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Zhuang Y, Jiang W, Zhao Z, Li W, Deng Z, Liu J. Ion channel-mediated mitochondrial volume regulation and its relationship with mitochondrial dynamics. Channels (Austin) 2024; 18:2335467. [PMID: 38546173 PMCID: PMC10984129 DOI: 10.1080/19336950.2024.2335467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/21/2024] [Indexed: 04/04/2024] Open
Abstract
The mitochondrion, one of the important cellular organelles, has the major function of generating adenosine triphosphate and plays an important role in maintaining cellular homeostasis, governing signal transduction, regulating membrane potential, controlling programmed cell death and modulating cell proliferation. The dynamic balance of mitochondrial volume is an important factor required for maintaining the structural integrity of the organelle and exerting corresponding functions. Changes in the mitochondrial volume are closely reflected in a series of biological functions and pathological changes. The mitochondrial volume is controlled by the osmotic balance between the cytoplasm and the mitochondrial matrix. Thus, any disruption in the influx of the main ion, potassium, into the cells can disturb the osmotic balance between the cytoplasm and the matrix, leading to water movement between these compartments and subsequent alterations in mitochondrial volume. Recent studies have shown that mitochondrial volume homeostasis is closely implicated in a variety of diseases. In this review, we provide an overview of the main influencing factors and research progress in the field of mitochondrial volume homeostasis.
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Affiliation(s)
- Yujia Zhuang
- Hand and Foot Surgery Department, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
- Clinical College of Shantou University Medical College, Shantou, China
| | - Wenting Jiang
- Operating room, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
| | - Zhe Zhao
- Hand and Foot Surgery Department, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
| | - Wencui Li
- Hand and Foot Surgery Department, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
| | - Zhiqin Deng
- Hand and Foot Surgery Department, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
| | - Jianquan Liu
- Hand and Foot Surgery Department, Shenzhen Second People’s Hospital/the First Hospital Affiliated to Shenzhen University, Shenzhen, China
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2
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Wang J, Wang M, Moshiri A, Harris RA, Raveendran M, Nguyen T, Kim S, Young L, Wang K, Wiseman R, O'Connor DH, Johnson Z, Martinez M, Montague MJ, Sayers K, Lyke M, Vallender E, Stout T, Li Y, Thomasy SM, Rogers J, Chen R. Genetic diversity of 1,845 rhesus macaques improves genetic variation interpretation and identifies disease models. Nat Commun 2024; 15:5658. [PMID: 38969634 PMCID: PMC11226599 DOI: 10.1038/s41467-024-49922-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 06/25/2024] [Indexed: 07/07/2024] Open
Abstract
Understanding and treating human diseases require valid animal models. Leveraging the genetic diversity in rhesus macaque populations across eight primate centers in the United States, we conduct targeted-sequencing on 1845 individuals for 374 genes linked to inherited human retinal and neurodevelopmental diseases. We identify over 47,000 single nucleotide variants, a substantial proportion of which are shared with human populations. By combining rhesus and human allele frequencies with established variant prediction methods, we develop a machine learning-based score that outperforms established methods in predicting missense variant pathogenicity. Remarkably, we find a marked number of loss-of-function variants and putative deleterious variants, which may lead to the development of rhesus disease models. Through phenotyping of macaques carrying a pathogenic OPA1:p.A8S variant, we identify a genetic model of autosomal dominant optic atrophy. Finally, we present a public website housing variant and genotype data from over two thousand rhesus macaques.
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Affiliation(s)
- Jun Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Meng Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Ala Moshiri
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA
| | - R Alan Harris
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Muthuswamy Raveendran
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Tracy Nguyen
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Laura Young
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Keqing Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Roger Wiseman
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - David H O'Connor
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Zach Johnson
- Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
| | - Melween Martinez
- Caribbean Primate Research Center, University of Puerto Rico, Punta Santiago, Humacao, Puerto Rico
| | - Michael J Montague
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ken Sayers
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Martha Lyke
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Eric Vallender
- Tulane National Primate Research Center, Tulane university, Covington, Louisiana, USA
| | - Tim Stout
- Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sara M Thomasy
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis, Sacramento, California, USA
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- California National Primate Research Center, University of California-Davis, Davis, California, USA
| | - Jeffrey Rogers
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.
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3
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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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4
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Lombardo M, Cusumano A, Mancino R, Aiello F, Sorge RP, Nucci C, Cesareo M. Short Wavelength Automated Perimetry, Standard Automated Perimetry, and Optical Coherence Tomography in Dominant Optic Atrophy. J Clin Med 2024; 13:1971. [PMID: 38610740 PMCID: PMC11012462 DOI: 10.3390/jcm13071971] [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: 01/27/2024] [Revised: 02/19/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Background: Blue-yellow axis dyschromatopsia is well-known in Autosomal Dominant Optic Atrophy (ADOA) patients, but there were no data on the correlation between retinal structure and short-wavelength automated perimetry (SWAP) values in this pathology. Methods: In this cross-sectional case-control study, we assessed the correlation between best corrected visual acuity (BCVA), standard automated perimetry (SAP), SWAP, and optical coherence tomography (OCT) parameters of 9 ADOA patients compared with healthy controls. Correlation analysis was performed between BCVA, mean deviation, pattern standard deviation (PSD), and fovea sensitivity (FS) values and the OCT thickness of each retinal layer and the peripapillary retinal nerve fiber layer (pRNFL). Results: The following significant and strong correlations were found: between BCVA and ganglion cell layer (GCL) and the global (G) pRNFL thicknesses; between SAP FS and GCL and the G-pRNFL thicknesses; between SWAP PSD and total retina, GCL, inner plexiform layer, inner nuclear layer, inner retinal layer and the temporal pRNFL thicknesses. We found a constant shorter duration of the SITA-SWAP compared with the SITA-STANDARD strategy. Conclusions: SWAP, SAP, and BCVA values provided relevant clinical information about retinal involvement in our ADOA patients. The perimetric functional parameters that seemed to correlate better with structure involvement were FS on SAP and PSD on SWAP.
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Affiliation(s)
- Marco Lombardo
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Andrea Cusumano
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Raffaele Mancino
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Francesco Aiello
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Roberto Pietro Sorge
- Laboratory of Biometry, Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Carlo Nucci
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Massimo Cesareo
- Ophthalmology Unit, Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
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5
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Del Negro I, Pauletto G, Verriello L, Spadea L, Salati C, Ius T, Zeppieri M. Uncovering the Genetics and Physiology behind Optic Neuritis. Genes (Basel) 2023; 14:2192. [PMID: 38137014 PMCID: PMC10742654 DOI: 10.3390/genes14122192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
Optic neuritis (ON) is an inflammatory condition affecting the optic nerve, leading to vision impairment and potential vision loss. This manuscript aims to provide a comprehensive review of the current understanding of ON, including its definition, epidemiology, physiology, genetics, molecular pathways, therapy, ongoing clinical studies, and future perspectives. ON is characterized by inflammation of the optic nerve, often resulting from an autoimmune response. Epidemiological studies have shown a higher incidence in females and an association with certain genetic factors. The physiology of ON involves an immune-mediated attack on the myelin sheath surrounding the optic nerve, leading to demyelination and subsequent impairment of nerve signal transmission. This inflammatory process involves various molecular pathways, including the activation of immune cells and the release of pro-inflammatory cytokines. Genetic factors play a significant role in the susceptibility to ON. Several genes involved in immune regulation and myelin maintenance have been implicated in the disease pathogenesis. Understanding the genetic basis can provide insights into disease mechanisms and potential therapeutic targets. Therapy for ON focuses on reducing inflammation and promoting nerve regeneration. Future perspectives involve personalized medicine approaches based on genetic profiling, regenerative therapies to repair damaged myelin, and the development of neuroprotective strategies. Advancements in understanding molecular pathways, genetics, and diagnostic tools offer new opportunities for targeted therapies and improved patient outcomes in the future.
