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Koe ASL, Tan YY, Vora S. X-linked myotubular myopathy in a family of two infant siblings: A case report and review. Pediatr Neonatol 2024:S1875-9572(24)00113-X. [PMID: 39013721 DOI: 10.1016/j.pedneo.2024.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/22/2024] [Accepted: 02/16/2024] [Indexed: 07/18/2024] Open
Abstract
X-linked myotubular myopathy (XLMTM) is a severe type of congenital skeletal muscle disorder usually presenting at birth requiring extensive resuscitation. While having phenotypic variability, its diagnosis carries a poor prognosis due to high rates of hospitalization and mortality by early infancy. Management of patients with XLMTM should therefore be guided by shared decision-making with parents, considering the severity and progression of the disease, quality of life, and demands on caregivers. We describe a family unit of two half-siblings presenting with the severe neonatal form of XLMTM, with varying prognosis and outcomes. Furthermore, a novel maternally-derived c.343-1G > A variant in intron-5 of the MTM1 gene was identified in this family. Hereby, we propose an algorithm for the management of XLMTM, outlining important considerations during the antenatal and postnatal follow-up period.
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Affiliation(s)
- Amelia Suan-Lin Koe
- Department of Neonatology, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899.
| | - Yee Yin Tan
- Department of Neonatology, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899
| | - Shrenik Vora
- Department of Neonatology, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899
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Reumers SFI, Braun F, Spillane JE, Böhm J, Pennings M, Schouten M, van der Kooi AJ, Foley AR, Bönnemann CG, Kamsteeg EJ, Erasmus CE, Schara-Schmidt U, Jungbluth H, Voermans NC. Spectrum of Clinical Features in X-Linked Myotubular Myopathy Carriers: An International Questionnaire Study. Neurology 2021; 97:e501-e512. [PMID: 34011573 DOI: 10.1212/wnl.0000000000012236] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 04/26/2021] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To characterize the spectrum of clinical features in a cohort of X-linked myotubular myopathy (XL-MTM) carriers, including prevalence, genetic features, clinical symptoms, and signs, as well as associated disease burden. METHODS We performed a cross-sectional online questionnaire study among XL-MTM carriers. Participants were recruited from patient associations, medical centers, and registries in the United Kingdom, Germany, and the Netherlands. We used a custom-made questionnaire, the Checklist Individual Strength (CIS), the Frenchay Activities Index (FAI), the Short Form 12 (SF-12) health survey, and the McGill Pain Questionnaire. Carriers were classified as manifesting or nonmanifesting on the basis of self-reported ambulation and muscle weakness. RESULTS The prevalence of manifesting carriers in this study population (n = 76) was 51%, subdivided into mild (independent ambulation, 39%), moderate (assisted ambulation, 9%), and severe (wheelchair dependent, 3%) phenotypes. In addition to muscle weakness, manifesting carriers frequently reported fatigue (70%) and exercise intolerance (49%). Manifesting carriers scored higher on the overall CIS (p = 0.001), the fatigue subscale (p < 0.001), and least severe pain subscale (p = 0.005) than nonmanifesting carriers. They scored lower on the FAI (p = 0.005) and the physical component of the SF-12 health survey (p < 0.001). CONCLUSIONS The prevalence of manifesting XL-MTM carriers may be higher than currently assumed, most having a mild phenotype and a wide variety of symptoms. Manifesting carriers are particularly affected by fatigue, limitations of daily activities, pain, and reduced quality of life. Our findings should increase awareness and provide useful information for health care providers and future clinical trials.
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Affiliation(s)
- Stacha F I Reumers
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Frederik Braun
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Jennifer E Spillane
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Johann Böhm
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Maartje Pennings
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Meyke Schouten
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Anneke J van der Kooi
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - A Reghan Foley
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Carsten G Bönnemann
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Erik-Jan Kamsteeg
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Corrie E Erasmus
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Ulrike Schara-Schmidt
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Heinz Jungbluth
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK
| | - Nicol C Voermans
- From the Department of Neurology (S.F.I.R., N.C.V.), Donders Institute for Brain, Cognition and Behaviour, Department of Human Genetics (M.P., E.-j.K.), and Department of Clinical Genetics (M.S.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatric Neurology and Neuromuscular Centre (F.B., U.S.-S.), University Hospital Essen, Germany; Department of Neurology (J.E.S.), St. Thomas Hospital, and Department of Paediatric Neurology (H.J.), Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK; Department of Neurobiology and Genetics (J.B.), Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France; Department of Neurology (A.J.v.d.K.), Amsterdam University Medical Center, Neuroscience Institute, the Netherlands; Neuromuscular and Neurogenetic Disorders of Childhood Section (A.R.F., C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Department of Pediatric Neurology (C.E.E.), Radboud University Medical Center Amalia Children's Hospital, Nijmegen, the Netherlands; and Muscle Signalling Section (H.J.), Randall Division for Cell and Molecular Biophysics, King's College, London, UK.
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Argov Z, de Visser M. Dysphagia in adult myopathies. Neuromuscul Disord 2020; 31:5-20. [PMID: 33334661 DOI: 10.1016/j.nmd.2020.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 12/11/2022]
Abstract
Dysphagia (impaired swallowing) is not a rare problem in various neuromuscular disorders, both in the pediatric and the adult patient population. On many occasions such patients are first presented to other medical specialists or health professionals. Disorders of deglutition are probably underrecognized in patients with a neuromuscular disease as a result of patient's and doctor's delay. This review will focus on dysphagia in adults suffering from a myopathy. Dysphagia in myopathies usually affects the oropharyngeal phases which rely mostly on voluntary muscle activity of the mouth, pharynx and upper esophageal sphincter. Dysphagia is known to contribute to a reduction of quality of life and may also lead to increased morbidity and mortality. The review includes an overview on symptomatology and tools of assessments, and elaborates on dysphagia in specific hereditary and acquired myopathies.
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Affiliation(s)
- Zohar Argov
- Department of Neurology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Marianne de Visser
- Department of Neurology, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, the Netherlands.
