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Bekerman VP, Berman E, You B, Turbin R, Frohman L. A Novel Mitochondrial Mutation for Lebers Hereditary Optic Neuropathy Presenting With Vitamin B12 Deficiency. J Neuroophthalmol 2023; 43:e136-e138. [PMID: 34417767 DOI: 10.1097/wno.0000000000001391] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Vladislav P Bekerman
- Department of Ophthalmology and Visual Science (VPB, RT, LF), Rutgers-New Jersey Medical School, Newark, New Jersey; Storm Eye Institute (EB), Medical University of South Carolina, Charleston, South Carolina; and Departments of Genetics (BY) and Neurosciences (RT, LF), Rutgers-New Jersey Medical School, Newark, New Jersey
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Sundaramurthy S, SelvaKumar A, Ching J, Dharani V, Sarangapani S, Yu-Wai-Man P. Leber hereditary optic neuropathy-new insights and old challenges. Graefes Arch Clin Exp Ophthalmol 2021; 259:2461-2472. [PMID: 33185731 DOI: 10.1007/s00417-020-04993-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/16/2020] [Accepted: 10/23/2020] [Indexed: 12/20/2022] Open
Abstract
Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial DNA (mtDNA) disorder with the majority of patients harboring one of three primary mtDNA point mutations, namely, m.3460G>A (MTND1), m.11778G>A (MTND4), and m.14484T>C (MTND6). LHON is characterized by bilateral subacute loss of vision due to the preferential loss of retinal ganglion cells (RGCs) within the inner retina, resulting in optic nerve degeneration. This review describes the clinical features associated with mtDNA LHON mutations and recent insights gained into the disease mechanisms contributing to RGC loss in this mitochondrial disorder. Although treatment options remain limited, LHON research has now entered an active translational phase with ongoing clinical trials, including gene therapy to correct the underlying pathogenic mtDNA mutation.
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Affiliation(s)
- Srilekha Sundaramurthy
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India.
| | - Ambika SelvaKumar
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Jared Ching
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Vidhya Dharani
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Sripriya Sarangapani
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India
| | - Patrick Yu-Wai-Man
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
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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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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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Carelli V, d'Adamo P, Valentino ML, La Morgia C, Ross-Cisneros FN, Caporali L, Maresca A, Loguercio Polosa P, Barboni P, De Negri A, Sadun F, Karanjia R, Salomao SR, Berezovsky A, Chicani F, Moraes M, Moraes Filho M, Belfort R, Sadun AA. Parsing the differences in affected with LHON: genetic versus environmental triggers of disease conversion. Brain 2015; 139:e17. [PMID: 26657166 DOI: 10.1093/brain/awv339] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Valerio Carelli
- 1 IRCCS Istituto delle Scienze Neurologiche di Bologna, Bellaria Hospital, Bologna, Italy 2 Neurology Unit, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Pio d'Adamo
- 3 Medical Genetics, Department of Reproductive Sciences, Development and Public Health, University of Trieste, Trieste, Italy 4 IRCCS-Burlo Garofolo Children Hospital, Trieste, Italy
| | - Maria Lucia Valentino
- 1 IRCCS Istituto delle Scienze Neurologiche di Bologna, Bellaria Hospital, Bologna, Italy 2 Neurology Unit, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Chiara La Morgia
- 1 IRCCS Istituto delle Scienze Neurologiche di Bologna, Bellaria Hospital, Bologna, Italy 2 Neurology Unit, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | | | - Leonardo Caporali
- 1 IRCCS Istituto delle Scienze Neurologiche di Bologna, Bellaria Hospital, Bologna, Italy
