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Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 PMCID: PMC11346376 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
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Affiliation(s)
- Tiago M. Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E. Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E. Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B. Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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2
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Hong S, Kim S, Kim K, Lee H. Clinical Approaches for Mitochondrial Diseases. Cells 2023; 12:2494. [PMID: 37887337 PMCID: PMC10605124 DOI: 10.3390/cells12202494] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/28/2023] Open
Abstract
Mitochondria are subcontractors dedicated to energy production within cells. In human mitochondria, almost all mitochondrial proteins originate from the nucleus, except for 13 subunit proteins that make up the crucial system required to perform 'oxidative phosphorylation (OX PHOS)', which are expressed by the mitochondria's self-contained DNA. Mitochondrial DNA (mtDNA) also encodes 2 rRNA and 22 tRNA species. Mitochondrial DNA replicates almost autonomously, independent of the nucleus, and its heredity follows a non-Mendelian pattern, exclusively passing from mother to children. Numerous studies have identified mtDNA mutation-related genetic diseases. The consequences of various types of mtDNA mutations, including insertions, deletions, and single base-pair mutations, are studied to reveal their relationship to mitochondrial diseases. Most mitochondrial diseases exhibit fatal symptoms, leading to ongoing therapeutic research with diverse approaches such as stimulating the defective OXPHOS system, mitochondrial replacement, and allotropic expression of defective enzymes. This review provides detailed information on two topics: (1) mitochondrial diseases caused by mtDNA mutations, and (2) the mechanisms of current treatments for mitochondrial diseases and clinical trials.
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Affiliation(s)
- Seongho Hong
- Korea Mouse Phenotyping Center, Seoul National University, Seoul 08826, Republic of Korea;
- Department of Medicine, Korea University College of Medicine, Seoul 02708, Republic of Korea
| | - Sanghun Kim
- Laboratory Animal Resource and Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju 28116, Republic of Korea;
- College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Kyoungmi Kim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul 02841, Republic of Korea
- Department of Physiology, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Hyunji Lee
- Department of Medicine, Korea University College of Medicine, Seoul 02708, Republic of Korea
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3
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Girard A, Heindl B, Clarkson S, Litovsky S, Ubogu E, Schwartzlow C, Tallaj J. Cardiogenic shock in a woman with a mitochondrial cardiomyopathy: a case report. Eur Heart J Case Rep 2023; 7:ytad183. [PMID: 37123653 PMCID: PMC10133997 DOI: 10.1093/ehjcr/ytad183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/02/2022] [Accepted: 04/12/2023] [Indexed: 05/02/2023]
Abstract
Background Mitochondrial cardiomyopathy (MCM) is an alteration in cardiac structure and function caused by gene mutations or deletions affecting components of the mitochondrial respiratory chain. We report a case of MCM presenting as cardiogenic shock, ultimately requiring left ventricular assist device (LVAD) placement. Case summary A 35-year-old woman with chronic weakness and non-ischaemic cardiomyopathy, on home dobutamine, was referred to our institution for heart transplantation evaluation. She was admitted to the hospital for suspected cardiogenic shock after laboratory tests revealed a lactate level of 5.4 mmol/L (ref: 0.5-2.2 mmol/L). Her hospital course was complicated by persistently undulating lactate levels (0.2-8.6 mmol/L) that increased with exertion and did not correlate with mixed venous oxygen saturation measurements obtained from a pulmonary artery catheter. Electrodiagnostic testing demonstrated a proximal appendicular and axial myopathy. A left deltoid muscle biopsy was performed that demonstrated evidence of a mitochondrial disease on light and electron microscopy. Muscle genetic testing revealed two large-scale mitochondrial deoxyribonucleic acid sequence deletions, confirming the diagnosis of MCM. She subsequently underwent LVAD placement, which was complicated by significant right ventricular failure requiring early mechanical support. She was ultimately discharged home with chronic inotropic support. Discussion Mitochondrial cardiomyopathy in adults is a diagnostic and therapeutic challenge. Prompt diagnosis should be made in patients with unknown causes of heart failure via skeletal muscle histopathology guided by electrodiagnostic studies, and targeted genetic testing in affected tissue. Outcomes in adult MCM patients who receive an LVAD are unknown and warrant further investigation.
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Affiliation(s)
| | - Brittain Heindl
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Stephen Clarkson
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Silvio Litovsky
- Division of Anatomic Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Eroboghene Ubogu
- Division of Neuromuscular Disease, Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Coreen Schwartzlow
- Division of Neuromuscular Disease, Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35233, USA
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Ewert R, Elhadad MA, Habedank D, Heine A, Stubbe B. Primary mitochondrial disease as a rare cause of unclear breathlessness and distinctive performance degradation - a case report. BMC Pulm Med 2023; 23:104. [PMID: 36991405 DOI: 10.1186/s12890-023-02391-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/16/2023] [Indexed: 03/31/2023] Open
Abstract
BACKGROUND Primary muscular disorders (metabolic myopathies, including mitochondrial disorders) are a rare cause of dyspnea. We report a case of dyspnea caused by a mitochondrial disorder with a pattern of clinical findings that can be classified in the known pathologies of mitochondrial deletion syndrome. CASE PRESENTATION The patient presented to us at 29 years of age, having had tachycardia, dyspnea, and functional impairment since childhood. She had been diagnosed with bronchial asthma and mild left ventricular hypertrophy and treated accordingly, but her symptoms had worsened. After more than 20 years of progressive physical and social limitations was a mitochondrial disease suspected in the exercise testing. We performed cardiopulmonary exercise testing (CPET) with right heart catheterization showed typical signs of mitochondrial myopathy. Genetic testing confirmed the presence of a ~ 13 kb deletion in mitochondrial DNA from the muscle. The patient was treated with dietary supplements for 1 year. In the course of time, the patient gave birth to a healthy child, which is developing normally. CONCLUSION CPET and lung function data over 5 years demonstrated stable disease. We conclude that CPET and lung function analysis should be used consistently to evaluate the cause of dyspnea and for long-term observation.
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Affiliation(s)
- Ralf Ewert
- Department of Internal Medicine B, Pneumology, University Hospital Greifswald, F.-Sauerbruchstr, 17475, Greifswald, Germany
| | - Mohamed A Elhadad
- Department of Internal Medicine B, Pneumology, University Hospital Greifswald, F.-Sauerbruchstr, 17475, Greifswald, Germany
| | - Dirk Habedank
- Department of Internal Medicine B, Pneumology, University Hospital Greifswald, F.-Sauerbruchstr, 17475, Greifswald, Germany
- DRK-Hospital Berlin, Berlin, Germany
| | - Alexander Heine
- Department of Internal Medicine B, Pneumology, University Hospital Greifswald, F.-Sauerbruchstr, 17475, Greifswald, Germany
| | - Beate Stubbe
- Department of Internal Medicine B, Pneumology, University Hospital Greifswald, F.-Sauerbruchstr, 17475, Greifswald, Germany.
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5
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Tolle I, Tiranti V, Prigione A. Modeling mitochondrial DNA diseases: from base editing to pluripotent stem-cell-derived organoids. EMBO Rep 2023; 24:e55678. [PMID: 36876467 PMCID: PMC10074100 DOI: 10.15252/embr.202255678] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 01/12/2023] [Accepted: 02/15/2023] [Indexed: 03/07/2023] Open
Abstract
Mitochondrial DNA (mtDNA) diseases are multi-systemic disorders caused by mutations affecting a fraction or the entirety of mtDNA copies. Currently, there are no approved therapies for the majority of mtDNA diseases. Challenges associated with engineering mtDNA have in fact hindered the study of mtDNA defects. Despite these difficulties, it has been possible to develop valuable cellular and animal models of mtDNA diseases. Here, we describe recent advances in base editing of mtDNA and the generation of three-dimensional organoids from patient-derived human-induced pluripotent stem cells (iPSCs). Together with already available modeling tools, the combination of these novel technologies could allow determining the impact of specific mtDNA mutations in distinct human cell types and might help uncover how mtDNA mutation load segregates during tissue organization. iPSC-derived organoids could also represent a platform for the identification of treatment strategies and for probing the in vitro effectiveness of mtDNA gene therapies. These studies have the potential to increase our mechanistic understanding of mtDNA diseases and may open the way to highly needed and personalized therapeutic interventions.
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Affiliation(s)
- Isabella Tolle
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Valeria Tiranti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
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6
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Abstract
Mitochondrial diseases require customized approaches for reproductive counseling, addressing differences in recurrence risks and reproductive options. The majority of mitochondrial diseases is caused by mutations in nuclear genes and segregate in a Mendelian way. Prenatal diagnosis (PND) or preimplantation genetic testing (PGT) are available to prevent the birth of another severely affected child. In at least 15%-25% of cases, mitochondrial diseases are caused by mitochondrial DNA (mtDNA) mutations, which can occur de novo (25%) or be maternally inherited. For de novo mtDNA mutations, the recurrence risk is low and PND can be offered for reassurance. For maternally inherited, heteroplasmic mtDNA mutations, the recurrence risk is often unpredictable, due to the mitochondrial bottleneck. PND for mtDNA mutations is technically possible, but often not applicable given limitations in predicting the phenotype. Another option for preventing the transmission of mtDNA diseases is PGT. Embryos with mutant load below the expression threshold are being transferred. Oocyte donation is another safe option to prevent the transmission of mtDNA disease to a future child for couples who reject PGT. Recently, mitochondrial replacement therapy (MRT) became available for clinical application as an alternative to prevent the transmission of heteroplasmic and homoplasmic mtDNA mutations.