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Souza LS, Almeida CF, Yamamoto GL, Pavanello RDCM, Gurgel-Giannetti J, da Costa SS, Anequini IP, do Carmo SA, Wang JYT, Scliar MDO, Castelli EC, Otto PA, Zanoteli E, Vainzof M. Manifesting carriers of X-linked myotubular myopathy: Genetic modifiers modulating the phenotype. NEUROLOGY-GENETICS 2020; 6:e513. [PMID: 33062893 PMCID: PMC7524580 DOI: 10.1212/nxg.0000000000000513] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/16/2020] [Indexed: 12/18/2022]
Abstract
Objective To analyze the modulation of the phenotype in manifesting carriers of recessive X-linked myotubular myopathy (XLMTM), searching for possible genetic modifiers. Methods Twelve Brazilian families with XLMTM were molecularly and clinically evaluated. In 2 families, 4 of 6 and 2 of 5 manifesting female carriers were identified. These females were studied for X chromosome inactivation. In addition, whole-exome sequencing was performed, looking for possible modifier variants. We also determined the penetrance rate among carriers of the mutations responsible for the condition. Results Mutations in the MTM1 gene were identified in all index patients from the 12 families, being 4 of them novel. In the heterozygotes, X chromosome inactivation was random in 3 of 4 informative manifesting carriers. The disease penetrance rate was estimated to be 30%, compatible with incomplete penetrance. Exome comparative analyses identified variants within a segment of 4.2 Mb on chromosome 19, containing the killer cell immunoglobulin-like receptor cluster of genes that were present in all nonmanifesting carriers and absent in all manifesting carriers. We hypothesized that these killer cell immunoglobulin-like receptor variants may modulate the phenotype, acting as a protective factor in the nonmanifesting carriers. Conclusions Affected XLMTM female carriers have been described with a surprisingly high frequency for a recessive X-linked disease, raising the question about the pattern of inheritance or the role of modifier factors acting on the disease phenotype. We demonstrated the possible existence of genetic mechanisms and variants accountable for the clinical manifestation in these women, which can become future targets for therapies.
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Affiliation(s)
- Lucas Santos Souza
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Camila Freitas Almeida
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Guilherme Lopes Yamamoto
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Rita de Cássia Mingroni Pavanello
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Juliana Gurgel-Giannetti
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Silvia Souza da Costa
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Isabela Pessa Anequini
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Silvana Amanda do Carmo
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Jaqueline Yu Ting Wang
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Marília de Oliveira Scliar
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Erick C Castelli
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Paulo Alberto Otto
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Edmar Zanoteli
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
| | - Mariz Vainzof
- Human Genome and Stem Cell Research Center (L.S.S., C.F.A., G.L.Y., R.d.C.M.P., S.S.d.C., I.P.A., S.A.d.C., J.Y.T.W., M.d.O.S., P.A.O., M.V.), University of São Paulo; Department of Pediatrics (J.G.-G.), Medical School of Federal University of Minas Gerais, Belo Horizonte; Pathology Department (E.C.C.), School of Medicine, São Paulo State University (UNESP), Botucatu; and Department of Neurology (E.Z.), Medical School (FMUSP), University of São Paulo, Brazil
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Cocanougher BT, Flynn L, Yun P, Jain M, Waite M, Vasavada R, Wittenbach JD, de Chastonay S, Chhibber S, Innes AM, MacLaren L, Mozaffar T, Arai AE, Donkervoort S, Bönnemann CG, Foley AR. Adult MTM1-related myopathy carriers: Classification based on deep phenotyping. Neurology 2019; 93:e1535-e1542. [PMID: 31541013 DOI: 10.1212/wnl.0000000000008316] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 05/13/2019] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To better characterize adult myotubularin 1 (MTM1)-related myopathy carriers and recommend a phenotypic classification. METHODS This cohort study was performed at the NIH Clinical Center. Participants were required to carry a confirmed MTM1 mutation and were recruited via the Congenital Muscle Disease International Registry (n = 8), a traveling local clinic of the Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH and Cure CMD (n = 1), and direct physician referral (n = 1). Neuromuscular examinations, muscle MRI, dynamic breathing MRI, cardiac MRI, pulmonary function tests (PFTs), physical therapy assessments including the Motor Function Measure 32 (MFM-32) scale, and X chromosome inactivation (XCI) studies were performed. RESULTS Phenotypic categories were proposed based on ambulatory status and muscle weakness. Carriers were categorized as severe (nonambulatory; n = 1), moderate (minimal independent ambulation/assisted ambulation; n = 3), mild (independent ambulation but with evidence of muscle weakness; n = 4), and nonmanifesting (no evidence of muscle weakness; n = 2). Carriers with more severe muscle weakness exhibited greater degrees of respiratory insufficiency and abnormal signal on muscle imaging. Skeletal asymmetries were evident in both manifesting and nonmanifesting carriers. Skewed XCI did not explain phenotypic severity. CONCLUSION This work illustrates the phenotypic range of MTM1-related myopathy carriers in adulthood and recommends a phenotypic classification. This classification, defined by ambulatory status and muscle weakness, is supported by muscle MRI, PFT, and MFM-32 scale composite score findings, which may serve as markers of disease progression and outcome measures in future gene therapy or other clinical trials.
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Affiliation(s)
- Benjamin T Cocanougher
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Lauren Flynn
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Pomi Yun
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Minal Jain
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Melissa Waite
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Ruhi Vasavada
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Jason D Wittenbach
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Sabine de Chastonay
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Sameer Chhibber
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - A Micheil Innes
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Linda MacLaren
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Tahseen Mozaffar
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Andrew E Arai
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Sandra Donkervoort
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - Carsten G Bönnemann
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine
| | - A Reghan Foley
- From the University of Rochester School of Medicine and Dentistry (B.T.C.), NY; Howard Hughes Medical Institute Janelia Research Campus (B.T.C., J.D.W.), Ashburn, VA; St Catharine's College (B.T.C.), University of Cambridge, UK; Clinical Center, NINDS (L.F.), Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, NINDS (P.Y., S.D., C.G.B., A.R.F.), Clinical Research Center, Rehabilitation Medicine Department (M.J., M.W., R.V.), and Advanced Cardiovascular Imaging Laboratory, NHLBI (A.E.A.), NIH, Bethesda, MD; Congenital Muscle Disease International Registry (CMDIR) (S.d.C.), Cure CMD, Torrance, CA; Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine (A.M.I.), and Department of Clinical Neurosciences (S.C.), University of Calgary; Department of Medical Genetics and Alberta Children's Hospital (L.M.), Calgary, Canada; and Department of Neurology (T.M.), University of California, Irvine.
