1
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Iorga RE, Munteanu-Dănulescu RS, Danielescu C. A challenging differential diagnosis - Leber's Hereditary Optic Neuropathy. Rom J Ophthalmol 2024; 68:65-71. [PMID: 38617721 PMCID: PMC11007558 DOI: 10.22336/rjo.2024.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2024] [Indexed: 04/16/2024] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is the most common maternally inherited disease linked to mitochondrial DNA (mtDNA). The patients present with subacute asymmetric bilateral vision loss. Approximately 95% of the LHON cases are caused by m.3460G>A (MTND1), m.11778G>A (MTND4), and m.14484T>C (MTND6) mutations. The hallmark of hereditary optic neuropathies determined by mitochondrial dysfunction is the vulnerability and degeneration of retinal ganglion cells (RGC). We present the case of a 28-year-old man who came to our clinic complaining of a subacute decrease in visual acuity of his left eye. From his medical history, we found out that one month before he had the same symptoms in the right eye. From the family history, we noted that an uncle has had vision problems since childhood. We carried out complete blood tests, including specific antibodies for autoimmune and infectious diseases. Laboratory tests and MRI were within normal limits. A blood test of the mtDNA showed the presence of 11778 G>A mutation on the mtND6 gene. The medical history, the fundus appearance, the OCT, and the paraclinical investigations, made us diagnose our patient with Leber's hereditary optic neuropathy. As soon as possible, we began the treatment with systemic idebenone, 900 mg/day. We examined the patient 2, 6, and 10 weeks after initiating the treatment. Abbreviations: LHON = Leber's Hereditary Optic Neuropathy, mtDNA = mitochondrial DNA, VA = visual acuity, RE = right eye, LE = left eye, OCT = Optical coherence tomography, pRNFL = peripapillary retinal nerve fiber layer, GCL = retinal ganglion cells layer, MRI = magnetic resonance imaging, VEP = visual evoked potentials, VEP IT = VEP implicit time, VEP A = VEP amplitude.
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Affiliation(s)
- Raluca Eugenia Iorga
- “Grigore T. Popa” University of Medicine and Pharmacy, Faculty of Medicine, Iaşi, Romania
- Department of Ophthalmology, “N. Oblu” Clinical Emergency Hospital, Iași, Romania
| | | | - Ciprian Danielescu
- “Grigore T. Popa” University of Medicine and Pharmacy, Faculty of Medicine, Iaşi, Romania
- Department of Ophthalmology, “N. Oblu” Clinical Emergency Hospital, Iași, Romania
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2
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Badeeb NO, Karanjia R. Visual Recovery in Leber Hereditary Optic Neuropathy From a Rare mt.14568 Mutation on ND6 Gene. J Neuroophthalmol 2023; 43:e134-e135. [PMID: 35439208 DOI: 10.1097/wno.0000000000001565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Nooran O Badeeb
- Department of Ophthalmology (NB, RK), University of Ottawa, Ottawa, Canada; Department of Ophthalmology (NB), University of Jeddah, Jeddah, Saudi Arabia; Department of Ophthalmology (RK), Doheny Eye Centers, David Geffen School of Medicine at UCLA, Los Angeles, California; Ottawa Hospital Research Institute (RK), The Ottawa Hospital, Ottawa, Canada; and Doheny Eye Institute (RK), Los Angeles, California
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3
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Major TC, Arany ES, Schon K, Simo M, Karcagi V, van den Ameele J, Yu Wai Man P, Chinnery PF, Olimpio C, Horvath R. Case report: Mutations in DNAJC30 causing autosomal recessive Leber hereditary optic neuropathy are common amongst Eastern European individuals. Front Neurol 2023; 14:1292320. [PMID: 38107630 PMCID: PMC10722306 DOI: 10.3389/fneur.2023.1292320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 11/03/2023] [Indexed: 12/19/2023] Open
Abstract
Background Leber Hereditary Optic Neuropathy (LHON) is the most common inherited mitochondrial disease characterized by bilateral, painless, subacute visual loss with a peak age of onset in the second to third decade. Historically, LHON was thought to be exclusively maternally inherited due to mutations in mitochondrial DNA (mtDNA); however, recent studies have identified an autosomal recessive form of LHON (arLHON) caused by point mutations in the nuclear gene, DNAJC30. Case Presentations In this study, we report the cases of three Eastern European individuals presenting with bilateral painless visual loss, one of whom was also exhibiting motor symptoms. After a several-year-long diagnostic journey, all three patients were found to carry the homozygous c.152A>G (p.Tyr51Cys) mutation in DNAJC30. This has been identified as the most common arLHON pathogenic variant and has been shown to exhibit a significant founder effect amongst Eastern European individuals. Conclusion This finding adds to the growing cohort of patients with arLHON and demonstrates the importance of DNAJC30 screening in patients with molecularly undiagnosed LHON, particularly in Eastern European individuals. It is of heightened translational significance as patients diagnosed with arLHON exhibit a better prognosis and response to therapeutic treatment with the co-enzyme Q10 analog idebenone.
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Affiliation(s)
- Toby Charles Major
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Eszter Sara Arany
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Schon
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Genetics, East Anglian Medical Genetics Service, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Magdolna Simo
- University Clinic of Neurology, Semmelweis University, Budapest, Hungary
| | | | - Jelle van den Ameele
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Patrick Yu Wai Man
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- NIHR Biomedical Research Centre, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
| | - Patrick F. Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Catarina Olimpio
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Genetics, East Anglian Medical Genetics Service, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
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4
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Zaslavsky K, Donaldson L, Margolin E. Conversion to Leber Hereditary Optic Neuropathy After Hyperbaric Oxygen Therapy. J Neuroophthalmol 2023; 43:e70-e73. [PMID: 34629399 DOI: 10.1097/wno.0000000000001357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Kirill Zaslavsky
- Department of Ophthalmology and Vision Sciences (KZ, LD, EM), University of Toronto, Toronto, Canada ; and Division of Neurology (EM), Department of Medicine, University of Toronto, Toronto, Canada
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5
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Baglivo M, Nasca A, Lamantea E, Vinci S, Spagnolo M, Marchet S, Prokisch H, Catania A, Lamperti C, Ghezzi D. Evaluation of Mitochondrial Dysfunction and Idebenone Responsiveness in Fibroblasts from Leber's Hereditary Optic Neuropathy (LHON) Subjects. Int J Mol Sci 2023; 24:12580. [PMID: 37628761 PMCID: PMC10454080 DOI: 10.3390/ijms241612580] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/02/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a disease that affects the optical nerve, causing visual loss. The diagnosis of LHON is mostly defined by the identification of three pathogenic variants in the mitochondrial DNA. Idebenone is widely used to treat LHON patients, but only some of them are responders to treatment. In our study, we assessed the maximal respiration rate (MRR) and other respiratory parameters in eight fibroblast lines from subjects carrying LHON pathogenic variants. We measured also the effects of idebenone treatment on cell growth and mtDNA amounts. Results showed that LHON fibroblasts had significantly reduced respiratory parameters in untreated conditions, but no significant gain in MRR after idebenone supplementation. No major toxicity toward mitochondrial function and no relevant compensatory effect in terms of mtDNA quantity were found for the treatment at the tested conditions. Our findings confirmed that fibroblasts from subjects harboring LHON pathogenic variants displayed impaired respiration, regardless of the disease penetrance and severity. Testing responsiveness to idebenone treatment in cultured cells did not fully recapitulate in vivo data. The in-depth evaluation of cellular respiration in fibroblasts is a good approach to evaluating novel mtDNA variants associated with LHON but needs further evaluation as a potential biomarker for disease prognosis and treatment responsiveness.
