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Ulfig N, Steinbrecher A, Stoltenburg-Didinger G, Rezaie P. Differential activation of mononuclear phagocytes in cerebellar malformation associated with Walker-Warburg syndrome. Neuropathology 2007; 28:333-40. [PMID: 18069971 DOI: 10.1111/j.1440-1789.2007.00856.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Walker-Warburg syndrome (WWS) is an autosomal recessive disorder with alterations affecting the CNS that are characteristic of type-II lissencephaly and dysplasia/hypoplasia of the cerebellum. Other than these features, WWS is typically also accompanied by muscular dystrophy and abnormalities affecting the eyes. There is at present little information on the state of microglial and mononuclear phagocytic cell responses within the brain in WWS. In this case report, we present evidence for focal and differential activation of mononuclear phagocytes specifically confined to the dysplastic cerebellum of an infant at 5 months of age, diagnosed with WWS.
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Affiliation(s)
- Norbert Ulfig
- Neuroembryonic Research Laboratory, Institute of Anatomy, University of Rostock, Rostock, Germany.
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152
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Muntoni F, Brockington M, Godfrey C, Ackroyd M, Robb S, Manzur A, Kinali M, Mercuri E, Kaluarachchi M, Feng L, Jimenez-Mallebrera C, Clement E, Torelli S, Sewry CA, Brown SC. Muscular dystrophies due to defective glycosylation of dystroglycan. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2007; 26:129-135. [PMID: 18646561 PMCID: PMC2949305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Muscular dystrophies are a clinically and genetically heterogeneous group of disorders. Until recently most of the proteins associated with muscular dystrophies were believed to be proteins of the sarcolemma associated with reinforcing the plasma membrane or in facilitating its re-sealing following injury. In the last few years a novel and frequent pathogenic mechanism has been identified that involves the abnormal glycosylation of alpha-dystroglycan (ADG). This peripheral membrane protein undergoes complex and crucial glycosylation steps that enable it to interact with LG domain containing extracellular matrix proteins such as laminins, agrin and perlecan. Mutations in six genes (POMT1, POMT2, POMGnT1, fukutin, FKRP and LARGE) have been identified in patients with reduced glycosylation of ADG. While initially a clear correlation between gene defect and phenotype was observed for each of these 6 genes (for example, Walker Warburg syndrome was associated with mutations in POMT1 and POMT2, Fukuyama congenital muscular dystrophy associated with fukutin mutations, and Muscle Eye Brain disease associated with POMGnT1 mutations), we have recently demonstrated that allelic mutations in each of these 6 genes can result in a much wider spectrum of clinical conditions. Thus, the crucial aspect in determining the phenotypic severity is not which gene is primarily mutated, but how severely the mutation affects the glycosylation of ADG. Systematic mutation analysis of these 6 glycosyltransferases in patients with a dystroglycan glycosylation disorder identifies mutations in approximately 65% suggesting that more genes have yet to be identified.
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Affiliation(s)
- F Muntoni
- Dubowitz Neuromuscular Centre, Department of Paediatrics, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK
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153
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Abstract
Background There is a marked variation in clinical phenotypes that have been associated with mutations in FKRP, ranging from severe congenital muscular dystrophies to limb-girdle muscular dystrophy type 2I (LGMD2I). Methods We screened the FKRP gene in two cohorts totaling 87 patients with the LGMD phenotype. Results The c.826C>A, p.L276I mutation was present in six patients and a compound heterozygote mutation in a seventh patient. Six patients had a mild LGMD2I phenotype, which resembles that of Becker muscular dystrophy. The other patient had onset before the age of 3 years, and thus may follow a more severe course. Conclusion These findings suggest that LGMD2I may be common in certain North American populations. This diagnosis should be considered early in the evaluation of LGMD.
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154
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Darin N, Kroksmark AK, Ahlander AC, Moslemi AR, Oldfors A, Tulinius M. Inflammation and response to steroid treatment in limb-girdle muscular dystrophy 2I. Eur J Paediatr Neurol 2007; 11:353-7. [PMID: 17446099 DOI: 10.1016/j.ejpn.2007.02.018] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Accepted: 02/28/2007] [Indexed: 10/23/2022]
Abstract
Limb-girdle muscular dystrophy (LGMD) type 2I, caused by mutations in the fukutin-related protein gene (FKRP), is one of the most common forms of LGMD in childhood. We describe two patients with LGMD2I and a Duchenne-like phenotype. In addition to the common L276I mutation, both patients had a new mutation in FKRP, L169P and P89L, respectively. Clinical onset was triggered by viral upper respiratory tract infections. In addition to the common dystrophic pattern with a weak immune histochemical staining for alpha-dystroglycan, muscle biopsy showed inflammatory changes. This was especially striking in one of the patients with up-regulation of MHC class 1 antigen, suggestive of myositis. Both patients showed a good clinical response to treatment with prednisolone, which was initiated at daily dosage of 0.35 mg/kg/day. Our results provide evidence for an inflammatory involvement in the pathological expression of LGMD2I and open up the possibility that this disorder could be treatable with corticosteroids.
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Affiliation(s)
- N Darin
- Department of Pediatrics, Sahlgrenska University Hospital, Göteborg, Sweden.
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155
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Babić I, Brajenović-Milić B, Petrović O, Mustać E, Kapović M. Prenatal diagnosis of complete trisomy 19q. Prenat Diagn 2007; 27:644-7. [PMID: 17437325 DOI: 10.1002/pd.1742] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This communication presents the first case of complete trisomy 19q, prenatally detected by ultrasound investigation. Real-time high-resolution ultrasound examination was performed at 19 weeks of gestation. After termination of the pregnancy, autopsy investigation was done. GTG-banding, fluorescence in situ hybridization m-(FISH) analysis, and FISH analysis with a 19q subtelomeric specific probe were used for identification of the fetal karyotype. Sonographic examination revealed an enlarged cisterna magna, cerebellar hypoplasia and aplasia of the inferior part of the vermis, combined and bilateral kidney malformations, significant nuchal fold, absence of fetal nasal bones, and intracardial calcifications. Autopsy confirmed ultrasound findings, but also revealed situs viscerum inversus of the lungs. Fetal karyotype was defined as: 46,XY,der(21)t(19;21)(q11;p13)mat. Our ultrasound and autopsy findings will certainly contribute to better knowledge of phenotype characterization of this rare chromosomal disorder.
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Affiliation(s)
- Ivana Babić
- School of Medicine, Department of Biology and Medical Genetics, University of Rijeka.