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Affiliation(s)
- Ilaria Del Negro
- Clinical Neurology Unit, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital, 33100 Udine, Italy;
| | - Giada Pauletto
- Neurology Unit, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital, 33100 Udine, Italy; (G.P.)
| | - Lorenzo Verriello
- Neurology Unit, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital, 33100 Udine, Italy; (G.P.)
| | - Leopoldo Spadea
- Eye Clinic, Policlinico Umberto I, “Sapienza” University of Rome, 00142 Rome, Italy
| | - Carlo Salati
- Department of Ophthalmology, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital, 33100 Udine, Italy
| | - Tamara Ius
- Neurosurgery Unit, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital of Udine, 33100 Udine, Italy
| | - Marco Zeppieri
- Department of Ophthalmology, Head-Neck and Neurosciences Department, Santa Maria della Misericordia University Hospital, 33100 Udine, Italy
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6
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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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7
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Pohl KA, Zhang X, Pham AH, Chan JW, Sadun AA, Yang XJ. Establishing induced pluripotent stem cell lines from two dominant optic atrophy patients with distinct OPA1 mutations and clinical pathologies. Front Genet 2023; 14:1251216. [PMID: 37745862 PMCID: PMC10513078 DOI: 10.3389/fgene.2023.1251216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 08/17/2023] [Indexed: 09/26/2023] Open
Abstract
Dominant optic atrophy (DOA) is an inherited disease that leads to the loss of retinal ganglion cells (RGCs), the projection neurons that relay visual information from the retina to the brain through the optic nerve. The majority of DOA cases can be attributed to mutations in optic atrophy 1 (OPA1), a nuclear gene encoding a mitochondrial-targeted protein that plays important roles in maintaining mitochondrial structure, dynamics, and bioenergetics. Although OPA1 is ubiquitously expressed in all human tissues, RGCs appear to be the primary cell type affected by OPA1 mutations. DOA has not been extensively studied in human RGCs due to the general unavailability of retinal tissues. However, recent advances in stem cell biology have made it possible to produce human RGCs from pluripotent stem cells (PSCs). To aid in establishing DOA disease models based on human PSC-derived RGCs, we have generated iPSC lines from two DOA patients who carry distinct OPA1 mutations and present very different disease symptoms. Studies using these OPA1 mutant RGCs can be correlated with clinical features in the patients to provide insights into DOA disease mechanisms.
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Affiliation(s)
- Katherine A. Pohl
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Xiangmei Zhang
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Anh H. Pham
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Jane W. Chan
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Alfredo A. Sadun
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Xian-Jie Yang
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
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8
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Millet AMC, Coustham C, Champigny C, Botella M, Demeilliers C, Devin A, Galinier A, Belenguer P, Bordeneuve-Guibé J, Davezac N. OPA1 deficiency impairs oxidative metabolism in cycling cells, underlining a translational approach for degenerative diseases. Dis Model Mech 2023; 16:dmm050266. [PMID: 37497665 PMCID: PMC10538295 DOI: 10.1242/dmm.050266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023] Open
Abstract
Dominant optic atrophy is an optic neuropathy with varying clinical symptoms and progression. A severe disorder is associated with certain OPA1 mutations and includes additional symptoms for >20% of patients. This underscores the consequences of OPA1 mutations in different cellular populations, not only retinal ganglionic cells. We assessed the effects of OPA1 loss of function on oxidative metabolism and antioxidant defences using an RNA-silencing strategy in a human epithelial cell line. We observed a decrease in the mitochondrial respiratory chain complexes, associated with a reduction in aconitase activity related to an increase in reactive oxygen species (ROS) production. In response, the NRF2 (also known as NFE2L2) transcription factor was translocated into the nucleus and upregulated SOD1 and GSTP1. This study highlights the effects of OPA1 deficiency on oxidative metabolism in replicative cells, as already shown in neurons. It underlines a translational process to use cycling cells to circumvent and describe oxidative metabolism. Moreover, it paves the way to predict the evolution of dominant optic atrophy using mathematical models that consider mitochondrial ROS production and their detoxifying pathways.
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Affiliation(s)
- Aurélie M. C. Millet
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | - Corentin Coustham
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
- ISAE-SUPAERO, Toulouse University, 31400 Toulouse, France
| | - Camille Champigny
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | - Marlène Botella
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | | | - Anne Devin
- Laboratoire Métabolisme Energétique Cellulaire IBGC du CNRS, 1 rue Camille Saint Saëns, 33077 Bordeaux cedex, France
| | - Anne Galinier
- RESTORE – Université de Toulouse, CNRS ERL5311, EFS, INP-ENVT, Inserm U1031, UPS, Bâtiment INCERE, 4bis avenue Hubert Curien, 31100 Toulouse, France
| | - Pascale Belenguer
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | | | - Noélie Davezac
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
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9
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Muñoz JP, Basei FL, Rojas ML, Galvis D, Zorzano A. Mechanisms of Modulation of Mitochondrial Architecture. Biomolecules 2023; 13:1225. [PMID: 37627290 PMCID: PMC10452872 DOI: 10.3390/biom13081225] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
Mitochondrial network architecture plays a critical role in cellular physiology. Indeed, alterations in the shape of mitochondria upon exposure to cellular stress can cause the dysfunction of these organelles. In this scenario, mitochondrial dynamics proteins and the phospholipid composition of the mitochondrial membrane are key for fine-tuning the modulation of mitochondrial architecture. In addition, several factors including post-translational modifications such as the phosphorylation, acetylation, SUMOylation, and o-GlcNAcylation of mitochondrial dynamics proteins contribute to shaping the plasticity of this architecture. In this regard, several studies have evidenced that, upon metabolic stress, mitochondrial dynamics proteins are post-translationally modified, leading to the alteration of mitochondrial architecture. Interestingly, several proteins that sustain the mitochondrial lipid composition also modulate mitochondrial morphology and organelle communication. In this context, pharmacological studies have revealed that the modulation of mitochondrial shape and function emerges as a potential therapeutic strategy for metabolic diseases. Here, we review the factors that modulate mitochondrial architecture.
