Publications by authors named "Norma Beatriz Romero"

40 Publications

A novel PHKA1 mutation associating myopathy and cognitive impairment: Expanding the spectrum of phosphorylase kinase b (PhK) deficiency.

J Neurol Sci 2021 May 18;424:117391. Epub 2021 Mar 18.

APHP-GH Pitié-Salpêtrière, Centre de référence des maladies neuromusculaires Nord/Est/Ile de France, Myology Institute, Paris, France. Electronic address:

Muscle phosphorylase kinase b deficiency (PhK) is a rare disorder of glycogen metabolism characterized by exercise-induced myalgia and cramps, myoglobinuria and progressive muscle weakness. PhK deficiency is due to mutations in the PHKA1 gene inherited in an X-linked manner and is associated to glycogenosis type VIII (GSD VIII also called GSD IXd). PHKA1 gene codes for the αM subunit of the PhK, a multimeric protein complex responsible for the control of glycogen breakdown in muscle. Until now, few patients have been reported with X-linked recessive muscle PhK deficiency due to PHKA1 mutations. All reported patients presented with exercise intolerance and mild myopathy and one of them had cognitive impairment, leading to speculate about a central nervous system involvement in GSD VIII. Here we report in a sibling a novel mutation in the PHKA1 gene associated with a progressive myopathy, exercise intolerance, muscle hypertrophy and cognitive impairment as an associated feature. This report expands the genetic and clinical spectrum of the extremely rare PHKA1-related PhK deficiency and presents new evidences about its involvement in brain development.
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http://dx.doi.org/10.1016/j.jns.2021.117391DOI Listing
May 2021

Clinical phenotype and loss of the slow skeletal muscle troponin T in three new patients with recessive TNNT1 nemaline myopathy.

J Med Genet 2020 Sep 29. Epub 2020 Sep 29.

Neuropediatric Department, University Hospital Centre Toulouse, Toulouse, France

Background: Congenital nemaline myopathies are rare pathologies characterised by muscle weakness and rod-shaped inclusions in the muscle fibres.

Methods: Using next-generation sequencing, we identified three patients with pathogenic variants in the () gene, coding for the troponin T (TNT) skeletal muscle isoform.

Results: The clinical phenotype was similar in all patients, associating hypotonia, orthopaedic deformities and progressive chronic respiratory failure, leading to early death. The anatomopathological phenotype was characterised by a disproportion in the muscle fibre size, endomysial fibrosis and nemaline rods. Molecular analyses of revealed a homozygous deletion of exons 8 and 9 in patient 1; a heterozygous nonsense mutation in exon 9 and retention of part of intron 4 in muscle transcripts in patient 2; and a homozygous, very early nonsense mutation in patient 3.Western blot analyses confirmed the absence of the TNT protein resulting from these mutations.

Discussion: The clinical and anatomopathological presentations of our patients reinforce the homogeneous character of the phenotype associated with recessive mutations. Previous studies revealed an impact of recessive variants on the tropomyosin-binding affinity of TNT. We report in our patients a complete loss of TNT protein due to open reading frame disruption or to post-translational degradation of TNT.
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http://dx.doi.org/10.1136/jmedgenet-2019-106714DOI Listing
September 2020

Homoplasmic deleterious MT-ATP6/8 mutations in adult patients.

Mitochondrion 2020 11 26;55:64-77. Epub 2020 Aug 26.

INSERM U1016 Institut Cochin, CNRS UMR 8104, Université Paris-Decartes-Paris5, Paris, France. Electronic address:

To address the frequency of complex V defects, we systematically sequenced MT-ATP6/8 genes in 512 consecutive patients. We performed functional analysis in muscle or fibroblasts for 12 out of 27 putative homoplasmic mutations and in cybrids for four. Fibroblasts, muscle and cybrids with known deleterious mutations underwent parallel analysis. It included oxidative phosphorylation spectrophotometric assays, western blots, structural analysis, ATP production, glycolysis and cell proliferation evaluation. We demonstrated the deleterious nature of three original mutations. Striking gradation in severity of the mutations consequences and differences between muscle, fibroblasts and cybrids implied a likely under-diagnosis of human complex V defects.
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http://dx.doi.org/10.1016/j.mito.2020.08.004DOI Listing
November 2020

HNRNPDL-related muscular dystrophy: expanding the clinical, morphological and MRI phenotypes.

J Neurol 2019 Oct 2;266(10):2524-2534. Epub 2019 Jul 2.

Neuropathology and Neuromuscular Diseases Laboratory, Buenos Aires, Argentina.

Autosomal dominant limb girdle muscular dystrophy D3 HNRNPDL-related is a rare dominant myopathy caused by mutations in HNRNPDL. Only three unrelated families have been described worldwide, a Brazilian and a Chinese carrying the mutation c.1132G>A p.(Asp378Asn), and one Uruguayan with the mutation c.1132G>C p. (Asp378His), both mutations occurring in the same codon. The present study enlarges the clinical, morphological and muscle MRI spectrum of AD-HNRNPDL-related myopathies demonstrating the significant particularities of the disease. We describe two new unrelated Argentinean families, carrying the previously reported c.1132G>C p.(Asp378His) HNRNPDL mutation. There was a wide phenotypic spectrum including oligo-symptomatic cases, pure limb girdle muscle involvement or distal lower limb muscle weakness. Scapular winging was the most common finding, observed in all patients. Muscle MRIs of the thigh, at different stages of the disease, showed particular involvement of adductor magnus and vastus besides a constant preservation of the rectus femoris and the adductor longus muscles, defining a novel MRI pattern. Muscle biopsy findings were characterized by the presence of numerous rimmed vacuoles, cytoplasmic bodies, and abundant autophagic material at the histochemistry and ultrastructural levels. HNRNPDL-related LGMD D3 results in a wide range of clinical phenotypes from the classic proximal form of LGMD to a more distal phenotype. Thigh MRI suggests a specific pattern. Codon 378 of HNRNPDL gene can be considered a mutation hotspot for HNRNPDL-related myopathy. Pathologically, the disease can be classified among the autophagic rimmed vacuolar myopathies as with the other multisystem proteinopathies.
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http://dx.doi.org/10.1007/s00415-019-09437-3DOI Listing
October 2019

'Dusty core disease' (DuCD): expanding morphological spectrum of RYR1 recessive myopathies.

Acta Neuropathol Commun 2019 01 5;7(1). Epub 2019 Jan 5.

Neuromuscular Morphology Unit, Myology Institute, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France.