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6
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Zhao Y, Zhao Z, Shen H, Bing Q, Hu J. Characterization and genetic diagnosis of centronuclear myopathies in seven Chinese patients. Neurol Sci 2018; 39:2043-2051. [PMID: 30232666 DOI: 10.1007/s10072-018-3534-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 08/09/2018] [Indexed: 11/24/2022]
Abstract
Centronuclear myopathies (CNMs) are a group of clinically and genetically heterogeneous muscle disorders. Here, we report a cohort of seven CNM patients with their clinical, histological, and morphological features. In addition, using the next-generation sequencing (NGS) technique (5/7 patients), we identified small indels: intronic, exonic, and missense mutations in MTM1, DNM2, and RYR1 genes. Further genetic studies revealed skewed X-chromosome inactivation in two female patients carrying MTM1 mutations. Based on the results of genetic analysis, these seven patients were classified as (1) X-linked recessive myotubular myopathy (patients 1-3) with MTM1 mutations and mild phenotype, (2) the autosomal dominant CNM (patients 4-6) with DNM2 mutations, and (3) the autosomal recessive CNM (patient 7) with RYR1 mutations. In all patients, histological findings featured a high proportion of fibers with central nuclei. Radial arrangement of the sarcoplasmic strands was observed in DNM2-CNM and RYR1-CNM patients. Muscle magnetic resonance imaging (MRI) revealed a proximal pattern of involvement presented in both MTM1-CNM and RYR1-CNM patients. A distal pattern of involvement was present in DNM2-CNM patients. Our findings thereby identified a number of novel features that expand the reported clinicopathological phenotype of CNMs in China.
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Affiliation(s)
- Yan Zhao
- Department of Neuromuscular Disorder, Third Hospital of Hebei Medical University, 139# Ziqiang Road, Shijiazhuang, 050051, Hebei, People's Republic of China
| | - Zhe Zhao
- Department of Neuromuscular Disorder, Third Hospital of Hebei Medical University, 139# Ziqiang Road, Shijiazhuang, 050051, Hebei, People's Republic of China
| | - Hongrui Shen
- Department of Neuromuscular Disorder, Third Hospital of Hebei Medical University, 139# Ziqiang Road, Shijiazhuang, 050051, Hebei, People's Republic of China
| | - Qi Bing
- Department of Neuromuscular Disorder, Third Hospital of Hebei Medical University, 139# Ziqiang Road, Shijiazhuang, 050051, Hebei, People's Republic of China
| | - Jing Hu
- Department of Neuromuscular Disorder, Third Hospital of Hebei Medical University, 139# Ziqiang Road, Shijiazhuang, 050051, Hebei, People's Republic of China.
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Felice KJ, Whitaker CH, Wu Q. Whole exome sequencing discloses a pathogenic MTM1 gene mutation and ends the diagnostic odyssey in an older woman with a progressive and seemingly sporadic myopathy: Case report and literature review of MTM1 manifesting female carriers. Neuromuscul Disord 2018; 28:339-345. [PMID: 29567349 DOI: 10.1016/j.nmd.2018.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/29/2018] [Accepted: 02/02/2018] [Indexed: 01/28/2023]
Abstract
We report the case of a 58-year-old woman with a progressive and seemingly sporadic myopathy who, later through whole exome sequencing, was diagnosed as a manifesting carrier of a myotubularin 1 gene mutation (c.342_342 + 4delAGTAA). As the case was a diagnostic challenge for 7 years, we thought it would be helpful to report the patient and review the other 25 cases thus far described. The manifesting carrier state is a rare cause for myopathic weakness in a female but should be strongly considered in kindreds with known affected males with myotubularin 1 gene mutations, and families with history of gestational polyhydramnios or male infantile death. Although the clinical phenotype is quite variable, the findings of ptosis, ophthalmoparesis, facial weakness, and asymmetrical limb involvement should raise the suspicion of the manifesting carrier state. Necklace fibers appear to be a highly sensitive and specific pathologic finding in such cases.
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Affiliation(s)
- Kevin J Felice
- Muscular Dystrophy Association Care Center, Department of Neuromuscular Medicine, Hospital for Special Care, New Britain, Connecticut, USA.
| | - Charles H Whitaker
- Muscular Dystrophy Association Care Center, Department of Neuromuscular Medicine, Hospital for Special Care, New Britain, Connecticut, USA
| | - Qian Wu
- Department of Pathology, University of Connecticut School of Medicine, Farmington, Connecticut, USA
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Affected female carriers of MTM1 mutations display a wide spectrum of clinical and pathological involvement: delineating diagnostic clues. Acta Neuropathol 2017; 134:889-904. [PMID: 28685322 DOI: 10.1007/s00401-017-1748-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/24/2017] [Accepted: 07/02/2017] [Indexed: 01/14/2023]
Abstract
X-linked myotubular myopathy (XLMTM), a severe congenital myopathy, is caused by mutations in the MTM1 gene located on the X chromosome. A majority of affected males die in the early postnatal period, whereas female carriers are believed to be usually asymptomatic. Nevertheless, several affected females have been reported. To assess the phenotypic and pathological spectra of carrier females and to delineate diagnostic clues, we characterized 17 new unrelated affected females and performed a detailed comparison with previously reported cases at the clinical, muscle imaging, histological, ultrastructural and molecular levels. Taken together, the analysis of this large cohort of 43 cases highlights a wide spectrum of clinical severity ranging from severe neonatal and generalized weakness, similar to XLMTM male, to milder adult forms. Several females show a decline in respiratory function. Asymmetric weakness is a noteworthy frequent specific feature potentially correlated to an increased prevalence of highly skewed X inactivation. Asymmetry of growth was also noted. Other diagnostic clues include facial weakness, ptosis and ophthalmoplegia, skeletal and joint abnormalities, and histopathological signs that are hallmarks of centronuclear myopathy such as centralized nuclei and necklace fibers. The histopathological findings also demonstrate a general disorganization of muscle structure in addition to these specific hallmarks. Thus, MTM1 mutations in carrier females define a specific myopathy, which may be independent of the presence of an XLMTM male in the family. As several of the reported affected females carry large heterozygous MTM1 deletions not detectable by Sanger sequencing, and as milder phenotypes present as adult-onset limb-girdle myopathy, the prevalence of this myopathy is likely to be greatly underestimated. This report should aid diagnosis and thus the clinical management and genetic counseling of MTM1 carrier females. Furthermore, the clinical and pathological history of this cohort may be useful for therapeutic projects in males with XLMTM, as it illustrates the spectrum of possible evolution of the disease in patients surviving long term.
