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Abstract
PURPOSE OF REVIEW To review the advances in our understanding of the genetics of inclusion body myositis (IBM) in the past year. RECENT FINDINGS One large genetic association study focusing on immune-related genes in IBM has refined the association within the human leukocyte antigen (HLA) region to HLA-DRB1 alleles, and identified certain amino acid positions in HLA-DRB1 that may explain this risk. A suggestive association with CCR5 may indicate genetic overlap with other autoimmune diseases. Sequencing studies of candidate genes involved in related neuromuscular or neurodegenerative diseases have identified rare variants in VCP and SQSTM1. Proteomic studies of rimmed vacuoles in IBM and subsequent genetic analyses of candidate genes identified rare missense variants in FYCO1. Complex, large-scale mitochondrial deletions in cytochrome c oxidase-deficient muscle fibres expand our understanding of mitochondrial abnormalities in IBM. SUMMARY The pathogenesis of IBM is likely multifactorial, including inflammatory and degenerative changes, and mitochondrial abnormalities. There has been considerable progress in our understanding of the genetic architecture of IBM, using complementary genetic approaches to investigate these different pathways.
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Affiliation(s)
- Simon Rothwell
- Centre for Musculoskeletal Research, Division of Musculoskeletal and Dermatological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester
| | - James B. Lilleker
- Centre for Musculoskeletal Research, Division of Musculoskeletal and Dermatological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester
- Greater Manchester Neurosciences Centre, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Stott Lane, Salford
| | - Janine A. Lamb
- Centre for Epidemiology, Division of Population Health, Health Services Research and Primary Care, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
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Rothwell S, Cooper RG, Lundberg IE, Gregersen PK, Hanna MG, Machado PM, Herbert MK, Pruijn GJM, Lilleker JB, Roberts M, Bowes J, Seldin MF, Vencovsky J, Danko K, Limaye V, Selva‐O'Callaghan A, Platt H, Molberg Ø, Benveniste O, Radstake TRDJ, Doria A, De Bleecker J, De Paepe B, Gieger C, Meitinger T, Winkelmann J, Amos CI, Ollier WE, Padyukov L, Lee AT, Lamb JA, Chinoy H. Immune-Array Analysis in Sporadic Inclusion Body Myositis Reveals HLA-DRB1 Amino Acid Heterogeneity Across the Myositis Spectrum. Arthritis Rheumatol 2017; 69:1090-1099. [PMID: 28086002 PMCID: PMC5516174 DOI: 10.1002/art.40045] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 01/10/2017] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Inclusion body myositis (IBM) is characterized by a combination of inflammatory and degenerative changes affecting muscle. While the primary cause of IBM is unknown, genetic factors may influence disease susceptibility. To determine genetic factors contributing to the etiology of IBM, we conducted the largest genetic association study of the disease to date, investigating immune-related genes using the Immunochip. METHODS A total of 252 Caucasian patients with IBM were recruited from 11 countries through the Myositis Genetics Consortium and compared with 1,008 ethnically matched controls. Classic HLA alleles and amino acids were imputed using SNP2HLA. RESULTS The HLA region was confirmed as the most strongly associated region in IBM (P = 3.58 × 10-33 ). HLA imputation identified 3 independent associations (with HLA-DRB1*03:01, DRB1*01:01, and DRB1*13:01), although the strongest association was with amino acid positions 26 and 11 of the HLA-DRB1 molecule. No association with anti-cytosolic 5'-nucleotidase 1A-positive status was found independent of HLA-DRB1*03:01. There was no association of HLA genotypes with age at onset of IBM. Three non-HLA regions reached suggestive significance, including the chromosome 3 p21.31 region, an established risk locus for autoimmune disease, where a frameshift mutation in CCR5 is thought to be the causal variant. CONCLUSION This is the largest, most comprehensive genetic association study to date in IBM. The data confirm that HLA is the most strongly associated region and identifies novel amino acid associations that may explain the risk in this locus. These amino acid associations differentiate IBM from polymyositis and dermatomyositis and may determine properties of the peptide-binding groove, allowing it to preferentially bind autoantigenic peptides. A novel suggestive association within the chromosome 3 p21.31 region suggests a role for CCR5.
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Affiliation(s)
| | | | | | | | | | | | - Megan K. Herbert
- Beth Israel Deaconess Medical Center, Boston, Massachusetts, and Radboud University NijmegenNijmegenThe Netherlands
| | | | - James B. Lilleker
- University of Manchester, Manchester, UK, and Salford Royal NHS Foundation TrustSalfordUK
| | | | | | | | | | | | - Vidya Limaye
- Royal Adelaide Hospital, AdelaideSouth AustraliaAustralia
| | | | | | | | | | | | | | | | | | | | - Thomas Meitinger
- Technische Universität München, Munich, Germany, and Helmholtz Zentrum MünchenNeuherbergGermany
| | - Juliane Winkelmann
- Technische Universität München, Munich, Germany, and Helmholtz Zentrum MünchenNeuherbergGermany
| | | | | | | | - Annette T. Lee
- Feinstein Institute for Medical ResearchManhassetNew York
| | | | - Hector Chinoy
- Central Manchester University Hospitals NHS Foundation Trust, University of ManchesterManchesterUK
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Machado PM, Ahmed M, Brady S, Gang Q, Healy E, Morrow JM, Wallace AC, Dewar L, Ramdharry G, Parton M, Holton JL, Houlden H, Greensmith L, Hanna MG. Ongoing developments in sporadic inclusion body myositis. Curr Rheumatol Rep 2014; 16:477. [PMID: 25399751 PMCID: PMC4233319 DOI: 10.1007/s11926-014-0477-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sporadic inclusion body myositis (IBM) is an acquired muscle disorder associated with ageing, for which there is no effective treatment. Ongoing developments include: genetic studies that may provide insights regarding the pathogenesis of IBM, improved histopathological markers, the description of a new IBM autoantibody, scrutiny of the diagnostic utility of clinical features and biomarkers, the refinement of diagnostic criteria, the emerging use of MRI as a diagnostic and monitoring tool, and new pathogenic insights that have led to novel therapeutic approaches being trialled for IBM, including treatments with the objective of restoring protein homeostasis and myostatin blockers. The effect of exercise in IBM continues to be investigated. However, despite these ongoing developments, the aetiopathogenesis of IBM remains uncertain. A translational and multidisciplinary collaborative approach is critical to improve the diagnosis, treatment, and care of patients with IBM.