Several morphological phenotypes have been associated to RYR1-recessive myopathies. We recharacterized the RYR1-recessive morphological spectrum by a large monocentric study performed on 54 muscle biopsies from a large cohort of 48 genetically confirmed patients, using histoenzymology, immunohistochemistry, and ultrastructural studies. We also analysed the level of RyR1 expression in patients' muscle biopsies. We defined "dusty cores" the irregular areas of myofibrillar disorganisation characterised by a reddish-purple granular material deposition with uneven oxidative stain and devoid of ATPase activity, which represent the characteristic lesion in muscle biopsy in 54% of patients. We named Dusty Core Disease (DuCD) the corresponding entity of congenital myopathy. Dusty cores had peculiar histological and ultrastructural characteristics compared to the other core diseases. DuCD muscle biopsies also showed nuclear centralization and type1 fibre predominance. Dusty cores were not observed in other core myopathies and centronuclear myopathies. The other morphological groups in our cohort of patients were: Central Core (CCD: 21%), Core-Rod (C&R:15%) and Type1 predominance "plus" (T1P+:10%). DuCD group was associated to an earlier disease onset, a more severe clinical phenotype and a lowest level of RyR1 expression in muscle, compared to the other groups. Variants located in the bridge solenoid and the pore domains were more frequent in DuCD patients. In conclusion, DuCD is the most frequent histopathological presentation of RYR1-recessive myopathies. Dusty cores represent the unifying morphological lesion among the DuCD pathology spectrum and are the morphological hallmark for the recessive form of disease.
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http://dx.doi.org/10.1186/s40478-018-0655-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6320585PMC
January 2019

Human diaphragm atrophy in amyotrophic lateral sclerosis is not predicted by routine respiratory measures.

Eur Respir J 2019 02 14;53(2). Epub 2019 Feb 14.

AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Département de Neurologie, Centre référent SLA, Paris, France.

Amyotrophic lateral sclerosis (ALS) patients show progressive respiratory muscle weakness leading to death from respiratory failure. However, there are no data on diaphragm histological changes in ALS patients and how they correlate with routine respiratory measurements.We collected 39 diaphragm biopsies concomitantly with laparoscopic insertion of intradiaphragmatic electrodes during a randomised controlled trial evaluating early diaphragm pacing in ALS (https://clinicaltrials.gov; NCT01583088). Myofibre type, size and distribution were evaluated by immunofluorescence microscopy and correlated with spirometry, respiratory muscle strength and phrenic nerve conduction parameters. The relationship between these variables and diaphragm atrophy was assessed using multivariate regression models.All patients exhibited significant slow- and fast-twitch diaphragmatic atrophy. Vital capacity (VC), maximal inspiratory pressure, sniff nasal inspiratory pressure (SNIP) and twitch transdiaphragmatic pressure did not correlate with the severity of diaphragm atrophy. Inspiratory capacity (IC) correlated modestly with slow-twitch myofibre atrophy. Supine fall in VC correlated weakly with fast-twitch myofibre atrophy. Multivariate analysis showed that IC, SNIP and functional residual capacity were independent predictors of slow-twitch diaphragmatic atrophy, but not fast-twitch atrophy.Routine respiratory tests are poor predictors of diaphragm structural changes. Improved detection of diaphragm atrophy is essential for clinical practice and for management of trials specifically targeting diaphragm muscle function.
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http://dx.doi.org/10.1183/13993003.01749-2018DOI Listing
February 2019

Loss of Sarcomeric Scaffolding as a Common Baseline Histopathologic Lesion in Titin-Related Myopathies.

J Neuropathol Exp Neurol 2018 12;77(12):1101-1114

Neuromuscular Morphology Unit, Myology Institute, GHU Pitié-Salpêtrière, Paris, France.

Titin-related myopathies are heterogeneous clinical conditions associated with mutations in TTN. To define their histopathologic boundaries and try to overcome the difficulty in assessing the pathogenic role of TTN variants, we performed a thorough morphological skeletal muscle analysis including light and electron microscopy in 23 patients with different clinical phenotypes presenting pathogenic autosomal dominant or autosomal recessive (AR) mutations located in different TTN domains. We identified a consistent pattern characterized by diverse defects in oxidative staining with prominent nuclear internalization in congenital phenotypes (AR-CM) (n = 10), ± necrotic/regenerative fibers, associated with endomysial fibrosis and rimmed vacuoles (RVs) in AR early-onset Emery-Dreifuss-like (AR-ED) (n = 4) and AR adult-onset distal myopathies (n = 4), and cytoplasmic bodies (CBs) as predominant finding in hereditary myopathy with early respiratory failure (HMERF) patients (n = 5). Ultrastructurally, the most significant abnormalities, particularly in AR-CM, were multiple narrow core lesions and/or clear small areas of disorganizations affecting one or a few sarcomeres with M-band and sometimes A-band disruption and loss of thick filaments. CBs were noted in some AR-CM and associated with RVs in HMERF and some AR-ED cases. As a whole, we described recognizable histopathological patterns and structural alterations that could point toward considering the pathogenicity of TTN mutations.
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http://dx.doi.org/10.1093/jnen/nly095DOI Listing
December 2018

Novel mutations causing prenatal-onset muscle weakness with arthrogryposis and congenital bone fractures.

J Med Genet 2019 09 16;56(9):617-621. Epub 2018 Oct 16.

Departement of Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Inserm U1258, CNRS UMR7104, Université de Strasbourg, Illkirch, France.

Background: The activating signal cointegrator 1 (ASC-1) complex acts as a transcriptional coactivator for a variety of transcription factors and consists of four subunits: ASCC1, ASCC2, ASCC3 and TRIP4. A single homozygous mutation in has recently been reported in two families with a severe muscle and bone disorder.

Objective: We aim to contribute to a better understanding of the ASCC1-related disorder.

Methods: Here, we provide a clinical, histological and genetic description of three additional ASCC1 families.

Results: All patients presented with severe prenatal-onset muscle weakness, neonatal hypotonia and arthrogryposis, and congenital bone fractures. The muscle biopsies from the affected infants revealed intense oxidative rims beneath the sarcolemma and scattered remnants of sarcomeres with enlarged Z-bands, potentially representing a histopathological hallmark of the disorder. Sequencing identified recessive nonsense or frameshift mutations in , including two novel mutations.

