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Lambiri DW, Levin LA. Maculopapillary Bundle Degeneration in Optic Neuropathies. Curr Neurol Neurosci Rep 2024; 24:203-218. [PMID: 38833037 DOI: 10.1007/s11910-024-01343-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2024] [Indexed: 06/06/2024]
Abstract
PURPOSE OF REVIEW Degeneration of the maculopapillary bundle (MPB) is a prominent feature in a spectrum of optic neuropathies. MPB-selective degeneration is seen in specific conditions, such as nutritional and toxic optic neuropathies, Leber hereditary optic neuropathy (LHON), and dominant optic atrophy (DOA). Despite their distinct etiologies and clinical presentations, which encompass variations in age of incidence and monocular or binocular onset, these disorders share a core molecular mechanism: compromised mitochondrial homeostasis. This disruption is characterized by dysfunctions in mitochondrial metabolism, biogenesis, and protein synthesis. This article provides a comprehensive understanding of the MPB's role in optic neuropathies, emphasizing the importance of mitochondrial mechanisms in the pathogenesis of these conditions. RECENT FINDINGS Optical coherence tomography studies have characterized the retinal nerve fiber layer changes accompanying mitochondrial-affiliated optic neuropathies. Selective thinning of the temporal optic nerve head is preceded by thickening in early stages of these disorders which correlates with reductions in macular ganglion cell layer thinning and vascular atrophy. A recently proposed mechanism underpinning the selective atrophy of the MPB involves the positive feedback of reactive oxygen species generation as a common consequence of mitochondrial dysfunction. Additionally, new research has revealed that the MPB can undergo degeneration in the early stages of glaucoma, challenging the historically held belief that this area was not involved in this common optic neuropathy. A variety of anatomical risk factors influence the propensity of glaucomatous MPB degeneration, and cases present distinct patterns of ganglion cell degeneration that are distinct from those observed in mitochondria-associated diseases. This review synthesizes clinical and molecular research on primary MPB disorders, highlighting the commonalities and differences in their pathogenesis. KEY POINTS (BOX) 1. Temporal degeneration of optic nerve fibers accompanied by cecocentral scotoma is a hallmark of maculopapillary bundle (MPB) degeneration. 2. Mechanisms of MPB degeneration commonly implicate mitochondrial dysfunction. 3. Recent research challenges the traditional belief that the MPB is uninvolved in glaucoma by showing degeneration in the early stages of this common optic neuropathy, yet with features distinct from other MPB-selective neuropathies. 4. Reactive oxygen species generation is a mechanism linking mitochondrial mechanisms of MPB-selective optic neuropathies, but in-vivo and in-vitro studies are needed to validate this hypothesis.
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Affiliation(s)
- Darius W Lambiri
- Faculty of Medicine and Health Sciences, McGill University, Montreal, Canada
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada
| | - Leonard A Levin
- Faculty of Medicine and Health Sciences, McGill University, Montreal, Canada.
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada.
- Department of Neurology & Neurosurgery, McGill University, Montreal, Canada.
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Valentin K, Georgi T, Riedl R, Aminfar H, Singer C, Klopstock T, Wedrich A, Schneider M. Idebenone Treatment in Patients with OPA1-Dominant Optic Atrophy: A Prospective Phase 2 Trial. Neuroophthalmology 2023; 47:237-247. [PMID: 38130806 PMCID: PMC10732653 DOI: 10.1080/01658107.2023.2251575] [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: 03/23/2023] [Accepted: 07/31/2023] [Indexed: 12/23/2023] Open
Abstract
The aim of this study was to evaluate the therapeutic effect of idebenone in patients with OPA1-dominant optic atrophy (DOA). Sixteen patients with genetically confirmed OPA1-DOA were treated with 900 mg idebenone daily for 12 months. The primary endpoint was the best recovery/least deterioration of visual acuity. Secondary endpoints were the changes of visual acuity, colour vision, contrast sensitivity, visual field, peripapillary retinal nerve fibre layer thickness (pRNFLT), and visual-related quality of life. For the primary endpoint, a significant increase was observed for the right eye (p = .0027), for the left eye (p = .0111) and for the better-seeing eye (p = .0152). For visual fields, a significant improvement was observed for the left eye between baseline and 9 months (p = .0038). Regarding pRNFLT, a significant decrease was found for the left eye between baseline and 3 months (p = .0413) and between baseline and 6 months (p = .0448). In the visual function questionnaire, a significant improvement was observed in the subscale general vision (p = .0156) and in the composite score (p = .0256). In conclusion, best recovery of visual acuity improved, even though the amount of improvement was small. Furthermore, a maintenance of visual function after 12 months of idebenone intake could be observed as well as a significant improvement in vision-related quality of life.Whether this effect is due to idebenone treatment, the placebo effect, or is explainable by the natural progression of DOA, remains unclear. Trial registration: EU Clinical Trials Register, EudraCT Number: 2019-001493-28.
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Affiliation(s)
| | - Thomas Georgi
- Department of Ophthalmology, Medical University of Graz, Graz, Austria
| | - Regina Riedl
- Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria
| | - Haleh Aminfar
- Department of Ophthalmology, Medical University of Graz, Graz, Austria
| | - Christoph Singer
- Department of Ophthalmology, Medical University of Graz, Graz, Austria
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, Munich, Germany
| | - Andreas Wedrich
- Department of Ophthalmology, Medical University of Graz, Graz, Austria
| | - Mona Schneider
- Department of Ophthalmology, Medical University of Graz, Graz, Austria
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Ju WK, Perkins GA, Kim KY, Bastola T, Choi WY, Choi SH. Glaucomatous optic neuropathy: Mitochondrial dynamics, dysfunction and protection in retinal ganglion cells. Prog Retin Eye Res 2023; 95:101136. [PMID: 36400670 DOI: 10.1016/j.preteyeres.2022.101136] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/04/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022]
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by a slow, progressive, and multifactorial degeneration of retinal ganglion cells (RGCs) and their axons, resulting in vision loss. Despite its high prevalence in individuals 60 years of age and older, the causing factors contributing to glaucoma progression are currently not well characterized. Intraocular pressure (IOP) is the only proven treatable risk factor. However, lowering IOP is insufficient for preventing disease progression. One of the significant interests in glaucoma pathogenesis is understanding the structural and functional impairment of mitochondria in RGCs and their axons and synapses. Glaucomatous risk factors such as IOP elevation, aging, genetic variation, neuroinflammation, neurotrophic factor deprivation, and vascular dysregulation, are potential inducers for mitochondrial dysfunction in glaucoma. Because oxidative phosphorylation stress-mediated mitochondrial dysfunction is associated with structural and functional impairment of mitochondria in glaucomatous RGCs, understanding the underlying mechanisms and relationship between structural and functional alterations in mitochondria would be beneficial to developing mitochondria-related neuroprotection in RGCs and their axons and synapses against glaucomatous neurodegeneration. Here, we review the current studies focusing on mitochondrial dynamics-based structural and functional alterations in the mitochondria of glaucomatous RGCs and therapeutic strategies to protect RGCs against glaucomatous neurodegeneration.
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Affiliation(s)
- Won-Kyu Ju
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Tonking Bastola
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA
| | - Woo-Young Choi
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA; Department of Plastic Surgery, College of Medicine, Chosun University, Gwang-ju, South Korea
| | - Soo-Ho Choi
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
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Swirski S, May O, Ahlers M, Wissinger B, Greschner M, Jüschke C, Neidhardt J. In Vivo Efficacy and Safety Evaluations of Therapeutic Splicing Correction Using U1 snRNA in the Mouse Retina. Cells 2023; 12:cells12060955. [PMID: 36980294 PMCID: PMC10047704 DOI: 10.3390/cells12060955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/14/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Efficacy and safety considerations constitute essential steps during development of in vivo gene therapies. Herein, we evaluated efficacy and safety of splice factor-based treatments to correct mutation-induced splice defects in an Opa1 mutant mouse line. We applied adeno-associated viruses to the retina. The viruses transduced retinal cells with an engineered U1 snRNA splice factor designed to correct the Opa1 splice defect. We found the treatment to be efficient in increasing wild-type Opa1 transcripts. Correspondingly, Opa1 protein levels increased significantly in treated eyes. Measurements of retinal morphology and function did not reveal therapy-related side-effects supporting the short-term safety of the treatment. Alterations of potential off-target genes were not detected. Our data suggest that treatments of splice defects applying engineered U1 snRNAs represent a promising in vivo therapeutic approach. The therapy increased wild-type Opa1 transcripts and protein levels without detectable morphological, functional or genetic side-effects in the mouse eye. The U1 snRNA-based therapy can be tailored to specific disease gene mutations, hence, raising the possibility of a wider applicability of this promising technology towards treatment of different inherited retinal diseases.