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Affiliation(s)
- Juan Pablo Muñoz
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Institut d’Investigació Biomèdica Sant Pau (IIB SANT PAU), 08041 Barcelona, Spain
| | - Fernanda Luisa Basei
- Faculdade de Ciências Farmacêuticas, Universidade Estadual de Campinas, 13083-871 Campinas, SP, Brazil
| | - María Laura Rojas
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
| | - David Galvis
- Programa de Química Farmacéutica, Universidad CES, Medellín 050031, Colombia
| | - Antonio Zorzano
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
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10
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Barretta F, Uomo F, Caldora F, Mocerino R, Adamo D, Testa F, Simonelli F, Scudiero O, Tinto N, Frisso G, Mazzaccara C. Combined MITOchondrial-NUCLEAR (MITO-NUCLEAR) Analysis for Mitochondrial Diseases Diagnosis: Validation and Implementation of a One-Step NGS Method. Genes (Basel) 2023; 14:genes14051087. [PMID: 37239447 DOI: 10.3390/genes14051087] [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: 03/20/2023] [Revised: 05/08/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
BACKGROUND Next-generation sequencing (NGS) technology is revolutionizing diagnostic screening for mitochondrial diseases (MDs). Moreover, an investigation by NGS still requires analyzing the mitochondrial genome and nuclear genes separately, with limitations in terms of time and costs. We describe the validation and implementation of a custom blended MITOchondrial-NUCLEAR (MITO-NUCLEAR) assay for the simultaneous identification of genetic variants both in whole mtDNA and in nuclear genes included in a clinic exome panel. Furthermore, the MITO-NUCLEAR assay, implemented in our diagnostic process, has allowed us to arrive at a molecular diagnosis in a young patient. METHODS Massive sequencing strategy was applied for the validation experiments, performed using multiple tissues (blood, buccal swab, fresh tissue, tissue from slide, and formalin-fixed paraffin-embedded tissue section) and two different blend-in ratios of the mitochondrial probes: nuclear probes; 1:900 and 1:300. RESULTS Data suggested that 1:300 was the optimal probe dilution, where 100% of the mtDNA was covered at least 3000×, the median coverage was >5000×, and 93.84% of nuclear regions were covered at least 100×. CONCLUSIONS Our custom Agilent SureSelect MITO-NUCLEAR panel provides a potential "one-step" investigation that may be applied to both research and genetic diagnosis of MDs, allowing the simultaneous discovery of nuclear and mitochondrial mutations.
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Affiliation(s)
- Ferdinando Barretta
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore, 80131 Naples, Italy
| | - Fabiana Uomo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
| | - Filomena Caldora
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
| | - Rossella Mocerino
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
| | - Daniela Adamo
- Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, 80131 Naples, Italy
| | - Francesco Testa
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania Luigi Vanvitelli, 80138 Naples, Italy
| | - Olga Scudiero
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore, 80131 Naples, Italy
| | - Nadia Tinto
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore, 80131 Naples, Italy
| | - Giulia Frisso
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore, 80131 Naples, Italy
| | - Cristina Mazzaccara
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore, 80131 Naples, Italy
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11
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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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12
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Evaluation of a Less Invasive Cochlear Implant Surgery in OPA1 Mutations Provoking Deafblindness. Genes (Basel) 2023; 14:genes14030627. [PMID: 36980899 PMCID: PMC10048538 DOI: 10.3390/genes14030627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/10/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
Cochlear implantation (CI) for deafblindness may have more impact than for non-syndromic hearing loss. Deafblind patients have a double handicap in a society that is more and more empowered by fast communication. CI is a remedy for deafness, but requires revision surgery every 20 to 25 years, and thus placement should be minimally invasive. Furthermore, failed reimplantation surgery will have more impact on a deafblind person. In this context, we assessed the safety of minimally invasive robotically assisted cochlear implant surgery (RACIS) for the first time in a deafblind patient. Standard pure tone audiometry and speech audiometry were performed in a patient with deafblindness as part of this robotic-assisted CI study before and after surgery. This patient, with an optic atrophy 1 (OPA1) (OMIM#165500) mutation consented to RACIS for the second (contralateral) CI. The applicability and safety of RACIS were evaluated as well as her subjective opinion on her disability. RACIS was uneventful with successful surgical and auditory outcomes in this case of deafblindness due to the OPA1 mutation. RACIS appears to be a safe and beneficial intervention to increase communication skills in the cases of deafblindness due to an OPA1 mutation. The use of RACIS use should be widespread in deafblindness as it minimizes surgical trauma and possible failures.
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13
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Jun JW, Seo Y, Han SH, Han J. The importance of genome sequencing: unraveling SSBP1 variant missed by exome sequencing. Ophthalmic Genet 2022; 44:286-290. [PMID: 35946466 DOI: 10.1080/13816810.2022.2109685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
BACKGROUND Single-stranded DNA-binding protein 1 (SSBP1) plays an essential role in mitochondrial DNA (mtDNA) replication and maintenance, as well as development of retina. Here, we describe the clinical findings and genetic basis of a family with two members affected with bilateral optic atrophy. MATERIALS AND METHODS Clinical data were retrospectively collected from an electronic medical record system. Genetic results were obtained using exome sequencing (ES) and genome sequencing (GS). RESULTS A 36-year-old man presented with low vision in both eyes since early childhood, with a best-corrected visual acuity of 20/500 in both eyes. He exhibited generalized optic atrophy and diffuse retinal nerve fiber layer thinning without retinal degeneration in both eyes. The family history was consistent with autosomal dominant traits. ES was performed; however, we did not identify any pathogenic variants in the known dominant optic atrophy genes. Subsequently, GS was performed, and it revealed a novel heterozygous c.364A>G p.(Lys122Glu) variant in SSBP1. In silico prediction supported it as deleterious, while segregation analysis detected it in his affected mother and his unaffected sister. No foveopathy or retinal degeneration was observed in the patient's family members. CONCLUSIONS We report a novel pathogenic heterozygous SSBP1 variant in a family with autosomal dominant optic atrophy and incomplete penetrance. Furthermore, we demonstrated that GS is advantageous over ES even for the discovery of coding variants, providing uniform coverage. Therefore, GS should be emphasized to improve the molecular diagnostic rate of inherited optic neuropathy.
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Affiliation(s)
- Jae Won Jun
- Department of Ophthalmology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Yuri Seo
- Department of Ophthalmology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea
| | - Sueng-Han Han
- Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jinu Han
- Department of Ophthalmology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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14
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Chang YH, Kang EYC, Liu PK, Levi SR, Wang HH, Tseng YJ, Seo GH, Lee H, Yeh LK, Chen KJ, Wu WC, Lai CC, Liu L, Wang NK. Photoreceptor Manifestations of Primary Mitochondrial Optic Nerve Disorders. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 35506936 PMCID: PMC9078049 DOI: 10.1167/iovs.63.5.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose To compare the manifestations of photoreceptors (PRs) in three hereditary optic neuropathies affected by primary mitochondrial dysfunction and discuss whether the retinal ganglion cells (RGCs) or the PRs are preferentially affected. Methods A retrospective analysis of patients with genetically confirmed diagnoses of optic neuropathies associated with mitochondrial dysfunction was performed. This cohort included Leber's hereditary optic neuropathy (LHON), autosomal dominant optic atrophy type 1 (OPA1), and optic atrophy type 13 (OPA13). Patient chart evaluations included clinical characteristics, best-corrected visual acuity (BCVA), fundus photography, spectral-domain optical coherence tomography (SD-OCT), electroretinogram (ERG), and visual evoked potential data. Results This analysis included seven patients with LHON, six with OPA1, and one with OPA13 from a tertiary medical center. Thirteen of the 14 individuals were male. The average BCVA at diagnosis was 20/285 and 20/500 in the right and left eyes, respectively. Five of the seven patients with LHON, and three of the six patients with OPA1 also showed a mild amplitude reduction or delayed latency on light-adapted ERG and 30-Hz flicker responses; however, SD-OCT imaging did not show correlated PR abnormalities. Notably, a 7-year follow-up of a patient with OPA13 revealed degeneration of RGCs prior to the degeneration of PRs. Follow-up data also demonstrated continuous loss of cone outer segment tips on SD-OCT imaging. Conclusions RGCs are, in general, affected by mitochondrial dysfunction, whereas variable PR dysfunction exists in patients with LHON and OPA1, especially with respect to the cone responses. Involvement of PRs is particularly evident in OPA13 after RGC degenerations.