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9
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Cassandrini D, Trovato R, Rubegni A, Lenzi S, Fiorillo C, Baldacci J, Minetti C, Astrea G, Bruno C, Santorelli FM. Congenital myopathies: clinical phenotypes and new diagnostic tools. Ital J Pediatr 2017; 43:101. [PMID: 29141652 PMCID: PMC5688763 DOI: 10.1186/s13052-017-0419-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/02/2017] [Indexed: 12/26/2022] Open
Abstract
Congenital myopathies are a group of genetic muscle disorders characterized clinically by hypotonia and weakness, usually from birth, and a static or slowly progressive clinical course. Historically, congenital myopathies have been classified on the basis of major morphological features seen on muscle biopsy. However, different genes have now been identified as associated with the various phenotypic and histological expressions of these disorders, and in recent years, because of their unexpectedly wide genetic and clinical heterogeneity, next-generation sequencing has increasingly been used for their diagnosis. We reviewed clinical and genetic forms of congenital myopathy and defined possible strategies to improve cost-effectiveness in histological and imaging diagnosis.
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Affiliation(s)
| | - Rosanna Trovato
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Anna Rubegni
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Sara Lenzi
- Neurology, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Chiara Fiorillo
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy.,Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genoa, Italy
| | - Jacopo Baldacci
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Carlo Minetti
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G. Gaslini, Genoa, Italy.,Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genoa, Italy
| | - Guja Astrea
- Neurology, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Claudio Bruno
- Department of Neuroscience, Center of Myology and Neurodegenerative Disorders, Istituto G. Gaslini, Genoa, Italy
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Savarese M, Musumeci O, Giugliano T, Rubegni A, Fiorillo C, Fattori F, Torella A, Battini R, Rodolico C, Pugliese A, Piluso G, Maggi L, D'Amico A, Bruno C, Bertini E, Santorelli FM, Mora M, Toscano A, Minetti C, Nigro V. Novel findings associated with MTM1 suggest a higher number of female symptomatic carriers. Neuromuscul Disord 2016; 26:292-9. [PMID: 27017278 PMCID: PMC4862961 DOI: 10.1016/j.nmd.2016.02.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/08/2015] [Accepted: 02/04/2016] [Indexed: 12/16/2022]
Abstract
504 myopathic patients have been screened for MTM1 variants by NGS and CGH array approaches. Seven novel XLMTM patients and the fifth case of a large Xq28 deletion have been identified. The identification of two sporadic manifesting female carriers suggests that their number may be underestimated. Large NGS panels, including the MTM1 gene, are useful tools to identify sporadic female XLMTM patients. The identification of MTM1 variants, also as incidental findings, complicates genetic counseling.
Mutations in the MTM1 gene cause X-linked myotubular myopathy (XLMTM), characterized by neonatal hypotonia and respiratory failure, and are responsible for a premature mortality in affected males. Female carriers are usually asymptomatic but they may present with muscular weakness because of a hypothesized skewed pattern of X-chromosome inactivation. By combining next generation sequencing (NGS) and CGH array approaches, we have investigated the role of MTM1 variants in a large cohort of undiagnosed patients with a wide spectrum of myopathies. Seven novel XLMTM patients have been identified, including two girls with an unremarkable family history for myotubular myopathy. Moreover, we have detected and finely mapped a large deletion causing a myotubular myopathy with abnormal genital development. Our data confirm that the severe neonatal onset of the disease in male infants is sufficient to address the direct molecular testing toward the MTM1 gene and, above all, suggest that the number of undiagnosed symptomatic female carriers is probably underestimated.
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Affiliation(s)
- Marco Savarese
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Napoli, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Olimpia Musumeci
- Dipartimento di Neuroscienze, Università degli Studi di Messina, Messina, Italy
| | - Teresa Giugliano
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Napoli, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | | | | | - Annalaura Torella
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Napoli, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Carmelo Rodolico
- Dipartimento di Neuroscienze, Università degli Studi di Messina, Messina, Italy
| | | | - Giulio Piluso
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Napoli, Italy
| | - Lorenzo Maggi
- Dipartimento di Neuroscienze, Istituto Besta, Milano, Italy
| | | | - Claudio Bruno
- Center of Myology and Neurodegenerative Disorders, Istituto Giannina Gaslini, Genova, Italy
| | | | | | - Marina Mora
- Dipartimento di Neuroscienze, Istituto Besta, Milano, Italy
| | - Antonio Toscano
- Dipartimento di Neuroscienze, Università degli Studi di Messina, Messina, Italy
| | - Carlo Minetti
- Center of Myology and Neurodegenerative Disorders, Istituto Giannina Gaslini, Genova, Italy
| | - Vincenzo Nigro
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Napoli, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.