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Affiliation(s)
- Pedro M. Machado
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Mhoriam Ahmed
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG UK
| | - Stefen Brady
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Qiang Gang
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Estelle Healy
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Jasper M. Morrow
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Amanda C. Wallace
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Liz Dewar
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Gita Ramdharry
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Matthew Parton
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Janice L. Holton
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Henry Houlden
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
| | - Linda Greensmith
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG UK
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, University College London, Box 102, 8-11 Queen Square, London, WC1N 3BG UK
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Gang Q, Bettencourt C, Machado P, Hanna MG, Houlden H. Sporadic inclusion body myositis: the genetic contributions to the pathogenesis. Orphanet J Rare Dis 2014; 9:88. [PMID: 24948216 PMCID: PMC4071018 DOI: 10.1186/1750-1172-9-88] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 06/12/2014] [Indexed: 11/10/2022] Open
Abstract
Sporadic inclusion body myositis (sIBM) is the commonest idiopathic inflammatory muscle disease in people over 50 years old. It is characterized by slowly progressive muscle weakness and atrophy, with typical pathological changes of inflammation, degeneration and mitochondrial abnormality in affected muscle fibres. The cause(s) of sIBM are still unknown, but are considered complex, with the contribution of multiple factors such as environmental triggers, ageing and genetic susceptibility. This review summarizes the current understanding of the genetic contributions to sIBM and provides some insights for future research in this mysterious disease with the advantage of the rapid development of advanced genetic technology. An international sIBM genetic study is ongoing and whole-exome sequencing will be applied in a large cohort of sIBM patients with the aim of unravelling important genetic risk factors for sIBM.
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Affiliation(s)
- Qiang Gang
- Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
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Rose MR. 188th ENMC International Workshop: Inclusion Body Myositis, 2-4 December 2011, Naarden, The Netherlands. Neuromuscul Disord 2013; 23:1044-55. [PMID: 24268584 DOI: 10.1016/j.nmd.2013.08.007] [Citation(s) in RCA: 242] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/13/2013] [Accepted: 08/19/2013] [Indexed: 11/29/2022]
Affiliation(s)
- M R Rose
- Dept of Neurology, Kings College Hospital, Denmark Hill, London SE5 9RS, United Kingdom.
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Needham M, Mastaglia FL. Inclusion body myositis: current pathogenetic concepts and diagnostic and therapeutic approaches. Lancet Neurol 2007; 6:620-31. [PMID: 17582362 DOI: 10.1016/s1474-4422(07)70171-0] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Inclusion body myositis is the most common acquired muscle disease in older individuals, and its prevalence varies among countries and ethnic groups. The aetiology and pathogenesis of sporadic inclusion body myositis are still poorly understood; however genetic factors, ageing, and environmental triggers might all have a role. Unlike other inflammatory myopathies, sporadic inclusion body myositis causes slowly progressing muscular weakness and atrophy, it has a distinctive pattern of muscle involvement, and is unresponsive to conventional forms of immunotherapy. This review covers the clinical presentation, diagnosis, treatment, and the latest information on genetic susceptibility and pathogenesis of sporadic inclusion body myositis.
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Affiliation(s)
- Merrilee Needham
- Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Queen Elizabeth II Medical Centre, Perth, Australia
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Abstract
Sporadic inclusion-body myositis (sIBM) is the most common acquired muscle disease in Caucasians over the age of 50 years. Pathologically it is marked by inflammatory, degenerative, and mitochondrial changes that interact in a yet-unknown way to cause progressive muscle degeneration and weakness. The cause of the disease is unknown, but it is thought to involve a complex interplay between environmental factors, genetic susceptibility, and aging. The strongest evidence for genetic susceptibility comes from studies of the major histocompatibility complex (MHC), where different combinations of alleles have been associated with sIBM in different ethnic groups. The rare occurrence of familial cases of inclusion-body myositis (fIBM) adds additional evidence for genetic susceptibility. Other candidate genes such as those encoding some of the proteins accumulating in muscle fibers have been investigated, with negative results. The increased understanding of related disorders, the hereditary inclusion-body myopathies (hIBM), may also provide clues to the underlying pathogenesis of sIBM, but to date there is no indication that the genes responsible for these conditions are involved in sIBM. This review summarizes current understanding of the contribution of genetic susceptibility factors to the development of sIBM.
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Affiliation(s)
- M Needham
- Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Level 4, A Block, Queen Elizabeth II Medical Centre, Nedlands, Western Australia 6009, Australia.
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Askanas V, Engel WK. Does overexpression of betaAPP in aging muscle have a pathogenic role and a relevance to Alzheimer's disease? Clues from inclusion body myositis, cultured human muscle, and transgenic mice. THE AMERICAN JOURNAL OF PATHOLOGY 1998; 153:1673-7. [PMID: 9846956 PMCID: PMC1866347 DOI: 10.1016/s0002-9440(10)65680-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- V Askanas
- Neuromuscular Center, Department of Neurology, University of Southern California School of Medicine, Good Samaritan Hospital, Los Angeles 90017-1912, USA.
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