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156
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Martin PT. Mechanisms of disease: congenital muscular dystrophies-glycosylation takes center stage. ACTA ACUST UNITED AC 2007; 2:222-30. [PMID: 16932553 PMCID: PMC2855642 DOI: 10.1038/ncpneuro0155] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Accepted: 02/10/2006] [Indexed: 11/09/2022]
Abstract
Recent studies have defined a group of muscular dystrophies, now termed the dystroglycanopathies, as novel disorders of glycosylation. These conditions include Walker-Warburg syndrome, muscle-eye-brain disease, Fukuyama-type congenital muscular dystrophy, congenital muscular dystrophy types 1C and 1D, and limb-girdle muscular dystrophy type 2I. Although clinical findings can be highly variable, dystroglycanopathies are all characterized by cortical malformations and ocular defects at the more severe end of the clinical spectrum, in addition to muscular dystrophy. All of these disorders are defined by the underglycosylation of alpha-dystroglycan. Defective glycosylation of dystroglycan severs the link between this important cell adhesion molecule and the extracellular matrix, thereby contributing to cellular pathology. Recent experiments indicate that glycosylation might not only define forms of muscular dystrophy but also provide an avenue to the development of therapies for these disorders.
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Affiliation(s)
- Paul T Martin
- Columbus Children's Research Institute, Departments of Pediatrics and Neurology, Ohio State University, Columbus, OH 43205, USA.
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157
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Biancheri R, Rossi A, Bruno C, Minetti C. Muscle and the Cerebellum. Neuroradiol J 2007; 20:427-33. [DOI: 10.1177/197140090702000407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 07/23/2007] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - A. Rossi
- Pediatric Neuroradiology Unit, G. Gaslini Institute; Genova, Italy
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158
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Schröder JE, Tegeler MR, Grosshans U, Porten E, Blank M, Lee J, Esapa C, Blake DJ, Kröger S. Dystroglycan regulates structure, proliferation and differentiation of neuroepithelial cells in the developing vertebrate CNS. Dev Biol 2007; 307:62-78. [PMID: 17512925 DOI: 10.1016/j.ydbio.2007.04.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 04/08/2007] [Accepted: 04/16/2007] [Indexed: 10/23/2022]
Abstract
In the developing CNS alpha- and beta-dystroglycan are highly concentrated in the endfeet of radial neuroepithelial cells at the contact site to the basal lamina. We show that injection of anti-dystroglycan Fab fragments, knockdown of dystroglycan using RNAi, and overexpression of a dominant-negative dystroglycan protein by microelectroporation in neuroepithelial cells of the chick retina and optic tectum in vivo leads to the loss of their radial morphology, to hyperproliferation, to an increased number of postmitotic neurons, and to an altered distribution of several basally concentrated proteins. Moreover, these treatments also altered the oriented growth of axons from retinal ganglion cells and from tectal projection neurons. In contrast, expression of non-cleavable dystroglycan protein in neuroepithelial cells reduced their proliferation and their differentiation to postmitotic neurons. These results demonstrate that dystroglycan plays a key role in maintaining neuroepithelial cell morphology, and that interfering with dystroglycan function influences proliferation and differentiation of neuroepithelial cells. These data also suggest that an impaired dystroglycan function in neuroepithelial cells might be responsible for some of the severe brain abnormalities observed in certain forms of congenital muscular dystrophy.
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Affiliation(s)
- Jörn E Schröder
- Department of Physiological Chemistry, University of Mainz, Duesbergweg 6, D-55099 Mainz, Germany
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159
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Nistal M, Rodríguez JI, García-Fernández E, Cajaiba MM, Reyes-Múgica M. Fetal gonadoblastoid testicular dysplasia: a focal failure of testicular development. Pediatr Dev Pathol 2007; 10:274-81. [PMID: 17638428 DOI: 10.2350/06-09-0158.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 01/26/2007] [Indexed: 11/20/2022]
Abstract
Fetal gonadoblastoid testicular dysplasia (FGTD) is an extremely rare lesion, which, in its original description, appeared in association with hydrops fetalis and other malformations. Its phenotype strongly resembles gonadoblastoma, although in contrast with that rare tumor, FGTD is not associated with the intersexual states or gonadal dysgenesis that accompany such neoplasm. Two reports described an association of FGTD and a morphologically similar lesion with Walker-Warburg syndrome. However, we have not confirmed such an observation, although a nonspecific muscle disorder was found in one of the examples we describe in this article. Here we study 2 additional cases, providing a detailed topographical, histomorphological, and immunophenotypical analysis. A review of all 5 previously described cases is conducted. The features of this lesion support the notion that a focal defect in testicular development is its most likely pathogenesis.
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Affiliation(s)
- Manuel Nistal
- Department of Pathology, Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain
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160
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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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161
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Abstract
A number of forms of congenital muscular dystrophy (CMD) have been identified that involve defects in the glycosylation of dystroglycan with O-mannosyl-linked glycans. There are at least six genes that can affect this type of glycosylation, and defects in these genes give rise to disorders that have many aspects of muscle and brain pathology in common. Overexpression of one gene implicated in CMD, LARGE, was recently shown to increase dystroglycan glycosylation and restore its function in cells taken from CMD patients. Overexpression of Galgt2, a glycosyltransferase not implicated in CMD, also alters dystroglycan glycosylation and inhibits muscular dystrophy in a mouse model of Duchenne muscular dystrophy. These findings suggest that a common approach to therapy in muscular dystrophies may be to increase the glycosylation of dystroglycan with particular glycan structures.
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Affiliation(s)
- Paul T Martin
- Columbus Children's Research Institute, Department of Pediatrics, Ohio State University, 700 Children's Drive, Columbus, OH 43205, USA.
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162
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Hu H, Yang Y, Eade A, Xiong Y, Qi Y. Breaches of the pial basement membrane and disappearance of the glia limitans during development underlie the cortical lamination defect in the mouse model of muscle-eye-brain disease. J Comp Neurol 2007; 501:168-83. [PMID: 17206611 DOI: 10.1002/cne.21238] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Neuronal overmigration is the underlying cellular mechanism of cerebral cortical malformations in syndromes of congenital muscular dystrophies caused by defects in O-mannosyl glycosylation. Overmigration involves multiple developmental abnormalities in the brain surface basement membrane, Cajal-Retzius cells, and radial glia. We tested the hypothesis that breaches in basement membrane and the underlying glia limitans are the key initial events of the cellular pathomechanisms by carrying out a detailed developmental study with a mouse model of muscle-eye-brain disease, mice deficient in O-mannose beta31,2-N-acetylglucosaminyltransferase 1 (POMGnT1). The pial basement membrane was normal in the knockout mouse at E11.5. It was breached during rapid cerebral cortical expansion at E13.5. Radial glial endfeet, which comprise glia limitans, grew out of the neural boundary. Neurons moved out of the neural boundary through these breaches. The overgrown radial glia and emigrated neurons disrupted the overlying pia mater. The overmigrated neurons did not participate in cortical plate (CP) development; rather they formed a diffuse cell zone (DCZ) outside the original cortical boundary. Together, the DCZ and the CP formed the knockout cerebral cortex, with disappearance of the basement membrane and the glia limitans. These results suggest that disappearance of the basement membrane and the glia limitans at the cerebral cortical surface during development underlies cortical lamination defects in congenital muscular dystrophies and a cellular mechanism of cortical malformation distinct from that of the reeler mouse, double cortex syndrome, and periventricular heterotopia.
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Affiliation(s)
- Huaiyu Hu
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York 13210, USA.
