen in five patients with a muscle-eye-brain-like phenotype, three patients with POMGnT1, one with LARGE, and one with POMT2 mutations. Prominent cerebellar cysts were always seen with POMGnT1 mutations, but rarely seen in POMT1 and POMT2. Brainstem and pontine abnormalities were common in patients with POMT2, POMGnT1, and LARGE mutations. INTERPRETATION Our results expand the spectrum of brain involvement associated with mutations in LARGE, POMGnT1, POMT1, and POMT2. Pontine clefts were visible in some dystroglycanopathy patients. Infratentorial structures were often affected in isolation, highlighting their susceptibility to involvement in these conditions.
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Affiliation(s)
- Emma Clement
- Dubowitz Neuromuscular Unit, Institute of Child Health and Great Ormond Street Hospital, London, United Kingdom
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29
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Moore CJ, Hewitt JE. Dystroglycan glycosylation and muscular dystrophy. Glycoconj J 2008; 26:349-57. [PMID: 18773291 DOI: 10.1007/s10719-008-9182-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 08/14/2008] [Accepted: 08/18/2008] [Indexed: 11/25/2022]
Abstract
Dystroglycan is an integral member of the skeletal muscle dystrophin glycoprotein complex, which links dystrophin to proteins in the extracellular matrix. Recently, a group of human muscular dystrophy disorders have been demonstrated to result from defective glycosylation of the alpha-dystroglycan subunit. Genetic studies of these diseases have identified six genes that encode proteins required for the synthesis of essential carbohydrate structures on dystroglycan. Here we highlight their known or postulated functions. This glycosylation pathway appears to be highly specific (dystroglycan is the only substrate identified thus far) and to be highly conserved during evolution.
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Affiliation(s)
- Christopher J Moore
- Institute of Genetics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
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30
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Messina S, Mora M, Pegoraro E, Pini A, Mongini T, D'Amico A, Pane M, Aiello C, Bruno C, Biancheri R, Berardinelli A, Boito C, Farina L, Morandi L, Moroni I, Pezzani R, Pichiecchio A, Ricci E, Ruggieri A, Saredi S, Scuderi C, Tessa A, Toscano A, Tortorella G, Trevisan CP, Uggetti C, Santorelli FM, Bertini E, Mercuri E. POMT1 and POMT2 mutations in CMD patients: a multicentric Italian study. Neuromuscul Disord 2008; 18:565-71. [PMID: 18513969 DOI: 10.1016/j.nmd.2008.04.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 03/08/2008] [Accepted: 04/02/2008] [Indexed: 11/18/2022]
Abstract
Mutations in POMT1 and POMT2 genes were originally identified in Walker-Warburg syndrome (WWS) and subsequently reported in patients with milder phenotypes characterised by mental retardation with or without brain abnormalities and without ocular malformations. As part of a multicentric Italian study we screened the POMT1 and POMT2 genes in 61 congenital muscular dystrophy (CMD) patients with alpha-dystroglycan reduction on muscle biopsy and/or clinical and radiological findings suggestive of the known forms of CMD with alpha-dystroglycan deficiency. The aim of the study was to establish how frequently mutations in POMT1 and POMT2 occur in CMD patients in the Italian population and to evaluate the spectrum of associated phenotypes. Thirteen patients showed mutations in POMT1 and five harboured mutations in POMT2, accounting for a total of 20 different mutations, eight of which were novel (two in POMT1 and six in POMT2). Normal brain MRI associated with mental retardation and microcephaly was the most frequent finding in patients with mutations in POMT1 (six out of 13), but was also found in a patient with POMT2 mutations. Predominant cerebellar hypoplasia was also frequent both in patients with POMT1 (three out of 13) and POMT2 (three out of 5) mutations. A MEB phenotype with frontal cortical dysplasia and pons abnormalities was found in two patients with POMT1 and in one with POMT2 mutations, while a WWS phenotype was only found in a case with mutations in POMT1. Mutations causing frameshifts and stop codons were responsible for the more severe phenotypes. Our results provide further evidence that, as previously reported for FKRP, the array of mutations in POMT1 and POMT2 is ample and the spectrum of associated phenotypes is wider than initially thought.