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11
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Longo G, Russo S, Novelli G, Sangiuolo F, D'Apice M. Mutation spectrum of the MTM1
gene in XLMTM patients: 10 years of experience in prenatal and postnatal diagnosis. Clin Genet 2015; 89:93-8. [DOI: 10.1111/cge.12674] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/01/2015] [Accepted: 09/01/2015] [Indexed: 11/28/2022]
Affiliation(s)
- G. Longo
- Department of Biomedicine and Prevention; University of Rome ‘Tor Vergata’; Rome Italy
| | - S. Russo
- Fondazione PTV “Policlinico Tor Vergata”; U.O.C. of Medical Genetics; Rome Italy
| | - G. Novelli
- Department of Biomedicine and Prevention; University of Rome ‘Tor Vergata’; Rome Italy
- Fondazione PTV “Policlinico Tor Vergata”; U.O.C. of Medical Genetics; Rome Italy
| | - F. Sangiuolo
- Department of Biomedicine and Prevention; University of Rome ‘Tor Vergata’; Rome Italy
- Fondazione PTV “Policlinico Tor Vergata”; U.O.C. of Medical Genetics; Rome Italy
| | - M.R. D'Apice
- Fondazione PTV “Policlinico Tor Vergata”; U.O.C. of Medical Genetics; Rome Italy
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12
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Hunter JM, Kiefer J, Balak CD, Jooma S, Ahearn ME, Hall JG, Baumbach-Reardon L. Review of X-linked syndromes with arthrogryposis or early contractures-aid to diagnosis and pathway identification. Am J Med Genet A 2015; 167A:931-73. [DOI: 10.1002/ajmg.a.36934] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/05/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Jesse M. Hunter
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Jeff Kiefer
- Knowledge Mining; Translational Genomics Research Institute; Phoenix Arizona
| | - Christopher D. Balak
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Sonya Jooma
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Mary Ellen Ahearn
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Judith G. Hall
- Departments of Medical Genetics and Pediatrics; University of British Columbia and BC Children's Hospital Vancouver; British Columbia Canada
| | - Lisa Baumbach-Reardon
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
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13
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Oliveira J, Oliveira ME, Kress W, Taipa R, Pires MM, Hilbert P, Baxter P, Santos M, Buermans H, den Dunnen JT, Santos R. Expanding the MTM1 mutational spectrum: novel variants including the first multi-exonic duplication and development of a locus-specific database. Eur J Hum Genet 2012; 21:540-9. [PMID: 22968136 DOI: 10.1038/ejhg.2012.201] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Myotubular myopathy (MIM#310400), the X-linked form of Centronuclear myopathy (CNM) is mainly characterized by neonatal hypotonia and inability to maintain unassisted respiration. The MTM1 gene, responsible for this disease, encodes myotubularin - a lipidic phosphatase involved in vesicle trafficking regulation and maturation. Recently, it was shown that myotubularin interacts with desmin, being a major regulator of intermediate filaments. We report the development of a locus-specific database for MTM1 using the Leiden Open Variation database software (http://www.lovd.nl/MTM1), with data collated for 474 mutations identified in 472 patients (by June 2012). Among the entries are a total of 25 new mutations, including a large deletion encompassing introns 2-15. During database implementation it was noticed that no large duplications had been reported. We tested a group of eight uncharacterized CNM patients for this specific type of mutation, by multiple ligation-dependent probe amplification (MLPA) analysis. A large duplication spanning exons 1-5 was identified in a boy with a mild phenotype, with results pointing toward possible somatic mosaicism. Further characterization revealed that this duplication causes an in-frame deletion at the mRNA level (r.343_444del). Results obtained with a next generation sequencing approach suggested that the duplication extends into the neighboring MAMLD1 gene and subsequent cDNA analysis detected the presence of a MTM1/MAMLD1 fusion transcript. A complex rearrangement involving the duplication of exon 10 has since been reported, with detection also enabled by MLPA analysis. It is thus conceivable that large duplications in MTM1 may account for a number of CNM cases that have remained genetically unresolved.
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Affiliation(s)
- Jorge Oliveira
- Unidade de Investigação e Desenvolvimento, Departamento de Genética, Centro de Genética Médica Dr Jacinto Magalhães, Instituto Nacional de Saúde Dr Ricardo Jorge, IP, Porto, Portugal
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14
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Hedberg C, Lindberg C, Máthé G, Moslemi AR, Oldfors A. Myopathy in a woman and her daughter associated with a novel splice site MTM1 mutation. Neuromuscul Disord 2012; 22:244-51. [DOI: 10.1016/j.nmd.2011.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 09/20/2011] [Accepted: 10/13/2011] [Indexed: 01/26/2023]
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15
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Bevilacqua JA, Bitoun M, Biancalana V, Oldfors A, Stoltenburg G, Claeys KG, Lacène E, Brochier G, Manéré L, Laforêt P, Eymard B, Guicheney P, Fardeau M, Romero NB. "Necklace" fibers, a new histological marker of late-onset MTM1-related centronuclear myopathy. Acta Neuropathol 2009; 117:283-91. [PMID: 19084976 DOI: 10.1007/s00401-008-0472-1] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 12/02/2008] [Accepted: 12/03/2008] [Indexed: 12/31/2022]
Abstract
Mutations in the gene encoding the phosphoinositide phosphatase myotubularin 1 protein (MTM1) are usually associated with severe neonatal X-linked myotubular myopathy (XLMTM). However, mutations in MTM1 have also been recognized as the underlying cause of "atypical" forms of XLMTM in newborn boys, female infants, female manifesting carriers and adult men. We reviewed systematically the biopsies of a cohort of patients with an unclassified form of centronuclear myopathy (CNM) and identified four patients presenting a peculiar histological alteration in some muscle fibers that resembled a necklace ("necklace fibers"). We analyzed further the clinical and morphological features and performed a screening of the genes involved in CNM. Muscle biopsies in all four patients demonstrated 4-20% of fibers with internalized nuclei aligned in a basophilic ring (necklace) at 3 microm beneath the sarcolemma. Ultrastructurally, such necklaces consisted of myofibrils of smaller diameter, in oblique orientation, surrounded by mitochondria, sarcoplasmic reticulum and glycogen granules. In the four patients (three women and one man), myopathy developed in early childhood but was slowly progressive. All had mutations in the MTM1 gene. Two mutations have previously been reported (p.E404K and p.R241Q), while two are novel; a c.205_206delinsAACT frameshift change in exon 4 and a c.1234A>G mutation in exon 11 leading to an abnormal splicing and the deletion of nine amino acids in the catalytic domain of MTM1. Necklace fibers were seen neither in DNM2- or BIN1-related CNM nor in males with classical XLMTM. The presence of necklace fibers is useful as a marker to direct genetic analysis to MTM1 in CNM.