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163
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Verloes A, Elmaleh M, Gonzales M, Laquerrière A, Gressens P. Lissencéphalies : aspects cliniques et génétiques. Rev Neurol (Paris) 2007; 163:533-47. [PMID: 17571022 DOI: 10.1016/s0035-3787(07)90460-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The term lissencephaly covers a group of rare malformations sharing the common feature of anomalies in the appearance of brain convolutions (characterised by simplification or absence of folding) associated with abnormal organisation of the cortical layers as a result of neuronal migration defects during embryogenesis. Children with lissencephaly have feeding and swallowing problems, muscle tone anomalies (early hypotonia and subsequently limb hypertonia), seizures (in particular, infantile spasms) and severe psychomotor retardation. Multiple forms of lissencephaly have been described and their current classification is based on the associated malformations and underlying aetiology. Two large groups can be distinguished: classical lissencephaly (and its variants) and cobblestone lissencephaly. In classical lissencephaly (or type I), the cortex appears thickened, with four more or less disorganised layers rather than six normal layers. In the variants of classical lissencephaly, extra-cortical anomalies are also present (total or subtotal agenesis of the corpus callosum and/or cerebellar hypoplasia). The classical lissencephalies and the variant forms can be further divided into several subgroups. Four forms can be distinguished on the basis of their genetic aetiology: anomalies in the LIS1 gene (isolated lissencephaly and Miller-Dieker syndrome), anomalies in the TUBA3 and DCX genes, and lissencephalies caused by mutations in the ARX gene (XLAG syndrome, X-linked lissencephaly with agenesis of the corpus callosum). The incidence of all forms of type I lissencephaly is around 1 in 100,000 births. In addition to these four entities, isolated lissencephalies without a known genetic defect, lissencephalies with severe microcephaly (microlissencephaly) and lissencephalies associated with polymalformative syndromes are also included in the group of classical lissencephalies. Cobblestone lissencephaly (formally referred to as type II) is present in three entities: the Walker-Warburg, Fukuyama and MEB (Muscle-Eye-Brain) syndromes. It is characterised by global disorganisation of cerebral organogenesis with an uneven cortical surface (with a pebbled or cobblestone appearance). Microscopic examination reveals total disorganisation of the cortex and the absence of any distinguishable layers. Management is symptomatic only (swallowing problems require adapted feeding to prevent food aspiration, articular and respiratory physiotherapy to prevent orthopaedic problems resulting from hyptonia and treatment of gastrooesophageal reflux). The epilepsy is often resistant to treatment. The encephalopathy associated with lissencephaly is often very severe and affected children are completely dependent on the carer.
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164
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Balci B, Morris-Rosendahl DJ, Celebi A, Talim B, Topaloglu H, Dinçer P. Prenatal diagnosis of muscle-eye-brain disease. Prenat Diagn 2007; 27:51-4. [PMID: 17154333 DOI: 10.1002/pd.1622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVES To present a family in which it was possible to perform prenatal diagnosis for the recessively inherited muscle-eye-brain disease (MEB) using linkage analysis. METHODS Linkage analysis and direct sequencing of the POMGNT1 gene were carried out in a Turkish MEB family with one affected individual. Fetal DNA was obtained from an ongoing pregnancy by chorionic villus sampling (CVS). RESULTS Both linkage analysis of the POMGNT1/1p32-p34 region and direct sequencing for the novel familial mutation (R605H) demonstrated that the fetus did not have MEB. CONCLUSION We report the first case of prenatal diagnosis in MEB by molecular genetic analysis.
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Affiliation(s)
- Burcu Balci
- Hacettepe University, Faculty of Medicine, Department of Medical Biology, Sihhiye, Ankara, Turkey
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165
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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; 28:1020-7. [PMID: 17559086 DOI: 10.1002/humu.20561] [Citation(s) in RCA: 48] [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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166
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Keramaris-Vrantsis E, Lu PJ, Doran T, Zillmer A, Ashar J, Esapa CT, Benson MA, Blake DJ, Rosenfeld J, Lu QL. Fukutin-related protein localizes to the Golgi apparatus and mutations lead to mislocalization in muscle in vivo. Muscle Nerve 2007; 36:455-65. [PMID: 17554798 DOI: 10.1002/mus.20833] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mutations in the fukutin-related protein gene (FKRP) are associated with a spectrum of diseases from mild limb-girdle muscular dystrophy type 2I to severe congenital muscular dystrophy type 1C, muscle-eye-brain disease (MEB), and Walker-Warburg syndrome (WWS). The effect of mutations on the transportation of the mutant proteins may constitute the underlying mechanisms for the pathogenesis of these diseases. Here we examined the subcellular localization of mouse and human normal and mutant FKRP proteins in cells and in muscle in vivo. Both normal human and mouse FKRPs localize in part of the Golgi apparatus in muscle fibers. Mutations in the FKRP gene invariably altered the localization of the protein, leading to endoplasmic reticulum retention within cells and diminished Golgi localization in muscle fibers. Our results therefore suggest that an individual missense point mutation can confer at least two independent effects on the protein, causing (1) reduction or loss of the presumed glycosyltransferase activity directly and (2) mislocalization that could further alter the function of the protein. The complexity of the effect of individual missense point mutations may partly explain the wide variation of the FKRP-related myopathies.
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Affiliation(s)
- Elizabeth Keramaris-Vrantsis
- McColl Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Carolinas Medical Center, Charlotte, NC 28231, USA
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167
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de Visser M. Myopathies with early contractures. HANDBOOK OF CLINICAL NEUROLOGY 2007; 86:35-59. [PMID: 18808994 DOI: 10.1016/s0072-9752(07)86002-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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168
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Yis U, Uyanik G, Kurul S, Dirik E, Ozer E, Gross C, Hehr U. A case of Walker-Warburg syndrome resulting from a homozygous POMT1 mutation. Eur J Paediatr Neurol 2007; 11:46-9. [PMID: 17161965 DOI: 10.1016/j.ejpn.2006.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Revised: 10/10/2006] [Accepted: 10/30/2006] [Indexed: 11/19/2022]
Abstract
Walker--Warburg syndrome (WWS), the most severe alpha-dystroglycanopathy, is characterized by brain and eye anomalies, and congenital muscular dystrophy (CMD). So far at least four genes (POMT1, POMT2, Fukutin, and FKRP gene) have been implicated in WWS, accounting for about 30% of all cases. We report a male patient with WWS resulting from a homozygous nonsense mutation (R514X) in the POMT1 gene. The patient had congenital hydrocephalus which was detected at 29 weeks of gestation. A brain MRI obtained after birth revealed type II lissencephaly, hydrocephalus, and pontocerebellar hypoplasia. The case also exhibited severe ocular malformations and muscular hypotonia due to CMD.
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Affiliation(s)
- Uluç Yis
- Faculty of Medicine, Department of Child Neurology, University of Dokuz Eylul, 35340 Izmir, Turkey.