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Affiliation(s)
- Sebastian Swirski
- Human Genetics, Department of Human Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Oliver May
- Human Genetics, Department of Human Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Malte Ahlers
- Visual Neuroscience, Department of Neuroscience, Faculty of Medicine and Health Sciences, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Straße 7, 72076 Tübingen, Germany
| | - Martin Greschner
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Straße 7, 72076 Tübingen, Germany
- Research Center Neurosensory Science, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Christoph Jüschke
- Human Genetics, Department of Human Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - John Neidhardt
- Human Genetics, Department of Human Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
- Research Center Neurosensory Science, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
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First Description of Inheritance of a Postzygotic OPA1 Mosaic Variant. Genes (Basel) 2022; 13:genes13030478. [PMID: 35328032 PMCID: PMC8948733 DOI: 10.3390/genes13030478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/08/2022] [Accepted: 03/04/2022] [Indexed: 12/02/2022] Open
Abstract
Optic atrophy 1 (MIM #165500) is caused by pathogenic variants in the gene OPA1 (OPA1 MITOCHONDRIAL DYNAMIN-LIKE GTPase, MIM *605290) and is inherited in an autosomal dominant manner. We describe a 6-year-old male patient with severe early onset manifestation of optic atrophy, whose parents are subjectively asymptomatic. OPA1-sequence analysis revealed the heterozygous missense variant NM_015560.3:c.806C>T, p.(Ser269Phe) in the patient. Segregation analysis of the parents showed that the mother carried a low-grade postzygotic mosaic of this variant, which apparently also involves germline cells. In line with this, ophthalmological investigation of the mother showed subclinical manifestation of optic atrophy 1. This is the first report of an OPA1 postzygotic mosaic that was inherited to offspring.
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Cartes-Saavedra B, Macuada J, Lagos D, Arancibia D, Andrés ME, Yu-Wai-Man P, Hajnóczky G, Eisner V. OPA1 Modulates Mitochondrial Ca 2+ Uptake Through ER-Mitochondria Coupling. Front Cell Dev Biol 2022; 9:774108. [PMID: 35047497 PMCID: PMC8762365 DOI: 10.3389/fcell.2021.774108] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
Autosomal Dominant Optic Atrophy (ADOA), a disease that causes blindness and other neurological disorders, is linked to OPA1 mutations. OPA1, dependent on its GTPase and GED domains, governs inner mitochondrial membrane (IMM) fusion and cristae organization, which are central to oxidative metabolism. Mitochondrial dynamics and IMM organization have also been implicated in Ca2+ homeostasis and signaling but the specific involvements of OPA1 in Ca2+ dynamics remain to be established. Here we studied the possible outcomes of OPA1 and its ADOA-linked mutations in Ca2+ homeostasis using rescue and overexpression strategies in Opa1-deficient and wild-type murine embryonic fibroblasts (MEFs), respectively and in human ADOA-derived fibroblasts. MEFs lacking Opa1 required less Ca2+ mobilization from the endoplasmic reticulum (ER) to induce a mitochondrial matrix [Ca2+] rise ([Ca2+]mito). This was associated with closer ER-mitochondria contacts and no significant changes in the mitochondrial calcium uniporter complex. Patient cells carrying OPA1 GTPase or GED domain mutations also exhibited altered Ca2+ homeostasis, and the mutations associated with lower OPA1 levels displayed closer ER-mitochondria gaps. Furthermore, in Opa1 -/- MEF background, we found that acute expression of OPA1 GTPase mutants but no GED mutants, partially restored cytosolic [Ca2+] ([Ca2+]cyto) needed for a prompt [Ca2+]mito rise. Finally, OPA1 mutants' overexpression in WT MEFs disrupted Ca2+ homeostasis, partially recapitulating the observations in ADOA patient cells. Thus, OPA1 modulates functional ER-mitochondria coupling likely through the OPA1 GED domain in Opa1 -/- MEFs. However, the co-existence of WT and mutant forms of OPA1 in patients promotes an imbalance of Ca2+ homeostasis without a domain-specific effect, likely contributing to the overall ADOA progress.
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Affiliation(s)
- Benjamín Cartes-Saavedra
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Josefa Macuada
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniel Lagos
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Duxan Arancibia
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María E. Andrés
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Verónica Eisner
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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7
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Red Light Irradiation In Vivo Upregulates DJ-1 in the Retinal Ganglion Cell Layer and Protects against Axotomy-Related Dendritic Pruning. Int J Mol Sci 2021; 22:ijms22168380. [PMID: 34445085 PMCID: PMC8395066 DOI: 10.3390/ijms22168380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 07/30/2021] [Accepted: 07/30/2021] [Indexed: 12/26/2022] Open
Abstract
Retinal ganglion cells (RGCs) undergo dendritic pruning in a variety of neurodegenerative diseases, including glaucoma and autosomal dominant optic atrophy (ADOA). Axotomising RGCs by severing the optic nerve generates an acute model of RGC dendropathy, which can be utilized to assess the therapeutic potential of treatments for RGC degeneration. Photobiomodulation (PBM) with red light provided neuroprotection to RGCs when administered ex vivo to wild-type retinal explants. In the current study, we used aged (13–15-month-old) wild-type and heterozygous B6;C3-Opa1Q285STOP (Opa1+/−) mice, a model of ADOA exhibiting RGC dendropathy. These mice were pre-treated with 4 J/cm2 of 670 nm light for five consecutive days before the eyes were enucleated and the retinas flat-mounted into explant cultures for 0-, 8- or 16-h ex vivo. RGCs were imaged by confocal microscopy, and their dendritic architecture was quantified by Sholl analysis. In vivo 670 nm light pretreatment inhibited the RGC dendropathy observed in untreated wild-type retinas over 16 h ex vivo and inhibited dendropathy in ON-center RGCs in wild-type but not Opa1+/− retinas. Immunohistochemistry revealed that aged Opa1+/− RGCs exhibited increased nitrosative damage alongside significantly lower activation of NF-κB and upregulation of DJ-1. PBM restored NF-κB activation in Opa1+/− RGCs and enhanced DJ-1 expression in both genotypes, indicating a potential molecular mechanism priming the retina to resist future oxidative insult. These data support the potential of PBM as a treatment for diseases involving RGC degeneration.
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Weisschuh N, Schimpf-Linzenbold S, Mazzola P, Kieninger S, Xiao T, Kellner U, Neuhann T, Kelbsch C, Tonagel F, Wilhelm H, Kohl S, Wissinger B. Mutation spectrum of the OPA1 gene in a large cohort of patients with suspected dominant optic atrophy: Identification and classification of 48 novel variants. PLoS One 2021; 16:e0253987. [PMID: 34242285 PMCID: PMC8270428 DOI: 10.1371/journal.pone.0253987] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022] Open
Abstract
Autosomal dominant optic atrophy is one of the most common inherited optic neuropathies. This disease is genetically heterogeneous, but most cases are due to pathogenic variants in the OPA1 gene: depending on the population studied, 32–90% of cases harbor pathogenic variants in this gene. The aim of this study was to provide a comprehensive overview of the entire spectrum of likely pathogenic variants in the OPA1 gene in a large cohort of patients. Over a period of 20 years, 755 unrelated probands with a diagnosis of bilateral optic atrophy were referred to our laboratory for molecular genetic investigation. Genetic testing of the OPA1 gene was initially performed by a combined analysis using either single-strand conformation polymorphism or denaturing high performance liquid chromatography followed by Sanger sequencing to validate aberrant bands or melting profiles. The presence of copy number variations was assessed using multiplex ligation-dependent probe amplification. Since 2012, genetic testing was based on next-generation sequencing platforms. Genetic screening of the OPA1 gene revealed putatively pathogenic variants in 278 unrelated probands which represent 36.8% of the entire cohort. A total of 156 unique variants were identified, 78% of which can be considered null alleles. Variant c.2708_2711del/p.(V903Gfs*3) was found to constitute 14% of all disease-causing alleles. Special emphasis was placed on the validation of splice variants either by analyzing cDNA derived from patients´ blood samples or by heterologous splice assays using minigenes. Splicing analysis revealed different aberrant splicing events, including exon skipping, activation of exonic or intronic cryptic splice sites, and the inclusion of pseudoexons. Forty-eight variants that we identified were novel. Nine of them were classified as pathogenic, 34 as likely pathogenic and five as variant of uncertain significance. Our study adds a significant number of novel variants to the mutation spectrum of the OPA1 gene and will thereby facilitate genetic diagnostics of patients with suspected dominant optic atrophy.
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Affiliation(s)
- Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Simone Schimpf-Linzenbold
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.,CeGaT GmbH and Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Pascale Mazzola
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Sinja Kieninger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ting Xiao
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ulrich Kellner
- Zentrum für seltene Netzhauterkrankungen, AugenZentrum Siegburg, MVZ Augenärztliches Diagnostik- und Therapiecentrum Siegburg GmbH, Siegburg, Germany.,RetinaScience, Bonn, Germany
| | | | - Carina Kelbsch
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Felix Tonagel
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Helmut Wilhelm
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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Senthil S, Nakka M, Sachdeva V, Goyal S, Sahoo N, Choudhari N. Glaucoma Mimickers: A major review of causes, diagnostic evaluation, and recommendations. Semin Ophthalmol 2021; 36:692-712. [PMID: 33689583 DOI: 10.1080/08820538.2021.1897855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Background: Glaucoma is characterized by chronic progressive optic neuropathy with corresponding visual field changes, with or without raised intraocular pressure (IOP). When diagnosing glaucoma or monitoring its progression, the examiner has to rely on the appearance of the optic disc, characteristic retinal nerve fiber layer defects, and corresponding visual field defects. However, similar changes and symptoms may be observed in several other disorders of the optic nerve and retina that may mimic glaucoma, often leading to misdiagnosis. Methods and result: The consequences of misdiagnosis not only result in improper treatment that may impact vision but also would negatively affect the overall health, psychological well-being of the patient, and may have considerable economic implications.Conclusion: The current review describes various conditions that mimic glaucoma and the features that help differentiate these conditions from glaucoma.