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Affiliation(s)
- Mirko Baglivo
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Alessia Nasca
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Eleonora Lamantea
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Stefano Vinci
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Manuela Spagnolo
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Silvia Marchet
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Holger Prokisch
- Institute of Human Genetics, School of Medicine, Technical University of Munich, 81675 Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, 85764 Munich, Germany
| | - Alessia Catania
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Costanza Lamperti
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
| | - Daniele Ghezzi
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126 Milan, Italy
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
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6
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Wilson V, Kaur P, Singh S, Ramachandran RP, Jyothi V, Mahesh KV, Takkar A, Chandak G, Singh R. Clinical Profile of Patients with Leber Hereditary Optic Neuropathy-An Ambispective Study in Cohort from Northern Part of India. Ann Indian Acad Neurol 2023; 26:285-286. [PMID: 37538427 PMCID: PMC10394433 DOI: 10.4103/aian.aian_973_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/28/2023] [Indexed: 08/05/2023] Open
Affiliation(s)
- Vinny Wilson
- Department of Neurology, Armed Forces Medical College, Pune, Maharashtra, India
| | - Prabhjit Kaur
- Department of Neurology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Sofia Singh
- Department of Neurology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Radhika P. Ramachandran
- Genomic Research on Complex Diseases Laboratory (GRC Lab), CSIR-Center for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana, India
| | - Vislavath Jyothi
- Genomic Research on Complex Diseases Laboratory (GRC Lab), CSIR-Center for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana, India
| | - Karthik Vinay Mahesh
- Department of Neurology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Aastha Takkar
- Department of Neurology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Giriraj Chandak
- Genomic Research on Complex Diseases Laboratory (GRC Lab), CSIR-Center for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana, India
| | - Ramandeep Singh
- Department of Ophthalmology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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7
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Automated perimetry in diagnosing acute Leber's hereditary optic neuropathy. Can J Neurol Sci 2023; 50:315-316. [PMID: 35105407 DOI: 10.1017/cjn.2021.515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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8
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Watson EC, Davis RL, Ravishankar S, Copty J, Kummerfeld S, Sue CM. Low disease risk and penetrance in Leber hereditary optic neuropathy. Am J Hum Genet 2023; 110:166-169. [PMID: 36565700 PMCID: PMC9892766 DOI: 10.1016/j.ajhg.2022.11.013] [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: 02/26/2022] [Accepted: 11/21/2022] [Indexed: 12/24/2022] Open
Abstract
The risk of Leber hereditary optic neuropathy (LHON) has largely been extrapolated from disease cohorts, which underestimate the population prevalence of pathogenic primary LHON variants as a result of incomplete disease penetrance. Understanding the true population prevalence of primary LHON variants, alongside the rate of clinical disease, provides a better understanding of disease risk and variant penetrance. We identified pathogenic primary LHON variants in whole-genome sequencing data of a well-characterized population-based control cohort and found that the prevalence is far greater than previously estimated, as it occurs in approximately 1 in 800 individuals. Accordingly, we were able to more accurately estimate population risk and disease penetrance in LHON variant carriers, validating our findings by using other large control datasets. These findings will inform accurate counseling in relation to the risk of vision loss in LHON variant carriers and disease manifestation in their family. This Matters Arising paper is in response to Lopez Sanchez et al. (2021), published in The American Journal of Human Genetics. See also the response by Mackey et al. (2022), published in this issue.
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Affiliation(s)
- Eloise C. Watson
- Department of Neurogenetics, Kolling Institute, Faculty of Medicine and Health, University of Sydney and Northern Sydney Local Health District, Reserve Rd, St Leonards, NSW, Australia,Department of Neurology, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, NSW, Australia,Department of Neurology, Wellington Hospital, Capital and Coast District Health Board, Newtown, Wellington, New Zealand
| | - Ryan L. Davis
- Department of Neurogenetics, Kolling Institute, Faculty of Medicine and Health, University of Sydney and Northern Sydney Local Health District, Reserve Rd, St Leonards, NSW, Australia
| | | | - Joseph Copty
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Sarah Kummerfeld
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia,St Vincents Clinical School, UNSW, Sydney, NSW, Australia
| | - Carolyn M. Sue
- Department of Neurogenetics, Kolling Institute, Faculty of Medicine and Health, University of Sydney and Northern Sydney Local Health District, Reserve Rd, St Leonards, NSW, Australia,Department of Neurology, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, NSW, Australia,Corresponding author
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9
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Abstract
Mitochondrial optic neuropathies have a leading role in the field of mitochondrial medicine ever since 1988, when the first mutation in mitochondrial DNA was associated with Leber's hereditary optic neuropathy (LHON). Autosomal dominant optic atrophy (DOA) was subsequently associated in 2000 with mutations in the nuclear DNA affecting the OPA1 gene. LHON and DOA are both characterized by selective neurodegeneration of retinal ganglion cells (RGCs) triggered by mitochondrial dysfunction. This is centered on respiratory complex I impairment in LHON and defective mitochondrial dynamics in OPA1-related DOA, leading to distinct clinical phenotypes. LHON is a subacute, rapid, severe loss of central vision involving both eyes within weeks or months, with age of onset between 15 and 35 years old. DOA is a more slowly progressive optic neuropathy, usually apparent in early childhood. LHON is characterized by marked incomplete penetrance and a clear male predilection. The introduction of next-generation sequencing has greatly expanded the genetic causes for other rare forms of mitochondrial optic neuropathies, including recessive and X-linked, further emphasizing the exquisite sensitivity of RGCs to compromised mitochondrial function. All forms of mitochondrial optic neuropathies, including LHON and DOA, can manifest either as pure optic atrophy or as a more severe multisystemic syndrome. Mitochondrial optic neuropathies are currently at the forefront of a number of therapeutic programs, including gene therapy, with idebenone being the only approved drug for a mitochondrial disorder.
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Affiliation(s)
- Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto di Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy.
| | - Chiara La Morgia
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto di Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Patrick Yu-Wai-Man
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; Institute of Ophthalmology, University College London, London, United Kingdom
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10
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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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11
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Spiegel SJ, Sadun AA. Solutions to a Radical Problem: Overview of Current and Future Treatment Strategies in Leber's Hereditary Opic Neuropathy. Int J Mol Sci 2022; 23:13205. [PMID: 36361994 PMCID: PMC9656544 DOI: 10.3390/ijms232113205] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Leber's Hereditary Optic Neuropathy (LHON) is the most common primary mitochondrial DNA disorder. It is characterized by bilateral severe central subacute vision loss due to specific loss of Retinal Ganglion Cells and their axons. Historically, treatment options have been quite limited, but ongoing clinical trials show promise, with significant advances being made in the testing of free radical scavengers and gene therapy. In this review, we summarize management strategies and rational of treatment based on current insights from molecular research. This includes preventative recommendations for unaffected genetic carriers, current medical and supportive treatments for those affected, and emerging evidence for future potential therapeutics.
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Affiliation(s)
- Samuel J. Spiegel
- Gavin Herbert Eye Institute, University of California, Irvine, CA 92617, USA
| | - Alfredo A. Sadun
- Jules Stein and Doheny Eye Institute, University of California, Los Angeles, CA 90095, USA
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12
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Lambiri DW, Levin LA. Modeling Reactive Oxygen Species-Induced Axonal Loss in Leber Hereditary Optic Neuropathy. Biomolecules 2022; 12:biom12101411. [PMID: 36291620 PMCID: PMC9599876 DOI: 10.3390/biom12101411] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/29/2022] [Accepted: 09/30/2022] [Indexed: 11/17/2022] Open
Abstract
Leber hereditary optic neuropathy (LHON) is a rare syndrome that results in vision loss. A necessary but not sufficient condition for its onset is the existence of known mitochondrial DNA mutations that affect complex I biomolecular structure. Cybrids with LHON mutations generate higher rates of reactive oxygen species (ROS). This study models how ROS, particularly H2O2, could signal and execute the axonal degeneration process that underlies LHON. We modeled and explored several hypotheses regarding the influence of H2O2 on the dynamics of propagation of axonal degeneration in LHON. Zonal oxidative stress, corresponding to H2O2 gradients, correlated with the morphology of injury exhibited in the LHON pathology. If the axonal membrane is highly permeable to H2O2 and oxidative stress induces larger production of H2O2, small injuries could trigger cascading failures of neighboring axons. The cellular interdependence created by H2O2 diffusion, and the gradients created by tissue variations in H2O2 production and scavenging, result in injury patterns and surviving axonal loss distributions similar to LHON tissue samples. Specifically, axonal degeneration starts in the temporal optic nerve, where larger groups of small diameter fibers are located and propagates from that region. These findings correlate well with clinical observations of central loss of visual field, visual acuity, and color vision in LHON, and may serve as an in silico platform for modeling the mechanism of action for new therapeutics.
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Affiliation(s)
- Darius W. Lambiri
- Department of Physiology, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Leonard A. Levin
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, QC H4A 3S5, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada
- Correspondence:
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13
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Kieninger S, Xiao T, Weisschuh N, Kohl S, Rüther K, Kroisel PM, Brockmann T, Knappe S, Kellner U, Lagrèze W, Mazzola P, Haack TB, Wissinger B, Tonagel F. DNAJC30 disease-causing gene variants in a large Central European cohort of patients with suspected Leber's hereditary optic neuropathy and optic atrophy. J Med Genet 2022; 59:1027-1034. [PMID: 35091433 PMCID: PMC9554085 DOI: 10.1136/jmedgenet-2021-108235] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 01/07/2022] [Indexed: 01/18/2023]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) has been considered a prototypical mitochondriopathy and a textbook example for maternal inheritance linked to certain disease-causing variants in the mitochondrial genome. Recently, an autosomal recessive form of LHON (arLHON) has been described, caused by disease-causing variants in the nuclear encoded gene DNAJC30. METHODS AND RESULTS In this study, we screened the DNAJC30 gene in a large Central European cohort of patients with a clinical diagnosis of LHON or other autosomal inherited optic atrophies (OA). We identified likely pathogenic variants in 35/1202 patients, corresponding to a detection rate of 2.9%. The previously described missense variant c.152A>G;p.(Tyr51Cys) accounts for 90% of disease-associated alleles in our cohort and we confirmed a strong founder effect. Furthermore, we identified two novel pathogenic variants in DNAJC30: the nonsense variant c.610G>T;p.(Glu204*) and the in-frame deletion c.230_232del;p.(His77del). Clinical investigation of the patients with arLHON revealed a younger age of onset, a more frequent bilateral onset and an increased clinically relevant recovery compared with LHON associated with disease-causing variants in the mitochondrial DNA. CONCLUSION This study expands previous findings on arLHON and emphasises the importance of DNAJC30 in the genetic diagnostics of LHON and OA in European patients.