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169
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Vajsar J. MRI findings in congenital muscular dystrophies associated with brain abnormalities. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.6.765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetic resonance imaging (MRI) has become an important tool in diagnosing complex congenital muscular dystrophies (CMD) with brain abnormalities. Currently, there are two recognized types of CMDs with MRI brain abnormalities, firstly, laminin α2-chain-deficient CMD (MDC1A) with mutations in the LAMA2 gene, and secondly CMDs with hypoglycosylated α-dystroglycan which include Walker–Warburg syndrome (WWS), muscle–eye–brain disease (MEB), Fukuyama CMD (FCMD) and CMD types 1C and 1D (MDC1C and 1D). Brain MRI in MDC1A demonstrates abnormal white matter but rarely other brain abnormalities. In the latter group of CMDs, there is a whole spectrum of abnormalities involving both white and gray matter. The most severe MRI findings are in WWS. Patients with MEB, FCMD and MDC1C and lD also have gray and white matter abnormalities, which, in general, are less severe than those observed in WWS. There may be an overlap in these complex CMDs, both genotypically and in MRI findings.
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Affiliation(s)
- Jiri Vajsar
- The Hospital for Sick Children & University of Toronto, Division of Neurology, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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170
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Lisi MT, Cohn RD. Congenital muscular dystrophies: new aspects of an expanding group of disorders. Biochim Biophys Acta Mol Basis Dis 2006; 1772:159-72. [PMID: 17097859 DOI: 10.1016/j.bbadis.2006.09.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/11/2006] [Accepted: 09/13/2006] [Indexed: 12/24/2022]
Abstract
The congenital muscular dystrophies comprise a genetically and clinically heterogeneous group of disorders characterized by early onset of progressive muscle weakness and often involvement of other organ systems such as the brain and eyes. During the last decade, significant progress has been made to further characterize various forms of congenital muscular dystrophies based on their specific genetic and clinical appearance. This review represents an overview of the recent accomplishments as they relate to clinical, diagnostic, pathogenetic and therapeutic aspects of congenital muscular dystrophies.
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Affiliation(s)
- Matthew T Lisi
- McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics and Neurology, Johns Hopkins University School of Medicine, 600 N Wolfe Street, Blalock 1008 Baltimore, MD 21287, USA
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171
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Davies KE, Nowak KJ. Molecular mechanisms of muscular dystrophies: old and new players. Nat Rev Mol Cell Biol 2006; 7:762-73. [PMID: 16971897 DOI: 10.1038/nrm2024] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The study of the muscle cell in the muscular dystrophies (MDs) has shown that mutant proteins result in perturbations of many cellular components. MDs have been associated with mutations in structural proteins, signalling molecules and enzymes as well as mutations that result in aberrant processing of mRNA or alterations in post-translational modifications of proteins. These findings have not only revealed important insights for cell biologists, but have also provided unexpected and exciting new approaches for therapy.
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Affiliation(s)
- Kay E Davies
- Department of Physiology, Anatomy and Genetics, MRC Functional Genetics Unit, South Parks Road, Oxford OX1 3QX, UK.
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172
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Vajsar J, Schachter H. Walker-Warburg syndrome. Orphanet J Rare Dis 2006; 1:29. [PMID: 16887026 PMCID: PMC1553431 DOI: 10.1186/1750-1172-1-29] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 08/03/2006] [Indexed: 11/12/2022] Open
Abstract
Walker-Warburg Syndrome (WWS) is a rare form of autosomal recessive congenital muscular dystrophy associated with brain and eye abnormalities. WWS has a worldwide distribution. The overall incidence is unknown but a survey in North-eastern Italy has reported an incidence rate of 1.2 per 100,000 live births. It is the most severe form of congenital muscular dystrophy with most children dying before the age of three years. WWS presents at birth with generalized hypotonia, muscle weakness, developmental delay with mental retardation and occasional seizures. It is associated with type II cobblestone lissencephaly, hydrocephalus, cerebellar malformations, eye abnormalities and congenital muscular dystrophy characterized by hypoglycosylation of α-dystroglycan. Several genes have been implicated in the etiology of WWS, and others are as yet unknown. Several mutations were found in the Protein O-Mannosyltransferase 1 and 2 (POMT1 and POMT2) genes, and one mutation was found in each of the fukutin and fukutin-related protein (FKRP) genes. Laboratory investigations usually show elevated creatine kinase, myopathic/dystrophic muscle pathology and altered α-dystroglycan. Antenatal diagnosis is possible in families with known mutations. Prenatal ultrasound may be helpful for diagnosis in families where the molecular defect is unknown. No specific treatment is available. Management is only supportive and preventive.
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Affiliation(s)
- Jiri Vajsar
- Division of Child Neurology, The Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, Canada
| | - Harry Schachter
- Program in Structural Biology and Biochemistry, The Hospital for Sick Children and University of Toronto, 555 University Avenue, Toronto, ON, Canada
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173
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Quijano-Roy S, Martí-Carrera I, Makri S, Mayer M, Maugenre S, Richard P, Berard C, Viollet L, Leheup B, Guicheney P, Pinard JM, Estournet B, Carlier RY. Brain MRI abnormalities in muscular dystrophy due to FKRP mutations. Brain Dev 2006; 28:232-42. [PMID: 16368217 DOI: 10.1016/j.braindev.2005.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 08/12/2005] [Accepted: 08/17/2005] [Indexed: 10/25/2022]
Abstract
INTRODUCTION FKRP mutations cause a muscular dystrophy which may present in the neonatal period (MDC1C) or later in life (LGMD2I). Intelligence and brain imaging have been previously reported as being normal in FKRP-associated muscular dystrophy, except in rare cases presenting with mental retardation associated with structural brain abnormalities. PATIENTS AND METHODS We studied cerebral MRIs in twelve patients with FKRP-associated muscular dystrophy presenting in infancy or early childhood, at ages between 14 months and 43 years. Two patients had severe cognitive deficits, four had mild-moderate mental retardation and the rest were considered to have normal intelligence. All, but one were wheelchair-bound and 7 were mechanically ventilated. RESULTS Brain MRI was abnormal in 9 of 12 patients. Brain atrophy was seen in 8 patients. One child had isolated ventricular enlargement at 4 years. Cortical atrophy involved predominantly temporal and frontal lobes and was most important at later ages. In two cases with serial images this atrophy seemed progressive. Three patients, two with severe and one with moderate mental retardation, showed structural abnormalities of the posterior fossa with hypoplasia of the vermis and pons, and cerebellar hemispheric cysts. These abnormalities were stable with time. Two of these three patients also showed diffuse white matter abnormalities in early childhood, which regressed with time. CONCLUSIONS MRI abnormalities are common in patients with FKRP-associated muscular dystrophy presenting at birth or in early childhood. Progressive brain atrophy is the most frequent finding. Posterior fossa malformations and transient white matter changes may be seen in patients with associated mental retardation.
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Affiliation(s)
- Susana Quijano-Roy
- Unité de Neurologie Pédiatrique, Service de Pédiatrie, Rééducation et Réanimation Neurorespiratoire, Hôpital Raymond Poincaré, 92380, Garches, France.