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Affiliation(s)
- Sirisha Senthil
- VST Glaucoma Center, L V Prasad Eye Institute, Hyderabad, India
| | - Mamata Nakka
- VST Glaucoma Center, L V Prasad Eye Institute, Hyderabad, India
| | - Virender Sachdeva
- Nimmagada Prasad Children's Eye Care Centre, GMRV Campus, L V Prasad Eye Institute, Visakhapatnam, India
| | - Shaveta Goyal
- VST Glaucoma Center, L V Prasad Eye Institute, Hyderabad, India
| | - Nibedita Sahoo
- MTC Campus, L V Prasad Eye Institute, Bhubaneswar, India
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Charif M, Gueguen N, Ferré M, Elkarhat Z, Khiati S, LeMao M, Chevrollier A, Desquiret-Dumas V, Goudenège D, Bris C, Kane S, Alban J, Chupin S, Wetterwald C, Caporali L, Tagliavini F, LaMorgia C, Carbonelli M, Jurkute N, Barakat A, Gohier P, Verny C, Barth M, Procaccio V, Bonneau D, Zanlonghi X, Meunier I, Weisschuh N, Schimpf-Linzenbold S, Tonagel F, Kellner U, Yu-Wai-Man P, Carelli V, Wissinger B, Amati-Bonneau P, Reynier P, Lenaers G. Dominant ACO2 mutations are a frequent cause of isolated optic atrophy. Brain Commun 2021; 3:fcab063. [PMID: 34056600 PMCID: PMC8152918 DOI: 10.1093/braincomms/fcab063] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/24/2022] Open
Abstract
Biallelic mutations in ACO2, encoding the mitochondrial aconitase 2, have been identified in individuals with neurodegenerative syndromes, including infantile cerebellar retinal degeneration and recessive optic neuropathies (locus OPA9). By screening European cohorts of individuals with genetically unsolved inherited optic neuropathies, we identified 61 cases harbouring variants in ACO2, among whom 50 carried dominant mutations, emphasizing for the first time the important contribution of ACO2 monoallelic pathogenic variants to dominant optic atrophy. Analysis of the ophthalmological and clinical data revealed that recessive cases are affected more severely than dominant cases, while not significantly earlier. In addition, 27% of the recessive cases and 11% of the dominant cases manifested with extraocular features in addition to optic atrophy. In silico analyses of ACO2 variants predicted their deleterious impacts on ACO2 biophysical properties. Skin derived fibroblasts from patients harbouring dominant and recessive ACO2 mutations revealed a reduction of ACO2 abundance and enzymatic activity, and the impairment of the mitochondrial respiration using citrate and pyruvate as substrates, while the addition of other Krebs cycle intermediates restored a normal respiration, suggesting a possible short-cut adaptation of the tricarboxylic citric acid cycle. Analysis of the mitochondrial genome abundance disclosed a significant reduction of the mitochondrial DNA amount in all ACO2 fibroblasts. Overall, our data position ACO2 as the third most frequently mutated gene in autosomal inherited optic neuropathies, after OPA1 and WFS1, and emphasize the crucial involvement of the first steps of the Krebs cycle in the maintenance and survival of retinal ganglion cells.
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Affiliation(s)
- Majida Charif
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Naïg Gueguen
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Marc Ferré
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Zouhair Elkarhat
- Laboratory of Genomics and Human Genetics, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Salim Khiati
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Morgane LeMao
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Arnaud Chevrollier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Valerie Desquiret-Dumas
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - David Goudenège
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Céline Bris
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Selma Kane
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Jennifer Alban
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Stéphanie Chupin
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Leonardo Caporali
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Francesca Tagliavini
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Chiara LaMorgia
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Michele Carbonelli
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Neringa Jurkute
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Abdelhamid Barakat
- Laboratory of Genomics and Human Genetics, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Philippe Gohier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Christophe Verny
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Centre de référence des Maladies Neurogénétiques, Département de Neurologie, CHU d’Angers, Angers, France
| | - Magalie Barth
- Department of Pediatrics, Competence Center of Inherited Metabolic Disorders, Angers Hospital, Angers, France
| | - Vincent Procaccio
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Dominique Bonneau
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Isabelle Meunier
- National Center for Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | | | - Felix Tonagel
- Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ulrich Kellner
- Rare Retinal Disease Center, AugenZentrum Siegburg, MVZ ADTC Siegburg GmbH, Siegburg, Germany
- RetinaScience, 53113 Bonn, Germany
| | - Patrick Yu-Wai-Man
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Valerio Carelli
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Patrizia Amati-Bonneau
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Pascal Reynier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Guy Lenaers
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Correspondence to: Guy Lenaers MitoLab Team, Mitochondrial Medicine Research Centre, MitoVasc Unit, Université d'Angers UMR CNRS 6015, INSERM U1083, CHU Bât IRIS/IBS, Rue des Capucins 49933 Angers cedex 9, France E-mail:
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11
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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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12
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Jones PR. An Open-source Static Threshold Perimetry Test Using Remote Eye-tracking (Eyecatcher): Description, Validation, and Preliminary Normative Data. Transl Vis Sci Technol 2020; 9:18. [PMID: 32855865 PMCID: PMC7422828 DOI: 10.1167/tvst.9.8.18] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 05/12/2020] [Indexed: 01/06/2023] Open
Abstract
Purpose To describe, validate, and provide preliminary normative data for an open-source eye-movement perimeter (Eyecatcher). Methods Visual field testing was performed monocularly in 64 normally sighted young adults, using (i) a Humphrey Field Analyzer (HFA) and (ii) the novel Eyecatcher procedure. Eyecatcher used a remote eye-tracker to position stimuli relative to the current point of fixation, and observers responded by looking towards the stimulus. In both tests, Goldman III stimuli were sampled from a 24-2 grid, and were presented against a 10 cd/m2 background. Participants completed each test twice to assess test–retest repeatability. Results Mean Sensitivity (MS) did not differ between Eyecatcher and the HFA (P = 0.086), and both tests exhibited similar test–retest repeatability (CoREyecatcher = ±1.86 dB; CoRHFA = ±1.95 dB). Eyecatcher was also able to detect changes in sensitivity across the normal visual field (the “Hill of Vision”), and could differentiate the physiological blind spot from adjacent retinal locations. Mean sensitivities and 95% limits of agreement are described for each pointwise location. Conclusions Eyecatcher can use eye movements to assess visual fields in young, normally sighted adults. In such observers, it provides results similar to the current gold standard clinical device (HFA). Translational Relevance Given further development, eye movement perimeters such as Eyecatcher could be particularly useful for individuals unable to perform traditional perimetric assessments, such as young children or stroke patients. Full technical details and information on how to freely acquire the source code are included.
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Affiliation(s)
- Pete R Jones
- University College London (UCL), Institute of Ophthalmology, London, UK.,NIHR Moorfields Biomedical Research Centre, London, London, UK.,City, University of London, School of Health Sciences, Division of Optometry and Visual Sciences, London, UK
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13
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Romagnoli M, La Morgia C, Carbonelli M, Di Vito L, Amore G, Zenesini C, Cascavilla ML, Barboni P, Carelli V. Idebenone increases chance of stabilization/recovery of visual acuity in OPA1-dominant optic atrophy. Ann Clin Transl Neurol 2020; 7:590-594. [PMID: 32243103 PMCID: PMC7187718 DOI: 10.1002/acn3.51026] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/18/2020] [Accepted: 03/03/2020] [Indexed: 12/22/2022] Open
Abstract
We previously documented that idebenone treatment in OPA1‐Dominant Optic Atrophy (OPA1‐DOA) led to some degrees of visual improvement in seven patients. We here present the results of a cohort study, which investigated the effect of off‐label idebenone administration in a larger OPA1‐DOA group compared with untreated patients. Inclusion criteria were: OPA1‐DOA clinical and molecular diagnosis, baseline visual acuity (VA) greater than/equal to counting fingers and treatment duration greater than 7 months. We found a significant difference between the last visit and baseline VA in favor of stabilization/recovery in idebenone‐treated as compared to untreated patients. This effect was retained after controlling for confounders.
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Affiliation(s)
- Martina Romagnoli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Michele Carbonelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy
| | - Lidia Di Vito
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy
| | - Giulia Amore
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Corrado Zenesini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy
| | | | - Piero Barboni
- IRCCS Ospedale San Raffaele, Milan, Italy.,Studio Oculistico d'Azeglio, Bologna, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Ospedale Bellaria, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
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14
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Calcium mishandling in absence of primary mitochondrial dysfunction drives cellular pathology in Wolfram Syndrome. Sci Rep 2020; 10:4785. [PMID: 32179840 PMCID: PMC7075867 DOI: 10.1038/s41598-020-61735-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 02/18/2020] [Indexed: 02/06/2023] Open
Abstract
Wolfram syndrome (WS) is a recessive multisystem disorder defined by the association of diabetes mellitus and optic atrophy, reminiscent of mitochondrial diseases. The role played by mitochondria remains elusive, with contradictory results on the occurrence of mitochondrial dysfunction. We evaluated 13 recessive WS patients by deep clinical phenotyping, including optical coherence tomography (OCT), serum lactic acid at rest and after standardized exercise, brain Magnetic Resonance Imaging, and brain and muscle Magnetic Resonance Spectroscopy (MRS). Finally, we investigated mitochondrial bioenergetics, network morphology, and calcium handling in patient-derived fibroblasts. Our results do not support a primary mitochondrial dysfunction in WS patients, as suggested by MRS studies, OCT pattern of retinal nerve fiber layer loss, and, in fibroblasts, by mitochondrial bioenergetics and network morphology results. However, we clearly found calcium mishandling between endoplasmic reticulum (ER) and mitochondria, which, under specific metabolic conditions of increased energy requirements and in selected tissue or cell types, may turn into a secondary mitochondrial dysfunction. Critically, we showed that Wolframin (WFS1) protein is enriched at mitochondrial-associated ER membranes and that in patient-derived fibroblasts WFS1 protein is completely absent. These findings support a loss-of-function pathogenic mechanism for missense mutations in WFS1, ultimately leading to defective calcium influx within mitochondria.