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Affiliation(s)
- Sinja Kieninger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ting Xiao
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Klaus Rüther
- Facharztpraxis für Augenheilkunde, Berlin-Mitte, Germany
| | - Peter Michael Kroisel
- Diagnostic & Research Institute of Human Genetics, Diagnostic & Research Centre for Molecular BioMedicine, Medical University of Graz, Graz, Austria
| | - Tobias Brockmann
- Department of Ophthalmology, Universitätsmedizin Rostock, University of Rostock, Rostock, Germany
| | - Steffi Knappe
- Department of Ophthalmology, Universitätsmedizin Rostock, University of Rostock, Rostock, Germany
| | - Ulrich Kellner
- Zentrum für Seltene Netzhauterkrankungen, AugenZentrum Siegburg, MVZ Augenärztliches Diagnostik- und Therapiecentrum Siegburg GmbH, Siegburg, Germany
- RetinaScience, Bonn, Germany
| | - Wolf Lagrèze
- Eye Centre, Medical Centre - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Pascale Mazzola
- Institute of Human Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Tobias B Haack
- Institute of Human Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
- Centre for Rare Diseases, University of Tübingen, Tübingen, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Felix Tonagel
- Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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14
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Vikramdeo KS, Sudan SK, Singh AP, Singh S, Dasgupta S. Mitochondrial respiratory complexes: Significance in human mitochondrial disorders and cancers. J Cell Physiol 2022; 237:4049-4078. [PMID: 36074903 DOI: 10.1002/jcp.30869] [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: 11/17/2021] [Revised: 07/18/2022] [Accepted: 08/23/2022] [Indexed: 11/07/2022]
Abstract
Mitochondria are pivotal organelles that govern cellular energy production through the oxidative phosphorylation system utilizing five respiratory complexes. In addition, mitochondria also contribute to various critical signaling pathways including apoptosis, damage-associated molecular patterns, calcium homeostasis, lipid, and amino acid biosynthesis. Among these diverse functions, the energy generation program oversee by mitochondria represents an immaculate orchestration and functional coordination between the mitochondria and nuclear encoded molecules. Perturbation in this program through respiratory complexes' alteration results in the manifestation of various mitochondrial disorders and malignancy, which is alarmingly becoming evident in the recent literature. Considering the clinical relevance and importance of this emerging medical problem, this review sheds light on the timing and nature of molecular alterations in various respiratory complexes and their functional consequences observed in various mitochondrial disorders and human cancers. Finally, we discussed how this wealth of information could be exploited and tailored to develop respiratory complex targeted personalized therapeutics and biomarkers for better management of various incurable human mitochondrial disorders and cancers.
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Affiliation(s)
- Kunwar Somesh Vikramdeo
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Sarabjeet Kour Sudan
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Ajay P Singh
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Seema Singh
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Santanu Dasgupta
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
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15
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Pathological mitophagy disrupts mitochondrial homeostasis in Leber's hereditary optic neuropathy. Cell Rep 2022; 40:111124. [PMID: 35858578 PMCID: PMC9314546 DOI: 10.1016/j.celrep.2022.111124] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 03/27/2022] [Accepted: 06/29/2022] [Indexed: 01/18/2023] Open
Abstract
Leber’s hereditary optic neuropathy (LHON), a disease associated with a mitochondrial DNA mutation, is characterized by blindness due to degeneration of retinal ganglion cells (RGCs) and their axons, which form the optic nerve. We show that a sustained pathological autophagy and compartment-specific mitophagy activity affects LHON patient-derived cells and cybrids, as well as induced pluripotent-stem-cell-derived neurons. This is variably counterbalanced by compensatory mitobiogenesis. The aberrant quality control disrupts mitochondrial homeostasis as reflected by defective bioenergetics and excessive reactive oxygen species production, a stress phenotype that ultimately challenges cell viability by increasing the rate of apoptosis. We counteract this pathological mechanism by using autophagy regulators (clozapine and chloroquine) and redox modulators (idebenone), as well as genetically activating mitochondrial biogenesis (PGC1-α overexpression). This study substantially advances our understanding of LHON pathophysiology, providing an integrated paradigm for pathogenesis of mitochondrial diseases and druggable targets for therapy. Autophagy and mitophagy are abnormally activated in samples carrying LHON mutations Autophagy and mitophagy affect LHON cells’ viability Therapeutic approaches targeting autophagy reverts LHON cells’ apoptotic death
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16
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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: 6] [Impact Index Per Article: 3.0] [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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17
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Zeviani M, Carelli V. Mitochondrial Retinopathies. Int J Mol Sci 2021; 23:210. [PMID: 35008635 PMCID: PMC8745158 DOI: 10.3390/ijms23010210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
The retina is an exquisite target for defects of oxidative phosphorylation (OXPHOS) associated with mitochondrial impairment. Retinal involvement occurs in two ways, retinal dystrophy (retinitis pigmentosa) and subacute or chronic optic atrophy, which are the most common clinical entities. Both can present as isolated or virtually exclusive conditions, or as part of more complex, frequently multisystem syndromes. In most cases, mutations of mtDNA have been found in association with mitochondrial retinopathy. The main genetic abnormalities of mtDNA include mutations associated with neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) sometimes with earlier onset and increased severity (maternally inherited Leigh syndrome, MILS), single large-scale deletions determining Kearns-Sayre syndrome (KSS, of which retinal dystrophy is a cardinal symptom), and mutations, particularly in mtDNA-encoded ND genes, associated with Leber hereditary optic neuropathy (LHON). However, mutations in nuclear genes can also cause mitochondrial retinopathy, including autosomal recessive phenocopies of LHON, and slowly progressive optic atrophy caused by dominant or, more rarely, recessive, mutations in the fusion/mitochondrial shaping protein OPA1, encoded by a nuclear gene on chromosome 3q29.
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Affiliation(s)
- Massimo Zeviani
- Department of Neurosciences, The Clinical School, University of Padova, 35128 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Orus 2, 35128 Padova, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
- Programma di Neurogenetica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 6, 40139 Bologna, Italy
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18
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Zaslavsky K, Margolin EA. Leber's Hereditary Optic Neuropathy in Older Individuals Because of Increased Alcohol Consumption During the COVID-19 Pandemic. J Neuroophthalmol 2021; 41:316-320. [PMID: 34415266 DOI: 10.1097/wno.0000000000001333] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) is a disorder affecting oxidative phosphorylation in mitochondria. A majority of affected patients are men of 15 to 35 years of age. Phenotypic penetrance of this condition is only 50% in man and 10% in women and increases if the cellular energy demands go up, with the most common risk factors being smoking and alcohol use. METHODS Review of clinical features of 3 patients who were diagnosed with LHON in their sixth decade of life after doubling their alcohol intake during the recent COVID-19 pandemic. RESULTS All 3 patients were older than the age of 50 when they developed severe sequential visual loss. All have at least doubled their alcohol intake for at least 4 weeks preceding visual loss, and 2 who were smokers increased the number of cigarettes consumed daily because of the stress and boredom during the lockdowns triggered by the pandemic. CONCLUSIONS Significant increase in substance abuse in the general population during the recent lockdowns to combat the COVID-19 pandemic is well documented. We report 3 patients older than the age of 50, one of them a woman, who developed severe bilateral visual loss due to LHON after doubling their alcohol consumption and increasing number of cigarettes smoked daily during the pandemic. Clinicians are reminded to consider LHON in the differential diagnosis when encountering older patients with bilateral sequential visual loss and to specifically inquire about alcohol use and cigarette smoking in these patients.
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Affiliation(s)
- Kirill Zaslavsky
- Departments of Ophthalmology and Vision Sciences (KZ, EM), University of Toronto, Toronto, Canada ; and Department of Medicine (EM), Division of Neurology, University of Toronto, Toronto, Canada
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19
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Ng YS, Bindoff LA, Gorman GS, Klopstock T, Kornblum C, Mancuso M, McFarland R, Sue CM, Suomalainen A, Taylor RW, Thorburn DR, Turnbull DM. Mitochondrial disease in adults: recent advances and future promise. Lancet Neurol 2021; 20:573-584. [PMID: 34146515 DOI: 10.1016/s1474-4422(21)00098-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/17/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
Mitochondrial diseases are some of the most common inherited neurometabolic disorders, and major progress has been made in our understanding, diagnosis, and treatment of these conditions in the past 5 years. Development of national mitochondrial disease cohorts and international collaborations has changed our knowledge of the spectrum of clinical phenotypes and natural history of mitochondrial diseases. Advances in high-throughput sequencing technologies have altered the diagnostic algorithm for mitochondrial diseases by increasingly using a genetics-first approach, with more than 350 disease-causing genes identified to date. While the current management strategy for mitochondrial disease focuses on surveillance for multisystem involvement and effective symptomatic treatment, new endeavours are underway to find better treatments, including repurposing current drugs, use of novel small molecules, and gene therapies. Developments made in reproductive technology offer women the opportunity to prevent transmission of DNA-related mitochondrial disease to their children.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, 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; Directorate of Neurosciences, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Laurence A Bindoff
- Department of Clinical Medicine, University of Bergen, Bergen, Norway; Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, 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; Directorate of Neurosciences, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, LMU Hospital, Ludwig Maximilians University, Munich, Germany; German Center for Neurodegenerative Diseases, Munich, Germany; Munich Cluster for Systems Neurology, Munich, Germany
| | - Cornelia Kornblum
- Department of Neurology, Neuromuscular Disease Section, University Hospital Bonn, Bonn, Germany; Centre for Rare Diseases, University Hospital Bonn, Bonn, Germany
| | - Michelangelo Mancuso
- Department of Clinical and Experimental Medicine, Neurological Institute, University of Pisa, Italy
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, 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
| | - Carolyn M Sue
- Department of Neurogenetics, Kolling Institute, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Department of Neurology, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, NSW, Australia
| | - Anu Suomalainen
- Research Program in Stem Cells and Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Neuroscience Centre, HiLife, University of Helsinki, Helsinki, Finland; Helsinki University Hospital, HUSlab, Helsinki, Finland
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, 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
| | - David R Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia; Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, 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.