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174
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van Reeuwijk J, Maugenre S, van den Elzen C, Verrips A, Bertini E, Muntoni F, Merlini L, Scheffer H, Brunner HG, Guicheney P, van Bokhoven H. The expanding phenotype ofPOMT1mutations: from Walker-Warburg syndrome to congenital muscular dystrophy, microcephaly, and mental retardation. Hum Mutat 2006; 27:453-9. [PMID: 16575835 DOI: 10.1002/humu.20313] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The importance of O-glycosylation of alpha-dystroglycan (alpha-DG) is evident from the identification of POMT1 mutations in Walker-Warburg syndrome (WWS). Approximately one-fifth of the WWS patients show mutations in POMT1, which result in complete loss of protein mannosyltransferase activity. WWS patients are characterized by congenital muscular dystrophy (CMD) with severe brain and eye abnormalities. This suggests a crucial role for alpha-DG during development of these organs and tissues. Here we report new POMT1 mutations and polymorphisms in WWS patients. In addition, we report different compound heterozygous POMT1 mutations in four unrelated families that result in a less severe phenotype than WWS, characterized by CMD with calf hypertrophy, microcephaly, and mental retardation. Compared to WWS patients, these patients have milder structural brain abnormalities, and eye abnormalities were absent, except for myopia in some cases. In these patients we postulate that one or both transcripts for POMT1 confer residual protein O-mannosyltransferase activity. Our data suggest the existence of a disease spectrum of CMD including brain and eye abnormalities resulting from POMT1 mutations.
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Affiliation(s)
- Jeroen van Reeuwijk
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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175
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Liu J, Ball SL, Yang Y, Mei P, Zhang L, Shi H, Kaminski HJ, Lemmon VP, Hu H. A genetic model for muscle–eye–brain disease in mice lacking protein O-mannose 1,2-N-acetylglucosaminyltransferase (POMGnT1). Mech Dev 2006; 123:228-40. [PMID: 16458488 DOI: 10.1016/j.mod.2005.12.003] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 12/13/2005] [Accepted: 12/14/2005] [Indexed: 11/26/2022]
Abstract
Protein O-mannose beta1,2-N-acetyglucosaminyltransferase 1 (POMGnT1) is an enzyme involved in the synthesis of O-mannosyl glycans. Mutations of POMGnT1 in humans result in the muscle-eye-brain (MEB) disease. In this study, we have characterized a null mutation generated by gene trapping with a retroviral vector inserted into the second exon of the mouse POMGnT1 locus. Expression of POMGnT1 mRNA was abolished in mutant mice. Glycosylation of alpha-dystroglycan was also reduced. POMGnT1 mutant mice were viable with multiple developmental defects in muscle, eye, and brain, similar to the phenotypes observed in human MEB disease. The present study provides the first genetic animal model to further dissect the roles of POMGnT1 in MEB disease.
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Affiliation(s)
- Jianmin Liu
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 650 E. Adams Street, Syracuse, NY 13210, USA
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176
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Wopereis S, Lefeber DJ, Morava E, Wevers RA. Mechanisms in protein O-glycan biosynthesis and clinical and molecular aspects of protein O-glycan biosynthesis defects: a review. Clin Chem 2006; 52:574-600. [PMID: 16497938 DOI: 10.1373/clinchem.2005.063040] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Genetic diseases that affect the biosynthesis of protein O-glycans are a rapidly growing group of disorders. Because this group of disorders does not have a collective name, it is difficult to get an overview of O-glycosylation in relation to human health and disease. Many patients with an unsolved defect in N-glycosylation are found to have an abnormal O-glycosylation as well. It is becoming increasingly evident that the primary defect of these disorders is not necessarily localized in one of the glycan-specific transferases, but can likewise be found in the biosynthesis of nucleotide sugars, their transport to the endoplasmic reticulum (ER)/Golgi, and in Golgi trafficking. Already, disorders in O-glycan biosynthesis form a substantial group of genetic diseases. In view of the number of genes involved in O-glycosylation processes and the increasing scientific interest in congenital disorders of glycosylation, it is expected that the number of identified diseases in this group will grow rapidly over the coming years. CONTENT We first discuss the biosynthesis of protein O-glycans from their building blocks to their secretion from the Golgi. Subsequently, we review 24 different genetic disorders in O-glycosylation and 10 different genetic disorders that affect both N- and O-glycosylation. The key clinical, metabolic, chemical, diagnostic, and genetic features are described. Additionally, we describe methods that can be used in clinical laboratory screening for protein O-glycosylation biosynthesis defects and their pitfalls. Finally, we introduce existing methods that might be useful for unraveling O-glycosylation defects in the future.
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Affiliation(s)
- Suzan Wopereis
- Laboratory of Pediatrics and Neurology and Department of Pediatrics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
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177
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Vajsar J, Zhang W, Dobyns WB, Biggar D, Holden KR, Hawkins C, Ray P, Olney AH, Burson CM, Srivastava AK, Schachter H. Carriers and patients with muscle–eye–brain disease can be rapidly diagnosed by enzymatic analysis of fibroblasts and lymphoblasts. Neuromuscul Disord 2006; 16:132-6. [PMID: 16427280 DOI: 10.1016/j.nmd.2005.11.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 11/22/2005] [Accepted: 11/28/2005] [Indexed: 11/21/2022]
Abstract
We report a new fibroblast and lymphoblast based protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 enzymatic assay, which allows rapid and accurate diagnosis of carriers and patients with muscle-eye-brain type of congenital muscular dystrophy. Seven patients with genetically confirmed muscle-eye-brain disease were assayed for protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 enzyme activity. In three patients and their heterozygous parents, the assays were done on EBV-transformed lymphoblasts, in another three patients they were done on cultured fibroblasts and in the last patient on both fibroblasts and lymphoblasts. Cultured fibroblasts and lymphoblasts from the muscle-eye-brain patients showed a highly significant decrease in protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity relative to controls. The residual protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 level in fibroblasts (average 0.11 nmoles/h per mg) was about 13% of normal controls. The ratio of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity to the activity of a glycosyltransferase control (N-acetylglucosaminyltransferase 1; GnT1) in fibroblasts was on average 0.006 in muscle-eye-brain patients and 0.045 in controls. The average residual protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 level in lymphoblasts was 15% of normal controls. The average ratio of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1/GnT1 activity was 0.007 in muscle-eye-brain patients, 0.026 in heterozygous carriers and 0.046 in normal controls. Assay of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity in fibroblasts and lymphoblasts from muscle-eye-brain carriers and patients provides a rapid and relatively simple diagnostic test for this disease and could be used as a screening test in carriers and patients with complex congenital muscular dystrophy.
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Affiliation(s)
- Jiri Vajsar
- The Hospital for Sick Children, Toronto, Ont. Canada.