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7
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Mavraki E, Labrum R, Sergeant K, Alston CL, Woodward C, Smith C, Knowles CVY, Patel Y, Hodsdon P, Baines JP, Blakely EL, Polke J, Taylor RW, Fratter C. Genetic testing for mitochondrial disease: the United Kingdom best practice guidelines. Eur J Hum Genet 2023; 31:148-163. [PMID: 36513735 PMCID: PMC9905091 DOI: 10.1038/s41431-022-01249-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022] Open
Abstract
Primary mitochondrial disease describes a diverse group of neuro-metabolic disorders characterised by impaired oxidative phosphorylation. Diagnosis is challenging; >350 genes, both nuclear and mitochondrial DNA (mtDNA) encoded, are known to cause mitochondrial disease, leading to all possible inheritance patterns and further complicated by heteroplasmy of the multicopy mitochondrial genome. Technological advances, particularly next-generation sequencing, have driven a shift in diagnostic practice from 'biopsy first' to genome-wide analyses of blood and/or urine DNA. This has led to the need for a reference framework for laboratories involved in mitochondrial genetic testing to facilitate a consistent high-quality service. In the United Kingdom, consensus guidelines have been prepared by a working group of Clinical Scientists from the NHS Highly Specialised Service followed by national laboratory consultation. These guidelines summarise current recommended technologies and methodologies for the analysis of mtDNA and nuclear-encoded genes in patients with suspected mitochondrial disease. Genetic testing strategies for diagnosis, family testing and reproductive options including prenatal diagnosis are outlined. Importantly, recommendations for the minimum levels of mtDNA testing for the most common referral reasons are included, as well as guidance on appropriate referrals and information on the minimal appropriate gene content of panels when analysing nuclear mitochondrial genes. Finally, variant interpretation and recommendations for reporting of results are discussed, focussing particularly on the challenges of interpreting and reporting mtDNA variants.
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Affiliation(s)
- Eleni Mavraki
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Robyn Labrum
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Kate Sergeant
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Charlotte L Alston
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Cathy Woodward
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Conrad Smith
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Charlotte V Y Knowles
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Yogen Patel
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Philip Hodsdon
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jack P Baines
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Emma L Blakely
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - James Polke
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Robert W Taylor
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Carl Fratter
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
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8
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Björkman K, Vissing J, Østergaard E, Bindoff LA, de Coo IFM, Engvall M, Hikmat O, Isohanni P, Kollberg G, Lindberg C, Majamaa K, Naess K, Uusimaa J, Tulinius M, Darin N. Phenotypic spectrum and clinical course of single large-scale mitochondrial DNA deletion disease in the paediatric population: a multicentre study. J Med Genet 2023; 60:65-73. [PMID: 34872991 PMCID: PMC9811091 DOI: 10.1136/jmedgenet-2021-108006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/09/2021] [Indexed: 02/04/2023]
Abstract
BACKGROUND Large-scale mitochondrial DNA deletions (LMD) are a common genetic cause of mitochondrial disease and give rise to a wide range of clinical features. Lack of longitudinal data means the natural history remains unclear. This study was undertaken to describe the clinical spectrum in a large cohort of patients with paediatric disease onset. METHODS A retrospective multicentre study was performed in patients with clinical onset <16 years of age, diagnosed and followed in seven European mitochondrial disease centres. RESULTS A total of 80 patients were included. The average age at disease onset and at last examination was 10 and 31 years, respectively. The median time from disease onset to death was 11.5 years. Pearson syndrome was present in 21%, Kearns-Sayre syndrome spectrum disorder in 50% and progressive external ophthalmoplegia in 29% of patients. Haematological abnormalities were the hallmark of the disease in preschool children, while the most common presentations in older patients were ptosis and external ophthalmoplegia. Skeletal muscle involvement was found in 65% and exercise intolerance in 25% of the patients. Central nervous system involvement was frequent, with variable presence of ataxia (40%), cognitive involvement (36%) and stroke-like episodes (9%). Other common features were pigmentary retinopathy (46%), short stature (42%), hearing impairment (39%), cardiac disease (39%), diabetes mellitus (25%) and renal disease (19%). CONCLUSION Our study provides new insights into the phenotypic spectrum of childhood-onset, LMD-associated syndromes. We found a wider spectrum of more prevalent multisystem involvement compared with previous studies, most likely related to a longer time of follow-up.
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Affiliation(s)
- Kristoffer Björkman
- Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,The Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - John Vissing
- Copenhagen Neuromuscular Centre, Rigshospitalet, Kobenhavn, Denmark
| | - Elsebet Østergaard
- Department of Clinical Genetics, Rigshospitalet, Kobenhavn, Denmark,Department of Clinical Medicine, University of Copenhagen, Kobenhavn, Denmark
| | - Laurence A Bindoff
- Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway,Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Irenaeus F M de Coo
- Department of Toxicogenomics, Unit Clinical Genomics, Maastricht University, Maastricht, The Netherlands,Maastricht University School for Mental Health and Neuroscience, Maastricht, The Netherlands
| | - Martin Engvall
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden,Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Omar Hikmat
- Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway,Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Pirjo Isohanni
- Research Programs Unit, Stem Cells and Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland,University of Helsinki Children's Hospital, Helsinki, Finland
| | - Gittan Kollberg
- Department of Clinical Chemistry, University of Gothenburg, Gothenburg, Sweden
| | - Christopher Lindberg
- Department of Neurology, Neuromuscular Center, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Kari Majamaa
- Medical Research Center, Oulu University Faculty of Medicine, Oulu, Finland,Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Karin Naess
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden,Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Johanna Uusimaa
- PEDEGO Research Unit, Oulu University Faculty of Medicine, Oulu, Finland,Clinic for Children and Adolescents and Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Mar Tulinius
- Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,The Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Niklas Darin
- Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,The Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden
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9
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Abstract
Mitochondrial dysfunction, especially perturbation of oxidative phosphorylation and adenosine triphosphate (ATP) generation, disrupts cellular homeostasis and is a surprisingly frequent cause of central and peripheral nervous system pathology. Mitochondrial disease is an umbrella term that encompasses a host of clinical syndromes and features caused by in excess of 300 different genetic defects affecting the mitochondrial and nuclear genomes. Patients with mitochondrial disease can present at any age, ranging from neonatal onset to late adult life, with variable organ involvement and neurological manifestations including neurodevelopmental delay, seizures, stroke-like episodes, movement disorders, optic neuropathy, myopathy, and neuropathy. Until relatively recently, analysis of skeletal muscle biopsy was the focus of diagnostic algorithms, but step-changes in the scope and availability of next-generation sequencing technology and multiomics analysis have revolutionized mitochondrial disease diagnosis. Currently, there is no specific therapy for most types of mitochondrial disease, although clinical trials research in the field is gathering momentum. In that context, active management of epilepsy, stroke-like episodes, dystonia, brainstem dysfunction, and Parkinsonism are all the more important in improving patient quality of life and reducing mortality.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - Robert McFarland
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
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10
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Masingue M, Rucheton B, Bris C, Romero NB, Procaccio V, Eymard B. Highly asymmetrical distribution of muscle wasting correlates to the heteroplasmy in a patient carrying a large-scale mitochondrial DNA deletion: a novel pathophysiological mechanism for explaining asymmetry in mitochondrial myopathies. Neuromuscul Disord 2022; 32:923-930. [PMID: 36428163 DOI: 10.1016/j.nmd.2022.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022]
Abstract
Mitochondrial diseases are a heterogeneous group of pathologies, caused by missense mutations, sporadic large-scale deletions of mitochondrial DNA (mtDNA) or mutations of nuclear maintenance genes. We report the case of a patient in whom extended muscle pathology, biochemical and genetic mtDNA analyses have proven to be essential to elucidate a unique asymmetrical myopathic presentation. From the age of 34 years on, the patient has presented with oculomotor disorders, right facial peripheral palsy and predominantly left upper limb muscle weakness and atrophy. By contrast, he displayed no motor weakness on the right hemi-body, and no sensory symptoms, cerebellar syndrome, hypoacusis, or parkinsonism. Cardiac function was normal. CK levels were elevated (671 UI/L). Electroneuromyography (ENMG) and muscle MRI showed diffuse myogenic alterations, more pronounced on the left side muscles. Biopsy of the left deltoid muscle showed multiple mitochondrial defects, whereas in the right deltoid, mitochondrial defects were much less marked. Extended mitochondrial biochemical and molecular workup revealed a unique mtDNA deletion, with a 63.4% heteroplasmy load in the left deltoid, versus 8.1% in the right one. This case demonstrates that, in mitochondrial myopathies, heteroplasmy levels may drastically vary for the same type of muscle, rising the hypothesis of a new pathophysiological mechanism explaining asymmetry in hereditary myopathies.
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Affiliation(s)
- M Masingue
- Reference Center for Neuromuscular Disorders Nord/Est/Ile de France, Neuromuscular Morphology Unit, Institut de Myologie, CHU Pitié-Salpêtrière, APHP, Paris, France.
| | - B Rucheton
- UF de Biochimie des maladies neurométaboliques et neurodégénératives, Service de Biochimie Métabolique, AP-HP, Paris, France
| | - C Bris
- Department of Genetics, Angers Hospital, Angers, France; Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - N B Romero
- Reference Center for Neuromuscular Disorders Nord/Est/Ile de France, Neuromuscular Morphology Unit, Institut de Myologie, CHU Pitié-Salpêtrière, APHP, Paris, France; Université Sorbonne, UPMC Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, CHU Pitié-Salpêtrière, Paris, France
| | - V Procaccio
- Department of Genetics, Angers Hospital, Angers, France; Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - B Eymard
- Reference Center for Neuromuscular Disorders Nord/Est/Ile de France, Neuromuscular Morphology Unit, Institut de Myologie, CHU Pitié-Salpêtrière, APHP, Paris, France.
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11
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Chiaratti MR, Chinnery PF. Modulating mitochondrial DNA mutations: factors shaping heteroplasmy in the germ line and somatic cells. Pharmacol Res 2022; 185:106466. [PMID: 36174964 DOI: 10.1016/j.phrs.2022.106466] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/21/2022] [Accepted: 09/23/2022] [Indexed: 11/30/2022]
Abstract
Until recently it was thought that most humans only harbor one type of mitochondrial DNA (mtDNA), however, deep sequencing and single-cell analysis has shown the converse - that mixed populations of mtDNA (heteroplasmy) are the norm. This is important because heteroplasmy levels can change dramatically during transmission in the female germ line, leading to high levels causing severe mitochondrial diseases. There is also emerging evidence that low level mtDNA mutations contribute to common late onset diseases such as neurodegenerative disorders and cardiometabolic diseases because the inherited mutation levels can change within developing organs and non-dividing cells over time. Initial predictions suggested that the segregation of mtDNA heteroplasmy was largely stochastic, with an equal tendency for levels to increase or decrease. However, transgenic animal work and single-cell analysis have shown this not to be the case during germ-line transmission and in somatic tissues during life. Mutation levels in specific mtDNA regions can increase or decrease in different contexts and the underlying molecular mechanisms are starting to be unraveled. In this review we provide a synthesis of recent literature on the mechanisms of selection for and against mtDNA variants. We identify the most pertinent gaps in our understanding and suggest ways these could be addressed using state of the art techniques.