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15
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Mitochondrial fission and fusion: A dynamic role in aging and potential target for age-related disease. Mech Ageing Dev 2020; 186:111212. [PMID: 32017944 DOI: 10.1016/j.mad.2020.111212] [Citation(s) in RCA: 158] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/16/2020] [Accepted: 01/29/2020] [Indexed: 12/26/2022]
Abstract
The mitochondria is the major hub to convert energy for cellular processes. Dysregulation of mitochondrial function is one of the classical hallmarks of aging, and mitochondrial interventions have repeatedly been shown to improve outcomes in age-related diseases. Crucial to mitochondrial regulation is the dynamic nature of their network structure. Mitochondria separate and merge using fission and fusion processes in response to changes in energy and stress status. While many mitochondrial processes are already characterized in relation to aging, specific evidence in multicellular organisms causally linking mitochondrial dynamics to the regulation of lifespan is limited. There does exist, however, a large body of evidence connecting mitochondrial dynamics to other aging-related cellular processes and implicates them in a number of human diseases. Here, we discuss the mechanisms of mitochondrial fission and fusion, the current evidence of their role in aging of multicellular organisms, and how these connect to cell cycle regulation, quality control, and transmission of energy status. Finally, we discuss the current evidence implicating these processes in age-related human pathologies, such as neurodegenerative or cardio-metabolic diseases. We suggest that deeper understanding of the regulatory mechanisms within this system and downstream implications could benefit in understanding and intervention of these conditions.
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16
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Sheremet NL, Andreeva NA, Shmel'kova MS, Tsigankova PG. [Mitochondrial biogenesis in hereditary optic neuropathies]. Vestn Oftalmol 2019; 135:85-91. [PMID: 31714518 DOI: 10.17116/oftalma201913505185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The article offers a review of mitochondrial biogenesis in hereditary optic neuropathies. It covers the mechanisms of mitochondrial biogenesis, factors affecting it and tools for mitochondrial turnover assessment.
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Affiliation(s)
- N L Sheremet
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - N A Andreeva
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - M S Shmel'kova
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - P G Tsigankova
- Research Centre for Medical Genetics, 1 Moskvorech'e St., Moscow, Russian Federation, 115522
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17
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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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Kim S, Bae HW, Park CK, Lee K, Lee SY, Seong GJ, Kim CY. Nomogram Using Optical Coherence Tomography and Visual Field Parameters to Predict Brain Lesions in Patients with Bitemporal Hemianopia. Curr Eye Res 2018; 44:89-95. [DOI: 10.1080/02713683.2018.1518460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Sangah Kim
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Hyoung Won Bae
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Chan Keum Park
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Kwanghyun Lee
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Sang Yeop Lee
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Gong Je Seong
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Chan Yun Kim
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
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19
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Pretegiani E, Rosini F, Rufa A, Gallus G, Cardaioli E, Da Pozzo P, Bianchi S, Serchi V, Collura M, Franceschini R, Bianchi Marzoli S, Dotti M, Federico A. Genotype-phenotype and OCT correlations in Autosomal Dominant Optic Atrophy related to OPA1 gene mutations: Report of 13 Italian families. J Neurol Sci 2017; 382:29-35. [DOI: 10.1016/j.jns.2017.09.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/09/2017] [Accepted: 09/12/2017] [Indexed: 10/18/2022]
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20
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Finsterer J, Mancuso M, Pareyson D, Burgunder JM, Klopstock T. Mitochondrial disorders of the retinal ganglion cells and the optic nerve. Mitochondrion 2017; 42:1-10. [PMID: 29054473 DOI: 10.1016/j.mito.2017.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 10/02/2017] [Accepted: 10/06/2017] [Indexed: 12/13/2022]
Abstract
OBJECTIVES To summarise and discuss recent findings and future perspectives concerning mitochondrial disorders (MIDs) affecting the retinal ganglion cells and the optic nerve (mitochondrial optic neuropathy. MON). METHOD Literature review. RESULTS MON in MIDs is more frequent than usually anticipated. MON may occur in specific as well as non-specific MIDs. In specific and non-specific MIDs, MON may be a prominent or non-prominent phenotypic feature and due to mutations in genes located either in the mitochondrial DNA (mtDNA) or the nuclear DNA (nDNA). Clinically, MON manifests with painless, bilateral or unilateral, slowly or rapidly progressive visual impairment and visual field defects. In some cases, visual impairment may spontaneously recover. The most frequent MIDs with MON include LHON due to mutations in mtDNA-located genes and autosomal dominant optic atrophy (ADOA) or autosomal recessive optic atrophy (AROA) due to mutations in nuclear genes. Instrumental investigations for diagnosing MON include fundoscopy, measurement of visual acuity, visual fields, and color vision, visually-evoked potentials, optical coherence tomography, fluorescein angiography, electroretinography, and MRI of the orbita and cerebrum. In non-prominent MON, work-up of the muscle biopsy with transmission electron microscopy may indicate mitochondrial destruction. Treatment is mostly supportive but idebenone has been approved for LHON and experimental approaches are promising. CONCLUSIONS MON needs to be appreciated, requires extensive diagnostic work-up, and supportive treatment should be applied although loss of vision, as the most severe outcome, can often not be prevented.
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Affiliation(s)
| | - Michelangelo Mancuso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - Davide Pareyson
- Department of Clinical Neurosciences, C. Besta Neurological Institute, IRCCS Foundation, Milan, Italy.
| | - Jean-Marc Burgunder
- Department of Neurology, University of Bern, Switzerland; Department of Neurology, Sun Yat Sen University, Guangzhou, China; Department of Neurology, Sichuan University, Chendgu, China.
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur Institute, Ludwig-Maximilians-Universität München, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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21
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Geidel K, Wiedemann P, Unterlauft JD. Differenzialdiagnose juveniles Normaldruckglaukom. Ophthalmologe 2017; 114:828-831. [DOI: 10.1007/s00347-016-0407-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Liskova P, Tesarova M, Dudakova L, Svecova S, Kolarova H, Honzik T, Seto S, Votruba M. OPA1 analysis in an international series of probands with bilateral optic atrophy. Acta Ophthalmol 2017; 95:363-369. [PMID: 27860320 DOI: 10.1111/aos.13285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/02/2016] [Indexed: 01/16/2023]
Abstract
PURPOSE To determine the molecular genetic cause in previously unreported probands with optic atrophy from the United Kingdom, Czech Republic and Canada. METHODS OPA1 coding regions and flanking intronic sequences were screened by direct sequencing in 82 probands referred with a diagnosis of bilateral optic atrophy. Detected rare variants were assessed for pathogenicity by in silico analysis. Segregation of the identified variants was performed in available first degree relatives. RESULTS A total of 29 heterozygous mutations evaluated as pathogenic were identified in 42 probands, of these seven were novel. In two probands, only variants of unknown significance were found. 76% of pathogenic mutations observed in 30 (71%) of 42 probands were evaluated to lead to unstable transcripts resulting in haploinsufficiency. Three probands with the following disease-causing mutations c.1230+1G>A, c.1367G>A and c.2965dup were documented to suffer from hearing loss and/or neurological impairment. CONCLUSIONS OPA1 gene screening in patients with bilateral optic atrophy is an important part of clinical evaluation as it may establish correct clinical diagnosis. Our study expands the spectrum of OPA1 mutations causing dominant optic atrophy and supports the fact that haploinsufficiency is the most common disease mechanism.
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Affiliation(s)
- Petra Liskova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
- Department of Ophthalmology; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Marketa Tesarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Lubica Dudakova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Stepanka Svecova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Hana Kolarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Tomas Honzik
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Sharon Seto
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
| | - Marcela Votruba
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
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Characterization of two novel intronic OPA1 mutations resulting in aberrant pre-mRNA splicing. BMC MEDICAL GENETICS 2017; 18:22. [PMID: 28245802 PMCID: PMC5331656 DOI: 10.1186/s12881-017-0383-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/17/2017] [Indexed: 12/24/2022]
Abstract
BACKGROUND We report two novel splice region mutations in OPA1 in two unrelated families presenting with autosomal-dominant optic atrophy type 1 (ADOA1) (ADOA or Kjer type optic atrophy). Mutations in OPA1 encoding a mitochondrial inner membrane protein are a major cause of ADOA. METHODS We analyzed two unrelated families including four affected individuals clinically suspicious of ADOA. Standard ocular examinations were performed in affected individuals of both families. All coding exons, as well as exon-intron boundaries of the OPA1 gene were sequenced. In addition, multiplex ligation-dependent probe amplification (MLPA) was performed to uncover copy number variations in OPA1. mRNA processing was monitored using RT-PCR and subsequent cDNA analysis. RESULTS We report two novel splice region mutations in OPA1 in two unrelated individuals and their affected relatives, which were previously not described in the literature. In one family the heterozygous insertion and deletion c.[611-37_611-38insACTGGAGAATGTAAAGGGCTTT;611-6_611-16delCATATTTATCT] was found in all investigated family members leading to the activation of an intronic cryptic splice site. In the second family sequencing of OPA1 disclosed a de novo heterozygous deletion c.2012+4_2012+7delAGTA resulting in exon 18 and 19 skipping, which was not detected in healthy family members. CONCLUSION We identified two novel intronic mutations in OPA1 affecting the correct OPA1 pre-mRNA splicing, which was confirmed by OPA1 cDNA analysis. This study shows the importance of transcript analysis to determine the consequences of unclear intronic mutations in OPA1 in proximity to the intron-exon boundaries.