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MESH Headings
- Adolescent
- Adult
- Age of Onset
- Biopsy
- Female
- Humans
- Immunohistochemistry
- Magnetic Resonance Imaging
- Male
- Microscopy, Electron
- Middle Aged
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle Fibers, Skeletal/ultrastructure
- Muscle, Skeletal/pathology
- Muscle, Skeletal/ultrastructure
- Mutation
- Myofibrils/ultrastructure
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/metabolism
- Myopathies, Structural, Congenital/pathology
- Polymerase Chain Reaction
- Protein Tyrosine Phosphatases, Non-Receptor/genetics
- Protein Tyrosine Phosphatases, Non-Receptor/metabolism
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Affiliation(s)
- Jorge A Bevilacqua
- INSERM, Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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16
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Jungbluth H, Wallgren-Pettersson C, Laporte J. Centronuclear (myotubular) myopathy. Orphanet J Rare Dis 2008; 3:26. [PMID: 18817572 PMCID: PMC2572588 DOI: 10.1186/1750-1172-3-26] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 09/25/2008] [Indexed: 01/23/2023] Open
Abstract
Centronuclear myopathy (CNM) is an inherited neuromuscular disorder characterised by clinical features of a congenital myopathy and centrally placed nuclei on muscle biopsy. The incidence of X-linked myotubular myopathy is estimated at 2/100000 male births but epidemiological data for other forms are not currently available. The clinical picture is highly variable. The X-linked form usually gives rise to a severe phenotype in males presenting at birth with marked weakness and hypotonia, external ophthalmoplegia and respiratory failure. Signs of antenatal onset comprise reduced foetal movements, polyhydramnios and thinning of the ribs on chest radiographs; birth asphyxia may be the present. Affected infants are often macrosomic, with length above the 90th centile and large head circumference. Testes are frequently undescended. Both autosomal-recessive (AR) and autosomal-dominant (AD) forms differ from the X-linked form regarding age at onset, severity, clinical characteristics and prognosis. In general, AD forms have a later onset and milder course than the X-linked form, and the AR form is intermediate in both respects. Mutations in the myotubularin (MTM1) gene on chromosome Xq28 have been identified in the majority of patients with the X-linked recessive form, whilst AD and AR forms have been associated with mutations in the dynamin 2 (DNM2) gene on chromosome 19p13.2 and the amphiphysin 2 (BIN1) gene on chromosome 2q14, respectively. Single cases with features of CNM have been associated with mutations in the skeletal muscle ryanodine receptor (RYR1) and the hJUMPY (MTMR14) genes. Diagnosis is based on typical histopathological findings on muscle biopsy in combination with suggestive clinical features; muscle magnetic resonance imaging may complement clinical assessment and inform genetic testing in cases with equivocal features. Genetic counselling should be offered to all patients and families in whom a diagnosis of CNM has been made. The main differential diagnoses include congenital myotonic dystrophy and other conditions with severe neonatal hypotonia. Management of CNM is mainly supportive, based on a multidisciplinary approach. Whereas the X-linked form due to MTM1 mutations is often fatal in infancy, dominant forms due to DNM2 mutations and some cases of the recessive BIN1-related form appear to be associated with an overall more favourable prognosis.
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Affiliation(s)
- Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, St Thomas' Hospital, London, UK.
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17
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Abstract
This review focuses on congenital myopathies, a distinct but markedly heterogeneous group of muscle disorders that present with muscle weakness and typically appear at birth or in infancy. These myopathies have characteristic histopathologic abnormalities on muscle biopsy, allowing a preliminary morphologic classification. Advances in molecular genetics have allowed a more rational classification of these disorders and have reshuffled taxonomy for some of these conditions. Here, we focus on recent research advances in specific congenital myopathies, including nemaline myopathy, myotubular myopathy, centronuclear myopathy, central core myopathy, multi-minicore myopathy, congenital fiber-type disproportion myopathy, and hyaline body myopathy. Scientific progress has not only elucidated the pathologic mechanisms of these disorders, but it has also provided the basis for therapeutic strategies.
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Affiliation(s)
- Adele D'Amico
- Ospedale Bambino Gesù Research Chidren's Hospital, P.za S. Onofrio, 4, 00165 Rome, Italy
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18
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[Unilateral presentation of X-linked myotubular myopathy (XLMTM) in two out of three female carriers in a family with no affected male]. Rev Neurol (Paris) 2008; 164:169-76. [PMID: 18358876 DOI: 10.1016/j.neurol.2007.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 07/13/2007] [Accepted: 08/10/2007] [Indexed: 11/22/2022]
Abstract
INTRODUCTION X-linked myotubular myopathy (XLMTM), a recessive disorder, is caused by mutations affecting the myotubulatin (MTM1) gene located on the X chromosome. Most of the affected males die in the early postnatal period whereas female carriers are usually asymptomatic. CASE REPORTS We report a family in which two females (45 and 27 years old) in two different generations, presented unilateral weakness which had worsened since adolescence, and one 48-year-old woman presented minimal symptoms. In agreement with the computed tomography and magnetic resonance imaging findings, the EMG was compatible with myopathy. Serum creatine kinase was elevated in the second patient. The histological study showed centronuclear myopathy aspects, more severe in the second patient. Both presented c.1420C>T, p.Arg474X in exon 13 of the MTM1 gene, whereas the third patients with less pronounced manifestation, had a skewed pattern of X chromosome inactivation. DISCUSSION Symptomatic female carriers of XLMTM can present with asymmetric malformations, which must be distinguished from an autosomal-dominant centronuclear myopathy. CONCLUSION Unilateral presentation of weakness cannot rule out a diagnosis of myopathy. Detection of symptomatic female carriers of an X linked recessive disease, with a severe presentation in males, is important for genetic counselling.
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Pénisson-Besnier I, Biancalana V, Reynier P, Cossée M, Dubas F. Diagnosis of myotubular myopathy in the oldest known manifesting female carrier: a clinical and genetic study. Neuromuscul Disord 2007; 17:180-5. [PMID: 17251023 DOI: 10.1016/j.nmd.2006.10.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/26/2006] [Accepted: 10/27/2006] [Indexed: 10/23/2022]
Abstract
X-linked myotubular myopathy is a congenital myopathy due to mutation in the MTM1 gene, encoding myotubularin. Most of the affected male neonates die early of respiratory failure. The female carriers are usually asymptomatic. The authors report a novel MTM1 mutation in a 77-year-old woman. She presented with progressive ptosis since childhood, proximal limb weakness, and a severe restrictive respiratory dysfunction with a hemidiaphragmatic paresis, leading to death at 84 years of age. The muscle biopsy showed centrally nucleated fibers and mitochondrial abnormalities. A stop mutation Leu498X in MTM1 gene was identified in the proband and in her two healthy daughters. The X-inactivation pattern was random in the proband's blood and muscle DNA, and in blood DNA from her two unaffected MTM1 mutation carrier daughters. Two large heteroplasmic deletions were also detected in the muscle mitochondrial DNA of the propositus, raising the question of their putative impact on the phenotype.
