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Lindgren U, Hedberg-Oldfors C, Pullerits R, Lindberg C, Oldfors A. Inclusion body myositis with early onset: a population-based study. J Neurol 2023; 270:5483-5492. [PMID: 37498322 PMCID: PMC10576680 DOI: 10.1007/s00415-023-11878-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023]
Abstract
INTRODUCTION Inclusion body myositis (IBM), an inflammatory myopathy with progressive weakness without efficient treatment, typically presents after 45 years of age and younger patients are sparsely studied. METHODS In a population-based study during a 33-year period, 142 patients with IBM were identified in western Sweden. Six patients fell outside the European Neuromuscular Centre 2011 criteria for IBM due to young age at symptom onset, verified by a muscle biopsy < 50 years of age. These were defined as early-onset IBM and included in this study. Medical records, muscle strength, comorbidities, muscle biopsies, and nuclear- and mitochondrial DNA were examined and compared with patients with IBM and age matched controls from the same population. RESULTS The median age at symptom onset was 36 (range 34-45) years and at diagnosis 43 (range 38-58) years. Four patients were deceased at a median age of 59 (range 50-75) years. The median survival from diagnosis was 14 (range 10-18) years. The prevalence December 31 2017 was 1.2 per million inhabitants and the mean incidence 0.12 patients per million inhabitants and year. The mean decline in quadriceps strength ± 1 standard deviation was 1.21 ± 0.2 Newton or 0.91 ± 0.2% per month and correlated to time from diagnosis (p < 0.001). Five patients had swallowing difficulties. All patients displayed mitochondrial changes in muscle including cytochrome c oxidase deficiency and the mitochondrial DNA mutation load was high. CONCLUSIONS Early-onset IBM is a severe disease, causing progressive muscle weakness, high muscle mitochondrial DNA mutation load and a reduced cumulative survival in young and middle-aged individuals.
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Affiliation(s)
- Ulrika Lindgren
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
- Neuromuscular Center, Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden.
| | - Carola Hedberg-Oldfors
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Rille Pullerits
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Immunology and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Christopher Lindberg
- Neuromuscular Center, Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Anders Oldfors
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Leukocyte cytokine responses in adult patients with mitochondrial DNA defects. J Mol Med (Berl) 2022; 100:963-971. [PMID: 35635577 PMCID: PMC9885136 DOI: 10.1007/s00109-022-02206-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/11/2022] [Accepted: 05/06/2022] [Indexed: 02/01/2023]
Abstract
Patients with oxidative phosphorylation (OxPhos) defects causing mitochondrial diseases appear particularly vulnerable to infections. Although OxPhos defects modulate cytokine production in vitro and in animal models, little is known about how circulating leukocytes of patients with inherited mitochondrial DNA (mtDNA) defects respond to acute immune challenges. In a small cohort of healthy controls (n = 21) and patients (n = 12) with either the m.3243A > G mutation or single, large-scale mtDNA deletions, we examined (i) cytokine responses (IL-6, TNF-α, IL-1β) in response to acute lipopolysaccharide (LPS) exposure and (ii) sensitivity to the immunosuppressive effects of glucocorticoid signaling (dexamethasone) on cytokine production. In dose-response experiments to determine the half-maximal effective LPS concentration (EC50), relative to controls, leukocytes from patients with mtDNA deletions showed 74-79% lower responses for IL-6 and IL-1β (pIL-6 = 0.031, pIL-1β = 0.009). Moreover, whole blood from patients with mtDNA deletions (pIL-6 = 0.006), but not patients with the m.3243A > G mutation, showed greater sensitivity to the immunosuppressive effects of dexamethasone. Together, these ex vivo data provide preliminary evidence that some systemic OxPhos defects may compromise immune cytokine responses and increase the sensitivity to immune cytokine suppression by glucocorticoids. Further work in larger cohorts is needed to define the nature of immune dysregulation in patients with mitochondrial disease, and their potential implications for disease phenotypes. KEY MESSAGES: Little is known about leukocyte cytokine responses in patients with mitochondrial diseases. Leukocytes of patients with mtDNA deletions show blunted LPS sensitivity and cytokine responses. Leukocytes of patients with mtDNA deletions are more sensitive to glucocorticoid-mediated IL-6 suppression. Work in larger cohorts is needed to delineate potential immune alterations in mitochondrial diseases.