| | - Alessandra Maresca
- 1 IRCCS Istituto delle Scienze Neurologiche di Bologna, Bellaria Hospital, Bologna, Italy 2 Neurology Unit, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Paola Loguercio Polosa
- 6 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Piero Barboni
- 7 IRCCS Istituto Scientifico San Raffaele, Milan, Italy
| | | | | | - Rustum Karanjia
- 10 Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Solange R Salomao
- 11 Department of Ophthalmology, Federal University of Sao Paulo (UNIFESP) and IPEPO (Instituto da Visão), Sao Paulo, Brazil
| | - Adriana Berezovsky
- 11 Department of Ophthalmology, Federal University of Sao Paulo (UNIFESP) and IPEPO (Instituto da Visão), Sao Paulo, Brazil
| | - Filipe Chicani
- 11 Department of Ophthalmology, Federal University of Sao Paulo (UNIFESP) and IPEPO (Instituto da Visão), Sao Paulo, Brazil
| | | | | | - Rubens Belfort
- 11 Department of Ophthalmology, Federal University of Sao Paulo (UNIFESP) and IPEPO (Instituto da Visão), Sao Paulo, Brazil
| | - Alfredo A Sadun
- 5 Doheny Eye Institute, Los Angeles, CA, USA 10 Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Grzybowski A, Zülsdorff M, Wilhelm H, Tonagel F. Toxic optic neuropathies: an updated review. Acta Ophthalmol 2015; 93:402-410. [PMID: 25159832 DOI: 10.1111/aos.12515] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/03/2014] [Indexed: 01/29/2023]
Abstract
Toxic optic neuropathy (TON) is caused by the damage to the optic nerve through different toxins, including drugs, metals, organic solvents, methanol and carbon dioxide. A similar clinical picture may also be caused by nutritional deficits, including B vitamins, folic acid and proteins with sulphur-containing amino acids. This review summarizes the present knowledge on disease-causing factors, clinical presentation, diagnostics and treatment in TON. It discusses in detail known and hypothesized relations between drugs, including tuberculostatic drugs, antimicrobial agents, antiepileptic drugs, antiarrhythmic drugs, disulfiram, halogenated hydroquinolones, antimetabolites, tamoxifen and phosphodiesterase type 5 inhibitors and optic neuropathy.
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Affiliation(s)
- Andrzej Grzybowski
- Department of Ophthalmology; Poznań City Hospital; Poznań Poland
- Departtment of Ophthalmology; University of Warmia and Mazury; Olsztyn Poland
| | | | - Helmut Wilhelm
- Centre for Ophthalmology; University of Tuebingen; Tuebingen Germany
| | - Felix Tonagel
- Centre for Ophthalmology; University of Tuebingen; Tuebingen Germany
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Paquay S, Benoit V, Wetzburger C, Cordonnier M, Meire F, Charon A, Roland D, Van Coster R, Nassogne MC, Maystadt I. Uncommon Leber "plus" disease associated with mitochondrial mutation m.11778G>A in a premature child. J Child Neurol 2014; 29:NP18-23. [PMID: 23864591 DOI: 10.1177/0883073813492895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 11/16/2022]
Abstract
Leber hereditary optic neuropathy is a well-known mitochondrial disorder that leads to bilateral subacute visual failure. Although visual impairment is often the sole clinical feature, additional and severe neurologic abnormalities also have been documented for this disease. We report on a 13-year-old boy who has presented with severe visual failure since early childhood in a context of prematurity. In the first years of his life, clinical features included delayed psychomotor development and ataxia. The clinical presentation, which was initially attributed to prematurity, worsened thereafter, and the child developed acute neurologic degradation with the typical radiological findings of Leigh syndrome. The mitochondrial DNA point mutation 11778G>A was identified in the ND4 gene. The probable influence of environmental background on clinical expression of Leber optic neuropathy, particularly those of prematurity and oxygen therapy, is discussed in our manuscript.