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Genetic and Clinical Analyses of DOA and LHON in 304 Chinese Patients with Suspected Childhood-Onset Hereditary Optic Neuropathy. PLoS One 2017; 12:e0170090. [PMID: 28081242 PMCID: PMC5230780 DOI: 10.1371/journal.pone.0170090] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/28/2016] [Indexed: 02/08/2023] Open
Abstract
Leber hereditary optic neuropathy (LHON) and dominant optic atrophy (DOA), the most common forms of hereditary optic neuropathy, are easily confused, and it is difficult to distinguish one from the other in the clinic, especially in young children. The present study was designed to survey the mutation spectrum of common pathogenic genes (OPA1, OPA3 and mtDNA genes) and to analyze the genotype-phenotype characteristics of Chinese patients with suspected childhood-onset hereditary optic neuropathy. Genomic DNA and clinical data were collected from 304 unrelated Chinese probands with suspected hereditary optic neuropathy with an age of onset below 14 years. Sanger sequencing was used to screen variants in the coding and adjacent regions of OPA1, OPA3 and the three primary LHON-related mutation sites in mitochondrial DNA (mtDNA) (m.3460G>A, m.11778G>A and m.14484T>C). All patients underwent a complete ophthalmic examination and were compared with age-matched controls. We identified 89/304 (29.3%) primary mtDNA mutations related to LHON in 304 probands, including 76 mutations at m.11778 (76/89, 85.4% of all mtDNA mutations), four at m.3460 (4/89, 4.5%) and nine at m.14484 (9/89, 10.1%). This result was similar to the mutation frequency among Chinese patients with LHON of any age. Screening of OPA1 revealed 23 pathogenic variants, including 11 novel and 12 known pathogenic mutations. This study expanded the OPA1 mutation spectrum, and our results showed that OPA1 mutation is another common cause of childhood-onset hereditary optic neuropathy in Chinese pediatric patients, especially those with disease onset during preschool age.
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Suárez-Rivero JM, Villanueva-Paz M, de la Cruz-Ojeda P, de la Mata M, Cotán D, Oropesa-Ávila M, de Lavera I, Álvarez-Córdoba M, Luzón-Hidalgo R, Sánchez-Alcázar JA. Mitochondrial Dynamics in Mitochondrial Diseases. Diseases 2016; 5:diseases5010001. [PMID: 28933354 PMCID: PMC5456341 DOI: 10.3390/diseases5010001] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 12/13/2016] [Accepted: 12/21/2016] [Indexed: 01/09/2023] Open
Abstract
Mitochondria are very versatile organelles in continuous fusion and fission processes in response to various cellular signals. Mitochondrial dynamics, including mitochondrial fission/fusion, movements and turnover, are essential for the mitochondrial network quality control. Alterations in mitochondrial dynamics can cause neuropathies such as Charcot-Marie-Tooth disease in which mitochondrial fusion and transport are impaired, or dominant optic atrophy which is caused by a reduced mitochondrial fusion. On the other hand, mitochondrial dysfunction in primary mitochondrial diseases promotes reactive oxygen species production that impairs its own function and dynamics, causing a continuous vicious cycle that aggravates the pathological phenotype. Mitochondrial dynamics provides a new way to understand the pathophysiology of mitochondrial disorders and other diseases related to mitochondria dysfunction such as diabetes, heart failure, or Hungtinton’s disease. The knowledge about mitochondrial dynamics also offers new therapeutics targets in mitochondrial diseases.
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Affiliation(s)
- Juan M Suárez-Rivero
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Marina Villanueva-Paz
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Patricia de la Cruz-Ojeda
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Mario de la Mata
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - David Cotán
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Manuel Oropesa-Ávila
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Isabel de Lavera
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Mónica Álvarez-Córdoba
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - Raquel Luzón-Hidalgo
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
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Lasserre JP, Dautant A, Aiyar RS, Kucharczyk R, Glatigny A, Tribouillard-Tanvier D, Rytka J, Blondel M, Skoczen N, Reynier P, Pitayu L, Rötig A, Delahodde A, Steinmetz LM, Dujardin G, Procaccio V, di Rago JP. Yeast as a system for modeling mitochondrial disease mechanisms and discovering therapies. Dis Model Mech 2016; 8:509-26. [PMID: 26035862 PMCID: PMC4457039 DOI: 10.1242/dmm.020438] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial diseases are severe and largely untreatable. Owing to the many essential processes carried out by mitochondria and the complex cellular systems that support these processes, these diseases are diverse, pleiotropic, and challenging to study. Much of our current understanding of mitochondrial function and dysfunction comes from studies in the baker's yeast Saccharomyces cerevisiae. Because of its good fermenting capacity, S. cerevisiae can survive mutations that inactivate oxidative phosphorylation, has the ability to tolerate the complete loss of mitochondrial DNA (a property referred to as ‘petite-positivity’), and is amenable to mitochondrial and nuclear genome manipulation. These attributes make it an excellent model system for studying and resolving the molecular basis of numerous mitochondrial diseases. Here, we review the invaluable insights this model organism has yielded about diseases caused by mitochondrial dysfunction, which ranges from primary defects in oxidative phosphorylation to metabolic disorders, as well as dysfunctions in maintaining the genome or in the dynamics of mitochondria. Owing to the high level of functional conservation between yeast and human mitochondrial genes, several yeast species have been instrumental in revealing the molecular mechanisms of pathogenic human mitochondrial gene mutations. Importantly, such insights have pointed to potential therapeutic targets, as have genetic and chemical screens using yeast. Summary: In this Review, we discuss the use of budding yeast to understand mitochondrial diseases and help in the search for their treatments.
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Affiliation(s)
- Jean-Paul Lasserre
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
| | - Alain Dautant
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
| | - Raeka S Aiyar
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Roza Kucharczyk
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Annie Glatigny
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la terrasse, Gif-sur-Yvette 91198, France
| | - Déborah Tribouillard-Tanvier
- Institut National de la Santé et de la Recherche Médicale UMR1078, Université de Bretagne Occidentale, Faculté de Médecine et des Sciences de la Santé, Etablissement Français du Sang (EFS) Bretagne, CHRU Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest F-29200, France
| | - Joanna Rytka
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Marc Blondel
- Institut National de la Santé et de la Recherche Médicale UMR1078, Université de Bretagne Occidentale, Faculté de Médecine et des Sciences de la Santé, Etablissement Français du Sang (EFS) Bretagne, CHRU Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest F-29200, France
| | - Natalia Skoczen
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Pascal Reynier
- UMR CNRS 6214-INSERM U1083, Angers 49933, Cedex 9, France Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers 49933, Cedex 9, France
| | - Laras Pitayu
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, rue Gregor Mendel, Orsay 91405, France
| | - Agnès Rötig
- Inserm U1163, Hôpital Necker-Enfants-Malades, Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, 149 rue de Sèvres, Paris 75015, France
| | - Agnès Delahodde
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, rue Gregor Mendel, Orsay 91405, France
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany Stanford Genome Technology Center, Department of Biochemistry, Stanford University, Palo Alto, CA 94304, USA Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305-5301, USA
| | - Geneviève Dujardin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la terrasse, Gif-sur-Yvette 91198, France
| | - Vincent Procaccio
- UMR CNRS 6214-INSERM U1083, Angers 49933, Cedex 9, France Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers 49933, Cedex 9, France
| | - Jean-Paul di Rago
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
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A randomized, placebo-controlled trial of the benzoquinone idebenone in a mouse model of OPA1-related dominant optic atrophy reveals a limited therapeutic effect on retinal ganglion cell dendropathy and visual function. Neuroscience 2016; 319:92-106. [PMID: 26820596 DOI: 10.1016/j.neuroscience.2016.01.042] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/15/2016] [Accepted: 01/19/2016] [Indexed: 12/19/2022]
Abstract
Dominant optic atrophy (DOA) arises from mutations in the OPA1 gene that promotes fusion of the inner mitochondrial membrane and plays a role in maintaining ATP levels. Patients display optic disc pallor, retinal ganglion cell (RGC) loss and bilaterally reduced vision. We report a randomized, placebo-controlled trial of idebenone at 2000 mg/kg/day in 56 Opa1 mutant mice (B6;C3-Opa1(Q285STOP)), with RGC dendropathy and visual loss, and 63 wildtype mice. We assessed cellular responses in the retina, brain and liver and RGC morphology, by diolistic labeling, Sholl analysis and quantification of dendritic morphometric features. Vision was assessed by optokinetic responses. ATP levels were raised by 0.57 nmol/mg (97.73%, p=0.035) in brain from idebenone-treated Opa1 mutant mice, but in the liver there was an 80.35% (p=0.011) increase in oxidative damage. NQO1 expression in Opa1 mutant mice was reduced in the brain (to 30.5%, p=0.002) but not in retina, and neither expression level was induced by idebenone. ON-center RGCs failed to show major recovery, other than improvements in secondary dendritic length (by 53.89%, p=0.052) and dendritic territory (by 2.22 × 10(4) μm(2) or 90.24%, p=0.074). An improvement in optokinetic response was observed (by 12.2 ± 3.2s, p=0.003), but this effect was not sustained over time. OFF-center RGCs from idebenone-treated wildtype mice showed shrinkage in total dendritic length by 2.40 mm (48.05%, p=0.025) and a 47.37% diminished Sholl profile (p=0.029). Visual function in wildtype idebenone-treated mice was impaired (2.9 fewer head turns than placebo, p=0.007). Idebenone appears largely ineffective in protecting Opa1 heterozygous RGCs from dendropathy. The detrimental effect of idebenone in wildtype mice has not been previously observed and raises some concerns.