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MESH Headings
- Aged, 80 and over
- Blepharoptosis/etiology
- Blepharoptosis/genetics
- Blotting, Southern
- Chromosomes, Human, X
- Creatine Kinase/blood
- DNA/genetics
- Dynamin II/genetics
- Female
- Heterozygote
- Humans
- Lactic Acid/blood
- Muscle, Skeletal/diagnostic imaging
- Muscle, Skeletal/pathology
- Myopathies, Structural, Congenital/diagnosis
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/pathology
- Pedigree
- Phenotype
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases, Non-Receptor
- Respiratory Paralysis/genetics
- Respiratory Paralysis/pathology
- Reverse Transcriptase Polymerase Chain Reaction
- Tomography, X-Ray Computed
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Affiliation(s)
- Isabelle Pénisson-Besnier
- Centre de référence Maladies Neuromusculaires rares Nantes-Angers, Centre Hospitalier Universitaire d'Angers, 4 rue Larrey, F-49033 Angers, France.
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20
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Affiliation(s)
- Nigel G Laing
- Centre for Medical Research, University of Western Australia, West Australian Institute for Medical Research, Nedlands, Western Australia, Australia
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21
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Pierson CR, Tomczak K, Agrawal P, Moghadaszadeh B, Beggs AH. X-linked myotubular and centronuclear myopathies. J Neuropathol Exp Neurol 2005; 64:555-64. [PMID: 16042307 DOI: 10.1097/01.jnen.0000171653.17213.2e] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Recent work has significantly enhanced our understanding of the centronuclear myopathies and, in particular, myotubular myopathy. These myopathies share similar morphologic appearances with other diseases, namely the presence of hypotrophic myofibers with prominent internalized or centrally placed nuclei. Early workers suggested that this alteration represented an arrest in myofiber maturation, while other hypotheses implicated either failure in myofiber maturation or neurogenic causes. Despite similarities in morphology, distinct patterns of inheritance and some differences in clinical features have been recognized among cases. A severe form, known as X-linked myotubular myopathy (XLMTM), presents at or near birth. Affected males have profound global hypotonia and weakness, accompanied by respiratory difficulties that often require ventilation. Most of these patients die in infancy or early childhood, but some survive into later childhood or even adulthood. The responsible gene (MTM1) has been cloned; it encodes a phosphoinositide lipid phosphatase known as myotubularin that appears to be important in muscle maintenance. In autosomal recessive centronuclear myopathy (AR CNM), the onset of weakness typically occurs in infancy or early childhood. Some investigators have divided AR CNM into 3 subgroups: 1) an early-onset form with ophthalmoparesis, 2) an early-onset form without ophthalmoparesis, and 3) a late-onset form without ophthalmoparesis. Clinically, autosomal dominant CNM (AD CNM) is relatively mild and usually presents in adults with a diffuse weakness that is slowly progressive and may be accompanied by muscle hypertrophy. Overall, the autosomal disorders are not as clinically uniform as XLMTM, which has made their genetic characterization more difficult. Currently the responsible gene(s) remain unknown. This review will explore the historical evolution in understanding of these myopathies and give an update on their histopathologic features, genetics and pathogenesis.
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MESH Headings
- Adult
- Diagnosis, Differential
- Female
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/pathology
- Genetic Diseases, X-Linked/physiopathology
- Humans
- Male
- Muscle, Skeletal/pathology
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/pathology
- Myopathies, Structural, Congenital/physiopathology
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases, Non-Receptor
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22
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Begley MJ, Taylor GS, Kim SA, Veine DM, Dixon JE, Stuckey JA. Crystal Structure of a Phosphoinositide Phosphatase, MTMR2. Mol Cell 2003; 12:1391-402. [PMID: 14690594 DOI: 10.1016/s1097-2765(03)00486-6] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Myotubularin-related proteins are a large subfamily of protein tyrosine phosphatases (PTPs) that dephosphorylate D3-phosphorylated inositol lipids. Mutations in members of the myotubularin family cause the human neuromuscular disorders myotubular myopathy and type 4B Charcot-Marie-Tooth syndrome. The crystal structure of a representative member of this family, MTMR2, reveals a phosphatase domain that is structurally unique among PTPs. A series of mutants are described that exhibit altered enzymatic activity and provide insight into the specificity of myotubularin phosphatases toward phosphoinositide substrates. The structure also reveals that the GRAM domain, found in myotubularin family phosphatases and predicted to occur in approximately 180 proteins, is part of a larger motif with a pleckstrin homology (PH) domain fold. Finally, the MTMR2 structure will serve as a model for other members of the myotubularin family and provide a framework for understanding the mechanism whereby mutations in these proteins lead to disease.
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MESH Headings
- Amino Acid Sequence
- Binding Sites
- Charcot-Marie-Tooth Disease/genetics
- Charcot-Marie-Tooth Disease/metabolism
- Crystallography, X-Ray
- Humans
- Inositol 1,4,5-Trisphosphate/chemistry
- Inositol 1,4,5-Trisphosphate/metabolism
- Models, Molecular
- Molecular Sequence Data
- Molecular Structure
- Mutation, Missense
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/metabolism
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- Protein Tyrosine Phosphatases, Non-Receptor
- Sequence Alignment
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Affiliation(s)
- Michael J Begley
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Kristiansen M, Knudsen GP, Tanner SM, McEntagart M, Jungbluth H, Muntoni F, Sewry C, Gallati S, Ørstavik KH, Wallgren-Pettersson C. X-inactivation patterns in carriers of X-linked myotubular myopathy. Neuromuscul Disord 2003; 13:468-71. [PMID: 12899873 DOI: 10.1016/s0960-8966(03)00067-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
X-linked myotubular myopathy is a rare severe muscle disorder in affected male neonates. Most female carriers are free from symptoms. Skewed X inactivation has been proposed to be responsible for the affected phenotype seen in some carriers. We have compared the X inactivation patterns in blood DNA with the clinical phenotype in carriers of X-linked myotubular myopathy. The X-inactivation analysis was performed using HpaII predigestion of DNA followed by polymerase chain reaction of the highly polymorphic CAG repeat of the androgen receptor (AR) gene. The frequency of skewed X inactivation was similar in the X-linked myotubular myopathy carriers (22%) and in 235 controls (18%). Three overtly affected carriers had skewed X inactivation with the mutated X as the predominantly active X in at least two of them. Four females with mild symptoms had random X inactivation. The unaffected X-linked myotubular myopathy carriers had either skewed X inactivation in favour of expression from the normal X or random X-inactivation. Thus, there was a tendency for females with a more severe phenotype to have a skewed pattern of X inactivation, while females with an intermediate phenotype had a random pattern of X-inactivation.