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Affiliation(s)
- Yin-Hsi Chang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Eugene Yu-Chuan Kang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Pei-Kang Liu
- Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan.,Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, New York, United States
| | - Sarah R Levi
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, New York, United States
| | - Hung-Hsuan Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, New York, United States
| | - Yun-Ju Tseng
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, New York, United States
| | - Go Hun Seo
- Division of Medical Genetics, 3billion, Inc., Seoul, South Korea
| | - Hane Lee
- Division of Medical Genetics, 3billion, Inc., Seoul, South Korea
| | - Lung-Kun Yeh
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Kuan-Jen Chen
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wei-Chi Wu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chi-Chun Lai
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Department of Ophthalmology, Chang Gung Memorial Hospital, Keelung, Taiwan
| | - Laura Liu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan.,School of Traditional Chinese Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Nan-Kai Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, New York, New York, United States
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15
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Prevalence of Macular Microcystoid Lacunae in Autosomal Dominant Optic Atrophy Assessed With Adaptive Optics. J Neuroophthalmol 2022; 42:328-333. [PMID: 35439206 DOI: 10.1097/wno.0000000000001592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND To assess the prevalence of macular microcystoid lacunae in patients with autosomal dominant optic atrophy (ADOA) and its association with visual function and inner retinal morphology. METHODS The study included 140 participants with ADOA, with a mean age of 44 (SD ±19, range 7-82) years. Study participants with a genetically verified sequence variant in the OPA1 gene were examined with best-corrected visual acuity, contrast sensitivity, optical coherence tomography (Spectralis, Heidelberg) and adaptive optics fundus photography (rtx1, Imagine Eyes). Optically empty microcystoid spaces in the ganglion cell layer and inner plexiform layer were mapped by inspection of the 2 sets of images. Data were analyzed with a mixed model adjusted for age and sex with family and individual as random effect. RESULTS Microcystoid lacunae were present in 32 of 140 participants (23%) including 18 males and 14 females. Microcystoid lacunae were associated with younger age (P = 0.0503) and a smaller nerve fiber layer volume (P = 0.035). No association was found between presence of microcystoid lacunae and visual acuity (P = 0.2), contrast sensitivity (P = 0.8), axial length (P = 0.7), or ganglion cell layer volume (P = 0.2). The analysis showed moderately reduced visual acuity in patients with microcystoid lacunae. Normal and severely impaired visual function were seen only in participants without microcystoid lacunae. CONCLUSION In ADOA, macular microcystoid lacunae were found in 23% of the study participants and tended to be present in younger participants with moderate visual acuity reduction and a smaller nerve fiber layer volume. Further studies are needed to investigate whether cavities left by dead ganglion cells are predictors of decrease in visual function.
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16
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Choi YS, Oh JH, Hwang SK, Chun BY. Dominant Optic Atrophy Caused by the c.1334G>A Mutation of the OPA1 Gene. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2022. [DOI: 10.3341/jkos.2022.63.3.325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Purpose: Dominant optic atrophy is one of the most common hereditary optic neuropathies, causing progressive bilateral vision loss that begins early in life. Optic atrophy 1 (OPA1) gene mutation brings about mitochondrial dysfunction, which results in clinical manifestations of dominant optic atrophy. Here, we report a case of dominant optic atrophy caused by the c.1334G>A mutation of the OPA1 gene, the first known case in Korea to our knowledge.Case summary: A 12-year-old female patient with no specific medical history or systemic symptoms visited our clinic complaining of a progressive decrease in vision in either eye. Slit-lamp microscopy, intraocular pressure, ocular motility, and pupil reflex were normal. However, her best-corrected visual acuity in both eyes was 20/100, and her color vision was reduced to 8/12 in Ishihara’s test. Fundus examination showed temporal pallor of the optic nerve head in both eyes, and a corresponding cecocentral scotoma was observed on Goldmann visual field examination. Optical coherence tomography revealed significant thinning of the peripapillary retinal fiber layer and macular ganglion cell layer in both eyes. Genetic examination confirmed the c.1334G>A mutation of the OPA1 gene.Conclusions: We report a case of dominant optic nerve atrophy caused by c.1334G>A mutation of the OPA1 gene and its clinical manifestations.
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17
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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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18
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Harvey JP, Sladen PE, Yu-Wai-Man P, Cheetham ME. Induced Pluripotent Stem Cells for Inherited Optic Neuropathies-Disease Modeling and Therapeutic Development. J Neuroophthalmol 2022; 42:35-44. [PMID: 34629400 DOI: 10.1097/wno.0000000000001375] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Inherited optic neuropathies (IONs) cause progressive irreversible visual loss in children and young adults. There are limited disease-modifying treatments, and most patients progress to become severely visually impaired, fulfilling the legal criteria for blind registration. The seminal discovery of the technique for reprogramming somatic nondividing cells into induced pluripotent stem cells (iPSCs) has opened several exciting opportunities in the field of ION research and treatment. EVIDENCE ACQUISITION A systematic review of the literature was conducted with PubMed using the following search terms: autosomal dominant optic atrophy, ADOA, dominant optic atrophy, DOA, Leber hereditary optic neuropathy, LHON, optic atrophy, induced pluripotent stem cell, iPSC, iPSC derived, iPS, stem cell, retinal ganglion cell, and RGC. Clinical trials were identified on the ClinicalTrials.gov website. RESULTS This review article is focused on disease modeling and the therapeutic strategies being explored with iPSC technologies for the 2 most common IONs, namely, dominant optic atrophy and Leber hereditary optic neuropathy. The rationale and translational advances for cell-based and gene-based therapies are explored, as well as opportunities for neuroprotection and drug screening. CONCLUSIONS iPSCs offer an elegant, patient-focused solution to the investigation of the genetic defects and disease mechanisms underpinning IONs. Furthermore, this group of disorders is uniquely amenable to both the disease modeling capability and the therapeutic potential that iPSCs offer. This fast-moving area will remain at the forefront of both basic and translational ION research in the coming years, with the potential to accelerate the development of effective therapies for patients affected with these blinding diseases.
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Affiliation(s)
- Joshua Paul Harvey
- UCL Institute of Ophthalmology (JPH, PES, PY-W-M, MC), London, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust (JPH, PY-W-M), London, United Kingdom; Department of Clinical Neurosciences (PY-W-M), Cambridge Centre for Brain Repair, University of Cambridge, Cambridge, United Kingdom; and Department of Clinical Neurosciences (PY-W-M), John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
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19
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Chen Y, Chen D, Zhao S, Liu G, Li H, Wu ZY. Penetrance estimation of PRRT2 variants in paroxysmal kinesigenic dyskinesia and infantile convulsions. Front Med 2021; 15:877-886. [PMID: 34825340 DOI: 10.1007/s11684-021-0863-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/25/2021] [Indexed: 11/30/2022]
Abstract
Proline-rich transmembrane protein 2 (PRRT2) is the leading cause of paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), and infantile convulsions with choreoathetosis (ICCA). Reduced penetrance of PRRT2 has been observed in previous studies, whereas the exact penetrance has not been evaluated well. The objective of this study was to estimate the penetrance of PRRT2 and determine its influencing factors. We screened 222 PKD index patients and their available relatives, identified 39 families with pathogenic or likely pathogenic (P/LP) PRRT2 variants via Sanger sequencing, and obtained 184 PKD/BFIE/ICCA families with P/LP PRRT2 variants from the literature. Penetrance was estimated as the proportion of affected variant carriers. PRRT2 penetrance estimate was 77.6% (95% confidence interval (CI) 74.5%-80.7%) in relatives and 74.5% (95% CI 70.2%-78.8%) in obligate carriers. In addition, we first observed that penetrance was higher in truncated than in non-truncated variants (75.8% versus 50.0%, P = 0.01), higher in Asian than in Caucasian carriers (81.5% versus 68.5%, P = 0.004), and exhibited no difference in gender or parental transmission. Our results are meaningful for genetic counseling, implying that approximately three-quarters of PRRT2 variant carriers will develop PRRT2-related disorders, with patients from Asia or carrying truncated variants at a higher risk.