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Affiliation(s)
- Marcos R Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil.
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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12
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Yoshimi A, Ishikawa K, Niemeyer C, Grünert SC. Pearson syndrome: a multisystem mitochondrial disease with bone marrow failure. Orphanet J Rare Dis 2022; 17:379. [PMID: 36253820 PMCID: PMC9575259 DOI: 10.1186/s13023-022-02538-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 10/04/2022] [Indexed: 11/10/2022] Open
Abstract
Pearson syndrome (PS) is a rare fatal mitochondrial disorder caused by single large-scale mitochondrial DNA deletions (SLSMDs). Most patients present with anemia in infancy. Bone marrow cytology with vacuolization in erythroid and myeloid precursors and ring-sideroblasts guides to the correct diagnosis, which is established by detection of SLSMDs. Non hematological symptoms suggesting a mitochondrial disease are often lacking at initial presentation, thus PS is an important differential diagnosis in isolated hypogenerative anemia in infancy. Spontaneous resolution of anemia occurs in two-third of patients at the age of 1-3 years, while multisystem non-hematological complications such as failure to thrive, muscle hypotonia, exocrine pancreas insufficiency, renal tubulopathy and cardiac dysfunction develop during the clinical course. Some patients with PS experience a phenotypical change to Kearns-Sayre syndrome. In the absence of curative therapy, the prognosis of patients with PS is dismal. Most patients die of acute lactic acidosis and multi-organ failure in early childhood. There is a great need for the development of novel therapies to alter the natural history of patients with PS.
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Affiliation(s)
- Ayami Yoshimi
- Department of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Kaori Ishikawa
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, University Medical Center, University of Freiburg, Freiburg, Germany
| | - Charlotte Niemeyer
- Department of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sarah C Grünert
- Faculty of Life and Environmental Sciences and Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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13
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Ng YS, Lim AZ, Panagiotou G, Turnbull DM, Walker M. Endocrine Manifestations and New Developments in Mitochondrial Disease. Endocr Rev 2022; 43:583-609. [PMID: 35552684 PMCID: PMC9113134 DOI: 10.1210/endrev/bnab036] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Indexed: 11/19/2022]
Abstract
Mitochondrial diseases are a group of common inherited diseases causing disruption of oxidative phosphorylation. Some patients with mitochondrial disease have endocrine manifestations, with diabetes mellitus being predominant but also include hypogonadism, hypoadrenalism, and hypoparathyroidism. There have been major developments in mitochondrial disease over the past decade that have major implications for all patients. The collection of large cohorts of patients has better defined the phenotype of mitochondrial diseases and the majority of patients with endocrine abnormalities have involvement of several other systems. This means that patients with mitochondrial disease and endocrine manifestations need specialist follow-up because some of the other manifestations, such as stroke-like episodes and cardiomyopathy, are potentially life threatening. Also, the development and follow-up of large cohorts of patients means that there are clinical guidelines for the management of patients with mitochondrial disease. There is also considerable research activity to identify novel therapies for the treatment of mitochondrial disease. The revolution in genetics, with the introduction of next-generation sequencing, has made genetic testing more available and establishing a precise genetic diagnosis is important because it will affect the risk for involvement for different organ systems. Establishing a genetic diagnosis is also crucial because important reproductive options have been developed that will prevent the transmission of mitochondrial disease because of mitochondrial DNA variants to the next generation.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Albert Zishen Lim
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Grigorios Panagiotou
- Department of Diabetes and Endocrinology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Mark Walker
- Department of Diabetes and Endocrinology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
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14
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Lopriore P, Ricciarini V, Siciliano G, Mancuso M, Montano V. Mitochondrial Ataxias: Molecular Classification and Clinical Heterogeneity. Neurol Int 2022; 14:337-356. [PMID: 35466209 PMCID: PMC9036286 DOI: 10.3390/neurolint14020028] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/26/2022] [Accepted: 03/28/2022] [Indexed: 01/25/2023] Open
Abstract
Ataxia is increasingly being recognized as a cardinal manifestation in primary mitochondrial diseases (PMDs) in both paediatric and adult patients. It can be caused by disruption of cerebellar nuclei or fibres, its connection with the brainstem, or spinal and peripheral lesions leading to proprioceptive loss. Despite mitochondrial ataxias having no specific defining features, they should be included in hereditary ataxias differential diagnosis, given the high prevalence of PMDs. This review focuses on the clinical and neuropathological features and genetic background of PMDs in which ataxia is a prominent manifestation.
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15
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Extremely Rare Case of Fetal Anemia Due to Mitochondrial Disease Managed with Intrauterine Transfusion. Medicina (B Aires) 2022; 58:medicina58030328. [PMID: 35334505 PMCID: PMC8954106 DOI: 10.3390/medicina58030328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/26/2022] Open
Abstract
This report describes a rare case of fetal anemia, confirmed as a mitochondrial disease after birth, treated with intrauterine transfusion (IUT). Although mitochondrial diseases have been described in newborns, research on their prenatal features is lacking. A patient was referred to our institution at 32 gestational weeks owing to fetal hydrops. Fetal anemia was confirmed by cordocentesis. After IUT had been performed three times, the anemia and associated fetal hydrops showed improvement. However, after birth, the neonate had recurrent pancytopenia and lactic acidosis. He was eventually diagnosed with Pearson syndrome and died 2 months after birth. This is the first case report of fetal anemia associated with mitochondrial disease managed with IUT.
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16
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Mitochondrial Neurodegeneration. Cells 2022; 11:cells11040637. [PMID: 35203288 PMCID: PMC8870525 DOI: 10.3390/cells11040637] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 01/28/2022] [Accepted: 02/06/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondria are cytoplasmic organelles, which generate energy as heat and ATP, the universal energy currency of the cell. This process is carried out by coupling electron stripping through oxidation of nutrient substrates with the formation of a proton-based electrochemical gradient across the inner mitochondrial membrane. Controlled dissipation of the gradient can lead to production of heat as well as ATP, via ADP phosphorylation. This process is known as oxidative phosphorylation, and is carried out by four multiheteromeric complexes (from I to IV) of the mitochondrial respiratory chain, carrying out the electron flow whose energy is stored as a proton-based electrochemical gradient. This gradient sustains a second reaction, operated by the mitochondrial ATP synthase, or complex V, which condensates ADP and Pi into ATP. Four complexes (CI, CIII, CIV, and CV) are composed of proteins encoded by genes present in two separate compartments: the nuclear genome and a small circular DNA found in mitochondria themselves, and are termed mitochondrial DNA (mtDNA). Mutations striking either genome can lead to mitochondrial impairment, determining infantile, childhood or adult neurodegeneration. Mitochondrial disorders are complex neurological syndromes, and are often part of a multisystem disorder. In this paper, we divide the diseases into those caused by mtDNA defects and those that are due to mutations involving nuclear genes; from a clinical point of view, we discuss pediatric disorders in comparison to juvenile or adult-onset conditions. The complementary genetic contributions controlling organellar function and the complexity of the biochemical pathways present in the mitochondria justify the extreme genetic and phenotypic heterogeneity of this new area of inborn errors of metabolism known as ‘mitochondrial medicine’.
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17
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León BE, Kang S, Franca-Solomon G, Shang P, Choi DS. Alcohol-Induced Neuroinflammatory Response and Mitochondrial Dysfunction on Aging and Alzheimer's Disease. Front Behav Neurosci 2022; 15:778456. [PMID: 35221939 PMCID: PMC8866940 DOI: 10.3389/fnbeh.2021.778456] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/07/2021] [Indexed: 12/27/2022] Open
Abstract
Mitochondria are essential organelles central to various cellular functions such as energy production, metabolic pathways, signaling transduction, lipid biogenesis, and apoptosis. In the central nervous system, neurons depend on mitochondria for energy homeostasis to maintain optimal synaptic transmission and integrity. Deficiencies in mitochondrial function, including perturbations in energy homeostasis and mitochondrial dynamics, contribute to aging, and Alzheimer's disease. Chronic and heavy alcohol use is associated with accelerated brain aging, and increased risk for dementia, especially Alzheimer's disease. Furthermore, through neuroimmune responses, including pro-inflammatory cytokines, excessive alcohol use induces mitochondrial dysfunction. The direct and indirect alcohol-induced neuroimmune responses, including pro-inflammatory cytokines, are critical for the relationship between alcohol-induced mitochondrial dysfunction. In the brain, alcohol activates microglia and increases inflammatory mediators that can impair mitochondrial energy production, dynamics, and initiate cell death pathways. Also, alcohol-induced cytokines in the peripheral organs indirectly, but synergistically exacerbate alcohol's effects on brain function. This review will provide recent and advanced findings focusing on how alcohol alters the aging process and aggravates Alzheimer's disease with a focus on mitochondrial function. Finally, we will contextualize these findings to inform clinical and therapeutic approaches towards Alzheimer's disease.