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Abstract
Mitochondrial dysfunction underlies many human disorders, including those that affect the visual system. The retinal ganglion cells, whose axons form the optic nerve, are often damaged by mitochondrial-related diseases which result in blindness. Both mitochondrial DNA (mtDNA) and nuclear gene mutations impacting many different mitochondrial processes can result in optic nerve disease. Of particular importance are mutations that impair mitochondrial network dynamics (fusion and fission), oxidative phosphorylation (OXPHOS), and formation of iron-sulfur complexes. Current genetic knowledge can inform genetic counseling and suggest strategies for novel gene-based therapies. Identifying new optic neuropathy-causing genes and defining the role of current and novel genes in disease will be important steps toward the development of effective and potentially neuroprotective therapies.
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Affiliation(s)
- Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School and Massachusetts Eye and Ear, Boston, Massachusetts 02114;
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29
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Formichi P, Radi E, Giorgi E, Gallus GN, Brunetti J, Battisti C, Rufa A, Dotti MT, Franceschini R, Bracci L, Federico A. Analysis of opa1 isoforms expression and apoptosis regulation in autosomal dominant optic atrophy (ADOA) patients with mutations in the opa1 gene. J Neurol Sci 2015; 351:99-108. [DOI: 10.1016/j.jns.2015.02.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 11/29/2022]
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Abstract
AbstractRetinal ganglion cell (RGC) dendritic atrophy is an early feature of many forms of retinal degeneration, providing a challenge to RGC classification. The characterization of these changes is complicated by the possibility that selective labeling of any particular class can confound the estimation of dendritic remodeling. To address this issue we have developed a novel, robust, and quantitative RGC classification based on proximal dendritic features which are resistant to early degeneration. RGCs were labeled through the ballistic delivery of DiO and DiI coated tungsten particles to whole retinal explants of 20 adult Brown Norway rats. RGCs were grouped according to the Sun classification system. A comprehensive set of primary and secondary dendrite features were quantified and a new classification model derived using principal component (PCA) and discriminant analyses, to estimate the likelihood that a cell belonged to any given class. One-hundred and thirty one imaged RGCs were analyzed; according to the Sun classification, 24% (n = 31) were RGCA, 29% (n = 38) RGCB, 32% (n = 42) RGCC, and 15% (n = 20) RGCD. PCA gave a 3 component solution, separating RGCs based on descriptors of soma size and primary dendrite thickness, proximal dendritic field size and dendritic tree asymmetry. The new variables correctly classified 73.3% (n = 74) of RGCs from a training sample and 63.3% (n = 19) from a hold out sample indicating an effective model. Soma and proximal dendritic tree morphological features provide a useful surrogate measurement for the classification of RGCs in disease. While a definitive classification is not possible in every case, the technique provides a useful safeguard against sample bias where the normal criteria for cell classification may not be reliable.
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Abstract
Mitochondria are highly specialized in function, but mitochondrial and, therefore, cellular integrity is maintained through their dynamic nature. Through the frequent processes of fusion and fission, mitochondria continuously change in shape and adjust function to meet cellular requirements. Abnormalities in fusion/fission dynamics generate cellular dysfunction that may lead to diseases. Mutations in the genes encoding mitochondrial fusion/fission proteins, such as MFN2 and OPA1, have been associated with an increasing number of genetic disorders, including Charcot-Marie-Tooth disease type 2A (CMT2A) and autosomal dominant optic atrophy. In this review, we address the mitochondrial dynamic changes in several important genetic diseases, which will bring the new insight of clinical relevance of mitochondrial genetics.
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Affiliation(s)
- Le Chen
- Molecular & Cellular Cardiology, University of California, Davis, One Shields Avenue Davis, CA, 95616, USA,
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La Morgia C, Carbonelli M, Barboni P, Sadun AA, Carelli V. Medical management of hereditary optic neuropathies. Front Neurol 2014; 5:141. [PMID: 25132831 PMCID: PMC4117178 DOI: 10.3389/fneur.2014.00141] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/16/2014] [Indexed: 01/31/2023] Open
Abstract
Hereditary optic neuropathies are diseases affecting the optic nerve. The most common are mitochondrial hereditary optic neuropathies, i.e., the maternally inherited Leber's hereditary optic neuropathy (LHON) and dominant optic atrophy (DOA). They both share a mitochondrial pathogenesis that leads to the selective loss of retinal ganglion cells and axons, in particular of the papillo-macular bundle. Typically, LHON is characterized by an acute/subacute loss of central vision associated with impairment of color vision and swelling of retinal nerve fibers followed by optic atrophy. DOA, instead, is characterized by a childhood-onset and slowly progressive loss of central vision, worsening over the years, leading to optic atrophy. The diagnostic workup includes neuro-ophthalmologic evaluation and genetic testing of the three most common mitochondrial DNA mutations affecting complex I (11778/ND4, 3460/ND1, and 14484/ND6) for LHON and sequencing of the nuclear gene OPA1 for DOA. Therapeutic strategies are still limited including agents that bypass the complex I defect and exert an antioxidant effect (idebenone). Further strategies are aimed at stimulating compensatory mitochondrial biogenesis. Gene therapy is also a promising avenue that still needs to be validated.
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Affiliation(s)
- Chiara La Morgia
- UOC Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria , Bologna , Italy ; Unità di Neurologia, Dipartimento di Scienze Biomediche e NeuroMotorie (DIBINEM), Università di Bologna , Bologna , Italy
| | | | - Piero Barboni
- Studio Oculistico d'Azeglio , Bologna , Italy ; Istituto Scientifico San Raffaele , Milan , Italy
| | - Alfredo Arrigo Sadun
- Doheny Eye Institute, University of California Los Angeles , Los Angeles, CA , USA
| | - Valerio Carelli
- UOC Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria , Bologna , Italy ; Unità di Neurologia, Dipartimento di Scienze Biomediche e NeuroMotorie (DIBINEM), Università di Bologna , Bologna , Italy
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Kamakari S, Koutsodontis G, Tsilimbaris M, Fitsios A, Chrousos G. First report of OPA1 screening in Greek patients with autosomal dominant optic atrophy and identification of a previously undescribed OPA1 mutation. Mol Vis 2014; 20:691-703. [PMID: 24883014 PMCID: PMC4037535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 05/24/2014] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To describe the genotype-phenotype correlation in four Greek pedigrees with autosomal dominant optic atrophy (ADOA) and OPA1 mutations. METHODS Seven patients from four unrelated families (F1, F2, F3, F4) were clinically assessed for visual acuity, color vision, ptosis, afferent pupillary defects, and visual fields and underwent orthoptic assessment, slit-lamp biomicroscopy, and fundus examination to establish their clinical status. Genomic DNA was extracted from peripheral blood samples from all participants. The coding region (exons 1-28), including the intron-exon boundaries of the OPA1 gene, was screened in the probands of the four families, as well as in seven additional family members (four affected and three unaffected) with PCR and direct DNA sequencing. RESULTS All patients presented bilateral decrease in best-corrected visual acuity and temporal pallor of the optic disc. The visual fields of the adult patients showed characteristic scotomata. Other signs were present in some patients such as decreased color discrimination and a gray crescent within the neuroretinal rim. After the OPA1 gene was sequenced, a previously undescribed heterozygous splice-site mutation c.784-1G>T in intron 7 was detected in family F2. In families F1, F3, and F4, a previously reported in-frame deletion c.876_878delTGT/p.(Val294del), the frameshift c.2366delA/p.(Asn789Metfs*11), and splice-site c.1140+5G>C mutations were detected, respectively. CONCLUSIONS This is the first report of molecular characterization of Greek patients with ADOA. Our findings provide additional information regarding the genotype-phenotype correlation and establish the role of the OPA1 gene in Greek patients with ADOA.
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Affiliation(s)
- Smaragda Kamakari
- Ophthalmic Genetics Unit, OMMA Ophthalmological Institute of Athens, Greece
| | | | - Miltiadis Tsilimbaris
- Department of Ophthalmology, School of Medicine, University of Crete, Iraklion, Greece
| | - Athanasios Fitsios
- Pediatric Ophthalmology Department, MITERA Childrens’ Hospital, Athens, Greece
| | - Georgia Chrousos
- Pediatric Ophthalmology Department, MITERA Childrens’ Hospital, Athens, Greece
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Riazifar H, Jia Y, Chen J, Lynch G, Huang T. Chemically induced specification of retinal ganglion cells from human embryonic and induced pluripotent stem cells. Stem Cells Transl Med 2014; 3:424-32. [PMID: 24493857 DOI: 10.5966/sctm.2013-0147] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The loss of retinal ganglion cells (RGCs) is the primary pathological change for many retinal degenerative diseases. Although there is currently no effective treatment for this group of diseases, cell transplantation to replace lost RGCs holds great potential. However, for the development of cell replacement therapy, better understanding of the molecular details involved in differentiating stem cells into RGCs is essential. In this study, a novel, stepwise chemical protocol is described for the differentiation of human embryonic stem cells and induced pluripotent stem cells into functional RGCs. Briefly, stem cells were differentiated into neural rosettes, which were then cultured with the Notch inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT). The expression of neural and RGC markers (BRN3A, BRN3B, ATOH7/Math5, γ-synuclein, Islet-1, and THY-1) was examined. Approximately 30% of the cell population obtained expressed the neuronal marker TUJ1 as well the RGC markers. Moreover, the differentiated RGCs generated action potentials and exhibited both spontaneous and evoked excitatory postsynaptic currents, indicating that functional and mature RGCs were generated. In combination, these data demonstrate that a single chemical (DAPT) can induce PAX6/RX-positive stem cells to undergo differentiation into functional RGCs.