Conclusion: Overall, this work expands the mutation spectrum, sheds light on the muscle histology of the disorder and emphasises the physiological importance of the ASC-1 complex in fetal muscle and bone development.
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http://dx.doi.org/10.1136/jmedgenet-2018-105390DOI Listing
September 2019

A Roma founder mutation causes a novel phenotype of centronuclear myopathy with rigid spine.

Neurology 2018 07 27;91(4):e339-e348. Epub 2018 Jun 27.

From the Unidad de Enfermedades Neuromusculares, Department of Neurology (M.C.-S., C.P.), Instituto de Biomedicina de Sevilla (IBiS) (M.C.-S., F.M., C.P.), and Department of Pathology, Neuropathology Unit (E.R.), Hospital Universitario Virgen del Rocío, Sevilla, Spain; Laboratoire Diagnostic Génétique (V.B.), Faculté de Médecine-CHRU, Strasbourg; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC) (V.B., R.Á., J.L.), Illkirch, France; Harry Perkins Institute of Medical Research and Centre for Medical Research (B.M., N.G.L., L.K.), University of Western Australia, Nedlands; Department of Pathology (Neuropathology) (A.H.-L.), Hospital Universitario 12 de Octubre, Madrid Research Institute; Neuropathology Unit (M.O.), Department of Pathology and Neuromuscular Unit, Department of Neurology, IDIBELL-Hospital de Bellvitge, Hospitalet de Llobregat, Barcelona; Department of Neurology and IIS La Fe (N.M., J.J.V.), Hospital Universitari i Politècnic La Fe, Valencia; Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER) (N.M., J.D.-M., J.J.V.); Department of Neurology (E.K.), Consulta de Enfermedades Neuromusculares y Unidad de ELA, Hospital General Universitario Santa Lucía, Cartagena, Murcia; Department of Neurology (A.C.), Hospital Virgen de las Nieves, Granada; Department of Neurology (P.Q.), Hospital Torrecárdenas, Almería; Unidad de Enfermedades Neuromusculares (J.D.-M.), Department of Neurology, Universidad Autónoma de Barcelona, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Department of Diagnostic Genomics (M.D.), PathWest Laboratory Medicine WA, Perth, Australia; Department of Neurology (C.D.), Hospital 12 de Octubre, Madrid, Spain; Unité de Morphologie Neuromusculaire (N.B.R.), Centre de Référence de Pathologie Neuromusculaire Paris-Est, Institut de Myologie, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris; Université Sorbonne (N.B.R.), UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France; Department of Medicine (J.J.V.), Universitat de Valencia; Department of Experimental and Health Sciences (D.C.), Institute of Evolutionary Biology (CSIC-UPF), Universitat Pompeu Fabra, Barcelona, Spain; Centre National de la Recherche Scientifique (J.L.), UMR7104, Illkirch; and Institut National de la Santé et de la Recherche Médicale (J.L.), U964, Illkirch, France.

Objective: To describe a large series of patients, in which a novel founder mutation in the Roma population of southern Spain has been identified.

Methods: Patients diagnosed with centronuclear myopathy (CNM) at 5 major reference centers for neuromuscular disease in Spain (n = 53) were screened for mutations. Clinical, histologic, radiologic, and genetic features were analyzed.

Results: Eighteen patients from 13 families carried the p.Arg234Cys variant; 16 of them were homozygous for it and 2 had compound heterozygous p.Arg234Cys/p.Arg145Cys mutations. Both variants have only been identified in Roma, causing 100% of CNM in this ethnic group in our cohort. The haplotype analysis confirmed all families are related. In addition to clinical features typical of CNM, such as proximal limb weakness and ophthalmoplegia, most patients in our cohort presented with prominent axial weakness, often associated with rigid spine. Severe fat replacement of paravertebral muscles was demonstrated by muscle imaging. This phenotype seems to be specific to the p.Arg234Cys mutation, not reported in other mutations. Extreme clinical variability was observed in the 2 compound heterozygous patients for the p.Arg234Cys/p.Arg145Cys mutations, from a congenital onset with catastrophic outcome to a late-onset disease. Screening of European Roma controls (n = 758) for the p.Arg234Cys variant identified a carrier frequency of 3.5% among the Spanish Roma.

Conclusion: We have identified a founder Roma mutation associated with a highly specific phenotype, which is, from the present cohort, the main cause of CNM in Spain.
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http://dx.doi.org/10.1212/WNL.0000000000005862DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070382PMC
July 2018

A novel FLNC frameshift and an OBSCN variant in a family with distal muscular dystrophy.

PLoS One 2017 26;12(10):e0186642. Epub 2017 Oct 26.

Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy.

A novel FLNC c.5161delG (p.Gly1722ValfsTer61) mutation was identified in two members of a French family affected by distal myopathy and in one healthy relative. This FLNC c.5161delG mutation is one nucleotide away from a previously reported FLNC mutation (c.5160delC) that was identified in patients and in asymptomatic carriers of three Bulgarian families with distal muscular dystrophy, indicating a low penetrance of the FLNC frameshift mutations. Given these similarities, we believe that the two FLNC mutations alone can be causative of distal myopathy without full penetrance. Moreover, comparative analysis of the clinical manifestations indicates that patients of the French family show an earlier onset and a complete segregation of the disease. As a possible explanation of this, the two French patients also carry a OBSCN c.13330C>T (p.Arg4444Trp) mutation. The p.Arg4444Trp variant is localized within the OBSCN Ig59 domain that, together with Ig58, binds to the ZIg9/ZIg10 domains of titin at Z-disks. Structural and functional studies indicate that this OBSCN p.Arg4444Trp mutation decreases titin binding by ~15-fold. On this line, we suggest that the combination of the OBSCN p.Arg4444Trp variant and of the FLNC c.5161delG mutation, can cooperatively affect myofibril stability and increase the penetrance of muscular dystrophy in the French family.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0186642PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657976PMC
November 2017

Diseases of the skeletal muscle.

Handb Clin Neurol 2017 ;145:429-451

Neuromuscular Morphology Unit and Neuromuscular Pathology Reference Center Paris-Est, Center for Research in Myology, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France.