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Affiliation(s)
- Brandon Emanuel León
- Regenerative Sciences Program, Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, United States
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, United States
| | - Shinwoo Kang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, United States
| | - Gabriela Franca-Solomon
- Neuroscience Program, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Pei Shang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, United States
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, United States
- Neuroscience Program, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
- Department of Psychiatry and Psychology, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
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18
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Molecular Genetics Overview of Primary Mitochondrial Myopathies. J Clin Med 2022; 11:jcm11030632. [PMID: 35160083 PMCID: PMC8836969 DOI: 10.3390/jcm11030632] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/13/2022] [Accepted: 01/20/2022] [Indexed: 12/29/2022] Open
Abstract
Mitochondrial disorders are the most common inherited conditions, characterized by defects in oxidative phosphorylation and caused by mutations in nuclear or mitochondrial genes. Due to its high energy request, skeletal muscle is typically involved. According to the International Workshop of Experts in Mitochondrial Diseases held in Rome in 2016, the term Primary Mitochondrial Myopathy (PMM) should refer to those mitochondrial disorders affecting principally, but not exclusively, the skeletal muscle. The clinical presentation may include general isolated myopathy with muscle weakness, exercise intolerance, chronic ophthalmoplegia/ophthalmoparesis (cPEO) and eyelids ptosis, or multisystem conditions where there is a coexistence with extramuscular signs and symptoms. In recent years, new therapeutic targets have been identified leading to the launch of some promising clinical trials that have mainly focused on treating muscle symptoms and that require populations with defined genotype. Advantages in next-generation sequencing techniques have substantially improved diagnosis. So far, an increasing number of mutations have been identified as responsible for mitochondrial disorders. In this review, we focused on the principal molecular genetic alterations in PMM. Accordingly, we carried out a comprehensive review of the literature and briefly discussed the possible approaches which could guide the clinician to a genetic diagnosis.
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19
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Treatment and Management of Hereditary Metabolic Myopathies. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00023-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Klopstock T, Priglinger C, Yilmaz A, Kornblum C, Distelmaier F, Prokisch H. Mitochondrial Disorders. DEUTSCHES ARZTEBLATT INTERNATIONAL 2021; 118:741-748. [PMID: 34158150 DOI: 10.3238/arztebl.m2021.0251] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 11/19/2020] [Accepted: 05/20/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mitochondrial disorders are among the most common heritable diseases, with an overall lifetime risk of approximately one in 1500. Nonetheless, their diagnosis is often missed because of their extreme phenotypic and genotypic heterogeneity. METHODS This review is based on publications retrieved by a selective literature search on the clinical features, genetics, pathogenesis, diagnosis, and treatment of mitochondrial diseases. RESULTS Pathogenic defects of energy metabolism have been described to date in over 400 genes. Only a small number of these genes lie in the mitochondrial DNA; the corresponding diseases are either maternally inherited or of sporadic distribution. The remaining diseaseassociated genes are coded in nuclear DNA and cause diseases that are inherited according to Mendelian rules, mostly autosomal recessive. The most severely involved organs are generally those with the highest energy requirements, including the brain, the sensory epithelia, and the extraocular, cardiac, and skeletal musculature. Typical manifestations include epileptic seizures, stroke-like episodes, hearing loss, retinopathy, external ophthalmoparesis, exercise intolerance, and diabetes mellitus. More than two manifestations of these types should arouse suspicion of a disease of energy metabolism. The severity of mitochondrial disorders ranges from very severe disease, already evident in childhood, to relatively mild disease arising in late adulthood. The diagnosis is usually confirmed with molecular-genetic methods. Symptomatic treatment can improve patients' quality of life. The only disease-modifying treatment that has been approved to date is idebenone for the treatment of Leber hereditary optic neuropathy. Intravitreal gene therapy has also been developed for the treatment of this disease; its approval by the European Medicines Agency is pending. CONCLUSION Patients with mitochondrial diseases have highly varied manifestations and can thus present to physicians in practically any branch of medicine. A correct diagnosis is the prerequisite for genetic counseling and for the initiation of personalized treatment.
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21
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Disease Modeling of Mitochondrial Cardiomyopathy Using Patient-Specific Induced Pluripotent Stem Cells. BIOLOGY 2021; 10:biology10100981. [PMID: 34681080 PMCID: PMC8533352 DOI: 10.3390/biology10100981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/25/2021] [Accepted: 09/26/2021] [Indexed: 12/15/2022]
Abstract
Mitochondrial cardiomyopathy (MCM) is characterized as an oxidative phosphorylation disorder of the heart. More than 100 genetic variants in nuclear or mitochondrial DNA have been associated with MCM. However, the underlying molecular mechanisms linking genetic variants to MCM are not fully understood due to the lack of appropriate cellular and animal models. Patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) provide an attractive experimental platform for modeling cardiovascular diseases and predicting drug efficacy to such diseases. Here we introduce the pathological and therapeutic studies of MCM using iPSC-CMs and discuss the questions and latest strategies for research using iPSC-CMs.
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22
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Papadopoulos C, Papadimas GK. The Relevance of Blepharoptosis in Diagnostic Suspicion of Myopathies. Neurol India 2021; 69:177-180. [PMID: 33642296 DOI: 10.4103/0028-3886.310067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Blepharoptosis (ptosis) is classified, based on etiology, into mechanical, cerebral, neurogenic, neuromuscular, myogenic, and due to miscellaneous causes. Primary myopathic diseases are rare causes of blepharoptosis and many patients with myogenic ptosis undergo a series of extensive investigations before a myopathy is being considered. In this study, we report four patients with different myopathic disorders who had blepharoptosis as a presenting symptom of their disease. Moreover, we highlight frequent diagnostic errors and difficulties in patients with myopathies who present blepharoptosis. Lack of clear cut aggravation of symptoms by fatigue and response to cholinesterase inhibitors treatment, the association of proximal, distal or extraocular muscle weakness, and positive family history or evidence of a multi systemic disorder should prompt evaluation of an underlying myopathy.
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Affiliation(s)
| | - George K Papadimas
- Department of Neurology, Aegintion Hospital, Medical School of Athens, Greece
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23
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Abstract
Mitochondria are organelles with vital functions in almost all eukaryotic cells. Often described as the cellular 'powerhouses' due to their essential role in aerobic oxidative phosphorylation, mitochondria perform many other essential functions beyond energy production. As signaling organelles, mitochondria communicate with the nucleus and other organelles to help maintain cellular homeostasis, allow cellular adaptation to diverse stresses, and help steer cell fate decisions during development. Mitochondria have taken center stage in the research of normal and pathological processes, including normal tissue homeostasis and metabolism, neurodegeneration, immunity and infectious diseases. The central role that mitochondria assume within cells is evidenced by the broad impact of mitochondrial diseases, caused by defects in either mitochondrial or nuclear genes encoding for mitochondrial proteins, on different organ systems. In this Review, we will provide the reader with a foundation of the mitochondrial 'hardware', the mitochondrion itself, with its specific dynamics, quality control mechanisms and cross-organelle communication, including its roles as a driver of an innate immune response, all with a focus on development, disease and aging. We will further discuss how mitochondrial DNA is inherited, how its mutation affects cell and organismal fitness, and current therapeutic approaches for mitochondrial diseases in both model organisms and humans.
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Affiliation(s)
- Marlies P. Rossmann
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 01238, USA
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Sonia M. Dubois
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Suneet Agarwal
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Leonard I. Zon
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 01238, USA
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA
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24
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Mazzaccara C, Mirra B, Barretta F, Caiazza M, Lombardo B, Scudiero O, Tinto N, Limongelli G, Frisso G. Molecular Epidemiology of Mitochondrial Cardiomyopathy: A Search Among Mitochondrial and Nuclear Genes. Int J Mol Sci 2021; 22:ijms22115742. [PMID: 34072184 PMCID: PMC8197938 DOI: 10.3390/ijms22115742] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/18/2021] [Accepted: 05/22/2021] [Indexed: 12/23/2022] Open
Abstract
Mitochondrial Cardiomyopathy (MCM) is a common manifestation of multi-organ Mitochondrial Diseases (MDs), occasionally present in non-syndromic cases. Diagnosis of MCM is complex because of wide clinical and genetic heterogeneity and requires medical, laboratory, and neuroimaging investigations. Currently, the molecular screening for MCM is fundamental part of MDs management and allows achieving the definitive diagnosis. In this article, we review the current genetic knowledge associated with MDs, focusing on diagnosis of MCM and MDs showing cardiac involvement. We searched for publications on mitochondrial and nuclear genes involved in MCM, mainly focusing on genetic screening based on targeted gene panels for the molecular diagnosis of the MCM, by using Next Generation Sequencing. Here we report twelve case reports, four case-control studies, eleven retrospective studies, and two prospective studies, for a total of twenty-nine papers concerning the evaluation of cardiac manifestations in mitochondrial diseases. From the analysis of published causal mutations, we identified 130 genes to be associated with mitochondrial heart diseases. A large proportion of these genes (34.3%) encode for key proteins involved in the oxidative phosphorylation system (OXPHOS), either as directly OXPHOS subunits (22.8%), and as OXPHOS assembly factors (11.5%). Mutations in several mitochondrial tRNA genes have been also reported in multi-organ or isolated MCM (15.3%). This review highlights the main disease-genes, identified by extensive genetic analysis, which could be included as target genes in next generation panels for the molecular diagnosis of patients with clinical suspect of mitochondrial cardiomyopathies.
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Affiliation(s)
- Cristina Mazzaccara
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
- Correspondence: ; Tel.: +39-0817-462-422
| | - Bruno Mirra
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
| | - Ferdinando Barretta
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
| | - Martina Caiazza
- Monaldi Hospital, AO Colli, 80131 Naples, Italy; (M.C.); (G.L.)
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, 80134 Naples, Italy
| | - Barbara Lombardo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
| | - Olga Scudiero
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
| | - Nadia Tinto
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
| | - Giuseppe Limongelli
- Monaldi Hospital, AO Colli, 80131 Naples, Italy; (M.C.); (G.L.)
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, 80134 Naples, Italy
| | - Giulia Frisso
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy; (B.M.); (F.B.); (B.L.); (O.S.); (N.T.); (G.F.)