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Affiliation(s)
- Hamidreza Riazifar
- Department of Pediatrics, Division of Human Genetics, Department of Anatomy and Neurobiology, Department of Psychiatry and Human Behavior, MitoMed Molecular Diagnostic Laboratory, Department of Pathology, Department of Developmental and Cell Biology, and Department of Ophthalmology, University of California, Irvine, Irvine, California, USA; Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
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Skidd PM, Lessell S, Cestari DM. Autosomal Dominant Hereditary Optic Neuropathy (ADOA): A Review of the Genetics and Clinical Manifestations of ADOA and ADOA+. Semin Ophthalmol 2013; 28:422-6. [DOI: 10.3109/08820538.2013.825296] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kaden TR, Li W. AUTOPHAGY, MITOCHONDRIAL DYNAMICS AND RETINAL DISEASES. Asia Pac J Ophthalmol (Phila) 2013; 2:S2162-0989(23)01010-1. [PMID: 24205447 PMCID: PMC3816775 DOI: 10.1097/apo.0b013e31829d3e33] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Talia R. Kaden
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
- Yale University School of Medicine, New Haven, CT, USA
| | - Wei Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
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Barboni P, Valentino ML, La Morgia C, Carbonelli M, Savini G, De Negri A, Simonelli F, Sadun F, Caporali L, Maresca A, Liguori R, Baruzzi A, Zeviani M, Carelli V. Idebenone treatment in patients with OPA1-mutant dominant optic atrophy. Brain 2013; 136:e231. [PMID: 23388408 DOI: 10.1093/brain/aws280] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024] Open
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Baile MG, Claypool SM. The power of yeast to model diseases of the powerhouse of the cell. FRONT BIOSCI-LANDMRK 2013; 18:241-78. [PMID: 23276920 PMCID: PMC3874933 DOI: 10.2741/4098] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mitochondria participate in a variety of cellular functions. As such, mitochondrial diseases exhibit numerous clinical phenotypes. Because mitochondrial functions are highly conserved between humans and Saccharomyces cerevisiae, yeast are an excellent model to study mitochondrial disease, providing insight into both physiological and pathophysiological processes.
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Affiliation(s)
- Matthew G Baile
- Dept. of Physiology, Johns Hopkins School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205-2185, USA
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40
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Russo A, Delcassi L, Marchina E, Semeraro F. Correlation between visual acuity and OCT-measured retinal nerve fiber layer thickness in a family with ADOA and an OPA1 mutation. Ophthalmic Genet 2012; 34:69-74. [DOI: 10.3109/13816810.2012.702259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Lenaers G, Hamel C, Delettre C, Amati-Bonneau P, Procaccio V, Bonneau D, Reynier P, Milea D. Dominant optic atrophy. Orphanet J Rare Dis 2012; 7:46. [PMID: 22776096 PMCID: PMC3526509 DOI: 10.1186/1750-1172-7-46] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 03/15/2012] [Indexed: 11/18/2022] Open
Abstract
Definition of the disease Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. Epidemiology The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. Clinical description DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Aetiology Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. All OPA genes yet identified encode mitochondrial proteins embedded in the inner membrane and ubiquitously expressed, as are the proteins mutated in the Leber Hereditary Optic Neuropathy. OPA1 mutations affect mitochondrial fusion, energy metabolism, control of apoptosis, calcium clearance and maintenance of mitochondrial genome integrity. OPA3 mutations only affect the energy metabolism and the control of apoptosis. Diagnosis Patients are usually diagnosed during their early childhood, because of bilateral, mild, otherwise unexplained visual loss related to optic discs pallor or atrophy, and typically occurring in the context of a family history of DOA. Optical Coherence Tomography further discloses non-specific thinning of retinal nerve fiber layer, but a normal morphology of the photoreceptors layers. Abnormal visual evoked potentials and pattern ERG may also reflect the dysfunction of the RGCs and their axons. Molecular diagnosis is provided by the identification of a mutation in the OPA1 gene (75% of DOA patients) or in the OPA3 gene (1% of patients). Prognosis Visual loss in DOA may progress during puberty until adulthood, with very slow subsequent chronic progression in most of the cases. On the opposite, in DOA patients with associated extra-ocular features, the visual loss may be more severe over time. Management To date, there is no preventative or curative treatment in DOA; severely visually impaired patients may benefit from low vision aids. Genetic counseling is commonly offered and patients are advised to avoid alcohol and tobacco consumption, as well as the use of medications that may interfere with mitochondrial metabolism. Gene and pharmacological therapies for DOA are currently under investigation.
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Affiliation(s)
- Guy Lenaers
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier I et II, BP 74103, F-34091 Montpellier cedex 05, France.
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42
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TMEM126A mutation in a Moroccan family with autosomal recessive optic atrophy. Mol Vis 2012; 18:1849-57. [PMID: 22815638 PMCID: PMC3398502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 07/02/2012] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Nonsyndromic autosomal recessive optic atrophy (arOA) is extremely rare and its existence was disputed until a locus, optic atrophy 6 (OPA6), was mapped to 8q. Recently, a second locus, OPA7, was found on 11q in several families from North Africa, with one presumably ancestral mutation of transmembrane protein 126A (TMEM126A). Here we report an independently ascertained large consanguineous family of Moroccan descent with three siblings affected with nonsyndromic arOA. METHODS Assuming autosomal recessive inheritance, we identified a locus on 11q with homozygosity mapping, with a multipoint logarithm of the odds score of 3.84, and sequenced two candidate genes. Direct sequencing of the complete coding sequence of TMEM126A revealed mutation p.Arg55X, homozygous in all affected siblings and heterozygous in both unaffected parents. RESULTS This mutation was identical to that recently reported in families from North Africa, consistent with a single ancestral origin. In contrast to the recently reported patients, however, the siblings reported in this study had a relatively mild clinical course, with sudden onset in adolescence in the proband. Interestingly, the proband, but not the other affected siblings, had sensory-motor axonal neuropathy with electrophysiological data strongly suggestive of focal demyelinating abnormalities. An unaffected sibling had transient loss of vision after exercise, i.e., Uhthoff's sign of optic neuropathy, and was found to be a heterozygous carrier of the mutation. CONCLUSIONS Our results confirm genetic heterogeneity in arOA, illustrate clinical variability between families with the p.Arg55X mutation including the description of a mild phenotype in a heterozygote, and underscore the implication of mitochondrial proteins in optic and peripheral neuropathy.
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Piquereau J, Caffin F, Novotova M, Prola A, Garnier A, Mateo P, Fortin D, Huynh LH, Nicolas V, Alavi MV, Brenner C, Ventura-Clapier R, Veksler V, Joubert F. Down-regulation of OPA1 alters mouse mitochondrial morphology, PTP function, and cardiac adaptation to pressure overload. Cardiovasc Res 2012; 94:408-17. [PMID: 22406748 DOI: 10.1093/cvr/cvs117] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
AIMS The optic atrophy 1 (OPA1) protein is an essential protein involved in the fusion of the mitochondrial inner membrane. Despite its high level of expression, the role of OPA1 in the heart is largely unknown. We investigated the role of this protein in Opa1(+/-) mice, having a 50% reduction in OPA1 protein expression in cardiac tissue. METHODS AND RESULTS In mutant mice, cardiac function assessed by echocardiography was not significantly different from that of the Opa1(+/+). Electron and fluorescence microscopy revealed altered morphology of the Opa1(+/-) mice mitochondrial network; unexpectedly, mitochondria were larger with the presence of clusters of fused mitochondria and altered cristae. In permeabilized mutant ventricular fibres, mitochondrial functional properties were maintained, but direct energy channelling between mitochondria and myofilaments was weakened. Importantly, the mitochondrial permeability transition pore (PTP) opening in isolated permeabilized cardiomyocytes and in isolated mitochondria was significantly less sensitive to mitochondrial calcium accumulation. Finally, 6 weeks after transversal aortic constriction, Opa1(+/-) hearts demonstrated hypertrophy almost two-fold higher (P< 0.01) than in wild-type mice with altered ejection fraction (decrease in 43 vs. 22% in Opa1(+/+) mice, P< 0.05). CONCLUSIONS These results suggest that, in adult cardiomyocytes, OPA1 plays an important role in mitochondrial morphology and PTP functioning. These properties may be critical for cardiac function under conditions of chronic pressure overload.