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20
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Peverelli L, Catania A, Marchet S, Ciasca P, Cammarata G, Melzi L, Bellino A, Fancellu R, Lamantea E, Capristo M, Caporali L, La Morgia C, Carelli V, Ghezzi D, Bianchi Marzoli S, Lamperti C. Leber's Hereditary Optic Neuropathy: A Report on Novel mtDNA Pathogenic Variants. Front Neurol 2021; 12:657317. [PMID: 34177762 PMCID: PMC8220086 DOI: 10.3389/fneur.2021.657317] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/07/2021] [Indexed: 11/27/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is due to missense point mutations affecting mitochondrial DNA (mtDNA); 90% of cases harbor the m.3460G>A, m.11778G>A, and m.14484T>C primary mutations. Here, we report and discuss five families with patients affected by symptomatic LHON, in which we found five novel mtDNA variants. Remarkably, these mtDNA variants are located in complex I genes, though without strong deleterious effect on respiration in cellular models: this finding is likely linked to the tissue specificity of LHON. This study observes that in the case of a strong clinical suspicion of LHON, it is recommended to analyze the whole mtDNA sequence, since new rare mtDNA pathogenic variants causing LHON are increasingly identified.
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Affiliation(s)
- Lorenzo Peverelli
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy.,Neuromuscular and Rare Disease Unit, Department of Neuroscience, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Alessia Catania
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Silvia Marchet
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Ciasca
- Neuro-Ophthalmology Service and Ocular Electrophysiology Laboratory, Department of Ophthalmology, Scientific Institute Auxologico Capitanio Hospital, Milan, Italy
| | - Gabriella Cammarata
- Neuro-Ophthalmology Service and Ocular Electrophysiology Laboratory, Department of Ophthalmology, Scientific Institute Auxologico Capitanio Hospital, Milan, Italy
| | - Lisa Melzi
- Neuro-Ophthalmology Service and Ocular Electrophysiology Laboratory, Department of Ophthalmology, Scientific Institute Auxologico Capitanio Hospital, Milan, Italy
| | - Antonella Bellino
- Neuromuscular Disorders Unit, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Roberto Fancellu
- Neurology Unit, IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Ospedale Policlinico San Martino, Genoa, Italy
| | - Eleonora Lamantea
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Mariantonietta Capristo
- IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto delle Scienze Neurologiche di Bologna, Unità Operativa Complessa (UOC) Clinica Neurologica, Bologna, Italy
| | - Leonardo Caporali
- IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto delle Scienze Neurologiche di Bologna, Unità Operativa Complessa (UOC) Clinica Neurologica, Bologna, Italy
| | - Chiara La Morgia
- IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto delle Scienze Neurologiche di Bologna, Unità Operativa Complessa (UOC) Clinica Neurologica, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Valerio Carelli
- IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto delle Scienze Neurologiche di Bologna, Unità Operativa Complessa (UOC) Clinica Neurologica, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Stefania Bianchi Marzoli
- Neuro-Ophthalmology Service and Ocular Electrophysiology Laboratory, Department of Ophthalmology, Scientific Institute Auxologico Capitanio Hospital, Milan, Italy
| | - Costanza Lamperti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Istituto Neurologico Carlo Besta, Milan, Italy
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21
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Vandeputte J, Van Heetvelde M, Van Cauwenbergh C, Seneca S, De Baere E, Leroy BP, De Zaeytijd J. Mild Leber hereditary optic neuropathy (LHON) in a Western European family due to the rare Asian m.14502T>C variant in the MT-ND6 gene. Ophthalmic Genet 2021; 42:440-445. [PMID: 33858285 DOI: 10.1080/13816810.2021.1913611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Leber hereditary optic neuropathy (LHON) is a mitochondrial neurodegenerative disease. The majority (>90%) is related to three primary mitochondrial DNA (mtDNA) variants: ND1 m.3460G>A, ND4 m.11778G>A and ND6 m.14484T>C. The remaining 10% is associated with >40 secondary variants with variable penetrance and incidence between different ethnic backgrounds. MATERIALS AND METHODS Five sisters underwent an extensive ophthalmic workup including psychophysical, electrophysiological, multimodal brain imaging, biochemical testing and molecular screening. MT-ND6 protein modelling was performed. RESULTS A 23-year-old woman presented with acute central visual loss to counting fingers in the right eye. She developed a central visual field scotoma, severe color vision deficiencies and impaired pattern visual evoked responses. Progressive optic atrophy ensued. The left eye was unremarkable, except for borderline thinning of the temporal retinal nerve fiber layer. Alcohol use and passive smoking were noted. MtDNA analysis revealed a rare variant, m.14502T>C in MT-ND6, exclusively known to cause optic neuropathy in an Asian population. Three sisters of the proband, two of whom reported tobacco and alcohol abuse, had bilateral temporal optic disc pallor without functional impact. A fourth non-smoker sister had a completely normal eye exam. CONCLUSIONS The rare Asian m.14502T>C variant in the MT-ND6 gene was linked to a mild LHON phenotype in a Western European family. Penetrance in this family was likely triggered by alcohol and tobacco abuse. A full mtDNA sequencing is warranted in the case of high clinical suspicion of LHON when mutation analysis for the three common pathogenic variants is negative.
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Affiliation(s)
| | - Mattias Van Heetvelde
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Caroline Van Cauwenbergh
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium.,Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium.,Department of Head & Skin, Ghent University, Ghent, Belgium
| | - Sara Seneca
- Center for Medical Genetics, UZ Brussel, Research Group Reproduction & Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Bart P Leroy
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium.,Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium.,Department of Head & Skin, Ghent University, Ghent, Belgium.,Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Center for Cellular & Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Julie De Zaeytijd
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
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22
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Bai Z, Xie Y, Liu L, Shao J, Liu Y, Kong X. Genetic investigation of 211 Chinese families expands the mutational and phenotypical spectra of hereditary retinopathy genes through targeted sequencing technology. BMC Med Genomics 2021; 14:92. [PMID: 33781268 PMCID: PMC8008643 DOI: 10.1186/s12920-021-00935-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 03/08/2021] [Indexed: 11/15/2022] Open
Abstract
Background Hereditary retinopathy is a significant cause of blindness worldwide. Despite the discovery of many mutations in various retinopathies, a large number of patients remain genetically undiagnosed. Targeted next-generation sequencing of the human genome is a suitable approach for the molecular diagnosis of retinopathy. Methods We describe a cohort of 211 families from central China with various forms of retinopathy; 95 patients were investigated using multigene panel sequencing, and the other 116 with suspected Leber hereditary optic neuropathy (LHON) were tested by Sanger sequencing. The detected variation of targeted sequencing was verified by PCR-based Sanger sequencing. We performed a comprehensive analysis of the cases using sequencing data and ophthalmologic examination information. Results Potential causal mutations were identified in the majority of families with retinopathy (57.9% of 95 families) and suspected LHON (21.6% of 116 families). There were 68 variants of a certain significance distributed in 31 known disease-causing genes in the 95 families; 37 of the variants are novel and have not been reported to be related to hereditary retinopathy. The NGS panel solution provided a 45.3% potential diagnostic rate for retinopathy families, with candidate gene mutations of undefined pathogenicity revealed in another 12.6%of the families. Conclusion Our study uncovered novel mutations and phenotypic aspects of retinopathy and demonstrated the genetic and clinical heterogeneity of related conditions. The findings show the detection rate of pathogenic variants in patients with hereditary retinopathy in central China as well as the diversity and gene distribution of these variants. The significance of molecular genetic testing for patients with hereditary retinopathy is also highlighted. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-021-00935-w.
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Affiliation(s)
- Zhouxian Bai
- The Genetics and Prenatal Diagnosis Center, The Department of Obstetrics and Gynecology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Yanchuan Xie
- The Department of Central Laboratory, The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, 471003, Henan, China
| | - Lina Liu
- The Genetics and Prenatal Diagnosis Center, The Department of Obstetrics and Gynecology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Jingzhi Shao
- The Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Yuying Liu
- The Physical Examination Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Xiangdong Kong
- The Genetics and Prenatal Diagnosis Center, The Department of Obstetrics and Gynecology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China.