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Affiliation(s)
- Yulan Chen
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Dianfu Chen
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Shaoyun Zhao
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Gonglu Liu
- Department of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, 200040, China
| | - Hongfu Li
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China.
| | - Zhi-Ying Wu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China.
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20
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Strachan EL, Mac White-Begg D, Crean J, Reynolds AL, Kennedy BN, O’Sullivan NC. The Role of Mitochondria in Optic Atrophy With Autosomal Inheritance. Front Neurosci 2021; 15:784987. [PMID: 34867178 PMCID: PMC8634724 DOI: 10.3389/fnins.2021.784987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Optic atrophy (OA) with autosomal inheritance is a form of optic neuropathy characterized by the progressive and irreversible loss of vision. In some cases, this is accompanied by additional, typically neurological, extra-ocular symptoms. Underlying the loss of vision is the specific degeneration of the retinal ganglion cells (RGCs) which form the optic nerve. Whilst autosomal OA is genetically heterogenous, all currently identified causative genes appear to be associated with mitochondrial organization and function. However, it is unclear why RGCs are particularly vulnerable to mitochondrial aberration. Despite the relatively high prevalence of this disorder, there are currently no approved treatments. Combined with the lack of knowledge concerning the mechanisms through which aberrant mitochondrial function leads to RGC death, there remains a clear need for further research to identify the underlying mechanisms and develop treatments for this condition. This review summarizes the genes known to be causative of autosomal OA and the mitochondrial dysfunction caused by pathogenic mutations. Furthermore, we discuss the suitability of available in vivo models for autosomal OA with regards to both treatment development and furthering the understanding of autosomal OA pathology.
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Affiliation(s)
- Elin L. Strachan
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Delphi Mac White-Begg
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - John Crean
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Alison L. Reynolds
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Breandán N. Kennedy
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Niamh C. O’Sullivan
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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21
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Zhang XH, Xie Y, Xu QG, Cao K, Xu K, Jin ZB, Li Y, Wei SH. Mitochondrial Mutations in Ethambutol-Induced Optic Neuropathy. Front Cell Dev Biol 2021; 9:754676. [PMID: 34676220 PMCID: PMC8525703 DOI: 10.3389/fcell.2021.754676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/15/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Ethambutol-induced optic neuropathy (EON) is a well-recognized ocular complication in patients who take ethambutol as a tuberculosis treatment. The aim of the current study was to investigate the presence of mitochondrial mutations, including OPA1 and Leber's hereditary optic neuropathy (LHON)-mitochondrial DNA (mtDNA), in patients with EON and to determine their effect on clinical features of these patients. Methods: All 47 patients underwent clinical evaluations, including best-corrected visual acuity, fundus examination, and color fundus photography; 37 patients were then followed up over time. Molecular screening methods, including PCR-based sequencing of the OPA1 gene and LHON-mtDNA mutations, together with targeted exome sequencing, were used to detect mutations. Results: We detected 15 OPA1 mutations in 18 patients and two LHON-mtDNA mutations in four patients, for an overall mutation detection rate of 46.8%. The mean presentation age was significantly younger in the patients with the mitochondrial mutations (27.5 years) than in those without mutations (48 years). Fundus examination revealed a greater prevalence of optic disc hyperemia in the patients with mutations (70.5%) than without mutations (48%). Half of the patients with mutations and 91% of the patients without mutations had improved vision. After adjusting for confounders, the logistic regression revealed that the patients with optic disc pallor on the first visit (p = 0.004) or the patients with the mitochondrial mutations (p < 0.001) had a poorer vision prognosis. Conclusion: Our results indicated that carriers with OPA1 mutations might be more vulnerable for the toxicity of EMB to develop EON.
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Affiliation(s)
- Xiao-Hui Zhang
- Department of Ophthalmology, The Chinese People's Liberation Army General Hospital, The Chinese People's Liberation Army Medical School, Beijing, China.,Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yue Xie
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Quan-Gang Xu
- Department of Ophthalmology, The Chinese People's Liberation Army General Hospital, The Chinese People's Liberation Army Medical School, Beijing, China
| | - Kai Cao
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ke Xu
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Zi-Bing Jin
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yang Li
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shi-Hui Wei
- Department of Ophthalmology, The Chinese People's Liberation Army General Hospital, The Chinese People's Liberation Army Medical School, Beijing, China
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22
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Meunier I, Bocquet B, Defoort-Dhellemmes S, Smirnov V, Arndt C, Picot MC, Dollfus H, Charif M, Audo I, Huguet H, Zanlonghi X, Lenaers G. Characterization of SSBP1-related optic atrophy and foveopathy. Sci Rep 2021; 11:18703. [PMID: 34548540 PMCID: PMC8455542 DOI: 10.1038/s41598-021-98150-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 09/03/2021] [Indexed: 11/17/2022] Open
Abstract
Dominant optic atrophy (DOA) is genetically heterogeneous and most commonly caused by mutations in OPA1. To distinguish between the classical OPA1-related and the recently identified SSBP1-related DOAs, the retina and fovea of 27 patients carrying the SSBP1 p.Arg38Gln variant were scrutinized using 20° × 20° macular cube and 30° and 55° field fundus autofluorescence photographs. Age of onset, visual acuity, retinal nerve fiber layer and macular thicknesses were recorded. Three SSBP1-patients were asymptomatic, 10 had isolated DOA, and 12 had a combined DOA plus foveopathy. The foveopathy, with a tiny defect of the ellipsoid and interdigitation lines, was similar in all patients, independent of age. There were no significant statistical differences in terms of visual acuity and SD-OCT measurements between patients with isolated DOA (mean visual acuity in decimals: 0.54 ± 0.41) and those with combined foveopathy (0.50 ± 0.23). Two patients over 50 years of age developed a progressive rod-cone dystrophy, leading to severe visual impairment. SSBP1-related DOA shares similarities with OPA1-related DOA with an incomplete penetrance and an early childhood visual impairment. Nevertheless, the presence of a congenital foveopathy with no impact on visual acuity is a major criterion to distinguish SSBP1 cases and orient the appropriate genetic analysis.
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Affiliation(s)
- Isabelle Meunier
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France. .,Sensgene Care Network, Strasbourg, France. .,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France.