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Affiliation(s)
- Stéphanie Paquay
- Service de Neurologie Pédiatrique, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Valérie Benoit
- Département de Biologie Moléculaire, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Catherine Wetzburger
- Service de Neurologie Pédiatrique, Centre Hospitalier Universitaire de Charleroi, Charleroi, Belgium
| | - Monique Cordonnier
- Service d'Ophtalmologie, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Françoise Meire
- Service d'Ophtalmologie, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne Charon
- Service de Néonatologie, Grand Hôpital de Charleroi, Charleroi, Belgium
| | - Dominique Roland
- Centre des Maladies Métaboliques, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Rudy Van Coster
- Department of Pediatrics and Medical Genetics, University of Ghent, Ghent, Belgium
| | - Marie-Cécile Nassogne
- Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Isabelle Maystadt
- Centre de Génétique Humaine, Institut de Pathologie et de Génétique, Gosselies, Belgium
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Sadun AA, La Morgia C, Carelli V. Leber’s hereditary optic neuropathy: new quinone therapies change the paradigm. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.12.27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Are we there yet? Is neuro-ophthalmology at the cusp of a paradigm shift? Lessons from leber hereditary optic neuropathy. J Neuroophthalmol 2013; 33:189-97. [PMID: 23681244 DOI: 10.1097/wno.0b013e31829343a0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Pfeiffer ML, Hashemi N, Foroozan R, Lee AG. Late-onset Leber hereditary optic neuropathy. Clin Exp Ophthalmol 2013; 41:690-3. [DOI: 10.1111/ceo.12091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 01/10/2013] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Rod Foroozan
- Department of Ophthalmology; Baylor College of Medicine; Houston
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Abstract
Leber's hereditary optic neuropathy (LHON) is a rare disease primarily affecting the retinal ganglion cells. In most cases patients with LHON develop permanent visual loss with a large central scotoma in the visual field of both eyes. The optic disc becomes partially or completely pale. At the onset of the disease many patients are considered to suffer from an optic neuritis and are treated under the diagnostic and therapeutic regimen of optic neuritis. LHON is mostly only considered when high dose cortisone therapy fails to be effective or the second eye is affected. Thereafter, molecular genetic analysis will prove LHON in these cases. Detailed anamnesis including pedigree analysis in combination with observance of the peripapillary microangiopathic alterations at the fundus will help to speed up the diagnosis of LHON, but even after exact clinical and molecular genetic diagnosis of LHON some aspects of the disease still remain a mystery today.
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Affiliation(s)
- B Leo-Kottler
- Department für Augenheilkunde, Augenklinik, Schleichstr. 12-16, 72076, Tübingen, Deutschland.
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Yu-Wai-Man P, Griffiths PG, Chinnery PF. Mitochondrial optic neuropathies - disease mechanisms and therapeutic strategies. Prog Retin Eye Res 2011; 30:81-114. [PMID: 21112411 PMCID: PMC3081075 DOI: 10.1016/j.preteyeres.2010.11.002] [Citation(s) in RCA: 440] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.
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MESH Headings
- Animals
- DNA, Mitochondrial/genetics
- Disease Models, Animal
- Humans
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Autosomal Dominant/physiopathology
- Optic Atrophy, Autosomal Dominant/therapy
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/pathology
- Phenotype
- Point Mutation
- Retinal Ganglion Cells/pathology
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
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Abstract
The optic disc represents the anterior end of the optic nerve, the most forward extension of the central nervous system (CNS). The optic disc gives a rare glimpse into the CNS. Hence, diseases of the CNS are often manifested on fundus examination. Abnormalities of the optic disc may reflect eye disease (such as glaucoma), problems in development (as in various syndromes), or CNS disease (such as increased intracranial pressure). Each optic nerve is composed of about 1.2 million axons deriving from the retinal ganglion cells of one eye. Optic atrophy is a morphological sequela reflecting the loss of many or all of these axons. Myriad diseases such as hereditary, metabolic, tumor, and increased intracranial pressure can lead to optic atrophy. Some diseases, such as optic disc drusen, intracranial masses, orbital tumors, ischemic optic neuropathies, inflammations, and infiltrations, can produce optic disc edema before leading to optic atrophy. A number of new imaging modalities, such as optical coherence tomography (OCT), quantitate the thickness of the peripapillary retinal nerve fiber layer as an indirect measure of axonal loss or swelling. OCT can therefore be used to quantitate pathology or the response to therapy in various generalized CNS conditions, such as multiple sclerosis.