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Hernández-Ainsa C, López-Gallardo E, García-Jiménez MC, Climent-Alcalá FJ, Rodríguez-Vigil C, García Fernández de Villalta M, Artuch R, Montoya J, Ruiz-Pesini E, Emperador S. Development and characterization of cell models harbouring mtDNA deletions for in vitro study of Pearson syndrome. Dis Model Mech 2022; 15:dmm049083. [PMID: 35191981 PMCID: PMC8906170 DOI: 10.1242/dmm.049083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 12/06/2021] [Indexed: 01/19/2023] Open
Abstract
Pearson syndrome is a rare multisystem disease caused by single large-scale mitochondrial DNA deletions (SLSMDs). The syndrome presents early in infancy and is mainly characterised by refractory sideroblastic anaemia. Prognosis is poor and treatment is supportive, thus the development of new models for the study of Pearson syndrome and new therapy strategies is essential. In this work, we report three different cell models carrying an SLMSD: fibroblasts, transmitochondrial cybrids and induced pluripotent stem cells (iPSCs). All studied models exhibited an aberrant mitochondrial ultrastructure and defective oxidative phosphorylation system function, showing a decrease in different parameters, such as mitochondrial ATP, respiratory complex IV activity and quantity or oxygen consumption. Despite this, iPSCs harbouring 'common deletion' were able to differentiate into three germ layers. Additionally, cybrid clones only showed mitochondrial dysfunction when heteroplasmy level reached 70%. Some differences observed among models may depend on their metabolic profile; therefore, we consider that these three models are useful for the in vitro study of Pearson syndrome, as well as for testing new specific therapies. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Carmen Hernández-Ainsa
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, 50013 Zaragoza, Spain
- Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), 50009 Zaragoza, Spain
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - Ester López-Gallardo
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, 50013 Zaragoza, Spain
- Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), 50009 Zaragoza, Spain
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | | | | | | | | | - Rafael Artuch
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain
| | - Julio Montoya
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, 50013 Zaragoza, Spain
- Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), 50009 Zaragoza, Spain
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - Eduardo Ruiz-Pesini
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, 50013 Zaragoza, Spain
- Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), 50009 Zaragoza, Spain
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - Sonia Emperador
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, 50013 Zaragoza, Spain
- Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), 50009 Zaragoza, Spain
- Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
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Shi Y, Chen G, Sun D, Hu C, Liu Z, Shen D, Wang J, Song T, Zhang W, Li J, Ren X, Han T, Ding C, Wang Y, Fang F. Phenotypes and genotypes of mitochondrial diseases with mtDNA variations in Chinese children: A multi-center study. Mitochondrion 2021; 62:139-150. [PMID: 34800692 DOI: 10.1016/j.mito.2021.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 10/29/2021] [Accepted: 11/12/2021] [Indexed: 11/24/2022]
Abstract
Mitochondrial DNA (mtDNA) associated mitochondrial diseases hold a crucial position but comprehensive and systematic studies are relatively rare. Among the 262 patients of four children's hospitals in China, 96%-point mutations (30 alleles in 11 genes encoding tRNA, rRNA, Complex I and V) and 4%-deletions (seven of ten had not been reported before) were identified as the cause of 14 phenotypes. MILS presented the highest genetic heterogeneity, while the m.3243A > G mutation was the only "hotspot" mutation with a wide range of phenotypes. The degrees of heteroplasmy in the leukocytes of MM were higher than MELAS. The heteroplasmy level of patients was higher than that in mild and carrier group, while we found low-level heteroplasmy pathogenic mutations as well. Some homoplasmic variations (e.g., m.9176 T > C mutation) are having high incomplete penetrance. For a suspected MELAS, m.3243A > G mutation was recommended to detect first; while for a suspected LS, trios-WES and mtDNA genome sequencing by NGS were recommended first in both blood and urine.