| | - Béatrice Bocquet
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France.,Sensgene Care Network, Strasbourg, France.,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France
| | - Sabine Defoort-Dhellemmes
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Vasily Smirnov
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Carl Arndt
- Department of Ophthalmology, University Hospital of Reims, Reims, France
| | - Marie Christine Picot
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Hélène Dollfus
- Sensgene Care Network, Strasbourg, France.,Department of Ophthalmology, National Center for Rare Disorders in Ophthalmic Genetics CARGO, Strasbourg Hospital, Strasbourg, France
| | - Majida Charif
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Isabelle Audo
- Sensgene Care Network, Strasbourg, France.,CNRS, INSERM, Institut de la Vision, Sorbonne Université, Paris, France.,DHU Sight Restore, INSERM-DHOS CIC1423, CHNO des Quinze-Vingts, Paris, France
| | - Hélèna Huguet
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Xavier Zanlonghi
- Sensgene Care Network, Strasbourg, France.,Clinic Jules Verne, Nantes, France.,Department of Ophthalmology, University Hospital of Rennes, Rennes, France
| | - Guy Lenaers
- UMR CNRS 6015 - INSERM U1083, University of Angers MitoLab Team, University Hospital of Angers, Angers, France
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23
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Raviskanthan S, Ahuja P, Mortensen PW, Milea D, Lee AG. Delayed diagnosis of autosomal dominant optic atrophy until seventh decade of life. Can J Ophthalmol 2021; 57:e96-e100. [PMID: 34534508 DOI: 10.1016/j.jcjo.2021.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/05/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022]
Affiliation(s)
| | - Pranati Ahuja
- School of Medicine, University of Texas Medical Branch, Galveston, Tex
| | | | - Dan Milea
- Singapore National Eye Center, Singapore;; Singapore Eye Research Institute, Singapore;; Duke-NUS Medical School, Singapore;; Copenhagen University Hospital, Copenhagen, Denmark
| | - Andrew G Lee
- Blanton Eye Institute, Houston Methodist Hospital, Houston, Tex.;; Weill Cornell Medicine, New York, NY;; University of Texas Medical Branch, Galveston, Tex.;; University of Texas MD Anderson Cancer Center, Houston, Tex.;; Texas A&M College of Medicine, Bryan, Tex.;; University of Iowa Hospitals and Clinics, Iowa City, Iowa;.
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24
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Meunier I, Bocquet B, Charif M, Dhaenens CM, Manes G, Amati-Bonneau P, Roubertie A, Zanlonghi X, Lenaers G. A ROD-CONE DYSTROPHY IS SYSTEMATICALLY ASSOCIATED TO THE RTN4IP1 RECESSIVE OPTIC ATROPHY. Retina 2021; 41:1771-1779. [PMID: 33315831 PMCID: PMC8297537 DOI: 10.1097/iae.0000000000003054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE RTN4IP1 biallelic mutations cause a recessive optic atrophy, sometimes associated to more severe neurological syndromes, but so far, no retinal phenotype has been reported in RTN4IP1 patients, justifying their reappraisal. METHODS Seven patients from four families carrying biallelic RTN4IP1 variants were retrospectively reviewed, with emphasis on their age of onset, visual acuity, multimodal imaging including color and autofluorescence frames, spectral-domain optical coherence tomography with RNFL and macular analyses. RESULTS Seven patients from four RTN4IP1 families developed in their first decade of life a bilateral recessive optic atrophy with severe central visual loss, and primary nystagmus developed in 5 of 7 patients. Six patients were legally blind. In a second stage, the seven individuals developed a rod-cone dystrophy, sparing the macular zone and the far periphery. This retinal damage was identified by 55° field fundus autofluorescence frames and also by spectral-domain optical coherence tomography scans of the temporal part of the macular zone in five of the seven patients. Full-field electroretinography measurements disclosed reduced b-wave amplitude of the rod responses in all patients but two. Family 4 with the p.R103H and c.601A > T (p.K201*) truncating mutation had further combined neurological signs with cerebellar ataxia, seizures, and intellectual disability. CONCLUSION RTN4IP1 recessive optic atrophy is systematically associated to a rod-cone dystrophy, which suggests that both the retinal ganglion cells and the rods are affected as a result of a deficit in the mitochondrial respiratory chain. Thus, systematic widefield autofluorescence frames and temporal macular scans are recommended for the evaluation of patients with optic neuropathies.
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Affiliation(s)
- Isabelle Meunier
- Institute for Neurosciences of Montpellier U1051, University of Montpellier, Montpellier, France
- National Center in Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Béatrice Bocquet
- Institute for Neurosciences of Montpellier U1051, University of Montpellier, Montpellier, France
- National Center in Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Majida Charif
- Genetics, and Immuno-cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Claire-Marie Dhaenens
- Biochemistry and Molecular Biology Department—UF Génopathies, Univ Lille, Lille, France
| | - Gael Manes
- Institute for Neurosciences of Montpellier U1051, University of Montpellier, Montpellier, France
| | | | - Agathe Roubertie
- Institute for Neurosciences of Montpellier U1051, University of Montpellier, Montpellier, France
- National Center in Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | | | - Guy Lenaers
- MitoLab Team, UMR CNRS 6015—INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France
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25
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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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26
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Lenaers G, Neutzner A, Le Dantec Y, Jüschke C, Xiao T, Decembrini S, Swirski S, Kieninger S, Agca C, Kim US, Reynier P, Yu-Wai-Man P, Neidhardt J, Wissinger B. Dominant optic atrophy: Culprit mitochondria in the optic nerve. Prog Retin Eye Res 2021; 83:100935. [PMID: 33340656 DOI: 10.1016/j.preteyeres.2020.100935] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022]
Abstract
Dominant optic atrophy (DOA) is an inherited mitochondrial disease leading to specific degeneration of retinal ganglion cells (RGCs), thus compromising transmission of visual information from the retina to the brain. Usually, DOA starts during childhood and evolves to poor vision or legal blindness, affecting the central vision, whilst sparing the peripheral visual field. In 20% of cases, DOA presents as syndromic disorder, with secondary symptoms affecting neuronal and muscular functions. Twenty years ago, we demonstrated that heterozygous mutations in OPA1 are the most frequent molecular cause of DOA. Since then, variants in additional genes, whose functions in many instances converge with those of OPA1, have been identified by next generation sequencing. OPA1 encodes a dynamin-related GTPase imported into mitochondria and located to the inner membrane and intermembrane space. The many OPA1 isoforms, resulting from alternative splicing of three exons, form complex homopolymers that structure mitochondrial cristae, and contribute to fusion of the outer membrane, thus shaping the whole mitochondrial network. Moreover, OPA1 is required for oxidative phosphorylation, maintenance of mitochondrial genome, calcium homeostasis and regulation of apoptosis, thus making OPA1 the Swiss army-knife of mitochondria. Understanding DOA pathophysiology requires the understanding of RGC peculiarities with respect to OPA1 functions. Besides the tremendous energy requirements of RGCs to relay visual information from the eye to the brain, these neurons present unique features related to their differential environments in the retina, and to the anatomical transition occurring at the lamina cribrosa, which parallel major adaptations of mitochondrial physiology and shape, in the pre- and post-laminar segments of the optic nerve. Three DOA mouse models, with different Opa1 mutations, have been generated to study intrinsic mechanisms responsible for RGC degeneration, and these have further revealed secondary symptoms related to mitochondrial dysfunctions, mirroring the more severe syndromic phenotypes seen in a subgroup of patients. Metabolomics analyses of cells, mouse organs and patient plasma mutated for OPA1 revealed new unexpected pathophysiological mechanisms related to mitochondrial dysfunction, and biomarkers correlated quantitatively to the severity of the disease. Here, we review and synthesize these data, and propose different approaches for embracing possible therapies to fulfil the unmet clinical needs of this disease, and provide hope to affected DOA patients.
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Affiliation(s)
- Guy Lenaers
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France.
| | - Albert Neutzner
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland.
| | - Yannick Le Dantec
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France
| | - Christoph Jüschke
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Ting Xiao
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Sarah Decembrini
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland
| | - Sebastian Swirski
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Sinja Kieninger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Cavit Agca
- Molecular Biology, Genetics and Bioengineering Program, Sabanci University, Istanbul, Turkey; Nanotechnology Research and Application Center (SUNUM), Sabanci University, Istanbul, Turkey
| | - Ungsoo S Kim
- Kim's Eye Hospital, Seoul, South Korea; Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France; Department of Biochemistry, University Hospital of Angers, Angers, France
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK; UCL Institute of Ophthalmology, University College London, London, UK
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany.
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany.