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Affiliation(s)
- Jerome Piquereau
- INSERM, U-769, Faculté de Pharmacie, Université Paris-Sud, 5 rue J-B Clément, F-92296 Châtenay-Malabry, France
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Williams PA, Piechota M, von Ruhland C, Taylor E, Morgan JE, Votruba M. Opa1 is essential for retinal ganglion cell synaptic architecture and connectivity. Brain 2012; 135:493-505. [DOI: 10.1093/brain/awr330] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ranieri M, Del Bo R, Bordoni A, Ronchi D, Colombo I, Riboldi G, Cosi A, Servida M, Magri F, Moggio M, Bresolin N, Comi GP, Corti S. Optic atrophy plus phenotype due to mutations in the OPA1 gene: two more Italian families. J Neurol Sci 2011; 315:146-9. [PMID: 22197506 PMCID: PMC3315002 DOI: 10.1016/j.jns.2011.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 11/24/2011] [Accepted: 12/02/2011] [Indexed: 12/01/2022]
Abstract
Autosomal Dominant Optic Atrophy (ADOA) is characterized by the selective degeneration of retinal ganglion cells. The occurrence of mutations in the gene encoding the dynamin-like GTPase protein Optic Atrophy 1 (OPA1) has been observed in about 60–70% of ADOA cases. A subset of missense mutations, mostly within the GTPase domain, has recently been associated with a syndromic ADOA form called “OPA1 plus” phenotype presenting, at muscle level, mitochondrial DNA (mtDNA) instability. In this study we disclosed two OPA1 gene mutations in independent probands from two families affected by OPA1 plus phenotype: the previously reported c.985-2A > G substitution and a novel microdeletion (c.2819-1_2821del). The correlation between genotype and phenotype and the effects of these variants at the transcript level and in the muscle tissue were investigated, confirming the broad complexity in the phenotypic spectrum associated with these OPA1 mutations.
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Affiliation(s)
- Michela Ranieri
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
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46
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Van Bergen NJ, Crowston JG, Kearns LS, Staffieri SE, Hewitt AW, Cohn AC, Mackey DA, Trounce IA. Mitochondrial oxidative phosphorylation compensation may preserve vision in patients with OPA1-linked autosomal dominant optic atrophy. PLoS One 2011; 6:e21347. [PMID: 21731710 PMCID: PMC3120866 DOI: 10.1371/journal.pone.0021347] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 05/27/2011] [Indexed: 02/01/2023] Open
Abstract
Autosomal Dominant Optic Atrophy (ADOA) is the most common inherited optic atrophy where vision impairment results from specific loss of retinal ganglion cells of the optic nerve. Around 60% of ADOA cases are linked to mutations in the OPA1 gene. OPA1 is a fission-fusion protein involved in mitochondrial inner membrane remodelling. ADOA presents with marked variation in clinical phenotype and varying degrees of vision loss, even among siblings carrying identical mutations in OPA1. To determine whether the degree of vision loss is associated with the level of mitochondrial impairment, we examined mitochondrial function in lymphoblast cell lines obtained from six large Australian OPA1-linked ADOA pedigrees. Comparing patients with severe vision loss (visual acuity [VA]<6/36) and patients with relatively preserved vision (VA>6/9) a clear defect in mitochondrial ATP synthesis and reduced respiration rates were observed in patients with poor vision. In addition, oxidative phosphorylation (OXPHOS) enzymology in ADOA patients with normal vision revealed increased complex II+III activity and levels of complex IV protein. These data suggest that OPA1 deficiency impairs OXPHOS efficiency, but compensation through increases in the distal complexes of the respiratory chain may preserve mitochondrial ATP production in patients who maintain normal vision. Identification of genetic variants that enable this response may provide novel therapeutic insights into OXPHOS compensation for preventing vision loss in optic neuropathies.
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Affiliation(s)
- Nicole J. Van Bergen
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Jonathan G. Crowston
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Lisa S. Kearns
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Sandra E. Staffieri
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Alex W. Hewitt
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Amy C. Cohn
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - David A. Mackey
- University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Perth, Western Australia, Australia
| | - Ian A. Trounce
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
- * E-mail:
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Almind GJ, Grønskov K, Milea D, Larsen M, Brøndum-Nielsen K, Ek J. Genomic deletions in OPA1 in Danish patients with autosomal dominant optic atrophy. BMC MEDICAL GENETICS 2011; 12:49. [PMID: 21457585 PMCID: PMC3079616 DOI: 10.1186/1471-2350-12-49] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 04/04/2011] [Indexed: 05/26/2023]
Abstract
Background Autosomal dominant optic atrophy (ADOA, Kjer disease, MIM #165500) is the most common form of hereditary optic neuropathy. Mutations in OPA1 located at chromosome 3q28 are the predominant cause for ADOA explaining between 32 and 89% of cases. Although deletions of OPA1 were recently reported in ADOA, the frequency of OPA1 genomic rearrangements in Denmark, where ADOA has a high prevalence, is unknown. The aim of the study was to identify copy number variations in OPA1 in Danish ADOA patients. Methods Forty unrelated ADOA patients, selected from a group of 100 ADOA patients as being negative for OPA1 point mutations, were tested for genomic rearrangements in OPA1 by multiplex ligation probe amplification (MLPA). When only one probe was abnormal results were confirmed by additional manually added probes. Segregation analysis was performed in families with detected mutations when possible. Results Ten families had OPA1 deletions, including two with deletions of the entire coding region and eight with intragenic deletions. Segregation analysis was possible in five families, and showed that the deletions segregated with the disease. Conclusion Deletions in the OPA1 gene were found in 10 patients presenting with phenotypic autosomal dominant optic neuropathy. Genetic testing for deletions in OPA1 should be offered for patients with clinically diagnosed ADOA and no OPA1 mutations detected by DNA sequencing analysis.
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Affiliation(s)
- Gitte J Almind
- Center for Applied Human Molecular Genetics, The Kennedy Center, Glostrup, Denmark.
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Yu-Wai-Man P, Bailie M, Atawan A, Chinnery PF, Griffiths PG. Pattern of retinal ganglion cell loss in dominant optic atrophy due to OPA1 mutations. Eye (Lond) 2011; 25:596-602. [PMID: 21378995 DOI: 10.1038/eye.2011.2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The majority of patients with autosomal dominant optic atrophy (DOA) harbour pathogenic OPA1 mutations. Although DOA is characterised by the preferential loss of retinal ganglion cells (RGCs), about 20% of patients with OPA1 mutations will develop a more severe disease variant (DOA+), with additional neuromuscular features. In this prospective, observational case series, optical coherence tomography (OCT) was used to define the pattern of retinal nerve fibre layer (RNFL) loss in patients with both the pure and syndromal forms of DOA. METHODS Forty patients with a molecular diagnosis of DOA due to OPA1 mutations were prospectively recruited from our neuro-ophthalmology clinic: 26 patients with isolated optic atrophy and 14 patients manifesting DOA+ features. Peripapillary RNFL thickness was measured with the Fast RNFL (3.4) acquisition protocol on a Stratus OCT. RESULTS There was a statistically significant reduction in average RNFL thickness in the OPA1 group compared with normal controls (P<0.0001). The percentage decrease was greatest in the temporal quadrant (59.0%), followed by the inferior (49.6%), superior (41.8%), and nasal (25.9%) quadrants. Patients with DOA+ features had worse visual outcomes compared with patients with pure DOA. Except in the temporal quadrant, RNFL measurements were significantly thinner for the DOA+ group. There was an inverse correlation between average RNFL thickness and logarithm of the minimum angle of resolution (LogMAR) visual acuity (P<0.0001). CONCLUSIONS RGC loss in DOA is characterised by severe involvement of the temporal papillomacular bundle, with relative sparing of the nasal fibres. RNFL thinning is more pronounced in patients with DOA+ phenotypes.
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Affiliation(s)
- P Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
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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: 431] [Impact Index Per Article: 33.2] [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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Optic disc evaluation in optic neuropathies: the optic disc assessment project. Ophthalmology 2010; 118:964-70. [PMID: 21126771 DOI: 10.1016/j.ophtha.2010.09.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Optic nerve morphology is affected by genetic and acquired disease. Glaucoma is the most common optic neuropathy; autosomal-dominant optic atrophy (ADOA) and Leber's hereditary optic neuropathy (LHON) are the most prevalent hereditary optic neuropathies. These 3 entities can exhibit similar topographical changes at the optic nerve head. Both ADOA and LHON have been reported to be misdiagnosed as glaucoma. Our aim was to determine whether glaucoma subspecialists and neuro-ophthalmologists can distinguish these diagnoses on optic disc assessment alone. DESIGN Observational study. PARTICIPANTS Twenty-three optic nerve experts. METHODS We randomized and masked 60 high-resolution stereoscopic optic disc photographs (15 ADOA images, 15 LHON, 15 glaucoma, and 15 normal controls). Experts were asked to assess the discs on 12 conventional topographic features and assign a presumptive diagnosis. Intra- and interanalysis was performed using the index of qualitative variation and absolute deviation. MAIN OUTCOME MEASURES Can glaucoma specialists and neuro-ophthalmologists distinguish among the disease entities by optic nerve head phenotype. RESULTS The correct diagnosis was identified in 85%, 75%, 27%, and 16% of the normal, glaucoma, ADOA, and LHON disc groups, respectively. The proportion of correct diagnoses within the ADOA and LHON groups was significantly lower than both normal and glaucomatous (P<0.001). Where glaucoma was chosen as the most likely diagnosis, 61% were glaucomatous, 34% were pathologic but nonglaucomatous discs, and 5% were normal. There was greater agreement for individual parameters assessed within the normal disc set when compared with pathologic discs (P<0.05). The only parameter to have a significantly greater agreement within the glaucomatous disc set when compared with ADOA or LHON disc sets was pallor, whereby experts agreed on is absence in the glaucomatous discs but were not in agreement on its presence or its absence in the ADOA and LHON discs (P<0.01). CONCLUSIONS Optic neuropathies can result in similar topographic changes at the optic disc, particularly in late-stage disease, making it difficult to differentiate ADOA and LHON from glaucoma based on disc assessment alone. Other clinical parameters such as acuity, color vision, history of visual loss, and family history are required to make an accurate diagnosis.
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