- CEINGE Advanced Biotechnologies, 80145 Naples, Italy
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25
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Gusic M, Prokisch H. Genetic basis of mitochondrial diseases. FEBS Lett 2021; 595:1132-1158. [PMID: 33655490 DOI: 10.1002/1873-3468.14068] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
Mitochondrial disorders are monogenic disorders characterized by a defect in oxidative phosphorylation and caused by pathogenic variants in one of over 340 different genes. The implementation of whole-exome sequencing has led to a revolution in their diagnosis, duplicated the number of associated disease genes, and significantly increased the diagnosed fraction. However, the genetic etiology of a substantial fraction of patients exhibiting mitochondrial disorders remains unknown, highlighting limitations in variant detection and interpretation, which calls for improved computational and DNA sequencing methods, as well as the addition of OMICS tools. More intriguingly, this also suggests that some pathogenic variants lie outside of the protein-coding genes and that the mechanisms beyond the Mendelian inheritance and the mtDNA are of relevance. This review covers the current status of the genetic basis of mitochondrial diseases, discusses current challenges and perspectives, and explores the contribution of factors beyond the protein-coding regions and monogenic inheritance in the expansion of the genetic spectrum of disease.
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Affiliation(s)
- Mirjana Gusic
- Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Human Genetics, Technical University of Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Germany
| | - Holger Prokisch
- Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Human Genetics, Technical University of Munich, Germany
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26
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Antipova VN. A New Deletion of Mitochondrial DNA of a BALB/c Mouse. RUSS J GENET+ 2021. [DOI: 10.1134/s1022795421020022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Fontana GA, Gahlon HL. Mechanisms of replication and repair in mitochondrial DNA deletion formation. Nucleic Acids Res 2020; 48:11244-11258. [PMID: 33021629 PMCID: PMC7672454 DOI: 10.1093/nar/gkaa804] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/07/2020] [Accepted: 09/25/2020] [Indexed: 02/06/2023] Open
Abstract
Deletions in mitochondrial DNA (mtDNA) are associated with diverse human pathologies including cancer, aging and mitochondrial disorders. Large-scale deletions span kilobases in length and the loss of these associated genes contributes to crippled oxidative phosphorylation and overall decline in mitochondrial fitness. There is not a united view for how mtDNA deletions are generated and the molecular mechanisms underlying this process are poorly understood. This review discusses the role of replication and repair in mtDNA deletion formation as well as nucleic acid motifs such as repeats, secondary structures, and DNA damage associated with deletion formation in the mitochondrial genome. We propose that while erroneous replication and repair can separately contribute to deletion formation, crosstalk between these pathways is also involved in generating deletions.
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Affiliation(s)
- Gabriele A Fontana
- Department of Health Sciences and Technology, ETH Zürich, Schmelzbergstrasse 9, 8092 Zürich, Switzerland
| | - Hailey L Gahlon
- To whom correspondence should be addressed. Tel: +41 44 632 3731;
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28
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Ishikawa K, Nakada K. Attempts to understand the mechanisms of mitochondrial diseases: The reverse genetics of mouse models for mitochondrial disease. Biochim Biophys Acta Gen Subj 2020; 1865:129835. [PMID: 33358867 DOI: 10.1016/j.bbagen.2020.129835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/25/2020] [Accepted: 12/18/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mitochondrial disease is a general term for a disease caused by a decline in mitochondrial function. The pathology of this disease is extremely diverse and complex, and the mechanism of its pathogenesis is still unknown. Using mouse models that develop the disease via the same processes as in humans is the easiest path to understanding the underlying mechanism. However, creating a mouse model is extremely difficult due to the lack of technologies that enable editing of mitochondrial DNA (mtDNA). SCOPE OF REVIEW This paper outlines the complex pathogenesis of mitochondrial disease, and the difficulties in producing relevant mouse models. Then, the paper provides a detailed discussion on several mice created with mutations in mtDNA. The paper also introduces the pathology of mouse models with mutations including knockouts of nuclear genes that directly affect mitochondrial function. MAJOR CONCLUSIONS Several mice with mtDNA mutations and those with nuclear DNA mutations have been established. Although these models help elucidate the pathological mechanism of mitochondrial disease, they lack sufficient diversity to enable a complete understanding. Considering the variety of factors that affect the cause and mechanism of mitochondrial disease, it is necessary to account for this background diversity in mouse models as well. GENERAL SIGNIFICANCE Mouse models are indispensable for understanding the pathological mechanism of mitochondrial disease, as well as for searching new treatments. There is a need for the creation and examination of mouse models with more diverse mutations and altered nuclear backgrounds and breeding environments.
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Affiliation(s)
- Kaori Ishikawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8572, Japan; Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Kazuto Nakada
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8572, Japan; Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
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29
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Montano V, Gruosso F, Simoncini C, Siciliano G, Mancuso M. Clinical features of mtDNA-related syndromes in adulthood. Arch Biochem Biophys 2020; 697:108689. [PMID: 33227288 DOI: 10.1016/j.abb.2020.108689] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/06/2020] [Accepted: 11/15/2020] [Indexed: 01/26/2023]
Abstract
Mitochondrial diseases are the most common inheritable metabolic diseases, due to defects in oxidative phosphorylation. They are caused by mutations of nuclear or mitochondrial DNA in genes involved in mitochondrial function. The peculiarity of "mitochondrial DNA genetics rules" in part explains the marked phenotypic variability, the complexity of genotype-phenotype correlations and the challenge of genetic counseling. The new massive genetic sequencing technologies have changed the diagnostic approach, enhancing mitochondrial DNA-related syndromes diagnosis and often avoiding the need of a tissue biopsy. Here we present the most common phenotypes associated with a mitochondrial DNA mutation with the recent advances in diagnosis and in therapeutic perspectives.
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Affiliation(s)
- V Montano
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - F Gruosso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - C Simoncini
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - G Siciliano
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - M Mancuso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy.
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30
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Anteneová N, Kelifová S, Kolářová H, Vondráčková A, Tóthová I, Lišková P, Magner M, Zámečník J, Hansíková H, Zeman J, Tesařová M, Honzík T. The Phenotypic Spectrum of 47 Czech Patients with Single, Large-Scale Mitochondrial DNA Deletions. Brain Sci 2020; 10:brainsci10110766. [PMID: 33105723 PMCID: PMC7690373 DOI: 10.3390/brainsci10110766] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/20/2022] Open
Abstract
Background: In this retrospective study, we analysed clinical, biochemical and molecular genetic data of 47 Czech patients with Single, Large-Scale Mitochondrial DNA Deletions (SLSMD). Methods: The diagnosis was based on the long-range PCR (LX-PCR) screening of mtDNA isolated from muscle biopsy in 15 patients, and from the buccal swab, urinary epithelial cells and blood in 32 patients. Results: A total of 57% patients manifested before the age of 16. We did not find any significant difference between paediatric and adult manifestation in either the proportion of patients that would develop extraocular symptoms, or the timespan of its progression. The survival rate in patients with Pearson Syndrome reached 60%. Altogether, five patients manifested with atypical phenotype not fulfilling the latest criteria for SLSMD. No correlation was found between the disease severity and all heteroplasmy levels, lengths of the deletion and respiratory chain activities in muscle. Conclusions: Paediatric manifestation of Progressive External Ophthalmoplegia (PEO) is not associated with a higher risk of multisystemic involvement. Contrary to PEO and Kearns-Sayre Syndrome Spectrum, Pearson Syndrome still contributes to a significant childhood mortality. SLSMD should be considered even in cases with atypical presentation. To successfully identify carriers of SLSMD, a repeated combined analysis of buccal swab and urinary epithelial cells is needed.
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Affiliation(s)
- Nicole Anteneová
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Silvie Kelifová
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Hana Kolářová
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Alžběta Vondráčková
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Iveta Tóthová
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Petra Lišková
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
- Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital, U Nemocnice 2, 128 08 Prague 2, Czech Republic
| | - Martin Magner
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
- Department of Paediatrics, First Faculty of Medicine, Charles University and Thomayer Hospital, Vídeňská 800, 140 59 Prague 4, Czech Republic
| | - Josef Zámečník
- Department of Pathology and Molecular Medicine, Second Faculty of Medicine, Charles University and Motol University Hospital, V Úvalu 84, 150 06 Prague 5, Czech Republic;
| | - Hana Hansíková
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Jiří Zeman
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
| | - Markéta Tesařová
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
- Correspondence:
| | - Tomáš Honzík
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 128 08 Prague 2, Czech Republic; (N.A.); (S.K.); (H.K.); (A.V.); (I.T.); (P.L.); (M.M.); (H.H.); (J.Z.); (T.H.)
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31
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Varhaug KN, Nido GS, de Coo I, Isohanni P, Suomalainen A, Tzoulis C, Knappskog P, Bindoff LA. Using urine to diagnose large-scale mtDNA deletions in adult patients. Ann Clin Transl Neurol 2020; 7:1318-1326. [PMID: 32634300 PMCID: PMC7448145 DOI: 10.1002/acn3.51119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE The aim of this study was to evaluate if urinary sediment cells offered a robust alternative to muscle biopsy for the diagnosis of single mtDNA deletions. METHODS Eleven adult patients with progressive external ophthalmoplegia and a known single mtDNA deletion were investigated. Urinary sediment cells were used to isolate DNA, which was then subjected to long-range polymerase chain reaction. Where available, the patient`s muscle DNA was studied in parallel. Breakpoint and thus deletion size were identified using both Sanger sequencing and next generation sequencing. The level of heteroplasmy was determined using quantitative polymerase chain reaction. RESULTS We identified the deletion in urine in 9 of 11 cases giving a sensitivity of 80%. Breakpoints and deletion size were readily detectable in DNA extracted from urine. Mean heteroplasmy level in urine was 38% ± 26 (range 8 - 84%), and 57% ± 28 (range 12 - 94%) in muscle. While the heteroplasmy level in urinary sediment cells differed from that in muscle, we did find a statistically significant correlation between these two levels (R = 0.714, P = 0.031(Pearson correlation)). INTERPRETATION Our findings suggest that urine can be used to screen patients suspected clinically of having a single mtDNA deletion. Based on our data, the use of urine could considerably reduce the need for muscle biopsy in this patient group.