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27
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Xu X, Wang P, Jia X, Sun W, Li S, Xiao X, Hejtmancik JF, Zhang Q. Pathogenicity evaluation and the genotype-phenotype analysis of OPA1 variants. Mol Genet Genomics 2021; 296:845-862. [PMID: 33884488 DOI: 10.1007/s00438-021-01783-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 04/02/2021] [Indexed: 12/21/2022]
Abstract
Autosomal dominant optic atrophy (ADOA) is an important cause of irreversible visual impairment in children and adolescents. About 60-90% of ADOA is caused by the pathogenic variants of OPA1 gene. By evaluating the pathogenicity of OPA1 variants and summarizing the relationship between the genotype and phenotype, this study aimed to provide a reference for clinical genetic test involving OPA1. Variants in OPA1 were selected from the exome sequencing results in 7092 cases of hereditary eye diseases and control groups from our in-house data. At the same time, the urine cells of some optic atrophy patients with OPA1 variants as well as their family members were collected and oxygen consumption rates (OCR) were measured in these cells to evaluate the pathogenicity of variants. As a result, 97 variants were detected, including 94 rare variants and 3 polymorphisms. And the 94 rare variants were classified into three groups: pathogenic (33), variants of uncertain significance (19), and likely benign (42). Our results indicated that the frameshift variants at the 3' terminus might be pathogenic, while the variants in exon 7 and intron 4 might be benign. The penetrance of the missense variants was higher than that of truncation variants. The OCR of cells with pathogenic OPA1 variants were significantly lower than those without pathogenic variants. In conclusion, some variants might be benign although predicted pathogenic in previous studies while some might have unknown pathogenesis. Measuring the OCR in urine cells could be used as a method to evaluate the pathogenicity of some OPA1 variants.
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Affiliation(s)
- Xingyu Xu
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China.
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28
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Sharma G, Pfeffer G, Shutt TE. Genetic Neuropathy Due to Impairments in Mitochondrial Dynamics. BIOLOGY 2021; 10:268. [PMID: 33810506 PMCID: PMC8066130 DOI: 10.3390/biology10040268] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 12/12/2022]
Abstract
Mitochondria are dynamic organelles capable of fusing, dividing, and moving about the cell. These properties are especially important in neurons, which in addition to high energy demand, have unique morphological properties with long axons. Notably, mitochondrial dysfunction causes a variety of neurological disorders including peripheral neuropathy, which is linked to impaired mitochondrial dynamics. Nonetheless, exactly why peripheral neurons are especially sensitive to impaired mitochondrial dynamics remains somewhat enigmatic. Although the prevailing view is that longer peripheral nerves are more sensitive to the loss of mitochondrial motility, this explanation is insufficient. Here, we review pathogenic variants in proteins mediating mitochondrial fusion, fission and transport that cause peripheral neuropathy. In addition to highlighting other dynamic processes that are impacted in peripheral neuropathies, we focus on impaired mitochondrial quality control as a potential unifying theme for why mitochondrial dysfunction and impairments in mitochondrial dynamics in particular cause peripheral neuropathy.
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Affiliation(s)
- Govinda Sharma
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Gerald Pfeffer
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, Hotchkiss Brain Institute, Alberta Child Health Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Timothy E. Shutt
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
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29
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Functions of outer mitochondrial membrane proteins: mediating the crosstalk between mitochondrial dynamics and mitophagy. Cell Death Differ 2021; 28:827-842. [PMID: 33208889 PMCID: PMC7937681 DOI: 10.1038/s41418-020-00657-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/13/2020] [Accepted: 10/23/2020] [Indexed: 01/30/2023] Open
Abstract
Most cellular stress responses converge on the mitochondria. Consequently, the mitochondria must rapidly respond to maintain cellular homeostasis and physiological demands by fine-tuning a plethora of mitochondria-associated processes. The outer mitochondrial membrane (OMM) proteins are central to mediating mitochondrial dynamics, coupled with continuous fission and fusion. These OMM proteins also have vital roles in controlling mitochondrial quality and serving as mitophagic receptors for autophagosome enclosure during mitophagy. Mitochondrial fission segregates impaired mitochondria in smaller sizes from the mother mitochondria and may favor mitophagy for eliminating damaged mitochondria. Conversely, mitochondrial fusion mixes dysfunctional mitochondria with healthy ones to repair the damage by diluting the impaired components and consequently prevents mitochondrial clearance via mitophagy. Despite extensive research efforts into deciphering the interplay between fission-fusion and mitophagy, it is still not clear whether mitochondrial fission essentially precedes mitophagy. In this review, we summarize recent breakthroughs concerning OMM research, and dissect the functions of these proteins in mitophagy from their traditional roles in fission-fusion dynamics, in response to distinct context, at the intersection of the OMM platform. These insights into the OMM proteins in mechanistic researches would lead to new aspects of mitochondrial quality control and better understanding of mitochondrial homeostasis intimately tied to pathological impacts.
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30
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Lock JH, Irani NK, Newman NJ. Neuro-ophthalmic manifestations of mitochondrial disorders and their management. Taiwan J Ophthalmol 2020; 11:39-52. [PMID: 33767954 PMCID: PMC7971441 DOI: 10.4103/tjo.tjo_68_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 09/23/2020] [Indexed: 12/30/2022] Open
Abstract
The visual system has high metabolic requirements and is therefore particularly vulnerable to mitochondrial dysfunction. The most commonly affected tissues include the extraocular muscles, photoreceptors, retinal pigment epithelium, optic nerve and visual cortex. Hence, the most common manifestations of mitochondrial disorders are progressive external ophthalmoplegia, macular pattern dystrophy, pigmentary retinopathy, optic neuropathy and retrochiasmal visual field loss. With the exception of Leber hereditary optic neuropathy and stroke-like episodes seen in mitochondrial encephalopathy, lactic acidosis and stroke-like episodes, the majority of neuro-ophthalmic manifestations have an insidious onset. As such, some patients may not recognize subtle progressive visual symptoms. When mitochondrial disorders are highly suspected, meticulous examination performed by an ophthalmologist with targeted ancillary testing can help confirm the diagnosis. Similarly, neuro-ophthalmic symptoms and signs may be the first indication of mitochondrial disease and should prompt systemic investigations for potentially life-threatening associations, such as cardiac conduction defects. Finally, the ophthalmologist can offer symptomatic treatments for some of the most disabling manifestations of these disorders.