After the advances created by the use of cryostat sections and histochemistry 60 years ago, muscle histopathology is now living a real renaissance. In the field of genetic neuromuscular disorders, muscle biopsy analysis is fundamental to address questions about pathogenicity and protein expression when new genes are discovered through next-generation sequencing approaches. Moreover, the identification of the same gene mutated in previously considered distinct histopathologic entities imposes a constant reassessment of morphologic boundaries in several groups of disorders. In other fields like the acquired inflammatory myopathies, histologic analysis nowadays helps to affirm a diagnosis, set up therapeutic strategies, and verify the success of immunosuppressive treatment. In this exciting scenario morphologists are definitely key figures in the neuromuscular field. The objective of this chapter is to give an overview on morphology of the most frequent and recently identified muscle conditions, stressing the importance that only a combined analysis of clinical findings, muscle histology, and specific ancillary investigations is effective in reaching a precise diagnosis and orienting therapy.
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http://dx.doi.org/10.1016/B978-0-12-802395-2.00030-4DOI Listing
January 2018

Dynamin-2 mutations linked to Centronuclear Myopathy impair actin-dependent trafficking in muscle cells.

Sci Rep 2017 07 4;7(1):4580. Epub 2017 Jul 4.

Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.

Dynamin-2 is a ubiquitously expressed GTP-ase that mediates membrane remodeling. Recent findings indicate that dynamin-2 also regulates actin dynamics. Mutations in dynamin-2 cause dominant centronuclear myopathy (CNM), a congenital myopathy characterized by progressive weakness and atrophy of skeletal muscles. However, the muscle-specific roles of dynamin-2 affected by these mutations remain elusive. Here we show that, in muscle cells, the GTP-ase activity of dynamin-2 is involved in de novo actin polymerization as well as in actin-mediated trafficking of the glucose transporter GLUT4. Expression of dynamin-2 constructs carrying CNM-linked mutations disrupted the formation of new actin filaments as well as the stimulus-induced translocation of GLUT4 to the plasma membrane. Similarly, mature muscle fibers isolated from heterozygous knock-in mice that harbor the dynamin-2 mutation p.R465W, an animal model of CNM, exhibited altered actin organization, reduced actin polymerization and impaired insulin-induced translocation of GLUT4 to the sarcolemma. Moreover, GLUT4 displayed aberrant perinuclear accumulation in biopsies from CNM patients carrying dynamin-2 mutations, further suggesting trafficking defects. These results suggest that dynamin-2 is a key regulator of actin dynamics and GLUT4 trafficking in muscle cells. Our findings also support a model in which impairment of actin-dependent trafficking contributes to the pathological mechanism in dynamin-2-associated CNM.
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http://dx.doi.org/10.1038/s41598-017-04418-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5496902PMC
July 2017

Variants in the Oxidoreductase PYROXD1 Cause Early-Onset Myopathy with Internalized Nuclei and Myofibrillar Disorganization.

Am J Hum Genet 2016 Nov 13;99(5):1086-1105. Epub 2016 Oct 13.

Department of Pediatric Neurology, Hacettepe University Children's Hospital, 06100 Ankara, Turkey.

This study establishes PYROXD1 variants as a cause of early-onset myopathy and uses biospecimens and cell lines, yeast, and zebrafish models to elucidate the fundamental role of PYROXD1 in skeletal muscle. Exome sequencing identified recessive variants in PYROXD1 in nine probands from five families. Affected individuals presented in infancy or childhood with slowly progressive proximal and distal weakness, facial weakness, nasal speech, swallowing difficulties, and normal to moderately elevated creatine kinase. Distinctive histopathology showed abundant internalized nuclei, myofibrillar disorganization, desmin-positive inclusions, and thickened Z-bands. PYROXD1 is a nuclear-cytoplasmic pyridine nucleotide-disulphide reductase (PNDR). PNDRs are flavoproteins (FAD-binding) and catalyze pyridine-nucleotide-dependent (NAD/NADH) reduction of thiol residues in other proteins. Complementation experiments in yeast lacking glutathione reductase glr1 show that human PYROXD1 has reductase activity that is strongly impaired by the disease-associated missense mutations. Immunolocalization studies in human muscle and zebrafish myofibers demonstrate that PYROXD1 localizes to the nucleus and to striated sarcomeric compartments. Zebrafish with ryroxD1 knock-down recapitulate features of PYROXD1 myopathy with sarcomeric disorganization, myofibrillar aggregates, and marked swimming defect. We characterize variants in the oxidoreductase PYROXD1 as a cause of early-onset myopathy with distinctive histopathology and introduce altered redox regulation as a primary cause of congenital muscle disease.
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http://dx.doi.org/10.1016/j.ajhg.2016.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5097943PMC
November 2016

A new titinopathy: Childhood-juvenile onset Emery-Dreifuss-like phenotype without cardiomyopathy.

Neurology 2015 Dec 18;85(24):2126-35. Epub 2015 Nov 18.

From INSERM (R.D.C., C.R., K.C., I.R.), U951; Généthon (R.D.C., C.R., K.C., I.R.), R&D Department, INTEGRARE Research Unit, Evry; Neuromuscular Morphology Unit, Myology Institute (N.B.R., M.B.), and INSERM UMRS_974, CNRS FRE 3617, Center of Research in Myology (R.B.Y., F.L., N.B.R., E.M., M.B., I.N., G.B.), Sorbonne Universités, UPMC Univ Paris 06, and AP-HP, University Hospital, Reference Center for Neuromuscular Diseases, Myology Institute (R.B.Y., N.B.R., E.M., B.E.), Groupe Hospitalier La Pitié-Salpêtrière, Paris; Génopole Campus 2 (S.B., A.C.), PartnerChip, Evry; the Department of Medical Genetics (F.L., A.V., B.U.), Folkhälsan Institute of Genetics, University of Helsinki, Finland; AP-HP (J.N.), Groupe Hospitalier Cochin-Broca-Hôtel Dieu, Laboratoire de Biochimie et Génétique Moléculaire, Paris; CEA-IG-Centre National de Genotypage (L.B.A., C.C., R.O.), Evry; Neuromuscular Research Center (B.U.), Tampere University Hospital and University of Tampere, Finland; and the Department of Neurology (B.U.), Vaasa Central Hospital, Finland. R.D.C. is currently affiliated with Disease Genomics Group, Institut de Medicina Predictiva i Personalitzada del Càncer, Campus de Can Ruti, Camí de les Escoles, Badalona (Barcelona), Spain.

Objective: To identify the genetic defects present in 3 families with muscular dystrophy, contractures, and calpain 3 deficiency.

Methods: We performed targeted exome sequencing on one patient presenting a deficiency in calpain 3 on Western blot but for which mutations in the gene had been excluded. The identification of a homozygous truncating mutation in the M-line part of titin prompted us to sequence this region in 2 additional patients presenting similar clinical and biochemical characteristics.