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23
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Maresca A, Carelli V. Molecular Mechanisms behind Inherited Neurodegeneration of the Optic Nerve. Biomolecules 2021; 11:496. [PMID: 33806088 PMCID: PMC8064499 DOI: 10.3390/biom11040496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/01/2023] Open
Abstract
Inherited neurodegeneration of the optic nerve is a paradigm in neurology, as many forms of isolated or syndromic optic atrophy are encountered in clinical practice. The retinal ganglion cells originate the axons that form the optic nerve. They are particularly vulnerable to mitochondrial dysfunction, as they present a peculiar cellular architecture, with axons that are not myelinated for a long intra-retinal segment, thus, very energy dependent. The genetic landscape of causative mutations and genes greatly enlarged in the last decade, pointing to common pathways. These mostly imply mitochondrial dysfunction, which leads to a similar outcome in terms of neurodegeneration. We here critically review these pathways, which include (1) complex I-related oxidative phosphorylation (OXPHOS) dysfunction, (2) mitochondrial dynamics, and (3) endoplasmic reticulum-mitochondrial inter-organellar crosstalk. These major pathogenic mechanisms are in turn interconnected and represent the target for therapeutic strategies. Thus, their deep understanding is the basis to set and test new effective therapies, an urgent unmet need for these patients. New tools are now available to capture all interlinked mechanistic intricacies for the pathogenesis of optic nerve neurodegeneration, casting hope for innovative therapies to be rapidly transferred into the clinic and effectively cure inherited optic neuropathies.
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Affiliation(s)
- Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
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24
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Zhou HP, Ishikawa H, Yasumoto R, Sakurai K, Sawamura H. Leber hereditary optic neuropathy harboring a rare m.12811 T>C mitochondrial DNA mutation. Can J Ophthalmol 2021; 56:e82-e84. [PMID: 33493461 DOI: 10.1016/j.jcjo.2020.12.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/16/2020] [Accepted: 12/20/2020] [Indexed: 11/25/2022]
Affiliation(s)
- Han Peng Zhou
- Department of Ophthalmology, The University of Tokyo Hospital, Tokyo, Japan.
| | - Hitoshi Ishikawa
- Department of Ophthalmology, Kitasato University Hospital, Kitazato, Japan
| | - Ryoma Yasumoto
- Department of Clinical Laboratory, Kitasato University Hospital, Kitazato, Japan
| | - Keizo Sakurai
- Department of Clinical Laboratory, Kitasato University Hospital, Kitazato, Japan
| | - Hiromasa Sawamura
- Department of Ophthalmology, The University of Tokyo Hospital, Tokyo, Japan
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25
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Botelho GIS, Salomão SR, Tengan CH, Karanjia R, Moura FV, Rocha DM, da Silva PBE, Fernandes AG, Watanabe SES, Sacai PY, Belfort R, Carelli V, Sadun AA, Berezovsky A. Impaired Ganglion Cell Function Objectively Assessed by the Photopic Negative Response in Affected and Asymptomatic Members From Brazilian Families With Leber's Hereditary Optic Neuropathy. Front Neurol 2021; 11:628014. [PMID: 33584522 PMCID: PMC7874135 DOI: 10.3389/fneur.2020.628014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 12/21/2020] [Indexed: 01/13/2023] Open
Abstract
Purpose: The photopic negative response (PhNR) is an electrophysiological method that provides retinal ganglion cell function assessment using full-field stimulation that does not require clear optics or refractive correction. The purpose of this study was to assess ganglion cell function by PhNR in affected and asymptomatic carriers from Brazilian families with LHON. Methods: Individuals either under suspicion or previously diagnosed with LHON and their family members were invited to participate in this cross-sectional study. Screening for the most frequent LHON mtDNA mutations was performed. Visual acuity, color discrimination, visual fields, pattern-reversal visual evoked potentials (PRVEP), full-field electroretinography and PhNR were tested. A control group of healthy subjects was included. Full-field ERG PhNR were recorded using red (640 nm) flashes at 1 cd.s/m2, on blue (470 nm) rod saturating background. PhNR amplitude (μV) was measured using baseline-to-trough (BT). Optical coherence tomography scans of both the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were measured. PhNR amplitudes among affected, carriers and controls were compared by Kruskal-Wallis test followed by post-hoc Dunn test. The associations between PhNR amplitude and OCT parameters were analyzed by Spearman rank correlation. Results: Participants were 24 LHON affected patients (23 males, mean age=30.5 ± 11.4 yrs) from 19 families with the following genotype: m.11778G>A [N = 15 (62%), 14 males]; m.14484T>C [N = 5 (21%), all males] and m.3460G>A [N = 4 (17%), all males] and 14 carriers [13 females, mean age: 43.2 ± 13.3 yrs; m.11778G>A (N = 11); m.3460G>A (N = 2) and m.14484T>C (N = 1)]. Controls were eight females and seven males (mean age: 32.6 ± 11.5 yrs). PhNR amplitudes were significantly reduced (p = 0.0001) in LHON affected (-5.96 ± 3.37 μV) compared to carriers (-16.53 ± 3.40 μV) and controls (-23.91 ± 4.83; p < 0.0001) and in carriers compared to controls (p = 0.01). A significant negative correlation was found between PhNR amplitude and total macular ganglion cell thickness (r = -0.62, p < 0.05). Severe abnormalities in color discrimination, visual fields and PRVEPs were found in affected and subclinical abnormalities in carriers. Conclusions: In this cohort of Brazilian families with LHON the photopic negative response was severely reduced in affected patients and mildly reduced in asymptomatic carriers suggesting possible subclinical abnormalities in the latter. These findings were similar among pathogenic mutations.
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Affiliation(s)
- Gabriel Izan Santos Botelho
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Solange Rios Salomão
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Célia Harumi Tengan
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Rustum Karanjia
- Doheny Eye Institute, University of California Los Angeles, Los Angeles, CA, United States.,Department of Ophthalmology, Doheny Eye Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.,Ottawa Eye Institute, University of Ottawa, Ottawa, ON, Canada.,Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Felipo Victor Moura
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Daniel Martins Rocha
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula Baptista Eliseo da Silva
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Arthur Gustavo Fernandes
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Sung Eun Song Watanabe
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula Yuri Sacai
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Rubens Belfort
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.,Instituto da Visão-IPEPO, São Paulo, Brazil
| | - Valerio Carelli
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna School of Medicine, Bologna, Italy
| | - Alfredo Arrigo Sadun
- Doheny Eye Institute, University of California Los Angeles, Los Angeles, CA, United States.,Department of Ophthalmology, Doheny Eye Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Adriana Berezovsky
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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Amore G, Romagnoli M, Carbonelli M, Barboni P, Carelli V, La Morgia C. Therapeutic Options in Hereditary Optic Neuropathies. Drugs 2021; 81:57-86. [PMID: 33159657 PMCID: PMC7843467 DOI: 10.1007/s40265-020-01428-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Options for the effective treatment of hereditary optic neuropathies have been a long time coming. The successful launch of the antioxidant idebenone for Leber's Hereditary Optic Neuropathy (LHON), followed by its introduction into clinical practice across Europe, was an important step forward. Nevertheless, other options, especially for a variety of mitochondrial optic neuropathies such as dominant optic atrophy (DOA), are needed, and a number of pharmaceutical agents, acting on different molecular pathways, are currently under development. These include gene therapy, which has reached Phase III development for LHON, but is expected to be developed also for DOA, whilst most of the other agents (other antioxidants, anti-apoptotic drugs, activators of mitobiogenesis, etc.) are almost all at Phase II or at preclinical stage of research. Here, we review proposed target mechanisms, preclinical evidence, available clinical trials with primary endpoints and results, of a wide range of tested molecules, to give an overview of the field, also providing the landscape of future scenarios, including gene therapy, gene editing, and reproductive options to prevent transmission of mitochondrial DNA mutations.
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Affiliation(s)
- Giulia Amore
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Martina Romagnoli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | - Michele Carbonelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | | | - Valerio Carelli
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy.
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27
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Ng WSV, Trigano M, Freeman T, Varrichio C, Kandaswamy DK, Newland B, Brancale A, Rozanowska M, Votruba M. New avenues for therapy in mitochondrial optic neuropathies. THERAPEUTIC ADVANCES IN RARE DISEASE 2021; 2:26330040211029037. [PMID: 37181108 PMCID: PMC10032437 DOI: 10.1177/26330040211029037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/10/2021] [Indexed: 05/16/2023]
Abstract
Mitochondrial optic neuropathies are a group of optic nerve atrophies exemplified by the two commonest conditions in this group, autosomal dominant optic atrophy (ADOA) and Leber's hereditary optic neuropathy (LHON). Their clinical features comprise reduced visual acuity, colour vision deficits, centro-caecal scotomas and optic disc pallor with thinning of the retinal nerve fibre layer. The primary aetiology is genetic, with underlying nuclear or mitochondrial gene mutations. The primary pathology is owing to retinal ganglion cell dysfunction and degeneration. There is currently only one approved treatment and no curative therapy is available. In this review we summarise the genetic and clinical features of ADOA and LHON and then examine what new avenues there may be for therapeutic intervention. The therapeutic strategies to manage LHON and ADOA can be split into four categories: prevention, compensation, replacement and repair. Prevention is technically an option by modifying risk factors such as smoking cessation, or by utilising pre-implantation genetic diagnosis, although this is unlikely to be applied in mitochondrial optic neuropathies due to the non-life threatening and variable nature of these conditions. Compensation involves pharmacological interventions that ameliorate the mitochondrial dysfunction at a cellular and tissue level. Replacement and repair are exciting new emerging areas. Clinical trials, both published and underway, in this area are likely to reveal future potential benefits, since new therapies are desperately needed. Plain language summary Optic nerve damage leading to loss of vision can be caused by a variety of insults. One group of conditions leading to optic nerve damage is caused by defects in genes that are essential for cells to make energy in small organelles called mitochondria. These conditions are known as mitochondrial optic neuropathies and two predominant examples are called autosomal dominant optic atrophy and Leber's hereditary optic neuropathy. Both conditions are caused by problems with the energy powerhouse of cells: mitochondria. The cells that are most vulnerable to this mitochondrial malfunction are called retinal ganglion cells, otherwise collectively known as the optic nerve, and they take the electrical impulse from the retina in the eye to the brain. The malfunction leads to death of some of the optic nerve cells, the degree of vision loss being linked to the number of those cells which are impacted in this way. Patients will lose visual acuity and colour vision and develop a central blind spot in their field of vision. There is currently no cure and very few treatment options. New treatments are desperately needed for patients affected by these devastating diseases. New treatments can potentially arise in four ways: prevention, compensation, replacement and repair of the defects. Here we explore how present and possible future treatments might provide hope for those suffering from these conditions.