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Affiliation(s)
- Yuqing Shi
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Guohong Chen
- Department of Neurology, Zhengzhou University Affiliated Children's Hospital (Zhengzhou Children's Hospital), Zhengzhou 450053, Henan, China
| | - Dan Sun
- Department of Neurology, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430015, China
| | - Chaoping Hu
- Department of Neurology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Zhimei Liu
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Danmin Shen
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Junling Wang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Tianyu Song
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Weihua Zhang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Jiuwei Li
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Xiaotun Ren
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Tongli Han
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Changhong Ding
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Yi Wang
- Department of Neurology, Children's Hospital of Fudan University, Shanghai 201102, China.
| | - Fang Fang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
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5
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Blood biomarkers for assessment of mitochondrial dysfunction: An expert review. Mitochondrion 2021; 62:187-204. [PMID: 34740866 DOI: 10.1016/j.mito.2021.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 09/28/2021] [Accepted: 10/28/2021] [Indexed: 12/20/2022]
Abstract
Although mitochondrial dysfunction is the known cause of primary mitochondrial disease, mitochondrial dysfunction is often difficult to measure and prove, especially when biopsies of affected tissue are not available. In order to identify blood biomarkers of mitochondrial dysfunction, we reviewed studies that measured blood biomarkers in genetically, clinically or biochemically confirmed primary mitochondrial disease patients. In this way, we were certain that there was an underlying mitochondrial dysfunction which could validate the biomarker. We found biomarkers of three classes: 1) functional markers measured in blood cells, 2) biochemical markers of serum/plasma and 3) DNA markers. While none of the reviewed single biomarkers may perfectly reveal all underlying mitochondrial dysfunction, combining biomarkers that cover different aspects of mitochondrial impairment probably is a good strategy. This biomarker panel may assist in the diagnosis of primary mitochondrial disease patients. As mitochondrial dysfunction may also play a significant role in the pathophysiology of multifactorial disorders such as Alzheimer's disease and glaucoma, the panel may serve to assess mitochondrial dysfunction in complex multifactorial diseases as well and enable selection of patients who could benefit from therapies targeting mitochondria.
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Levy MA, Kerkhof J, Belmonte FR, Kaufman BA, Bhai P, Brady L, Bursztyn LLCD, Tarnopolsky M, Rupar T, Sadikovic B. Validation and clinical performance of a combined nuclear-mitochondrial next-generation sequencing and copy number variant analysis panel in a Canadian population. Am J Med Genet A 2020; 185:486-499. [PMID: 33300680 DOI: 10.1002/ajmg.a.61998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 12/17/2022]
Abstract
Diagnosing mitochondrial disorders is a challenge due to the heterogeneous clinical presentation and large number of associated genes. A custom next generation sequencing (NGS) panel was developed incorporating the full mitochondrial genome (mtDNA) plus 19 nuclear genes involved in structural mitochondrial defects and mtDNA maintenance. This assay is capable of simultaneously detecting small gene sequence variations and larger copy number variants (CNVs) in both the nuclear and mitochondrial components along with heteroplasmy detection down to 5%. We describe technical validations of this panel and its implementation for clinical testing in a Canadian reference laboratory, and report its clinical performance in the initial 950 patients tested. Using this assay, we demonstrate a diagnostic yield of 18.1% of patients with known pathogenic variants. In addition to the common 5 kb mtDNA deletion, we describe significant contribution of pathogenic CNVs in both the mitochondrial genome and nuclear genes in this patient population.
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Affiliation(s)
- Michael A Levy
- Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.,Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, Ontario, Canada
| | - Jennifer Kerkhof
- Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, Ontario, Canada
| | - Frances R Belmonte
- Division of Cardiology, Center for Metabolism and Mitochondrial Medicine and Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Brett A Kaufman
- Division of Cardiology, Center for Metabolism and Mitochondrial Medicine and Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Pratibha Bhai
- Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, Ontario, Canada
| | - Lauren Brady
- Division of Neuromuscular and Neurometabolic Disease, Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | | | - Mark Tarnopolsky
- Division of Neuromuscular and Neurometabolic Disease, Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Tony Rupar
- Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.,Departments of Biochemistry and Paediatrics, Schulich School of Medicine & Dentistry, Western University, and Biochemical Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, Ontario, Canada
| | - Bekim Sadikovic
- Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.,Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, Ontario, Canada
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