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Affiliation(s)
- S Messina
- Department of Paediatric Neurology, Catholic University, Policlinico Gemelli, 00168 Rome, Italy
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31
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Lommel M, Willer T, Strahl S. POMT2, a key enzyme in Walker–Warburg syndrome: somatic sPOMT2, but not testis-specific tPOMT2, is crucial for mannosyltransferase activity in vivo. Glycobiology 2008; 18:615-25. [DOI: 10.1093/glycob/cwn042] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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32
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Manya H, Bouchet C, Yanagisawa A, Vuillaumier-Barrot S, Quijano-Roy S, Suzuki Y, Maugenre S, Richard P, Inazu T, Merlini L, Romero NB, Leturcq F, Bezier I, Topaloglu H, Estournet B, Seta N, Endo T, Guicheney P. Protein O-mannosyltransferase activities in lymphoblasts from patients with alpha-dystroglycanopathies. Neuromuscul Disord 2008; 18:45-51. [PMID: 17869517 DOI: 10.1016/j.nmd.2007.08.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 07/23/2007] [Accepted: 08/08/2007] [Indexed: 11/19/2022]
Abstract
Defects in O-mannosylation of alpha-dystroglycan cause some forms of congenital muscular dystrophy (CMD), the so-called alpha-dystroglycanopathies. Six genes are responsible for these diseases with overlapping phenotypes. We investigated the usefulness of a biochemical approach for the diagnosis and investigation of the alpha-dystroglycanopathies using immortalized lymphoblasts prepared from genetically diagnosed and undiagnosed CMD patients and from control subjects. We measured the activities of protein O-mannose beta1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) and protein O-mannosyltransferase (POMT). Lymphoblasts from patients harbouring known mutations in either POMGNT1 or POMT1 showed a marked decrease in POMGnT1 or POMT activity, respectively, compared to controls. Furthermore, we identified pathogenic mutations in POMGNT1, POMT1 or POMT2 in six previously genetically uncharacterised patients who had very low enzyme activity. In conclusion, the lymphoblast-based enzymatic assay is a sensitive and useful method (i) to select patients harbouring POMGNT1, POMT1 or POMT2 mutations; (ii) to assess the pathogenicity of new or already described mutations.
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Affiliation(s)
- Hiroshi Manya
- Glycobiology Research Group, Tokyo Metropolitan Institute of Gerontology, Foundation for Research on Aging and Promotion of Human Welfare, Tokyo, Japan
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Biancheri R, Falace A, Tessa A, Pedemonte M, Scapolan S, Cassandrini D, Aiello C, Rossi A, Broda P, Zara F, Santorelli FM, Minetti C, Bruno C. POMT2 gene mutation in limb-girdle muscular dystrophy with inflammatory changes. Biochem Biophys Res Commun 2007; 363:1033-7. [PMID: 17923109 DOI: 10.1016/j.bbrc.2007.09.066] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2007] [Accepted: 09/12/2007] [Indexed: 01/06/2023]
Abstract
Defects in glycosylation of alpha-dystroglycan are associated with several forms of muscular dystrophies. Mutations in POMT2 gene have been identified in patients with congenital muscular dystrophy and brain involvement, either characterized by a Walker-Warburg/muscle-eye-brain phenotype, or by microcephaly, mental retardation, and cerebellar hypoplasia. We identified a POMT2 homozygous missense mutation in a girl with a mild limb-girdle muscular dystrophy (LGMD) phenotype, marked elevated serum creatine kinase levels, and absence of brain involvement. Muscle biopsy revealed myopathic and inflammatory changes and severe alpha-dystroglycan reduction. In view of the remarkable mild clinical picture, we propose to designate this phenotype as LGMD2N.
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Affiliation(s)
- Roberta Biancheri
- Muscular and Neurodegenerative Disease Unit, G. Gaslini Institute and University of Genova, Largo Gaslini 5, 16147 Genova, Italy.