Results: The 3 patients shared similar features: coexistence of limb-girdle weakness and early-onset diffuse joint contractures without cardiomyopathy. The biopsies showed rimmed vacuoles, a dystrophic pattern, and secondary reduction in calpain 3. We identified a novel homozygous mutation in the exon Mex3 of the TTN gene in the first patient. At protein level, this mutation introduces a stop codon at the level of Mex3. Interestingly, we identified truncating mutations in both alleles in the same region of the TTN gene in patients from 2 additional families. Molecular protein analyses confirm loss of the C-ter part of titin.

Conclusions: Our study broadens the phenotype of titinopathies with the report of a new clinical entity with prominent contractures and no cardiac abnormality and where the recessive mutations lead to truncation of the M-line titin and secondary calpain 3 deficiency.
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http://dx.doi.org/10.1212/WNL.0000000000002200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4691685PMC
December 2015

Acute rhabdomyolysis and inflammation.

J Inherit Metab Dis 2015 Jul 17;38(4):621-8. Epub 2015 Mar 17.

Institut Imagine, Institut National de la Santé et de la Recherche Médicale, Unité 1163, 75015, Paris, France.

Rhabdomyolysis results from the rapid breakdown of skeletal muscle fibers, which leads to leakage of potentially toxic cellular content into the systemic circulation. Acquired causes by direct injury to the sarcolemma are most frequent. The inherited causes are: i) metabolic with failure of energy production, including mitochondrial fatty acid ß-oxidation defects, LPIN1 mutations, inborn errors of glycogenolysis and glycolysis, more rarely mitochondrial respiratory chain deficiency, purine defects and peroxysomal α-methyl-acyl-CoA-racemase defect (AMACR), ii) structural causes with muscle dystrophies and myopathies, iii) calcium pump disorder with RYR1 gene mutations, iv) inflammatory causes with myositis. Irrespective of the cause of rhabdomyolysis, the pathology follows a common pathway, either by the direct injury to sarcolemma by increased intracellular calcium concentration (acquired causes) or by the failure of energy production (inherited causes), which leads to fiber necrosis. Rhabdomyolysis are frequently precipitated by febrile illness or exercise. These conditions are associated with two events, elevated temperature and high circulating levels of pro-inflammatory mediators such as cytokines and chemokines. To illustrate these points in the context of energy metabolism, protein thermolability and the potential benefits of arginine therapy, we focus on a rare cause of rhabdomyolysis, aldolase A deficiency. In addition, our studies on lipin-1 (LPIN1) deficiency raise the possibility that several diseases involved in rhabdomyolysis implicate pro-inflammatory cytokines and may even represent primarily pro-inflammatory diseases. Thus, not only thermolability of mutant proteins critical for muscle function, but also pro-inflammatory cytokines per se, may lead to metabolic decompensation and rhabdomyolysis.
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http://dx.doi.org/10.1007/s10545-015-9827-7DOI Listing
July 2015

A novel dynamin-2 gene mutation associated with a late-onset centronuclear myopathy with necklace fibres.

Neuromuscul Disord 2015 Apr 13;25(4):345-8. Epub 2015 Jan 13.

Department of Pathology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.

Nuclear centralisation and internalisation, sarcoplasmic radiating strands and type 1 muscle fibre predominance and hypotrophy characterise dynamin-2 (DNM2) associated centronuclear myopathy, whereas necklace fibres are typically seen in late onset myotubularin-1 (MTM1)-related myopathy. We report a woman with unilateral symptoms probably related to brachial plexus neuritis. Electromyography revealed localised neuropathic and generalised myopathic abnormalities. The typical features of DNM2 centronuclear myopathy with additional necklace fibres were found in the muscle biopsy. Sequencing of the DNM2 and MTM1 genes revealed a novel heterozygous missense mutation in exon 18 of the DNM2, leading to replacement of highly conserved proline at position 647 by arginine. The muscle symptoms have not progressed during the 3-year follow-up. However, the patient has developed bilateral subtle lens opacities. Our findings support the concept that necklace fibres may occasionally be found in DNM2-related myopathy, possibly indicating a common pathogenic mechanism in DNM2 and MTM1 associated centronuclear myopathy.
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http://dx.doi.org/10.1016/j.nmd.2015.01.001DOI Listing
April 2015

Clinical, histological and genetic characterisation of patients with tubular aggregate myopathy caused by mutations in STIM1.

J Med Genet 2014 Dec 17;51(12):824-33. Epub 2014 Oct 17.

Department of Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Illkirch, France Inserm, U964, Illkirch, France CNRS, UMR7104, Illkirch, France University of Strasbourg, Illkirch, France Collège de France, Chaire de Génétique Humaine, Illkirch, France.

Background: Tubular aggregate myopathies (TAMs) are muscle disorders characterised by abnormal accumulations of densely packed single-walled or double-walled membrane tubules in muscle fibres. Recently, STIM1, encoding a major calcium sensor of the endoplasmic reticulum, was identified as a TAM gene.

Methods: The present study aims to define the clinical, histological and ultrastructural phenotype of tubular aggregate myopathy and to assess the STIM1 mutation spectrum.

Results: We describe six new TAM families harbouring one known and four novel STIM1 mutations. All identified mutations are heterozygous missense mutations affecting highly conserved amino acids in the calcium-binding EF-hand domains, demonstrating the presence of a mutation hot spot for TAM. We show that the mutations induce constitutive STIM1 clustering, strongly suggesting that calcium sensing and consequently calcium homoeostasis is impaired. Histological and ultrastructural analyses define a common picture with tubular aggregates labelled with Gomori trichrome and Nicotinamide adenine dinucleotide (NADH) tetrazolium reductase, substantiating their endoplasmic reticulum origin. The aggregates were observed in both fibre types and were often accompanied by nuclear internalisation and fibre size variability. The phenotypical spectrum ranged from childhood onset progressive muscle weakness and elevated creatine kinase levels to adult-onset myalgia without muscle weakness and normal CK levels.

Conclusions: The present study expands the phenotypical spectrum of STIM1-related tubular aggregate myopathy. STIM1 should therefore be considered for patients with tubular aggregate myopathies involving either muscle weakness or myalgia as the first and predominant clinical sign.
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http://dx.doi.org/10.1136/jmedgenet-2014-102623DOI Listing
December 2014

N-WASP is required for Amphiphysin-2/BIN1-dependent nuclear positioning and triad organization in skeletal muscle and is involved in the pathophysiology of centronuclear myopathy.