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178
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Lamperti C, Cagliani R, Ciscato P, Moroni I, Viri M, Romeo A, Fagiolari G, Prelle A, Comi GP, Bresolin N, Moggio M. Congenital muscular dystrophy with muscle inflammation alpha dystroglycan glycosylation defect and no mutation in FKRP gene. J Neurol Sci 2006; 243:47-51. [PMID: 16386759 DOI: 10.1016/j.jns.2005.11.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 11/15/2005] [Accepted: 11/15/2005] [Indexed: 10/25/2022]
Abstract
Congenital muscular dystrophies (CMD) are autosomal recessive infantile disorders characterized by dystrophic changes at muscle biopsy and contractures. Central nervous system (CNS) abnormalities associated with mental retardation are often present. We describe a patient affected with muscle weakness, psychomotor developmental delay and normal brain MRI. Muscle biopsy showed complete absence of the alpha-dystroglycan (DG) glycosylated epitope and preservation of alpha-dystroglycan (alpha-DG) protein core. The analysis of FKRP, LARGE, POMT1 and POMGnT1 genes did not show any pathogenic mutations, suggesting that at least another gene may account for CMD with secondary glycosylated alpha-DG deficiency.
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Affiliation(s)
- Costanza Lamperti
- Centro Dino Ferrari, Dipartimento di Scienze Neurologiche, Unita' Operativa Neurologia, Fondazione I.R.C.C.S. Ospedale Maggiore Policlinico- Mangiagalli e Regina Elena, University of Milan, Milan, Italy
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179
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Mendell JR, Boué DR, Martin PT. The congenital muscular dystrophies: recent advances and molecular insights. Pediatr Dev Pathol 2006; 9:427-43. [PMID: 17163796 PMCID: PMC2855646 DOI: 10.2350/06-07-0127.1] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 08/30/2006] [Indexed: 01/16/2023]
Abstract
Over the past decade, molecular understanding of the congenital muscular dystrophies (CMDs) has greatly expanded. The diseases can be classified into 3 major groups based on the affected genes and the location of their expressed protein: abnormalities of extracellular matrix proteins (LAMA2, COL6A1, COL6A2, COL6A3), abnormalities of membrane receptors for the extracellular matrix (fukutin, POMGnT1, POMT1, POMT2, FKRP, LARGE, and ITGA7), and abnormal endoplasmic reticulum protein (SEPN1). The diseases begin in the perinatal period or shortly thereafter. A specific diagnosis can be challenging because the muscle pathology is usually not distinctive. Immunostaining of muscle using a battery of antibodies can help define a disorder that will need confirmation by gene testing. In muscle diseases with overlapping pathological features, such as CMD, careful attention to the clinical clues (e.g., family history, central nervous system features) can help guide the battery of immunostains necessary to target an unequivocal diagnosis.
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Affiliation(s)
- Jerry R Mendell
- Department of Pediatrics, Columbus Children's Hospital and Research Institute and The Ohio State University, 700 Children's Drive, Columbus, OH 43205, USA.
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180
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Torelli S, Brown SC, Brockington M, Dolatshad NF, Jimenez C, Skordis L, Feng LH, Merlini L, Jones DH, Romero N, Wewer U, Voit T, Sewry CA, Noguchi S, Nishino I, Muntoni F. Sub-cellular localisation of fukutin related protein in different cell lines and in the muscle of patients with MDC1C and LGMD2I. Neuromuscul Disord 2005; 15:836-43. [PMID: 16288869 DOI: 10.1016/j.nmd.2005.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 09/06/2005] [Accepted: 09/14/2005] [Indexed: 11/17/2022]
Abstract
MDC1C and LGMD2I are two allelic forms of muscular dystrophies caused by mutations in the gene encoding for fukutin related protein (FKRP). FKRP encodes for a putative glycosyltransferase, the precise function of which is unknown. However, the marked reduction of alpha-dystroglycan glycosylation in the muscle of MDC1C and LGMD2I patients suggests a role for FKRP in dystroglycan processing. Using a polyclonal antibody raised against FKRP we now show that endogenous FKRP locates to the Golgi apparatus of neuronal, oligodendroglial, and the cardiac muscle cell line H9c2. In differentiated C2C12 myotubes and in transverse sections of normal skeletal and cardiac muscle, endogenous FKRP surrounded the myonuclei. This localisation was unaffected in the skeletal muscle of patients with MDC1C and LGMD2I carrying various FKRP mutations. These observations imply a specific role for FKRP during striated muscle, neuronal and glial development and suggest that protein mis-localisation is not a common mechanism of disease in FKRP-related dystrophies.
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Affiliation(s)
- Silvia Torelli
- Dubowitz Neuromuscular Unit, Department of Paediatrics, Imperial College London, Hammersmith Campus, UK
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181
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Guglieri M, Magri F, Comi GP. Molecular etiopathogenesis of limb girdle muscular and congenital muscular dystrophies: Boundaries and contiguities. Clin Chim Acta 2005; 361:54-79. [PMID: 16002060 DOI: 10.1016/j.cccn.2005.05.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 05/11/2005] [Accepted: 05/12/2005] [Indexed: 10/25/2022]
Abstract
The muscular dystrophies are a heterogeneous group of inherited disorders characterized by progressive muscle wasting and weakness. These disorders present a large clinical variability regarding age of onset, patterns of skeletal muscle involvement, heart damage, rate of progression and mode of inheritance. Difficulties in classification are often caused by the relatively common sporadic occurrence of autosomal recessive forms as well as by intrafamilial clinical variability. Furthermore recent discoveries, particularly regarding the proteins linking the sarcolemma to components of the extracellular matrix, have restricted the gap existing between limb girdle (LGMD) and congenital muscular dystrophies (CMD). Therefore a renewed definition of boundaries between these two groups is required. Molecular genetic studies have demonstrated different causative mutations in the genes encoding a disparate collection of proteins involved in all aspects of muscle cell biology. These novel skeletal muscle genes encode highly diverse proteins with different localization within or at the surface of the skeletal muscle fibre, such as the sarcolemmal muscle membrane (dystrophin, sarcoglycans, dysferlin, caveolin-3), the extracellular matrix (alpha2 laminin, collagen VI), the sarcomere (telethonin, myotilin, titin, nebulin and ZASP), the muscle cytosol (calpain-3, TRIM32), the nucleus (emerin, lamin A/C) and the glycosilation pathway enzymes (fukutin and fukutin related proteins). The accumulating knowledge about the role of these different proteins in muscle pathology has led to a profound change in the original phenotype-based classification and shed new light on the molecular pathogenesis of these disorders.