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Bouchet C, Gonzales M, Vuillaumier-Barrot S, Devisme L, Lebizec C, Alanio E, Bazin A, Bessières-Grattagliano B, Bigi N, Blanchet P, Bonneau D, Bonnières M, Carles D, Delahaye S, Fallet-Bianco C, Figarella-Branger D, Gaillard D, Gasser B, Guimiot F, Joubert M, Laurent N, Liprandi A, Loget P, Marcorelles P, Martinovic J, Menez F, Patrier S, Pelluard-Nehmé F, Perez MJ, Rouleau-Dubois C, Triau S, Laquerrière A, Encha-Razavi F, Seta N. Molecular heterogeneity in fetal forms of type II lissencephaly. Hum Mutat 2007; 28:1020-1027. [PMID: 17559086 DOI: 10.1002/humu.20561] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Type II lissencephaly (type II LIS) is a group of autosomal recessive congenital muscular dystrophies (CMD) associated with defects in alpha-DG O-glycosylation, which comprises Walker-Warburg syndrome, Fukuyama cerebral and muscular dystrophy, or muscle-eye-brain disease. The most severe forms of these diseases often have a fetal presentation and lead to a pregnancy termination. We report here the first molecular study on fetal type II LIS in a series of 47 fetuses from 41 unrelated families. Sequencing of the different genes known to be involved in alpha-DG O-glycosylation allowed the molecular diagnosis in 22 families: involvement of POMT1 was demonstrated in 32% of cases, whereas POMGNT1 and POMT2 were incriminated in 15% and in 7% of cases, respectively. We found 30 different mutations in these three genes, 25 were described herein for the first time, 15 in POMT1, and five in POMT2 and POMGNT1. Despite sequencing of FKRP, FCMD, and LARGE, no definitive molecular diagnosis could be made for the other half of our cases. Preliminary results concerning genotype-phenotype correlations show that the choice of the first gene sequenced should depend on the clinical severity of the type II LIS; POMT1 and POMT2 for severest clinical picture and POMGNT1 for milder disease. The other genes, FKRP, FCMD, and LARGE, seem not to be implicated in the fetal form of CMD.
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Affiliation(s)
- C Bouchet
- Assistance Publique-Hôpitaux de Paris (APHP), Bichat-Claude Bernard Hospital, Biochimie Métabolique, Paris, France
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van Reeuwijk J, Grewal PK, Salih MAM, Beltrán-Valero de Bernabé D, McLaughlan JM, Michielse CB, Herrmann R, Hewitt JE, Steinbrecher A, Seidahmed MZ, Shaheed MM, Abomelha A, Brunner HG, van Bokhoven H, Voit T. Intragenic deletion in the LARGE gene causes Walker-Warburg syndrome. Hum Genet 2007; 121:685-690. [PMID: 17436019 PMCID: PMC1914248 DOI: 10.1007/s00439-007-0362-y] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 03/21/2007] [Indexed: 12/08/2022]
Abstract
Intragenic homozygous deletions in the Large gene are associated with a severe neuromuscular phenotype in the myodystrophy (myd) mouse. These mutations result in a virtual lack of glycosylation of alpha-dystroglycan. Compound heterozygous LARGE mutations have been reported in a single human patient, manifesting with mild congenital muscular dystrophy (CMD) and severe mental retardation. These mutations are likely to retain some residual LARGE glycosyltransferase activity as indicated by residual alpha-dystroglycan glycosylation in patient cells. We hypothesized that more severe LARGE mutations are associated with a more severe CMD phenotype in humans. Here we report a 63-kb intragenic LARGE deletion in a family with Walker-Warburg syndrome (WWS), which is characterized by CMD, and severe structural brain and eye malformations. This finding demonstrates that LARGE gene mutations can give rise to a wide clinical spectrum, similar as for other genes that have a role in the post-translational modification of the alpha-dystroglycan protein.