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Affiliation(s)
| | - Matthieu Trigano
- Mitochondria and Vision Lab, School of
Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Thomas Freeman
- Mitochondria and Vision Lab, School of
Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Carmine Varrichio
- School of Pharmacy and Pharmaceutical Sciences,
Cardiff University, Cardiff, UK
| | - Dinesh Kumar Kandaswamy
- Mitochondria and Vision Lab, School of
Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Ben Newland
- School of Pharmacy and Pharmaceutical Sciences,
Cardiff University, Cardiff, UK
| | - Andrea Brancale
- School of Pharmacy and Pharmaceutical Sciences,
Cardiff University, Cardiff, UK
| | - Malgorzata Rozanowska
- Mitochondria and Vision Lab, School of
Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Marcela Votruba
- School of Optometry and Vision Sciences,
Cardiff University, Maindy Road, Cardiff, CF24 4HQ, Wales, UK; Cardiff Eye
Unit, University Hospital of Wales, Cardiff, UK
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28
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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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29
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Schon KR, Ratnaike T, van den Ameele J, Horvath R, Chinnery PF. Mitochondrial Diseases: A Diagnostic Revolution. Trends Genet 2020; 36:702-717. [PMID: 32674947 DOI: 10.1016/j.tig.2020.06.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022]
Abstract
Mitochondrial disorders have emerged as a common cause of inherited disease, but are traditionally viewed as being difficult to diagnose clinically, and even more difficult to comprehensively characterize at the molecular level. However, new sequencing approaches, particularly whole-genome sequencing (WGS), have dramatically changed the landscape. The combined analysis of nuclear and mitochondrial DNA (mtDNA) allows rapid diagnosis for the vast majority of patients, but new challenges have emerged. We review recent discoveries that will benefit patients and families, and highlight emerging questions that remain to be resolved.
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Affiliation(s)
- Katherine R Schon
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Thiloka Ratnaike
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Department of Paediatrics, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Jelle van den Ameele
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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30
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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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31
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Mejia-Vergara AJ, Seleme N, Sadun AA, Karanjia R. Pathophysiology of Conversion to Symptomatic Leber Hereditary Optic Neuropathy and Therapeutic Implications: a Review. Curr Neurol Neurosci Rep 2020; 20:11. [DOI: 10.1007/s11910-020-01032-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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32
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An evaluation of genetic causes and environmental risks for bilateral optic atrophy. PLoS One 2019; 14:e0225656. [PMID: 31765440 PMCID: PMC6876833 DOI: 10.1371/journal.pone.0225656] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 11/08/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose To assess the clinical utility of next-generation sequencing (NGS) for the diagnosis of patients with optic atrophy (OA). Design Retrospective cohort study. Methods 97 patients were referred to the McMaster University Medical Center (Hamilton, Ontario) for evaluation of bilateral OA. All patients were sent for NGS including a 22 nuclear gene panel and/or complete mitochondrial DNA (mtDNA) sequencing. Positive genetic test results and abnormal vibration sensation were compared in patients +/- environmental exposures or a family history. Results 19/94 (20.2%) had a positive nuclear variant, of which 15/19 (78.9%) were in the OPA1 gene. No positive mtDNA variants were identified. The detection of a positive genetic variant was significantly different in patients who reported excessive ethanol use, but not in patients who smoke (0/19 (0%) vs. 19/78 (24.4%), P = 0.0164 and 4/22 (18.2%) vs. 15/74 (20.3%), P = 0.829, respectively). Patients with a positive family history were more likely to have a positive genetic variant compared to patients with a negative family history (P = 0.0112). There were significantly more excessive drinkers with an abnormal vibration sensation (P = 0.026), and with a similar trend in smokers (P = 0.074). Conclusions All positive genetic variants were identified in nuclear genes. We identified a potential independent pathophysiological link between a history of excessive ethanol consumption and bilateral OA. Further investigations should evaluate and identify potential environmental risk factors for OA.
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Lyu Y, Xu M, Chen J, Ji Y, Guan MX, Zhang J. Frequency and spectrum of MT-TT variants associated with Leber's hereditary optic neuropathy in a Chinese cohort of subjects. MITOCHONDRIAL DNA PART B-RESOURCES 2019; 4:2266-2280. [PMID: 33365504 PMCID: PMC7687527 DOI: 10.1080/23802359.2019.1627921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Leber’s hereditary optic neuropathy (LHON) is a maternally inherited eye disease. In our previous investigations, we have reported the spectrum and frequency of mitochondrial MT-ND1, MT-ND4 and MT-ND6 gene in Chinese LHON population. This study aimed to assess the molecular epidemiology of MT-TT mutations in Chinese families with LHON. A cohort of 352 Chinese Han probands lacking the known LHON-associated mtDNA mutations and 376 control subjects underwent molecular analysis of mtDNA. All variants were evaluated for evolutionary conservation, structural and functional consequences. Fifteen variants were identified in the MT-TT gene by mitochondrial genome analysis of LHON pedigrees, which was substantially higher than that of individuals from general Chinese populations. The incidences of the two known LHON-associated mutations, m.15927G > A and m.15951A > G, were 2.27% and 1.14%, respectively. Nine putative LHON-associated variants were identified in 20 probands, translated into 2.1% cases of this cohort. Moreover, mtDNAs in 41 probands carrying the MT-TT mutation(s) were widely dispersed among nine Eastern Asian haplogroups. Our results suggest that the MT-TT gene is a mutational hotspot for these 352 Chinese families lacking the known LHON-associated mutations. These data further showed the molecular epidemiology of MT-TT mutations in Chinese Han LHON pedigrees.
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Affiliation(s)
- Yuanyuan Lyu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Man Xu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jie Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - YanChun Ji
- School of Medicine, Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang, China
| | - Min-Xin Guan
- School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China.,School of Medicine, Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang, China
| | - Juanjuan Zhang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
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34
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Chen Z, Zhang F, Xu H. Human mitochondrial DNA diseases and Drosophila models. J Genet Genomics 2019; 46:201-212. [DOI: 10.1016/j.jgg.2019.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/05/2019] [Accepted: 03/25/2019] [Indexed: 01/06/2023]
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35
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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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36
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Strobbe D, Caporali L, Iommarini L, Maresca A, Montopoli M, Martinuzzi A, Achilli A, Olivieri A, Torroni A, Carelli V, Ghelli A. Haplogroup J mitogenomes are the most sensitive to the pesticide rotenone: Relevance for human diseases. Neurobiol Dis 2018; 114:129-139. [PMID: 29486301 DOI: 10.1016/j.nbd.2018.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/30/2018] [Accepted: 02/21/2018] [Indexed: 12/21/2022] Open
Abstract
There is growing evidence that the sequence variation of mitochondrial DNA (mtDNA), which clusters in population- and/or geographic-specific haplogroups, may result in functional effects that, in turn, become relevant in disease predisposition or protection, interaction with environmental factors and ultimately in modulating longevity. To unravel functional differences between mtDNA haplogroups we here employed transmitochondrial cytoplasmic hybrid cells (cybrids) grown in galactose medium, a culture condition that forces oxidative phosphorylation, and in the presence of rotenone, the classic inhibitor of respiratory Complex I. Under this experimental paradigm we assessed functional parameters such as cell viability and respiration, ATP synthesis, reactive oxygen species production and mtDNA copy number. Our analyses show that haplogroup J1, which is common in western Eurasian populations, is the most sensitive to rotenone, whereas K1 mitogenomes orchestrate the best compensation, possibly because of the haplogroup-specific missense variants impinging on Complex I function. Remarkably, haplogroups J1 and K1 fit the genetic associations previously established with Leber's hereditary optic neuropathy (LHON) for J1, as a penetrance enhancer, and with Parkinson's disease (PD) for K1, as a protective background. Our findings provide functional evidences supporting previous well-established genetic associations of specific haplogroups with two neurodegenerative pathologies, LHON and PD. Our experimental paradigm is instrumental to highlighting the subtle functional differences characterizing mtDNA haplogroups, which will be increasingly needed to dissect the role of mtDNA genetic variation in health, disease and longevity.