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Affiliation(s)
- Kristin N Varhaug
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway
| | - Gonzalo S Nido
- Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway.,Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Irenaeus de Coo
- Department of Neurology, Medical Spectrum Twente, Enschede, The Netherlands.,Department of Genetics and Cell Biology, University of Maastricht, Maastricht, The Netherlands
| | - Pirjo Isohanni
- Research Programs Unit, Stem Cells and Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Children´s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit, Stem Cells and Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,HUSlab, Helsinki University Hospital Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Hilife, Helsinki, Finland
| | - Charalampos Tzoulis
- Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway.,Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Per Knappskog
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Laurence A Bindoff
- Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway.,Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
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32
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Guo L, Wang X, Ji H. Clinical Phenotype and Genetic Features of a Pair of Chinese Twins with Kearns-Sayre Syndrome. DNA Cell Biol 2020; 39:1449-1457. [PMID: 32609007 DOI: 10.1089/dna.2019.5010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Kearns-Sayre Syndrome (KSS) is a severe mitochondrial disorder involving the central nervous system, eyes, ears, skeletal muscles, and heart. The mitochondrial DNA (mtDNA) rearrangements, especially the deletions, are present in almost all KSS patients and considered as the disease-causing factor. However, the size and position of mtDNA deletions are distinct in different individuals. In this study, we report the case of a pair of Chinese twins with KSS. The twin patients revealed typical KSS clinical symptoms, including heart block, bilateral sensorineural hearing loss, progressive external ophthalmoplegia, exercise intolerance, proximal limb weakness, and endocrine disorders. Using long-range polymerase chain reactions (long-range PCR) and next-generation sequencing (NGS), the genetic features of the twin patients were investigated. A large 6600 bp mtDNA deletion, ranging from position 8702 to 15,302, was detected in both patients. To our knowledge, this kind of mtDNA deletion has never been described previously. Our study enriched the mutation spectrum of KSS and showed that NGS is a powerful tool for detecting mtDNA large variants.
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Affiliation(s)
- Luo Guo
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, ENT Institute and Otorhinolaryngology Department, Fudan University Eye & ENT Hospital, Shanghai, People's Republic of China.,NHC Key Laboratory of Hearing Medicine and Fudan University, Shanghai, People's Republic of China
| | - Xin Wang
- Institutes of Biomedical Sciences, Fudan University, Shanghai, People's Republic of China.,Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Nantong University, Nantong, People's Republic of China
| | - Haiting Ji
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, ENT Institute and Otorhinolaryngology Department, Fudan University Eye & ENT Hospital, Shanghai, People's Republic of China.,NHC Key Laboratory of Hearing Medicine and Fudan University, Shanghai, People's Republic of China.,Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, China
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33
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La Morgia C, Maresca A, Caporali L, Valentino ML, Carelli V. Mitochondrial diseases in adults. J Intern Med 2020; 287:592-608. [PMID: 32463135 DOI: 10.1111/joim.13064] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/07/2020] [Accepted: 02/21/2020] [Indexed: 02/07/2023]
Abstract
Mitochondrial medicine is a field that expanded exponentially in the last 30 years. Individually rare, mitochondrial diseases as a whole are probably the most frequent genetic disorder in adults. The complexity of their genotype-phenotype correlation, in terms of penetrance and clinical expressivity, natural history and diagnostic algorithm derives from the dual genetic determination. In fact, in addition to the about 1.500 genes encoding mitochondrial proteins that reside in the nuclear genome (nDNA), we have the 13 proteins encoded by the mitochondrial genome (mtDNA), for which 22 specific tRNAs and 2 rRNAs are also needed. Thus, besides Mendelian genetics, we need to consider all peculiarities of how mtDNA is inherited, maintained and expressed to fully understand the pathogenic mechanisms of these disorders. Yet, from the initial restriction to the narrow field of oxidative phosphorylation dysfunction, the landscape of mitochondrial functions impinging on cellular homeostasis, driving life and death, is impressively enlarged. Finally, from the clinical standpoint, starting from the neuromuscular field, where brain and skeletal muscle were the primary targets of mitochondrial dysfunction as energy-dependent tissues, after three decades virtually any subspecialty of medicine is now involved. We will summarize the key clinical pictures and pathogenic mechanisms of mitochondrial diseases in adults.
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Affiliation(s)
- C La Morgia
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - A Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - L Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - M L Valentino
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - V Carelli
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
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34
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Wei W, Chinnery PF. Inheritance of mitochondrial DNA in humans: implications for rare and common diseases. J Intern Med 2020; 287:634-644. [PMID: 32187761 PMCID: PMC8641369 DOI: 10.1111/joim.13047] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/01/2019] [Accepted: 12/10/2019] [Indexed: 12/27/2022]
Abstract
The first draft human mitochondrial DNA (mtDNA) sequence was published in 1981, paving the way for two decades of discovery linking mtDNA variation with human disease. Severe pathogenic mutations cause sporadic and inherited rare disorders that often involve the nervous system. However, some mutations cause mild organ-specific phenotypes that have a reduced clinical penetrance, and polymorphic variation of mtDNA is associated with an altered risk of developing several late-onset common human diseases including Parkinson's disease. mtDNA mutations also accumulate during human life and are enriched in affected organs in a number of age-related diseases. Thus, mtDNA contributes to a wide range of human pathologies. For many decades, it has generally been accepted that mtDNA is inherited exclusively down the maternal line in humans. Although recent evidence has challenged this dogma, whole-genome sequencing has identified nuclear-encoded mitochondrial sequences (NUMTs) that can give the false impression of paternally inherited mtDNA. This provides a more likely explanation for recent reports of 'bi-parental inheritance', where the paternal alleles are actually transmitted through the nuclear genome. The presence of both mutated and wild-type variant alleles within the same individual (heteroplasmy) and rapid shifts in allele frequency can lead to offspring with variable severity of disease. In addition, there is emerging evidence that selection can act for and against specific mtDNA variants within the developing germ line, and possibly within developing tissues. Thus, understanding how mtDNA is inherited has far-reaching implications across medicine. There is emerging evidence that this highly dynamic system is amenable to therapeutic manipulation, raising the possibility that we can harness new understanding to prevent and treat rare and common human diseases where mtDNA mutations play a key role.
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Affiliation(s)
- W Wei
- From the, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Medical Research Council Mitochondrial Biology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - P F Chinnery
- From the, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Medical Research Council Mitochondrial Biology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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35
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Oliveira MT, Pontes CDB, Ciesielski GL. Roles of the mitochondrial replisome in mitochondrial DNA deletion formation. Genet Mol Biol 2020; 43:e20190069. [PMID: 32141473 PMCID: PMC7197994 DOI: 10.1590/1678-4685-gmb-2019-0069] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 08/12/2019] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletions are a common cause of human mitochondrial
diseases. Mutations in the genes encoding components of the mitochondrial
replisome, such as DNA polymerase gamma (Pol γ) and the mtDNA helicase Twinkle,
have been associated with the accumulation of such deletions and the development
of pathological conditions in humans. Recently, we demonstrated that changes in
the level of wild-type Twinkle promote mtDNA deletions, which implies that not
only mutations in, but also dysregulation of the stoichiometry between the
replisome components is potentially pathogenic. The mechanism(s) by which
alterations to the replisome function generate mtDNA deletions is(are) currently
under debate. It is commonly accepted that stalling of the replication fork at
sites likely to form secondary structures precedes the deletion formation. The
secondary structural elements can be bypassed by the replication-slippage
mechanism. Otherwise, stalling of the replication fork can generate single- and
double-strand breaks, which can be repaired through recombination leading to the
elimination of segments between the recombination sites. Here, we discuss
aberrances of the replisome in the context of the two debated outcomes, and
suggest new mechanistic explanations based on replication restart and template
switching that could account for all the deletion types reported for
patients.
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Affiliation(s)
- Marcos T Oliveira
- Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Ciências Agrárias e Veterinárias, Departamento de Tecnologia, Jaboticabal, SP, Brazil
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36
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Nissanka N, Moraes CT. Mitochondrial DNA heteroplasmy in disease and targeted nuclease-based therapeutic approaches. EMBO Rep 2020; 21:e49612. [PMID: 32073748 DOI: 10.15252/embr.201949612] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/11/2019] [Accepted: 01/29/2020] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes a subset of the genes which are responsible for oxidative phosphorylation. Pathogenic mutations in the human mtDNA are often heteroplasmic, where wild-type mtDNA species co-exist with the pathogenic mtDNA and a bioenergetic defect is only seen when the pathogenic mtDNA percentage surpasses a threshold for biochemical manifestations. mtDNA segregation during germline development can explain some of the extreme variation in heteroplasmy from one generation to the next. Patients with high heteroplasmy for deleterious mtDNA species will likely suffer from bona-fide mitochondrial diseases, which currently have no cure. Shifting mtDNA heteroplasmy toward the wild-type mtDNA species could provide a therapeutic option to patients. Mitochondrially targeted engineered nucleases, such as mitoTALENs and mitoZFNs, have been used in vitro in human cells harboring pathogenic patient-derived mtDNA mutations and more recently in vivo in a mouse model of a pathogenic mtDNA point mutation. These gene therapy tools for shifting mtDNA heteroplasmy can also be used in conjunction with other therapies aimed at eliminating and/or preventing the transfer of pathogenic mtDNA from mother to child.
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Affiliation(s)
- Nadee Nissanka
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Carlos T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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37
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Mitochondrial disorders and the eye. Surv Ophthalmol 2019; 65:294-311. [PMID: 31783046 DOI: 10.1016/j.survophthal.2019.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 11/16/2019] [Accepted: 11/18/2019] [Indexed: 01/27/2023]
Abstract
Mitochondria are cellular organelles that play a key role in energy metabolism and oxidative phosphorylation. Malfunctioning of mitochondria has been implicated as the cause of many disorders with variable inheritance, heterogeneity of systems involved, and varied phenotype. Metabolically active tissues are more likely to be affected, causing an anatomic and physiologic disconnect in the treating physicians' mind between presentation and underlying pathophysiology. We shall focus on disorders of mitochondrial metabolism relevant to an ophthalmologist. These disorders can affect all parts of the visual pathway (crystalline lens, extraocular muscles, retina, optic nerve, and retrochiasm). After the introduction reviewing mitochondrial structure and function, each disorder is reviewed in detail, including approaches to its diagnosis and most current management guidelines.