EMBO Mol Med 2014 Nov;6(11):1455-75

Myology Group, UMR S 787 INSERM, Université Pierre et Marie Curie Paris 6, Paris, France Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal

Mutations in amphiphysin-2/BIN1, dynamin 2, and myotubularin are associated with centronuclear myopathy (CNM), a muscle disorder characterized by myofibers with atypical central nuclear positioning and abnormal triads. Mis-splicing of amphiphysin-2/BIN1 is also associated with myotonic dystrophy that shares histopathological hallmarks with CNM. How amphiphysin-2 orchestrates nuclear positioning and triad organization and how CNM-associated mutations lead to muscle dysfunction remains elusive. We find that N-WASP interacts with amphiphysin-2 in myofibers and that this interaction and N-WASP distribution are disrupted by amphiphysin-2 CNM mutations. We establish that N-WASP functions downstream of amphiphysin-2 to drive peripheral nuclear positioning and triad organization during myofiber formation. Peripheral nuclear positioning requires microtubule/Map7/Kif5b-dependent distribution of nuclei along the myofiber and is driven by actin and nesprins. In adult myofibers, N-WASP and amphiphysin-2 are only involved in the maintenance of triad organization but not in the maintenance of peripheral nuclear positioning. Importantly, we confirmed that N-WASP distribution is disrupted in CNM and myotonic dystrophy patients. Our results support a role for N-WASP in amphiphysin-2-dependent nuclear positioning and triad organization and in CNM and myotonic dystrophy pathophysiology.
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http://dx.doi.org/10.15252/emmm.201404436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4237471PMC
November 2014

Congenital muscular dystrophy phenotype with neuromuscular spindles excess in a 5-year-old girl caused by HRAS mutation.

Neuromuscul Disord 2014 Nov 28;24(11):993-8. Epub 2014 Jun 28.

Institut de Myologie, UPMC Université, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France.

We report on a 5-year-old girl who presented with an association of symptoms reminiscent of an Ullrich-like congenital muscular dystrophy including congenital hypotonia, proximal joint contractures, hyperlaxity of distal joints, normal cognitive development, and kyphoscoliosis. There was an excess of neuromuscular spindles on the skeletal muscle biopsy. This very peculiar feature on muscle biopsy has been reported only in patients with mutations in the HRAS gene. Sequence analysis of the subject's HRAS gene from blood leukocytes and skeletal muscle revealed a previously described heterozygous missense mutation (c.187G>A, p. Glu63Lys). The present report thus extends the differential diagnosis of congenital muscular dystrophy with major "retractile" phenotypes and adds congenital muscular dystrophy to the clinical spectrum of HRAS-related disorders.
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http://dx.doi.org/10.1016/j.nmd.2014.06.437DOI Listing
November 2014

Extensive morphological and immunohistochemical characterization in myotubular myopathy.

Brain Behav 2013 Jul 19;3(4):476-86. Epub 2013 Jun 19.

Unité de Morphologie Neuromusculaire, Institut de Myologie GHU La Pitié-Salpêtrière, Paris, France ; Groupe Hospitalier-Universitaire La Pitié-Salpêtrière, AP-HP, Centre de référence des maladies neuromusculaires Paris-Est, Paris, France ; UPMC-Paris6 UR76, INSERM UMR974, CNRS UMR 7215, Institut de Myologie GHU La Pitié-Salpêtrière, Paris, France.

The X-linked myotubular myopathy (XLMTM) also called X-linked centronuclear myopathy is a rare congenital myopathy due to mutations in the MTM 1 gene encoding myotubularin. The disease gives rise to a severe muscle weakness in males at birth. The main muscle morphological characteristics (significant number of small muscle fibers with centralized nuclei and type 1 fiber predominance) are usually documented, but the sequence of formation and maintenance of this particular morphological pattern has not been extensively characterized in humans. In this study, we perform a reevaluation of morphological changes in skeletal muscle biopsies in severe XLMTM. We correlate the pathologic features observed in the muscle biopsies of 15 newborns with MTM 1-mutations according to the "adjusted-age" at the time of muscle biopsy, focusing on sequential analysis in the early period of the life (from 34 weeks of gestation to 3 months of age). We found a similar morphological pattern throughout the period analyzed; the proportion of myofibers with central nuclei was high in all muscle biopsies, independently of the muscle type, the age of the newborns at time of biopsy and the specific MTM 1 mutation. We did not observe a period free of morphological abnormalities in human skeletal muscle as observed in myotubularin-deficient mouse models. In addition, this study demonstrated some features of delayed maturation of the muscle fibers without any increase in the number of satellite cells, associated with a marked disorganization of the muscle T-tubules and cytoskeletal network in the skeletal muscle fibers.
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http://dx.doi.org/10.1002/brb3.147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3869686PMC
July 2013

Peripheral nerve hyperexcitability with preterminal nerve and neuromuscular junction remodeling is a hallmark of Schwartz-Jampel syndrome.

Neuromuscul Disord 2013 Dec 4;23(12):998-1009. Epub 2013 Sep 4.

Inserm, U975, Centre de recherche de l'Institut du Cerveau et de la Moelle Épinière (CRICM), Groupe hospitalier Pitié-Salpêtrière, Paris, France; Université Pierre et Marie Curie Paris 6, UMRS975, Paris, France; CNRS, UMR7225, Paris, France; Ecole Pratique des Hautes Etudes, Paris, France.

Schwartz-Jampel syndrome (SJS) is a recessive disorder with muscle hyperactivity that results from hypomorphic mutations in the perlecan gene, a basement membrane proteoglycan. Analyses done on a mouse model have suggested that SJS is a congenital form of distal peripheral nerve hyperexcitability resulting from synaptic acetylcholinesterase deficiency, nerve terminal instability with preterminal amyelination, and subtle peripheral nerve changes. We investigated one adult patient with SJS to study this statement in humans. Perlecan deficiency due to hypomorphic mutations was observed in the patient biological samples. Electroneuromyography showed normal nerve conduction, neuromuscular transmission, and compound nerve action potentials while multiple measures of peripheral nerve excitability along the nerve trunk did not detect changes. Needle electromyography detected complex repetitive discharges without any evidence for neuromuscular transmission failure. The study of muscle biopsies containing neuromuscular junctions showed well-formed post-synaptic element, synaptic acetylcholinesterase deficiency, denervation of synaptic gutters with reinnervation by terminal sprouting, and long nonmyelinated preterminal nerve segments. These data support the notion of peripheral nerve hyperexcitability in SJS, which would originate distally from synergistic actions of peripheral nerve and neuromuscular junction changes as a result of perlecan deficiency.
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http://dx.doi.org/10.1016/j.nmd.2013.07.005DOI Listing
December 2013

Skeletal muscle biopsy analysis in reducing body myopathy and other FHL1-related disorders.