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Affiliation(s)
- Jeroen van Reeuwijk
- Department of Human Genetics 855, Radboud University Nijmegen Medical Center, Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Prabhjit K. Grewal
- Institute of Genetics, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
- Department of Cellular and Molecular Medicine, University of California, San Diego, LA USA
| | - Mustafa A. M. Salih
- Department of Pediatrics, College of Medicine Department of Pediatrics, King Saud University, Riyadh, Saudi Arabia
| | - Daniel Beltrán-Valero de Bernabé
- Department of Human Genetics 855, Radboud University Nijmegen Medical Center, Box 9101, 6500 HB Nijmegen, The Netherlands
- Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA USA
| | - Jenny M. McLaughlan
- Institute of Genetics, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
| | - Caroline B. Michielse
- Department of Human Genetics 855, Radboud University Nijmegen Medical Center, Box 9101, 6500 HB Nijmegen, The Netherlands
- Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
| | - Ralf Herrmann
- Department of Pediatrics and Pediatric Neurology, University Hospital of Essen, Essen, Germany
| | - Jane E. Hewitt
- Institute of Genetics, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
| | - Alice Steinbrecher
- Department of Pediatrics and Pediatric Neurology, University Hospital of Essen, Essen, Germany
| | - Mohamed Z. Seidahmed
- Neonatology Unit and Department of Pediatrics, Security Forces Hospital, Riyadh, Saudi Arabia
| | - Mohamed M. Shaheed
- Neonatology Unit and Department of Pediatrics, Security Forces Hospital, Riyadh, Saudi Arabia
| | - Abdullah Abomelha
- Neonatology Unit and Department of Pediatrics, Security Forces Hospital, Riyadh, Saudi Arabia
| | - Han G. Brunner
- Department of Human Genetics 855, Radboud University Nijmegen Medical Center, Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Hans van Bokhoven
- Department of Human Genetics 855, Radboud University Nijmegen Medical Center, Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Thomas Voit
- Department of Pediatrics and Pediatric Neurology, University Hospital of Essen, Essen, Germany
- Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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Prados B, Peña A, Cotarelo RP, Valero MC, Cruces J. Expression of the murine Pomt1 gene in both the developing brain and adult muscle tissues and its relationship with clinical aspects of Walker-Warburg syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:1659-68. [PMID: 17456771 PMCID: PMC1854960 DOI: 10.2353/ajpath.2007.061264] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Walker-Warburg syndrome (WWS) is the most severe of a group of congenital disorders that have in common defects in the O-glycosylation of alpha-dystroglycan. WWS is characterized by congenital muscular dystrophy coupled with severe ocular and brain malformations. Moreover, in at least one-fifth of the reported cases, mutations in the POMT1 gene are responsible for this disease. During embryonic development (E8.5 to E11.5), the mouse Pomt1 gene is expressed in the tissues most severely affected in WWS, the muscle, eye, and brain. In this study, we show that mPomt1 expression is maintained in the muscle and eye in later developmental stages and, notably, that its expression is particularly strong in regions of brain and cerebellum that, when affected, could generate the defects observed in patients with WWS. We show that the Pomt1 protein is localized to the sarcoplasmic reticulum of muscle tissue cells in adult mice, where alpha-dystroglycan is O-glycosylated. Furthermore, the Pomt1 protein is localized to the acrosome of maturing spermatids, where alpha-dystroglycan is not glycosylated, so that Pomt1 might have a different target for O-mannosylation in the testes. This expression pattern in the testes could also be related to the gonadal anomalies observed in some patients with WWS.
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Affiliation(s)
- Belén Prados
- Department of Biochemistry, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain
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Abstract
During the past decade, considerable progress in the field of congenital muscular dystrophies (CMDs) had led to the identification of a growing number of causative genes. This genetic progress has uncovered crucial pathophysiological concepts and has been instrumental in redefining clinical phenotypes. Important new pathogenic mechanisms include the disorders of O-mannosyl-linked glycosylation of alpha-dystroglycan as well as the involvement of a collagen type VI in the pathogenesis of congenital disorders of muscle. Thus, an emerging theme among gene products involved in the pathogenesis of congenital muscular dystrophy is their intimate connection to the extracellular matrix. In this review, we focus on the clinical phenotypes that we are correlating with the novel genetic and biochemical findings encountered within CMD. This correlation will frequently lead to a considerably expanded clinical spectrum associated with a given CMD gene.
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Affiliation(s)
- Joachim Schessl
- Division of Neurology, The Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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