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38
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A Brief History of Mitochondrial Pathologies. Int J Mol Sci 2019; 20:ijms20225643. [PMID: 31718067 PMCID: PMC6888695 DOI: 10.3390/ijms20225643] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 01/19/2023] Open
Abstract
The history of "mitochondrial pathologies", namely genetic pathologies affecting mitochondrial metabolism because of mutations in nuclear DNA-encoded genes for proteins active inside mitochondria or mutations in mitochondrial DNA-encoded genes, began in 1988. In that year, two different groups of researchers discovered, respectively, large-scale single deletions of mitochondrial DNA (mtDNA) in muscle biopsies from patients with "mitochondrial myopathies" and a point mutation in the mtDNA gene for subunit 4 of NADH dehydrogenase (MTND4), associated with maternally inherited Leber's hereditary optic neuropathy (LHON). Henceforth, a novel conceptual "mitochondrial genetics", separate from mendelian genetics, arose, based on three features of mtDNA: (1) polyplasmy; (2) maternal inheritance; and (3) mitotic segregation. Diagnosis of mtDNA-related diseases became possible through genetic analysis and experimental approaches involving histochemical staining of muscle or brain sections, single-fiber polymerase chain reaction (PCR) of mtDNA, and the creation of patient-derived "cybrid" (cytoplasmic hybrid) immortal fibroblast cell lines. The availability of the above-mentioned techniques along with the novel sensitivity of clinicians to such disorders led to the characterization of a constantly growing number of pathologies. Here is traced a brief historical perspective on the discovery of autonomous pathogenic mtDNA mutations and on the related mendelian pathology altering mtDNA integrity.
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39
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Heighton JN, Brady LI, Sadikovic B, Bulman DE, Tarnopolsky MA. Genotypes of chronic progressive external ophthalmoplegia in a large adult-onset cohort. Mitochondrion 2019; 49:227-231. [PMID: 31521625 DOI: 10.1016/j.mito.2019.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 03/28/2019] [Accepted: 09/11/2019] [Indexed: 12/11/2022]
Abstract
Chronic progressive external ophthalmoplegia (CPEO) is a common presentation of mitochondrial disease. We performed a retrospective evaluation of the molecular genetic testing and genotype-phenotype correlations in a large cohort of adult-onset CPEO patients (N = 111). One hundred percent of patients tested had at least one mitochondrial DNA (mtDNA) deletion. Genetic testing of nuclear genes encoding mitochondrial proteins identified pathogenic/likely pathogenic variants likely to be associated with CPEO in 7.6% of patients. As expected, the nuclear gene most associated with DNA variation was POLG. A single likely pathogenic mitochondrial DNA variant (m.12278T>C) was identified in two unrelated patients. No significant differences were noted in the clinical phenotypes of patients with pathogenic or likely pathogenic nuclear variants in comparison to those with negative nuclear gene testing. Analysis of deletion size and heteroplasmy in muscle-derived mtDNA showed significant correlations with age of symptom onset but not disease severity (number of canonical CPEO features). Results suggest that smaller mtDNA deletions (p = 0.0127, r2 = 0.1201) and higher heteroplasmy of single mtDNA deletions (p = 0.0112, r2 = 0.2483) are associated with an earlier age of onset in CPEO patients.
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Affiliation(s)
- Julia N Heighton
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
| | - Lauren I Brady
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
| | - Bekim Sadikovic
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada; Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, ON, Canada
| | - Dennis E Bulman
- Newborn Screening Ontario and CHEO Research Institute, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
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40
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Gustafson MA, McCormick EM, Perera L, Longley MJ, Bai R, Kong J, Dulik M, Shen L, Goldstein AC, McCormack SE, Laskin BL, Leroy BP, Ortiz-Gonzalez XR, Ellington MG, Copeland WC, Falk MJ. Mitochondrial single-stranded DNA binding protein novel de novo SSBP1 mutation in a child with single large-scale mtDNA deletion (SLSMD) clinically manifesting as Pearson, Kearns-Sayre, and Leigh syndromes. PLoS One 2019; 14:e0221829. [PMID: 31479473 PMCID: PMC6719858 DOI: 10.1371/journal.pone.0221829] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 08/15/2019] [Indexed: 12/04/2022] Open
Abstract
Mitochondrial DNA (mtDNA) genome integrity is essential for proper mitochondrial respiratory chain function to generate cellular energy. Nuclear genes encode several proteins that function at the mtDNA replication fork, including mitochondrial single-stranded DNA-binding protein (SSBP1), which is a tetrameric protein that binds and protects single-stranded mtDNA (ssDNA). Recently, two studies have reported pathogenic variants in SSBP1 associated with hearing loss, optic atrophy, and retinal degeneration. Here, we report a 14-year-old Chinese boy with severe and progressive mitochondrial disease manifestations across the full Pearson, Kearns-Sayre, and Leigh syndromes spectrum, including infantile anemia and bone marrow failure, growth failure, ptosis, ophthalmoplegia, ataxia, severe retinal dystrophy of the rod-cone type, sensorineural hearing loss, chronic kidney disease, multiple endocrine deficiencies, and metabolic strokes. mtDNA genome sequencing identified a single large-scale 5 kilobase mtDNA deletion (m.8629_14068del5440), present at 68% and 16% heteroplasmy in the proband's fibroblast cell line and blood, respectively, suggestive of a mtDNA maintenance defect. On trio whole exome blood sequencing, the proband was found to harbor a novel de novo heterozygous mutation c.79G>A (p.E27K) in SSBP1. Size exclusion chromatography of p.E27K SSBP1 revealed it remains a stable tetramer. However, differential scanning fluorimetry demonstrated p.E27K SSBP1 relative to wild type had modestly decreased thermostability. Functional assays also revealed p.E27K SSBP1 had altered DNA binding. Molecular modeling of SSBP1 tetramers with varying combinations of mutant subunits predicted general changes in surface accessible charges, strength of inter-subunit interactions, and protein dynamics. Overall, the observed changes in protein dynamics and DNA binding behavior suggest that p.E27K SSBP1 can interfere with DNA replication and precipitate the introduction of large-scale mtDNA deletions. Thus, a single large-scale mtDNA deletion (SLSMD) with manifestations across the clinical spectrum of Pearson, Kearns-Sayre, and Leigh syndromes may result from a nuclear gene disorder disrupting mitochondrial DNA replication.
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Affiliation(s)
- Margaret A. Gustafson
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Elizabeth M. McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Matthew J. Longley
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Renkui Bai
- GeneDx, Gaithersburg, MD, United States of America
| | - Jianping Kong
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Matthew Dulik
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Lishuang Shen
- Center for Personalized Medicine, Department of Pathology & Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, United States of America
| | - Amy C. Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Shana E. McCormack
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
- Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Benjamin L. Laskin
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
- Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Bart P. Leroy
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Xilma R. Ortiz-Gonzalez
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Meredith G. Ellington
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - William C. Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Marni J. Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
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41
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Set KK, Sen K, Huq AHM, Agarwal R. Mitochondrial Disorders of the Nervous System: A Review. Clin Pediatr (Phila) 2019; 58:381-394. [PMID: 30607979 DOI: 10.1177/0009922818821890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kallol K Set
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Kuntal Sen
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - A H M Huq
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - Rajkumar Agarwal
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
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42
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Nissanka N, Minczuk M, Moraes CT. Mechanisms of Mitochondrial DNA Deletion Formation. Trends Genet 2019; 35:235-244. [PMID: 30691869 DOI: 10.1016/j.tig.2019.01.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 02/02/2023]
Abstract
Mitochondrial DNA (mtDNA) encodes a subset of genes which are essential for oxidative phosphorylation. Deletions in the mtDNA can ablate a number of these genes and result in mitochondrial dysfunction, which is associated with bona fide mitochondrial disorders. Although mtDNA deletions are thought to occur as a result of replication errors or following double-strand breaks, the exact mechanism(s) behind deletion formation have yet to be determined. In this review we discuss the current knowledge about the fate of mtDNA following double-strand breaks, including the molecular players which mediate the degradation of linear mtDNA fragments and possible mechanisms of recircularization. We propose that mtDNA deletions formed from replication errors versus following double-strand breaks can be mediated by separate pathways.
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Affiliation(s)
- Nadee Nissanka
- Department of Neurology, University of Miami, Miller School of Medicine, FL 33136, USA
| | - Michal Minczuk
- Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Carlos T Moraes
- Department of Neurology, University of Miami, Miller School of Medicine, FL 33136, USA.
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Mitochondrial DNA Deletions With Low-Level Heteroplasmy in Adult-Onset Myopathy. J Clin Neuromuscul Dis 2018; 19:117-123. [PMID: 29465611 DOI: 10.1097/cnd.0000000000000200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We report the cases of 2 patients who presented to our Myositis Center with myalgias and elevated creatine kinase levels. Muscle biopsy showed pathological features consistent with mitochondrial myopathy. In both cases, a single large deletion in mitochondrial DNA at low-level heteroplasmy was identified by next-generation sequencing in muscle tissue. In 1 case, the deletion was identified in muscle tissue but not blood. In both cases, the deletion was only identified on next-generation sequencing of muscle mitochondrial DNA and missed on array comparative genome hybridization testing. These cases demonstrate that next-generation sequencing of mitochondrial DNA in muscle tissue is the most sensitive method of molecular diagnosis for mitochondrial myopathy due to mitochondrial DNA deletions.