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Affiliation(s)
- Alfredo A Sadun
- Departments of Ophthalmology and Neurosurgery, Doheny Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
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Tońska K, Kodroń A, Bartnik E. Genotype-phenotype correlations in Leber hereditary optic neuropathy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1119-23. [PMID: 20211598 DOI: 10.1016/j.bbabio.2010.02.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/29/2010] [Accepted: 02/26/2010] [Indexed: 01/09/2023]
Abstract
Leber hereditary optic neuropathy (LHON), acute or subacute vision loss due to retinal ganglion cell death which in the long run leads to optic nerve atrophy is one of the most widely studied maternally inherited diseases caused by mutations in mitochondrial DNA. Although three common mutations, 11778G>A, 14484T>C or 3460G>A are responsible for over 90% of cases and affect genes encoding complex I subunits of the respiratory chain, their influence on bioenergetic properties of the cell is marginal and cannot fully explain the pathology of the disease. The following chain of events was proposed, based on biochemical and anatomical properties of retinal ganglion cells whose axons form the optic nerve: mitochondrial DNA mutations increase reactive oxygen species production in these sensitive cells, leading to caspase-independent apoptosis. As LHON is characterized by low penetrance and sex bias (men are affected about 5 times more frequently than women) the participation of the other factors-genetic and environmental-beside mtDNA mutations was studied. Mitochondrial haplogroups and smoking are some of the factors involved in the complex etiology of this disease.
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MESH Headings
- Apoptosis
- DNA, Mitochondrial/genetics
- Electron Transport Complex I/genetics
- Energy Metabolism
- Female
- Genetic Association Studies
- Humans
- Male
- Models, Biological
- Mutation, Missense
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/metabolism
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/metabolism
- Optic Nerve/pathology
- Penetrance
- Reactive Oxygen Species/metabolism
- Sex Characteristics
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Affiliation(s)
- Katarzyna Tońska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Ul. Pawinskiego 5a, 02-106 Warsaw, Poland
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The background of mitochondrial DNA haplogroup J increases the sensitivity of Leber's hereditary optic neuropathy cells to 2,5-hexanedione toxicity. PLoS One 2009; 4:e7922. [PMID: 19936068 PMCID: PMC2774515 DOI: 10.1371/journal.pone.0007922] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 10/28/2009] [Indexed: 12/21/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally inherited blinding disease due to mitochondrial DNA (mtDNA) point mutations in complex I subunit genes, whose incomplete penetrance has been attributed to both genetic and environmental factors. Indeed, the mtDNA background defined as haplogroup J is known to increase the penetrance of the 11778/ND4 and 14484/ND6 mutations. Recently it was also documented that the professional exposure to n-hexane might act as an exogenous trigger for LHON. Therefore, we here investigate the effect of the n-hexane neurotoxic metabolite 2,5-hexanedione (2,5-HD) on cell viability and mitochondrial function of different cell models (cybrids and fibroblasts) carrying the LHON mutations on different mtDNA haplogroups. The viability of control and LHON cybrids and fibroblasts, whose mtDNAs were completely sequenced, was assessed using the MTT assay. Mitochondrial ATP synthesis rate driven by complex I substrates was determined with the luciferine/luciferase method. Incubation with 2,5-HD caused the maximal loss of viability in control and LHON cells. The toxic effect of this compound was similar in control cells irrespective of the mtDNA background. On the contrary, sensitivity to 2,5-HD induced cell death was greatly increased in LHON cells carrying the 11778/ND4 or the 14484/ND6 mutation on haplogroup J, whereas the 11778/ND4 mutation in association with haplogroups U and H significantly improved cell survival. The 11778/ND4 mutation on haplogroup U was also more resistant to inhibition of complex I dependent ATP synthesis by 2,5-HD. In conclusion, this study shows that mtDNA haplogroups modulate the response of LHON cells to 2,5-HD. In particular, haplogroup J makes cells more sensitive to its toxic effect. This is the first evidence that an mtDNA background plays a role by interacting with an environmental factor and that 2,5-HD may be a risk element for visual loss in LHON. This proof of principle has broad implications for other neurodegenerative disorders such as Parkinson's disease.