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Affiliation(s)
- Michela Guglieri
- Centro Dino Ferrari, Dipartimento di Scienze Neurologiche Università degli Studi di Milano, I.R.C.C.S. Ospedale Maggiore Policlinico, Milano, Italy
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182
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Lee Y, Kameya S, Cox GA, Hsu J, Hicks W, Maddatu TP, Smith RS, Naggert JK, Peachey NS, Nishina PM. Ocular abnormalities in Largemyd and Largevls mice, spontaneous models for muscle, eye, and brain diseases. Mol Cell Neurosci 2005; 30:160-72. [PMID: 16111892 DOI: 10.1016/j.mcn.2005.07.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 07/03/2005] [Accepted: 07/06/2005] [Indexed: 11/25/2022] Open
Abstract
Here we demonstrate previously unreported ocular defects in mice homozygous for a new allele of the Large gene, veils, and for Large(myd) mice. Clinically, vitreal fibroplasia and retinal vessel tortuosity and fluorescein leakage are observed. These vascular defects may be due to the extreme disorganization of the astrocytic template on which endothelial cells migrate in the retina. Abnormal electroretinograms recorded from Large(vls) or Large(myd) mice are accompanied by disorganization of the outer plexiform layer (OPL) with a dramatic reduction in the number of synaptic complexes. In both mutants, the internal limiting membrane (ILM) is disrupted with ectopic cells in the vitreous. Interestingly, while all components of the dystrophin glycoprotein complex are present at reduced levels in the OPL, they were absent in the ILM of affected mice. Finally, hypoglycosylation of alpha-dystroglycan previously implicated in muscle and brain defects is also observed in the retina and may contribute to the ocular abnormalities.
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Affiliation(s)
- Yongsuk Lee
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
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183
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Abstract
It has become clear in the past half decade that a number of forms of congenital muscular dystrophy are in fact congenital disorders of glycosylation. Genes for Walker Warburg syndrome, muscle-eye-brain disease, Fukuyama congenital muscular dystrophy, congenital muscular dystrophy 1C and 1D, and limb girdle muscular dystrophy 21 have been identified, and gene mutations resulting in these diseases all cause the underglycosylation of alpha dystroglycan with O-linked carbohydrates. Unlike congenital disorders of glycosylation involving the N-linked pathway, these O-linked disorders possess distinctive muscle, eye, and brain phenotypes. Studies using mice and patient tissues strongly suggest that underglycosylation of dystroglycan inhibits the binding extracellular matrix proteins, effectively divorcing this important cell adhesion molecule from its extracellular environment. Moreover, defects in dystroglycan alone can account for most, if not all, cellular pathology. Thus, these disorders are now collectively referred to as dystroglycanopathies.
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Affiliation(s)
- Paul T Martin
- Center for Gene Therapy, Columbus Children's Research Institute, Departments of Pediatrics and Neurology, Ohio State University College of Medicine and Public Health, Columbus, OH 43205, USA
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184
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Abstract
LGMD refers to a class of muscular dystrophies with onset in the proximal muscles. They are genetically heterogeneous, with both autosomal recessive and dominant forms. The autosomal recessive forms are more common and in general follow a more severe course compared to the dominant forms. It is important to reach a specific genetic diagnosis beyond making a group diagnosis of LGMD to provide adequate genetic counseling, to predict risks for the patient such as the development of cardiomyopathy, and to be able to take advantage of specific treatments when they become available. Establishing a specific diagnosis requires knowledge about the individual clinical features, expert analysis of the muscule biopsy, and the guided initiation of appropriate genetic testing.
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Affiliation(s)
- Carsten G Bönnemann
- Division of Neurology and Neuromuscular Program, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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185
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Affiliation(s)
- Eugenio Mercuri
- Dubowitz Neuromuscular Centre, Hammersmith Hospital, London, England
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186
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Abstract
Walker-Warburg syndrome (WWS) is the most severe of a group of multiple congenital anomaly disorders known as the cobblestone lissencephalies. These are characterized by congenital muscular dystrophy in conjunction with severe brain malformation and ocular abnormalities. In the last 3 years, important progress has been made towards the elucidation of the genetic causes of these disorders. Mutations in three genes, POMT1, fukutin and FKRP, have been described for WWS, which together account for approximately 20% of patients with Walker-Warburg. It has become evident that some of the underlying genes may cause a broad spectrum of phenotypes, ranging from limb girdle muscular dystrophy type 2I to WWS. In some cases, a genotype-phenotype correlation can be recognized. In line with the known or proposed functions of the resolved genes, all patients with cobblestone lissencephaly show defects in the O-linked glycosylation of the glycoprotein alpha-dystroglycan. Perhaps, the missing genes underlying the remainder of the unexplained WWS patients have also to be sought in the pathways involved in O-linked protein glycosylation.
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Affiliation(s)
- J van Reeuwijk
- Department of Human Genetics, Radboud University Nijmegen Medical center, The Netherlands
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187
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Grewal PK, McLaughlan JM, Moore CJ, Browning CA, Hewitt JE. Characterization of the LARGE family of putative glycosyltransferases associated with dystroglycanopathies. Glycobiology 2005; 15:912-23. [PMID: 15958417 DOI: 10.1093/glycob/cwi094] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Large(myd) mouse has a loss-of-function mutation in the putative glycosyltransferase gene Large. Mutations in the human homolog (LARGE) have been described in a form of congenital muscular dystrophy (MDC1D). Other genes (POMT1, POMGnT1, fukutin, and FKRP) that encode known or putative glycosylation enzymes are also causally associated with human congenital muscular dystrophies. All these diseases are associated with hypoglycosylation of the membrane protein alpha-dystroglycan (alpha-DG) and consequent loss of extracellular ligand binding. Hence, they are termed dystroglycanopathies. A paralogous gene for LARGE (LARGE2 or GYLTL1B) may also have a role in DG glycosylation. Using database interrogation and reverse-transcriptase polymerase chain reaction (RT-PCR), we identified vertebrate orthologs of each of these LARGE genes in many vertebrates, including human, mouse, dog, chicken, zebrafish, and pufferfish. However, within invertebrate genomes, we were able to identify only single homologs. We suggest that vertebrate LARGE orthologs be referred to as LARGE1. RT-PCR, dot-blot, and northern analysis indicated that LARGE2 has a more restricted tissue-expression profile than LARGE1. Using epitope-tagged proteins, we show that both LARGE1 and LARGE2 localize to the Golgi apparatus. The high similarity between the LARGE paralogs suggests that LARGE2 may also act on DG. Overexpression of LARGE2 in mouse C2C12 myoblasts results in increased glycosylation of alpha-DG accompanied by an increase in laminin binding. Thus, there may be functional redundancy between LARGE1 and LARGE2. Consistent with this idea, we show that alpha-DG is still fully glycosylated in kidney (a tissue that expresses a high level of LARGE2 mRNA) of Large(myd) mutant mice.
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Affiliation(s)
- Prabhjit K Grewal
- Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
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188
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Muntoni F. Walker-Warburg syndrome and limb girdle muscular dystrophy; two sides of the same coin. Neuromuscul Disord 2005; 15:269-70. [PMID: 15792864 DOI: 10.1016/j.nmd.2005.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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189
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Balci B, Uyanik G, Dincer P, Gross C, Willer T, Talim B, Haliloglu G, Kale G, Hehr U, Winkler J, Topaloğlu H. An autosomal recessive limb girdle muscular dystrophy (LGMD2) with mild mental retardation is allelic to Walker-Warburg syndrome (WWS) caused by a mutation in the POMT1 gene. Neuromuscul Disord 2005; 15:271-5. [PMID: 15792865 DOI: 10.1016/j.nmd.2005.01.013] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 01/28/2005] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Mutations of the protein O-mannosyltransferase (POMT1) gene affect glycosylation of alpha-dystroglycan, leading to Walker-Warburg syndrome, a lethal disorder in early life with severe congenital muscular dystrophy, and brain and eye malformations. Recently, we described a novel form of recessive limb girdle muscular dystrophy with mild mental retardation, associated with an abnormal alpha-dystroglycan pattern in the muscle, suggesting a glycosylation defect. Here, we present evidence that this distinct phenotype results from a common mutation (A200P) in the POMT1 gene. Our findings further expand the phenotype of glycosylation disorders linked to POMT1 mutations. Furthermore, the A200P mutation is part of a conserved core haplotype, indicating an ancestral founder mutation.