J Neuropathol Exp Neurol 2013 Sep;72(9):833-45

Unité de Morphologie Neuromusculaire, Institut de Myologie, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France.

FHL1 mutations have been associated with various disorders that include reducing body myopathy (RBM), Emery-Dreifuss-like muscular dystrophy, isolated hypertrophic cardiomyopathy, and some overlapping conditions. We report a detailed histochemical, immunohistochemical, electron microscopic, and immunoelectron microscopic analyses of muscle biopsies from 18 patients carrying mutations in FHL1: 14 RBM patients (Group 1), 3 Emery-Dreifuss muscular dystrophy patients (Group 2), and 1 patient with hypertrophic cardiomyopathy and muscular hypertrophy (Group 2). Group 1 muscle biopsies consistently showed RBs associated with cytoplasmic bodies. The RBs showed prominent FHL1 immunoreactivity whereas desmin, αB-crystallin, and myotilin immunoreactivity surrounded RBs. By electron microscopy, RBs were composed of electron-dense tubulofilamentous material that seemed to spread progressively between the myofibrils and around myonuclei. By immunoelectron microscopy, FHL1 protein was found exclusively inside RBs. Group 2 biopsies showed mild dystrophic abnormalities without RBs; only minor nonspecific myofibrillar abnormalities were observed under electron microscopy. Molecular analysis revealed missense mutations in the second FHL1 LIM domain in Group 1 patients and ins/del or missense mutations within the fourth FHL1 LIM domain in Group 2 patients. Our findings expand the morphologic features of RBM, clearly demonstrate the localization of FHL1 in RBs, and further illustrate major morphologic differences among different FHL1-related myopathies.
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http://dx.doi.org/10.1097/NEN.0b013e3182a23506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5210222PMC
September 2013

Muscle histone deacetylase 4 upregulation in amyotrophic lateral sclerosis: potential role in reinnervation ability and disease progression.

Brain 2013 Aug 3;136(Pt 8):2359-68. Epub 2013 Jul 3.

APHP, Hôpital Pitié-Salpêtrière, Département de Neurologie, Centre référent SLA, Paris Cedex 13, France.

Amyotrophic lateral sclerosis is a typically rapidly progressive neurodegenerative disorder affecting motor neurons leading to progressive muscle paralysis and death, usually from respiratory failure, in 3-5 years. Some patients have slow disease progression and prolonged survival, but the underlying mechanisms remain poorly understood. Riluzole, the only approved treatment, only modestly prolongs survival and has no effect on muscle function. In the early phase of the disease, motor neuron loss is initially compensated for by collateral reinnervation, but over time this compensation fails, leading to progressive muscle wasting. The crucial role of muscle histone deacetylase 4 and its regulator microRNA-206 in compensatory reinnervation and disease progression was recently suggested in a mouse model of amyotrophic lateral sclerosis (transgenic mice carrying human mutations in the superoxide dismutase gene). Here, we sought to investigate whether the microRNA-206-histone deacetylase 4 pathway plays a role in muscle compensatory reinnervation in patients with amyotrophic lateral sclerosis and thus contributes to disease outcome differences. We studied muscle reinnervation using high-resolution confocal imaging of neuromuscular junctions in muscle samples obtained from 11 patients with amyotrophic lateral sclerosis, including five long-term survivors. We showed that the proportion of reinnervated neuromuscular junctions was significantly higher in long-term survivors than in patients with rapidly progressive disease. We analysed the expression of muscle candidate genes involved in the reinnervation process and showed that histone deacetylase 4 upregulation was significantly greater in patients with rapidly progressive disease and was negatively correlated with the extent of muscle reinnervation and functional outcome. Conversely, the proposed regulator of histone deacetylase 4, microRNA-206, was upregulated in both patient groups, but did not correlate with disease progression or reinnervation. We conclude that muscle expression of histone deacetylase 4 may be a key factor for muscle reinnervation and disease progression in patients with amyotrophic lateral sclerosis. Specific histone deacetylase 4 inhibitors may then constitute a therapeutic approach to enhancing motor performance and slowing disease progression in amyotrophic lateral sclerosis.
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http://dx.doi.org/10.1093/brain/awt164DOI Listing
August 2013

Congenital myopathies.

Handb Clin Neurol 2013 ;113:1321-36

Morphology Neuromuscular Unit of the Myology Institute, GHU Pitié-Salpêtrière, Paris, France. Electronic address:

Congenital myopathies are a heterogeneous group of inherited muscle disorders, characterized by the predominance of particular histopathological features on muscle biopsy, such as cores (central core disease) or rods (nemaline myopathy). Clinically, early onset of the disease, stable or slowly progressive muscle weakness, hypotonia and delayed motor development are common in most forms. As a result, the diagnosis of a subtype of congenital myopathy is largely based on the presence of specific structural abnormalities in the skeletal muscle detected by enzyme-histochemistry and electron microscopy studies. During the last decades there have been significant advances in the identification of the genetic basis of most congenital myopathies. However, there is significant genetic heterogeneity within the main groups of congenital myopathies, and mutations in one particular gene may also cause diverse clinical and morphological phenotypes. Thus, the nosography and nosology in this field is still evolving.
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http://dx.doi.org/10.1016/B978-0-444-59565-2.00004-6DOI Listing
March 2014

Main steps of skeletal muscle development in the human: morphological analysis and ultrastructural characteristics of developing human muscle.