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Affiliation(s)
- Daniela Strobbe
- Department of Pharmaceutical and Pharmacological Sciences, School of Medicine-University of Padua, Italy
| | | | - Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Bologna, Italy
| | | | - Monica Montopoli
- Department of Pharmaceutical and Pharmacological Sciences, School of Medicine-University of Padua, Italy
| | - Andrea Martinuzzi
- IRCCS "E. Medea" Scientific Institute Conegliano-Pieve di Soligo Research Center, Pieve di Soligo, Italy
| | - Alessandro Achilli
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Anna Olivieri
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Antonio Torroni
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bologna, Italy; Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.
| | - Anna Ghelli
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Bologna, Italy.
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International Consensus Statement on the Clinical and Therapeutic Management of Leber Hereditary Optic Neuropathy. J Neuroophthalmol 2017; 37:371-381. [PMID: 28991104 DOI: 10.1097/wno.0000000000000570] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Leber hereditary optic neuropathy (LHON) is currently estimated as the most frequent mitochondrial disease (1 in 27,000-45,000). Its molecular pathogenesis and natural history is now fairly well understood. LHON also is the first mitochondrial disease for which a treatment has been approved (idebenone-Raxone, Santhera Pharmaceuticals) by the European Medicine Agency, under exceptional circumstances because of the rarity and severity of the disease. However, what remains unclear includes the optimal target population, timing, dose, and frequency of administration of idebenone in LHON due to lack of accepted definitions, criteria, and general guidelines for the clinical management of LHON. To address these issues, a consensus conference with a panel of experts from Europe and North America was held in Milan, Italy, in 2016. The intent was to provide expert consensus statements for the clinical and therapeutic management of LHON based on the currently available evidence. We report the conclusions of this conference, providing the guidelines for clinical and therapeutic management of LHON.
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Joyal JS, Gantner ML, Smith LEH. Retinal energy demands control vascular supply of the retina in development and disease: The role of neuronal lipid and glucose metabolism. Prog Retin Eye Res 2017; 64:131-156. [PMID: 29175509 DOI: 10.1016/j.preteyeres.2017.11.002] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/11/2017] [Accepted: 11/15/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Jean-Sébastien Joyal
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, Qc, Canada; Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc, Canada.
| | - Marin L Gantner
- The Lowy Medical Research Institute, La Jolla, United States
| | - Lois E H Smith
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, 300 Longwood Avenue, Boston MA 02115, United States.
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Abstract
PURPOSE OF REVIEW Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial DNA (mtDNA) genetic disorder in the population. We address the clinical evolution of the disease, the secondary etiological factors that could contribute to visual loss, and the challenging task of developing effective treatments. RECENT FINDINGS LHON is characterized by a preclinical phase that reflects retinal ganglion cell (RGC) dysfunction before rapid visual deterioration ensues. Children can present atypically with slowly progressive visual loss or an insidious/subclinical onset that frequently results in considerable diagnostic delays. The LHON mtDNA mutation is not sufficient on its own to precipitate RGC loss and the current body of evidence supports a role for smoking and estrogen levels influencing disease conversion. Clinical trials are currently investigating the efficacy of adeno-associated viral vectors-based gene therapy approaches for patients carrying the m.11778G>A mutation. Mitochondrial replacement therapy is being developed as a reproductive option to prevent the maternal transmission of pathogenic mtDNA mutations. SUMMARY LHON is phenotypically more heterogeneous than previously considered and a complex interplay of genetic, environmental and hormonal factors modulates the risk of a LHON carrier losing vision. Advances in disease modelling, drug screening and genetic engineering offer promising avenues for therapeutic breakthroughs in LHON.
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40
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Clinical effects of chemical exposures on mitochondrial function. Toxicology 2017; 391:90-99. [PMID: 28757096 DOI: 10.1016/j.tox.2017.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/07/2017] [Accepted: 07/17/2017] [Indexed: 12/16/2022]
Abstract
Mitochondria are critical for the provision of ATP for cellular energy requirements. Tissue and organ functions are dependent on adequate ATP production, especially when energy demand is high. Mitochondria also play a role in a vast array of important biochemical pathways including apoptosis, generation and detoxification of reactive oxygen species, intracellular calcium regulation, steroid hormone and heme synthesis, and lipid metabolism. The complexity of mitochondrial structure and function facilitates its diverse roles but also enhances its vulnerability. Primary disorders of mitochondrial bioenergetics, or Primary Mitochondrial Diseases (PMD) are due to inherited genetic defects in the nuclear or mitochondrial genomes that result in defective oxidative phosphorylation capacity and cellular energy production. Secondary mitochondrial dysfunction is observed in a wide range of diseases such as Alzheimer's and Parkinson's disease. Several lines of evidence suggest that environmental exposures cause substantial mitochondrial dysfunction. Whereby literature from experimental and human studies on exposures associated with Alzheimer's and Parkinson's diseases exist, the significance of exposures as potential triggers in Primary Mitochondrial Disease (PMD) is an emerging clinical question that has not been systematically studied.
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Caporali L, Maresca A, Capristo M, Del Dotto V, Tagliavini F, Valentino ML, La Morgia C, Carelli V. Incomplete penetrance in mitochondrial optic neuropathies. Mitochondrion 2017; 36:130-137. [PMID: 28716668 DOI: 10.1016/j.mito.2017.07.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 06/27/2017] [Accepted: 07/13/2017] [Indexed: 01/06/2023]
Abstract
Incomplete penetrance characterizes the two most frequent inherited optic neuropathies, Leber's Hereditary Optic Neuropathy (LHON) and dominant optic atrophy (DOA), due to genetic errors in the mitochondrial DNA (mtDNA) and the nuclear DNA (nDNA), respectively. For LHON, compelling evidence has accumulated on the complex interplay of mtDNA haplogroups and environmental interacting factors, whereas the nDNA remains essentially non informative. However, a compensatory mechanism of activated mitochondrial biogenesis and increased mtDNA copy number, possibly driven by a permissive nDNA background, is documented in LHON; when successful it maintains unaffected the mutation carriers, but in some individuals it might be hampered by tobacco smoking or other environmental factors, resulting in disease onset. In females, mitochondrial biogenesis is promoted and maintained within the compensatory range by estrogens, partially explaining the gender bias in LHON. Concerning DOA, none of the above mechanisms has been fully explored, thus mtDNA haplogroups, environmental factors such as tobacco and alcohol, and further nDNA variants may all participate as protective factors or, on the contrary, favor disease expression and severity. Next generation sequencing, complemented by transcriptomics and proteomics, may provide some answers in the next future, even if the multifactorial model that seems to apply to incomplete penetrance in mitochondrial optic neuropathies remains problematic, and careful stratification of patients will play a key role for data interpretation. The deep understanding of which factors impinge on incomplete penetrance may shed light on the pathogenic mechanisms leading to optic nerve atrophy, on their possible compensation and, thus, on development of therapeutic strategies.
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Affiliation(s)
- Leonardo Caporali
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Alessandra Maresca
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | | | - Valentina Del Dotto
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Francesca Tagliavini
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Maria Lucia Valentino
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
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42
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Majander A, Bowman R, Poulton J, Antcliff RJ, Reddy MA, Michaelides M, Webster AR, Chinnery PF, Votruba M, Moore AT, Yu-Wai-Man P. Childhood-onset Leber hereditary optic neuropathy. Br J Ophthalmol 2017; 101:1505-1509. [PMID: 28314831 DOI: 10.1136/bjophthalmol-2016-310072] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 01/11/2023]
Abstract
BACKGROUND The onset of Leber hereditary optic neuropathy (LHON) is relatively rare in childhood. This study describes the clinical and molecular genetic features observed in this specific LHON subgroup. METHODS Our retrospective study consisted of a UK paediatric LHON cohort of 27 patients and 69 additional cases identified from a systematic review of the literature. Patients were included if visual loss occurred at the age of 12 years or younger with a confirmed pathogenic mitochondrial DNA mutation: m.3460G>A, m.11778G>A or m.14484T>C. RESULTS In the UK paediatric LHON cohort, three patterns of visual loss and progression were observed: (1) classical acute (17/27, 63%); (2) slowly progressive (4/27, 15%); and (3) insidious or subclinical (6/27, 22%). Diagnostic delays of 3-15 years occurred in children with an insidious mode of onset. Spontaneous visual recovery was more common in patients carrying the m.3460G>A and m.14484T>C mutations compared with the m.11778G>A mutation. Based a meta-analysis of 67 patients with available visual acuity data, 26 (39%) patients achieved a final best-corrected visual acuity (BCVA) ≥0.5 Snellen decimal in at least one eye, whereas 13 (19%) patients had a final BCVA <0.05 in their better seeing eye. CONCLUSIONS Although childhood-onset LHON carries a relatively better visual prognosis, approximately 1 in 5 patients will remain within the visual acuity criteria for legal blindness in the UK. The clinical presentation can be insidious and LHON should be considered in the differential diagnosis when faced with a child with unexplained subnormal vision and optic disc pallor.