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Affiliation(s)
- Burcu Balci
- Department of Medical Biology, Hacettepe University, Faculty of Medicine, Sihhiye, 06100 Ankara, Turkey
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190
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Matsumoto H, Hayashi YK, Kim DS, Ogawa M, Murakami T, Noguchi S, Nonaka I, Nakazawa T, Matsuo T, Futagami S, Campbell KP, Nishino I. Congenital muscular dystrophy with glycosylation defects of α-dystroglycan in Japan. Neuromuscul Disord 2005; 15:342-8. [PMID: 15833426 DOI: 10.1016/j.nmd.2005.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 01/19/2005] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
Glycosylation defects of alpha-dystroglycan (alpha-DG) cause various muscular dystrophies. We performed clinical, pathological and genetic analyses of 62 Japanese patients with congenital muscular dystrophy, whose skeletal muscle showed deficiency of glycosylated form of alpha-DG. We found, the first Japanese patient with congenital muscular dystrophy 1C with a novel compound heterozygous mutation in the fukutin-related protein gene. Fukuyama-type congenital muscular dystrophy was genetically confirmed in 54 of 62 patients. Two patients with muscle-eye-brain disease and one Walker-Warburg syndrome were also genetically confirmed. Four patients had no mutation in any known genes associated with glycosylation of alpha-DG. Interestingly, the molecular mass of alpha-DG in the skeletal muscle was similar and was reduced to approximately 90 kDa among these patients, even though the causative gene and the clinico-pathological severity were different. This result suggests that other factors can modify clinical features of the patients with glycosylation defects of alpha-DG.
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Affiliation(s)
- Hiroshi Matsumoto
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan
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191
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Patnaik SK, Stanley P. Mouse large can modify complex N- and mucin O-glycans on alpha-dystroglycan to induce laminin binding. J Biol Chem 2005; 280:20851-9. [PMID: 15788414 DOI: 10.1074/jbc.m500069200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The human LARGE gene encodes a protein with two putative glycosyltransferase domains and is required for the generation of functional alpha-dystroglycan (alpha-DG). Monoclonal antibodies IIH6 and VIA4-1 recognize the functional glycan epitopes of alpha-DG that are necessary for binding to laminin and other ligands. Overexpression of full-length mouse Large generated functionally glycosylated alpha-DG in Pro(-5) Chinese hamster ovary (CHO) cells, and the amount was increased by co-expression of protein:O-mannosyl N-acetylglucosaminyltransferase 1. However, functional alpha-DG represented only a small fraction of the alpha-DG synthesized by CHO cells or expressed from an alpha-DG construct. To identify features of the glycan epitopes induced by Large, the production of functionally glycosylated alpha-DG was investigated in several CHO glycosylation mutants. Mutants with defective transfer of sialic acid (Lec2), galactose (Lec8), or fucose (Lec13) to glycoconjugates, and the Lec15 mutant that cannot synthesize O-mannose glycans, all produced functionally glycosylated alpha-DG upon overexpression of Large. Laminin binding and the alpha-DG glycan epitopes were enhanced in Lec2 and Lec8 cells. In Lec15 cells, functional alpha-DG was increased by co-expression of core 2 N-acetylglucosaminyltransferase 1 with Large. Treatment with N-glycanase markedly reduced functionally glycosylated alpha-DG in Lec2 and Lec8 cells. The combined data provide evidence that Large does not transfer to Gal, Fuc, or sialic acid on alpha-DG nor induce the transfer of these sugars to alpha-DG. In addition, the data suggest that human LARGE may restore functional alpha-DG to muscle cells from patients with defective synthesis of O-mannose glycans via the modification of N-glycans and/or mucin O-glycans on alpha-DG.
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Affiliation(s)
- Santosh K Patnaik
- Department of Cell Biology, Albert Einstein College of Medicine, New York, New York 10461, USA
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192
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Muntoni F, Voit T. The congenital muscular dystrophies in 2004: a century of exciting progress. Neuromuscul Disord 2004; 14:635-49. [PMID: 15351421 DOI: 10.1016/j.nmd.2004.06.009] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2004] [Revised: 06/07/2004] [Accepted: 06/08/2004] [Indexed: 11/24/2022]
Abstract
The congenital muscular dystrophies are a heterogeneous group of inherited disorders. The clinical features range from severe and often early fatal disorders to relatively mild conditions compatible with survival into adult life. The recent advances in the genetic basis of congenital muscular dystrophies have allowed to significantly improve our understanding of their pathogenesis and clinical diversity. These advances have also allowed to classify these forms according to a combination of clinical features and primary biochemical defects. In this review we present how the congenital muscular dystrophies field has evolved over the last decade from a clinical and genetic point of view.
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Affiliation(s)
- Francesco Muntoni
- Department of Paediatrics and Neonatal, Dubowitz Neuromuscular Unit, Imperial College School of Medicine, Hammersmith Hospital Campus, Du Cane Road, London W12 ONN, UK.
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193
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Esapa CT, McIlhinney RAJ, Blake DJ. Fukutin-related protein mutations that cause congenital muscular dystrophy result in ER-retention of the mutant protein in cultured cells. Hum Mol Genet 2004; 14:295-305. [PMID: 15574464 DOI: 10.1093/hmg/ddi026] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the gene encoding fukutin-related protein (FKRP) cause a spectrum of diseases including congenital muscular dystrophy type 1C (MDC1C), limb girdle muscular dystrophy 2I (LGMD2I) and congenital muscular dystrophies (CMDs) with brain malformations and mental retardation. Although these diseases are associated with abnormal dystroglycan processing, the cellular consequences of the idiosyncratic FKRP mutations have not been determined. Here we show, in cultured cells, that FKRP mutants associated with the more severe disease phenotypes (S221R, A455D, P448L) are retained in the endoplasmic reticulum (ER), whereas the wild-type protein and the mutant L276I that causes LGMD2I are found predominantly in the Golgi apparatus. The ER-retained proteins have a shorter half-life than the wild-type FKRP and are preferentially degraded by the proteasome. Furthermore, calnexin binds preferentially to the ER-retained mutants suggesting that it may participate in the quality control pathway for FKRP. These data provide the first evidence that the ER-retention of mutant FKRP may play a role in the pathogenesis of CMD and potentially explain why the allelic disorder LGMD2I is milder, because the mutated protein is able to reach the Golgi apparatus.
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