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44
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Clonal expansion of mtDNA deletions: different disease models assessed by digital droplet PCR in single muscle cells. Sci Rep 2018; 8:11682. [PMID: 30076399 PMCID: PMC6076247 DOI: 10.1038/s41598-018-30143-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 07/18/2018] [Indexed: 01/07/2023] Open
Abstract
Deletions in mitochondrial DNA (mtDNA) are an important cause of human disease and their accumulation has been implicated in the ageing process. As mtDNA is a high copy number genome, the coexistence of deleted and wild-type mtDNA molecules within a single cell defines heteroplasmy. When deleted mtDNA molecules, driven by intracellular clonal expansion, reach a sufficiently high level, a biochemical defect emerges, contributing to the appearance and progression of clinical pathology. Consequently, it is relevant to determine the heteroplasmy levels within individual cells to understand the mechanism of clonal expansion. Heteroplasmy is reflected in a mosaic distribution of cytochrome c oxidase (COX)-deficient muscle fibers. We applied droplet digital PCR (ddPCR) to single muscle fibers collected by laser-capture microdissection (LCM) from muscle biopsies of patients with different paradigms of mitochondrial disease, characterized by the accumulation of single or multiple mtDNA deletions. By combining these two sensitive approaches, ddPCR and LCM, we document different models of clonal expansion in patients with single and multiple mtDNA deletions, implicating different mechanisms and time points for the development of COX deficiency in these molecularly distinct mitochondrial cytopathies.
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45
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Clinical syndromes associated with mtDNA mutations: where we stand after 30 years. Essays Biochem 2018; 62:235-254. [DOI: 10.1042/ebc20170097] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 01/16/2023]
Abstract
The landmark year 1988 can be considered as the birthdate of mitochondrial medicine, when the first pathogenic mutations affecting mtDNA were associated with human diseases. Three decades later, the field still expands and we are not ‘scraping the bottom of the barrel’ yet. Despite the tremendous progress in terms of molecular characterization and genotype/phenotype correlations, for the vast majority of cases we still lack a deep understanding of the pathogenesis, good models to study, and effective therapeutic options. However, recent technological advances including somatic cell reprogramming to induced pluripotent stem cells (iPSCs), organoid technology, and tailored endonucleases provide unprecedented opportunities to fill these gaps, casting hope to soon cure the major primary mitochondrial phenotypes reviewed here. This group of rare diseases represents a key model for tackling the pathogenic mechanisms involving mitochondrial biology relevant to much more common disorders that affect our currently ageing population, such as diabetes and metabolic syndrome, neurodegenerative and inflammatory disorders, and cancer.
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Tarín JJ, García-Pérez MA, Cano A. Potential risks to offspring of intrauterine exposure to maternal age-related obstetric complications. Reprod Fertil Dev 2018; 29:1468-1476. [PMID: 27504647 DOI: 10.1071/rd16163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/10/2016] [Indexed: 12/13/2022] Open
Abstract
Several hypotheses have been proposed to explain the negative effects of delayed motherhood on an offspring's morbidity later in life. However, these hypotheses are not supported by clinical and epidemiological evidence. Because advanced maternal age is associated with increased risk of obstetric complications, the aim of the present study was to ascertain whether the negative effects on offspring of intrauterine exposure to maternal age-related obstetric complications may explain the reported negative effects of delayed motherhood on offspring. To this end, a literature search was performed to identify relevant publications up to March 2016 on PubMed; references cited in relevant articles were also searched. There was a direct correlation between the risks to offspring conferred by intrauterine exposure to at least one of the obstetric complications present at the time of delivery in women aged ≥35 years and the risks to offspring of delayed motherhood. This correlation was not observed when comparing the risks to offspring of delayed motherhood and the risks associated with maternal transmission of defective mitochondria, chromosomal anomalies or DNA double-strand breaks. Most of the effects on offspring of intrauterine exposure to maternal age-related obstetric complications may be induced by epigenetic DNA reprogramming during critical periods of embryo or fetal development. Women wanting to enrol in a fertility preservation program to offset age-related declines in fertility should be informed not only about their chances of pregnancy and the percentage of live births, but also about the risks to themselves and their prospective offspring of delaying motherhood.
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Affiliation(s)
- Juan J Tarín
- Department of Cellular Biology, Functional Biology and Physical Anthropology, Faculty of Biological Sciences, University of Valencia, Dr. Moliner 50, Burjassot, Valencia 46100, Spain
| | - Miguel A García-Pérez
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Dr. Moliner 50, Burjassot, Valencia 46100, Spain
| | - Antonio Cano
- Department of Pediatrics, Obstetrics and Gynecology, Faculty of Medicine, University of Valencia, Avda. Blasco Ibañez 15, Valencia 46010, Spain
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Poulton J, Finsterer J, Yu-Wai-Man P. Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 2018; 21:419-429. [PMID: 28536827 DOI: 10.1007/s40291-017-0279-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim of this review was to provide an evidence-based approach to frequently asked questions relating to the risk of transmitting a maternally inherited mitochondrial disorder (MID). We do not address disorders linked with disturbed mitochondrial DNA (mtDNA) maintenance, causing mtDNA depletion or multiple mtDNA deletions, as these are autosomally inherited. The review addresses questions regarding prognosis, recurrence risks and the strategies available to prevent disease transmission. The clinical and genetic complexity of maternally inherited MIDs represent a major challenge for patients, their relatives and health professionals. Since many of the genetic and pathophysiological aspects of MIDs remain unknown, counselling of affected patients and at-risk family members remains difficult. MtDNA mutations are maternally transmitted or, more rarely, they are sporadic, occurring de novo (~25%). Females carrying homoplasmic mtDNA mutations will transmit the mutant species to all of their offspring, who may or may not exhibit a similar phenotype depending on modifying, secondary factors. Females carrying heteroplasmic mtDNA mutations will transmit a variable amount of mutant mtDNA to their offspring, which can result in considerable phenotypic heterogeneity among siblings. The majority of mtDNA rearrangements, such as single large-scale deletions, are sporadic, but there is a small risk of recurrence (~4%) among the offspring of affected women. The range and suitability of reproductive choices for prospective mothers is a complex area of mitochondrial medicine that needs to be managed by experienced healthcare professionals as part of a multidisciplinary team. Genetic counselling is facilitated by the identification of the underlying causative genetic defect. To provide more precise genetic counselling, further research is needed to clarify the secondary factors that account for the variable penetrance and the often marked differential expressivity of pathogenic mtDNA mutations both within and between families.
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Affiliation(s)
- Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Josef Finsterer
- Krankenanstalt Rudolfstiftung, Postfach 20, 1180, Vienna, Austria.
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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Abstract
Ataxia is one of the most frequent symptoms of mitochondrial disease. In most cases it occurs as part of a syndromic disorder and the combination of ataxia with other neurologic involvement such as epilepsy is common. Mitochondrial ataxias can be caused by disturbance of the cerebellum and its connections, involvement of proprioception (i.e., sensory ataxia) or a combination of both (spinocerebellar). There are no specific features that define an ataxia as mitochondrial, except perhaps the tendency for it to occur together with involvement of multiple other sites, both in the nervous system and outside. In this review we will concentrate on the mitochondrial disorders in which ataxia is a prominent and consistent feature and focus on the clinical features and genetic causes.
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Affiliation(s)
- Hilary J Vernon
- McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Laurence A Bindoff
- Department of Clinical Medicine, University of Bergen and Department of Neurology, Haukeland University Hospital, Bergen, Norway.
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Tidwell TR, Søreide K, Hagland HR. Aging, Metabolism, and Cancer Development: from Peto's Paradox to the Warburg Effect. Aging Dis 2017; 8:662-676. [PMID: 28966808 PMCID: PMC5614328 DOI: 10.14336/ad.2017.0713] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 06/13/2017] [Indexed: 12/15/2022] Open
Abstract
Medical advances made over the last century have increased our lifespan, but age-related diseases are a fundamental health burden worldwide. Aging is therefore a major risk factor for cardiovascular disease, cancer, diabetes, obesity, and neurodegenerative diseases, all increasing in prevalence. However, huge inter-individual variations in aging and disease risk exist, which cannot be explained by chronological age, but rather physiological age decline initiated even at young age due to lifestyle. At the heart of this lies the metabolic system and how this is regulated in each individual. Metabolic turnover of food to energy leads to accumulation of co-factors, byproducts, and certain proteins, which all influence gene expression through epigenetic regulation. How these epigenetic markers accumulate over time is now being investigated as the possible link between aging and many diseases, such as cancer. The relationship between metabolism and cancer was described as early as the late 1950s by Dr. Otto Warburg, before the identification of DNA and much earlier than our knowledge of epigenetics. However, when the stepwise gene mutation theory of cancer was presented, Warburg's theories garnered little attention. Only in the last decade, with epigenetic discoveries, have Warburg's data on the metabolic shift in cancers been brought back to life. The stepwise gene mutation theory fails to explain why large animals with more cells, do not have a greater cancer incidence than humans, known as Peto's paradox. The resurgence of research into the Warburg effect has given us insight to what may explain Peto's paradox. In this review, we discuss these connections and how age-related changes in metabolism are tightly linked to cancer development, which is further affected by lifestyle choices modulating the risk of aging and cancer through epigenetic control.
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Affiliation(s)
- Tia R. Tidwell
- Department of Mathematics and Natural Sciences, Centre for Organelle Research, University of Stavanger, Stavanger, Norway
- Gastrointestinal Translational Research Unit, Molecular Laboratory, Hillevaåg, Stavanger University Hospital, Stavanger, Norway
| | - Kjetil Søreide
- Gastrointestinal Translational Research Unit, Molecular Laboratory, Hillevaåg, Stavanger University Hospital, Stavanger, Norway
- Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Hanne R. Hagland
- Department of Mathematics and Natural Sciences, Centre for Organelle Research, University of Stavanger, Stavanger, Norway
- Gastrointestinal Translational Research Unit, Molecular Laboratory, Hillevaåg, Stavanger University Hospital, Stavanger, Norway
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50
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Meyer JN, Chan SSL. Sources, mechanisms, and consequences of chemical-induced mitochondrial toxicity. Toxicology 2017. [PMID: 28627407 DOI: 10.1016/j.tox.2017.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Joel N Meyer
- Nicholas School of the Environment and Integrated Toxicology and Environmental Health Program, Duke University, Durham, NC, 27708-0328, USA.
| | - Sherine S L Chan
- Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC, 29425, USA; Neuroene Therapeutics, Mt. Pleasant, SC 29464, USA.
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