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Aggarwal D, Carelli V, Sadun AA. Genotype–phenotype correlations in mitochondrial optic neuropathies. EXPERT REVIEW OF OPHTHALMOLOGY 2009. [DOI: 10.1586/eop.09.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kirkman MA, Yu-Wai-Man P, Korsten A, Leonhardt M, Dimitriadis K, De Coo IF, Klopstock T, Chinnery PF. Gene-environment interactions in Leber hereditary optic neuropathy. ACTA ACUST UNITED AC 2009; 132:2317-26. [PMID: 19525327 PMCID: PMC2732267 DOI: 10.1093/brain/awp158] [Citation(s) in RCA: 233] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) is a genetic disorder primarily due to mutations of mitochondrial DNA (mtDNA). Environmental factors are thought to precipitate the visual failure and explain the marked incomplete penetrance of LHON, but previous small studies have failed to confirm this to be the case. LHON has no treatment, so identifying environmental triggers is the key to disease prevention, whilst potentially revealing new mechanisms amenable to therapeutic manipulation. To address this issue, we conducted a large, multicentre epidemiological study of 196 affected and 206 unaffected carriers from 125 LHON pedigrees known to harbour one of the three primary pathogenic mtDNA mutations: m.3460G>A, m.11778G>A and m.14484T>C. A comprehensive history of exposure to smoking, alcohol and other putative environmental insults was collected using a structured questionnaire. We identified a strong and consistent association between visual loss and smoking, independent of gender and alcohol intake, leading to a clinical penetrance of 93% in men who smoked. There was a trend towards increased visual failure with alcohol, but only with a heavy intake. Based on these findings, asymptomatic carriers of a LHON mtDNA mutation should be strongly advised not to smoke and to moderate their alcohol intake.
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Affiliation(s)
- Matthew Anthony Kirkman
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK
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Yu-Wai-Man P, Griffiths PG, Hudson G, Chinnery PF. Inherited mitochondrial optic neuropathies. J Med Genet 2009; 46:145-58. [PMID: 19001017 PMCID: PMC2643051 DOI: 10.1136/jmg.2007.054270] [Citation(s) in RCA: 287] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 09/08/2008] [Accepted: 10/07/2008] [Indexed: 02/02/2023]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA) are the two most common inherited optic neuropathies and they result in significant visual morbidity among young adults. Both disorders are the result of mitochondrial dysfunction: LHON from primary mitochondrial DNA (mtDNA) mutations affecting the respiratory chain complexes; and the majority of DOA families have mutations in the OPA1 gene, which codes for an inner mitochondrial membrane protein critical for mtDNA maintenance and oxidative phosphorylation. Additional genetic and environmental factors modulate the penetrance of LHON, and the same is likely to be the case for DOA which has a markedly variable clinical phenotype. The selective vulnerability of retinal ganglion cells (RGCs) is a key pathological feature and understanding the fundamental mechanisms that underlie RGC loss in these disorders is a prerequisite for the development of effective therapeutic strategies which are currently limited.
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MESH Headings
- DNA, Mitochondrial
- Female
- GTP Phosphohydrolases/genetics
- Humans
- Male
- Optic Atrophy, Autosomal Dominant/diagnosis
- Optic Atrophy, Autosomal Dominant/epidemiology
- Optic Atrophy, Autosomal Dominant/genetics
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Hereditary, Leber/diagnosis
- Optic Atrophy, Hereditary, Leber/epidemiology
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/pathology
- Point Mutation
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Affiliation(s)
- P Yu-Wai-Man
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - P G Griffiths
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - G Hudson
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - P F Chinnery
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
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