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Affiliation(s)
- M Kristiansen
- Department of Medical Genetics, Institute of Medical Genetics, University of Oslo, Oslo, Norway.
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24
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Abstract
The introduction and application of molecular techniques have commenced to influence and alter the nosology of congenital myopathies. Long-known entities such as nemaline myopathies, core diseases, and desmin-related myopathies have now been found to be caused by unequivocal mutations. Several of these mutations and their genes have been identified by analyzing aggregates of proteins within muscle fibers as a morphological hallmark as in desminopathy and actinopathy, the latter a subtype among the nemaline myopathies. Immunohistochemistry has played a crucial role in recognizing this new group of protein aggregate myopathies within the spectrum of congenital myopathies. It is to be expected that other congenital myopathies marked by inclusion bodies may turn out to be such protein aggregate myopathies, depending on analysis of individual proteins within these protein aggregates and their association with putative gene mutations.
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Affiliation(s)
- Hans H Goebel
- Department of Neuropathology, Johannes Gutenberg University, Medical Center, Langenbeckstrasse 1, 55131 Mainz, Germany.
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Jungbluth H, Sewry CA, Buj-Bello A, Kristiansen M, Ørstavik KH, Kelsey A, Manzur AY, Mercuri E, Wallgren-Pettersson C, Muntoni F. Early and severe presentation of X-linked myotubular myopathy in a girl with skewed X-inactivation. Neuromuscul Disord 2003; 13:55-9. [PMID: 12467733 DOI: 10.1016/s0960-8966(02)00194-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
X-linked myotubular myopathy is a severe congenital myopathy in males, caused by mutations in the myotubularin (MTM1) gene on chromosome Xq28. In heterozygous carriers of MTM1 mutations, clinical symptoms are usually absent or only mild. We report a 6-year-old girl presenting at birth with marked hypotonia and associated feeding and respiratory difficulties. A muscle biopsy performed at 5 months suggested a diagnosis of myotubular myopathy. On examination at 6 years she had marked facial weakness with bilateral ptosis and external ophthalmoplegia, severe axial and proximal weakness and a mild scoliosis. Muscle magnetic resonance imaging showed a distinctive pattern of muscle involvement. Molecular genetic investigation of the MTM1 gene identified a heterozygous mutation in exon 12. X-inactivation studies in lymphocytes showed an extremely skewed pattern (97:3). This case emphasizes that investigation of the MTM1 gene and X-inactivation studies are indicated in isolated females with histopathological and clinical findings suggestive of myotubular myopathy.
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Affiliation(s)
- H Jungbluth
- Department of Paediatrics, Dubowitz Neuromuscular Centre, Imperial College Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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26
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Abstract
Nemaline myopathy is caused by mutations in one of at least six different genes. The clinical picture also varies widely, in terms of the grade and the distribution of muscle weakness. In familial cases, autosomal-recessive inheritance is more common than autosomal-dominant inheritance, and in some patients the disorder is caused by new dominant mutations. Because of the genetic heterogeneity and the large size of one of the genes commonly involved, that is, nebulin, no routine molecular genetic testing is yet available. Thus, the diagnosis often still rests on clinical and histologic criteria. Prenatal diagnosis can only reliably be performed in families where the causative mutation(s) have been identified. No clear-cut prognostic indicators are known, and treatment decisions can only be taken in casu. In the long-term management of patients with nemaline myopathy, respiratory capacity requires regular monitoring for early detection of insidious hypoventilation.
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Herman GE, Kopacz K, Zhao W, Mills PL, Metzenberg A, Das S. Characterization of mutations in fifty North American patients with X-linked myotubular myopathy. Hum Mutat 2002; 19:114-21. [PMID: 11793470 DOI: 10.1002/humu.10033] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
X-linked myotubular myopathy (MTM1) is a rare developmental disorder of skeletal muscle that is characterized by the presence of abnormal central nuclei in biopsy specimens taken from affected individuals. To date 133 different mutations have been identified in the MTM1 gene worldwide. We report here mutations detected in 50 additional U.S. families with biopsy-proven MTM1. Forty-one of the patients have not been described previously, including 18 with novel mutations. Eighty-eight percent of the mothers of sporadic cases that were studied were identified as carriers, extending the previously reported high-carrier frequency for this disorder. Clinical information collected on the majority of patients helps to further correlate genotype with phenotype, and implications of these data for genetic counseling in families are discussed.
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Affiliation(s)
- Gail E Herman
- Children's Research Institute and the Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA.
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28
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Abstract
Congenital myopathies and congenital myopathic dystrophies are distinct groups of inherited diseases of muscle, genetically heterogeneous, that manifest in early life or infancy. Congenital myopathic dystrophy is characterized by a dystrophic pattern, whereas no necrotic or degenerative changes are present in congenital myopathies. Much progress has been made in recent years in clarifying the classification of the congenital myopathies. This is a clinically and genetically heterogeneous group of conditions originally classified according to unique morphological changes seen in muscle. Not unlike the later-onset muscular dystrophies, the discovery of the genetic aetiology of many of the congenital myopathies has led to a revamping of how these conditions can now be diagnosed and this should enable physicians to give a more accurate prognosis to patients and their families. New mutations in the ryanodine receptor, slow tropomyosin, troponin T1, actin, and nebulin genes have been described in the last 2 years. Clinical and genetic guidelines for conditions like nemaline rod myopathy and central core disease have been suggested. The notion of minus and surplus protein myopathies has been developed. Several groups of congenital myopathic dystrophy have been identified. In the first category, without intellectual impairment or major structural brain abnormalities, half of the cases are merosin deficient due to mutations of the laminin alpha 2 chain gene. If generally the muscular phenotype is severe, mild allelic variants have been reported with early onset dystrophies and partial merosin deficiency. Among other pure congenital myopathic dystrophies unlinked to the laminin alpha 2 gene, one form has been assigned to chromosome 1q42. In the group of congenital myopathic dystrophies associated with mental retardation and structural brain abnormalities, two main entities are genetically characterized: (1) Fukuyama congenital myopathic dystrophy, affecting the Japanese population, is due to fukutin gene mutations, and (2) the muscle eye brain syndrome assigned to chromosome 1p32-34. In several cases, the gene localization remains unknown.
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Affiliation(s)
- N Tubridy
- Fédération de Neurologie, Institute of Myology and Inserm, La Pitié Salpêtrière, Paris, France
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