Handb Clin Neurol 2013 ;113:1299-310

Morphology Neuromuscular Unit of the Myology Institute, GHU Pitié-Salpêtrière, Paris, France. Electronic address:

During embryogenesis, paraxial mesoderm undergoes segmentation into somites, progressing from head to tail. Somites differentiate into dermomyotomes, then into dermatomes and myotomes. Some head muscles derive from the anterior paraxial and precordal mesoderm. Between 10 and 13 weeks of gestation, the fusion of myoblasts generates primary myotubes with central nuclei, and the latter form the second generation of myotubes which requires active innervation. Nicotinamide adenine dinucleotide dehydrogenase-tetrazolium reductase appears before succinate dehydrogenase, and ATPase shows an intermediary activity. β-Sarcoglycan appears by 7 gestational weeks and α-sarcoglycan by 10-12 weeks. β-Spectrin, dystrophin, and utrophin appear by 9 weeks, vimentin and desmin appear by 10 weeks and stain strongly between 10 and 15 weeks. Slow, embryonic myosin heavy chain (MHC) isoenzymes appear before 15 weeks, whereas fetal fast MCH occur later (15-18 weeks). Myotubes become myofibers with peripheral nuclei between 15 and 18 weeks. Large muscle fibers (Wohlfart B) are visible by 20-21 weeks, Wohlfart A by 21-25 weeks. Perimysium surrounds compacted and grouped fibers by 24 weeks, and utrophin disappears, whereas dystrophin stains intensely. At 29 weeks, type I fibers are visible, and by 31-33 weeks they are mature for ATPase staining. Three types of type II fibers can be seen. Vimentin disappears between 15 and 30 weeks, while desmin remains weakly positive at birth.
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http://dx.doi.org/10.1016/B978-0-444-59565-2.00002-2DOI Listing
March 2014

Whole-Body muscle MRI in a series of patients with congenital myopathy related to TPM2 gene mutations.

Neuromuscul Disord 2012 Oct;22 Suppl 2:S137-47

AP-HP, Hôpitaux Universitaires Paris-Ile-de-France Ouest, Pôle neuro-locomoteur, Hôpital R. Poincaré. Service d'imagerie médicale, Groupe Rachis Garches, F-92380 Garches, France.

Beta-tropomyosin 2 (TPM2) gene mutations are a rare cause of congenital myopathy with variable clinical and histological features. We describe muscle involvement using Whole-Body muscle Magnetic Resonance Imaging (WBMRI) in 8 individuals with genetically proven TPM2 mutations and different clinical and histological features (nemaline myopathy, 'cap disease', Bethlem-like phenotype, arthrogryposis). Most patients shared a recognizable MRI pattern with the involvement of masticatory and distal lower leg muscles. The lower leg showed constant soleus muscle involvement, and often also involvement of peroneus, tibialis anterior, and toe flexor muscles. Pelvic and shoulder girdles, and upper limbs muscles were quite spared. Two adult subjects (a patient and a paucisymptomatic parent) had a more diffuse involvement with striking fat infiltration of the rectus femoris muscle. Two children showed variant findings: one presented with masseter involvement associated with severe axial fat infiltration, the second had masticatory and distal leg muscle involvement (soleus and gastrocnemius muscles). Our study suggests that, independently of the clinical and histological presentation, most patients with TPM2 mutations show a predominant involvement of masticatory and distal leg muscles with the other regions relatively spared. More spread involvement may be observed. This cephalic-distal MRI pattern is not frequent in other known myopathies.
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http://dx.doi.org/10.1016/j.nmd.2012.06.347DOI Listing
October 2012

Mutations in FKBP14 cause a variant of Ehlers-Danlos syndrome with progressive kyphoscoliosis, myopathy, and hearing loss.

Am J Hum Genet 2012 Feb 19;90(2):201-16. Epub 2012 Jan 19.

Department of Paediatrics IV - Neonatology, Paediatric Neurology and Inherited Metabolic Disorders, Innsbruck Medical University, Austria.

We report on an autosomal-recessive variant of Ehlers-Danlos syndrome (EDS) characterized by severe muscle hypotonia at birth, progressive scoliosis, joint hypermobility, hyperelastic skin, myopathy, sensorineural hearing impairment, and normal pyridinoline excretion in urine. Clinically, the disorder shares many features with the kyphoscoliotic type of EDS (EDS VIA) and Ullrich congenital muscular dystrophy. Linkage analysis in a large Tyrolean kindred identified a homozygous frameshift mutation in FKBP14 in two affected individuals. Based on the cardinal clinical characteristics of the disorder, four additional individuals originating from different European countries were identified who carried either homozygous or compound heterozygous mutations in FKBP14. FKBP14 belongs to the family of FK506-binding peptidyl-prolyl cis-trans isomerases (PPIases). ER-resident FKBPs have been suggested to act as folding catalysts by accelerating cis-trans isomerization of peptidyl-prolyl bonds and to act occasionally also as chaperones. We demonstrate that FKBP14 is localized in the endoplasmic reticulum (ER) and that deficiency of FKBP14 leads to enlarged ER cisterns in dermal fibroblasts in vivo. Furthermore, indirect immunofluorescence of FKBP14-deficient fibroblasts indicated an altered assembly of the extracellular matrix in vitro. These findings suggest that a disturbance of protein folding in the ER affecting one or more components of the extracellular matrix might cause the generalized connective tissue involvement in this disorder. FKBP14 mutation analysis should be considered in all individuals with apparent kyphoscoliotic type of EDS and normal urinary pyridinoline excretion, in particular in conjunction with sensorineural hearing impairment.
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http://dx.doi.org/10.1016/j.ajhg.2011.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276673PMC
February 2012

Telethonin-deficiency initially presenting as a congenital muscular dystrophy.

Neuromuscul Disord 2011 Jun 6;21(6):433-8. Epub 2011 May 6.

AP-HP, Centre de Référence des Maladies Neuromusculaires Paris-Est, Groupe Hospitalier-Universitaire Pitié-Salpêtrière, Paris F-75013, France.

Congenital muscular dystrophies are defined by congenital or infantile onset of muscle weakness; while 12 culprit genes have been identified, many cases remain molecularly uncharacterized. On the other hand, mutations in the telethonin gene (TCAP) have been associated with a rare form of recessive limb girdle muscular dystrophy, usually presenting in the second decade. So far, three different mutations in telethonin have been reported in patients suffering from limb muscular dystrophy type 2G. We have identified a novel telethonin mutation in a child presenting with mildly delayed motor development and muscle weakness from infancy, clinically improving over the first decade, indicative of a CMD. Muscle biopsy showed a dystrophic process, with preserved laminin α2, collagen VI, and α-dystroglycan, but absent telethonin immunolabeling. Sequence analysis of TCAP showed a novel non-sense p.Gln58X (c.172C>T) homozygous mutation. Our observation indicates that telethonin deficiency may present in infancy with clinical features overlapping with mild forms of α-dystroglycanopathy. Therefore telethonin analysis should be performed in patients suffering from congenital muscular dystrophy of unknown cause.
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http://dx.doi.org/10.1016/j.nmd.2011.03.005DOI Listing
June 2011