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Affiliation(s)
- Anna Majander
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,Department of Ophthalmology, Helsinki University Hospital, and University of Helsinki, Helsinki, Finland
| | | | - Joanna Poulton
- Nuffield Department of Obstetrics & Gynaecology, University of Oxford, Oxford, UK
| | | | | | - Michel Michaelides
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Medical Research Council Mitochondrial Biology Unit, Cambridge, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Marcela Votruba
- School of Optometry and Vision Sciences, Cardiff University and Cardiff Eye Unit, University Hospital Wales, Cardiff, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,Ophthalmology Department, UCSF School of Medicine, San Francisco, California, USA
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,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
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Abstract
The report in 1988 that Leber Hereditary Optic Neuropathy (LHON) was the product of mitochondrial DNA (mtDNA) mutations provided the first demonstration of the clinical relevance of inherited mtDNA variation. From LHON studies, the medical importance was demonstrated for the mtDNA showing its coding for the most important energy genes, its maternal inheritance, its high mutation rate, its presence in hundreds to thousands of copies per cell, its quantitatively segregation of biallelic genotypes during both mitosis and meiosis, its preferential effect on the most energetic tissues including the eye and brain, its wide range of functional polymorphisms that predispose to common diseases, and its accumulation of mutations within somatic tissues providing the aging clock. These features of mtDNA genetics, in combination with the genetics of the 1-2000 nuclear DNA (nDNA) coded mitochondrial genes, is not only explaining the genetics of LHON but also providing a model for understanding the complexity of many common diseases. With the maturation of LHON biology and genetics, novel animal models for complex disease have been developed and new therapeutic targets and strategies envisioned, both pharmacological and genetic. Multiple somatic gene therapy approaches are being developed for LHON which are applicable to other mtDNA diseases. Moreover, the unique cytoplasmic genetics of the mtDNA has permitted the first successful human germline gene therapy via spindle nDNA transfer from mtDNA mutant oocytes to enucleated normal mtDNA oocytes. Such LHON lessons are actively being applied to common ophthalmological diseases like glaucoma and neurological diseases like Parkinsonism.
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Patergnani S, Fossati V, Bonora M, Giorgi C, Marchi S, Missiroli S, Rusielewicz T, Wieckowski MR, Pinton P. Mitochondria in Multiple Sclerosis: Molecular Mechanisms of Pathogenesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 328:49-103. [PMID: 28069137 DOI: 10.1016/bs.ircmb.2016.08.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mitochondria, the organelles that function as the powerhouse of the cell, have been increasingly linked to the pathogenesis of many neurological disorders, including multiple sclerosis (MS). MS is a chronic inflammatory demyelinating disease of the central nervous system (CNS) and a leading cause of neurological disability in young adults in the western world. Its etiology remains unknown, and while the inflammatory component of MS has been heavily investigated and targeted for therapeutic intervention, the failure of remyelination and the process of axonal degeneration are still poorly understood. Recent studies suggest a role of mitochondrial dysfunction in the neurodegenerative aspects of MS. This review is focused on mitochondrial functions under physiological conditions and the consequences of mitochondrial alterations in various CNS disorders. Moreover, we summarize recent findings linking mitochondrial dysfunction to MS and discuss novel therapeutic strategies targeting mitochondria-related pathways as well as emerging experimental approaches for modeling mitochondrial disease.
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Affiliation(s)
- S Patergnani
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - V Fossati
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - M Bonora
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - C Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - S Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - S Missiroli
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - T Rusielewicz
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - M R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - P Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy.
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45
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Giordano L, Deceglie S, d'Adamo P, Valentino ML, La Morgia C, Fracasso F, Roberti M, Cappellari M, Petrosillo G, Ciaravolo S, Parente D, Giordano C, Maresca A, Iommarini L, Del Dotto V, Ghelli AM, Salomao SR, Berezovsky A, Belfort R, Sadun AA, Carelli V, Loguercio Polosa P, Cantatore P. Cigarette toxicity triggers Leber's hereditary optic neuropathy by affecting mtDNA copy number, oxidative phosphorylation and ROS detoxification pathways. Cell Death Dis 2015; 6:e2021. [PMID: 26673666 PMCID: PMC4720897 DOI: 10.1038/cddis.2015.364] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 01/15/2023]
Abstract
Leber's hereditary optic neuropathy (LHON), the most frequent mitochondrial disease, is associated with mitochondrial DNA (mtDNA) point mutations affecting Complex I subunits, usually homoplasmic. This blinding disorder is characterized by incomplete penetrance, possibly related to several genetic modifying factors. We recently reported that increased mitochondrial biogenesis in unaffected mutation carriers is a compensatory mechanism, which reduces penetrance. Also, environmental factors such as cigarette smoking have been implicated as disease triggers. To investigate this issue further, we first assessed the relationship between cigarette smoke and mtDNA copy number in blood cells from large cohorts of LHON families, finding that smoking was significantly associated with the lowest mtDNA content in affected individuals. To unwrap the mechanism of tobacco toxicity in LHON, we exposed fibroblasts from affected individuals, unaffected mutation carriers and controls to cigarette smoke condensate (CSC). CSC decreased mtDNA copy number in all cells; moreover, it caused significant reduction of ATP level only in mutated cells including carriers. This implies that the bioenergetic compensation in carriers is hampered by exposure to smoke derivatives. We also observed that in untreated cells the level of carbonylated proteins was highest in affected individuals, whereas the level of several detoxifying enzymes was highest in carriers. Thus, carriers are particularly successful in reactive oxygen species (ROS) scavenging capacity. After CSC exposure, the amount of detoxifying enzymes increased in all cells, but carbonylated proteins increased only in LHON mutant cells, mostly from affected individuals. All considered, it appears that exposure to smoke derivatives has a more deleterious effect in affected individuals, whereas carriers are the most efficient in mitigating ROS rather than recovering bioenergetics. Therefore, the identification of genetic modifiers that modulate LHON penetrance must take into account also the exposure to environmental triggers such as tobacco smoke.
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MESH Headings
- DNA, Mitochondrial/genetics
- DNA, Mitochondrial/metabolism
- Female
- Humans
- Male
- Optic Atrophy, Hereditary, Leber/etiology
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/metabolism
- Optic Atrophy, Hereditary, Leber/pathology
- Oxidative Phosphorylation
- Reactive Oxygen Species/metabolism
- Smoking/adverse effects
- Smoking/genetics
- Smoking/metabolism
- Smoking/pathology
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Affiliation(s)
- L Giordano
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - S Deceglie
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - P d'Adamo
- Department of Reproductive Sciences, Medical Genetics, Development and Public Health, University of Trieste, Trieste, Italy
- IRCCS-Burlo Garofolo Children Hospital, Trieste, Italy
| | - M L Valentino
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), Neurology Unit, University of Bologna, Bologna, Italy
| | - C La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), Neurology Unit, University of Bologna, Bologna, Italy
| | - F Fracasso
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - M Roberti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - M Cappellari
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - G Petrosillo
- Institute of Biomembranes and Bioenergetics (IBBE) National Research Council (CNR), Bari, Italy
| | - S Ciaravolo
- Vectis s.r.l. Cava dei Tirreni (Salerno), Italy
| | - D Parente
- Vectis s.r.l. Cava dei Tirreni (Salerno), Italy
| | - C Giordano
- Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome, Rome, Italy
| | - A Maresca
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), Neurology Unit, University of Bologna, Bologna, Italy
| | - L Iommarini
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), Neurology Unit, University of Bologna, Bologna, Italy
| | - V Del Dotto
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - A M Ghelli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - S R Salomao
- Department of Ophthalmology, and Visual Sciences, Paulista School of Medicine Federal University of Sao Paulo—UNIFESP, Sao Paulo, Brazil
| | - A Berezovsky
- Department of Ophthalmology, and Visual Sciences, Paulista School of Medicine Federal University of Sao Paulo—UNIFESP, Sao Paulo, Brazil
| | - R Belfort
- Department of Ophthalmology, and Visual Sciences, Paulista School of Medicine Federal University of Sao Paulo—UNIFESP, Sao Paulo, Brazil
| | - A A Sadun
- Doheny Eye Institute, University of California Los Angeles (UCLA), Los Angeles, CA, USA
| | - V Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), Neurology Unit, University of Bologna, Bologna, Italy
| | - P Loguercio Polosa
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - P Cantatore
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
- Institute of Biomembranes and Bioenergetics (IBBE) National Research Council (CNR), Bari, Italy
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Yu-Wai-Man P, Hudson G, Klopstock T, Chinnery PF. Reply: Parsing the differences in affected with LHON: genetic versus environmental triggers of disease conversion. Brain 2015; 139:e18. [PMID: 26657167 DOI: 10.1093/brain/awv340] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Patrick Yu-Wai-Man
- 1 Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK 2 Departments of Neurology and Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - Gavin Hudson
- 1 Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Thomas Klopstock
- 1 Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK 4 German Center for Neurodegenerative Diseases (DZNE), München, Germany 5 Munich Cluster for Systems Neurology (SyNergy), München, Germany
| | - Patrick F Chinnery
- 1 Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK 6 Medical Research Council Mitochondrial Biology Unit, Cambridge, UK 7 Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, UK
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