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Affiliation(s)
- Jane H Lock
- Department of Ophthalmology, Royal Perth Hospital, Perth, WA, Australia.,Department of Ophthalmology, Sir Charles Gairdner Hospital, Perth, WA, Australia.,Department of Ophthalmology, Perth's Children's Hospital, Perth, WA, Australia
| | - Neha K Irani
- Department of Ophthalmology, Royal Perth Hospital, Perth, WA, Australia.,Department of Neurology, Fiona Stanley Hospital, Perth, WA, Australia.,Department of Neurology, Joondalup Health Campus, Perth, WA, Australia
| | - Nancy J Newman
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.,Department of Neurological Surgery, Emory University School of Medicine, Atlanta, GA, USA
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31
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Li JK, Li W, Gao FJ, Qu SF, Hu FY, Zhang SH, Li LL, Wang ZW, Qiu Y, Wang LS, Huang J, Wu JH, Chen F. Mutation Screening of mtDNA Combined Targeted Exon Sequencing in a Cohort With Suspected Hereditary Optic Neuropathy. Transl Vis Sci Technol 2020; 9:11. [PMID: 32855858 PMCID: PMC7422818 DOI: 10.1167/tvst.9.8.11] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/23/2020] [Indexed: 12/02/2022] Open
Abstract
Purpose Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (ADOA) are the two commonest forms of hereditary optic neuropathy. The aim of this study was to comprehensively investigate the incidence and spectrum of mutations in patients with suspected hereditary optic neuropathy by combining mitochondrial DNA (mtDNA) genome-wide and targeted exon sequencing. Methods A cohort of 1101 subjects were recruited to participate in the study, comprising 177 families (177 probands and their family members, a total of 537 subjects, including 254 patients) and 164 sporadic cases with suspected hereditary optic neuropathy, and 400 unrelated control subjects for genetic analysis: all subjects (including control subjects) underwent a comprehensive ophthalmologic examination and were subjected to sequencing analysis of mtDNA genome-wide and targeted exon. Overall, targeted exon sequencing was used to screen 792 genes associated with common hereditary eye diseases, and the mtDNA genome-wide were screened by next-generation sequencing. Results We found variants detected in 168 (40.2%, 168/418) of the 418 patients screened. Among these, 132 cases (78.6%, 132/168) were detected with known LHON disease-causing mtDNA variants; 40 cases (23.8%, 40/168) were detected with nuclear DNA (ntDNA) variants, which included 36 cases (21.4%, 36/168) with detected OPA1 mutations, 4 patients (2.4%, 4/168) with detected OPA3 mutations, and 2 patients (1.2%, 2/168) with detected TMEM126A homozygous mutation. Coexistence variation (mtDNA/mtDNA [n = 16], ntDNA/ntDNA [n = 4], mtDNA/ntDNA [n = 7]) was found in 27 patients (16.4%, 27/165), including mtDNA/ntDNA coexistence variation that was detected in seven patients. Among these ntDNA mutations, 38 distinct disease-causing variants, including autosomal recessive heterozygous mutations, were detected, which included 22 novel variants and two de novo variants. Total haplogroup distribution showed that 34.5% (29/84) and 28.6% (24/84) of the affected subjects with m.11778G>A belonged to haplogroup D and M, with a high frequency of subhaplogroups D4, D5, and M7. Conclusions The LHON-mtDNA mutations are the commonest genetic defects in this Chinese cohort, followed by the OPA1 mutations. To our knowledge, this is the first comprehensive study of LHON, ADOA, and autosomal recessive optic atrophy combined with mtDNA genome-wide and targeted exon sequencing, as well as haplogroup analysis, in a large cohort of Chinese patients with suspected hereditary optic neuropathy. Our findings provide a powerful basis for genetic counseling in patients with suspected hereditary optic neuropathy. Translational Relevance We applied mtDNA genome-wide sequencing combined with panel-based targeted exon sequencing to explore the pathogenic variation spectrum and genetic characteristics of patients with suspected hereditary optic neuropathy, providing a comprehensive research strategy for clinical assistant diagnosis, treatment, and genetic counseling.
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Affiliation(s)
- Jian-Kang Li
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China.,Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong.,BGI-Shenzhen, Shenzhen, China
| | - Wei Li
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China.,BGI-Shenzhen, Shenzhen, China
| | - Feng-Juan Gao
- Eye Institute, Eye, Ear, Nose and Throat Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China
| | - Shou-Fang Qu
- National Institutes for Food and Drug Control, Tiantan Xili Dongcheng District, Beijing, China
| | - Fang-Yuan Hu
- Eye Institute, Eye, Ear, Nose and Throat Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China
| | - Sheng-Hai Zhang
- Eye Institute, Eye, Ear, Nose and Throat Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China
| | - Li-Li Li
- National Institutes for Food and Drug Control, Tiantan Xili Dongcheng District, Beijing, China
| | - Zi-Wei Wang
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China.,BGI-Shenzhen, Shenzhen, China
| | - Yong Qiu
- BGI-Shenzhen, Shenzhen, China.,MGI, BGI-Shenzhen, Shenzhen, China
| | - Lu-Sheng Wang
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong.,BGI-Shenzhen, Shenzhen, China
| | - Jie Huang
- National Institutes for Food and Drug Control, Tiantan Xili Dongcheng District, Beijing, China
| | - Ji-Hong Wu
- Eye Institute, Eye, Ear, Nose and Throat Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen, China.,MGI, BGI-Shenzhen, Shenzhen, China
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Baderna V, Schultz J, Kearns LS, Fahey M, Thompson BA, Ruddle JB, Huq A, Maltecca F. A novel AFG3L2 mutation close to AAA domain leads to aberrant OMA1 and OPA1 processing in a family with optic atrophy. Acta Neuropathol Commun 2020; 8:93. [PMID: 32600459 PMCID: PMC7325028 DOI: 10.1186/s40478-020-00975-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 06/19/2020] [Indexed: 12/14/2022] Open
Abstract
Autosomal dominant optic atrophy (ADOA) is a neuro-ophthalmic condition characterized by bilateral degeneration of the optic nerves. Although heterozygous mutations in OPA1 represent the most common genetic cause of ADOA, a significant number of cases remain undiagnosed. Here, we describe a family with a strong ADOA history with most family members spanning three generation having childhood onset of visual symptoms. The proband, in addition to optic atrophy, had neurological symptoms consistent with relapsing remitting multiple sclerosis. Clinical exome analysis detected a novel mutation in the AFG3L2 gene (NM_006796.2:c.1010G > A; p.G337E), which segregated with optic atrophy in family members. AFG3L2 is a metalloprotease of the AAA subfamily which exerts quality control in the inner mitochondrial membrane. Interestingly, the identified mutation localizes close to the AAA domain of AFG3L2, while those localized in the proteolytic domain cause dominant spinocerebellar ataxia type 28 (SCA28) or recessive spastic ataxia with epilepsy (SPAX5). Functional studies in patient fibroblasts demonstrate that the p.G337E AFG3L2 mutation strongly destabilizes the long isoforms of OPA1 via OMA hyper-activation and leads to mitochondrial fragmentation, thus explaining the family phenotype. This study widens the clinical spectrum of neurodegenerative diseases caused by AFG3L2 mutations, which shall be considered as genetic cause of ADOA.
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33
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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: 27] [Impact Index Per Article: 6.8] [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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34
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Dard L, Blanchard W, Hubert C, Lacombe D, Rossignol R. Mitochondrial functions and rare diseases. Mol Aspects Med 2020; 71:100842. [PMID: 32029308 DOI: 10.1016/j.mam.2019.100842] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 12/19/2022]
Abstract
Mitochondria are dynamic cellular organelles responsible for a large variety of biochemical processes as energy transduction, REDOX signaling, the biosynthesis of hormones and vitamins, inflammation or cell death execution. Cell biology studies established that 1158 human genes encode proteins localized to mitochondria, as registered in MITOCARTA. Clinical studies showed that a large number of these mitochondrial proteins can be altered in expression and function through genetic, epigenetic or biochemical mechanisms including the interaction with environmental toxics or iatrogenic medicine. As a result, pathogenic mitochondrial genetic and functional defects participate to the onset and the progression of a growing number of rare diseases. In this review we provide an exhaustive survey of the biochemical, genetic and clinical studies that demonstrated the implication of mitochondrial dysfunction in human rare diseases. We discuss the striking diversity of the symptoms caused by mitochondrial dysfunction and the strategies proposed for mitochondrial therapy, including a survey of ongoing clinical trials.
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Affiliation(s)
- L Dard
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France
| | - W Blanchard
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France
| | - C Hubert
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France
| | - D Lacombe
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CHU de Bordeaux, Service de Génétique Médicale, F-33076, Bordeaux, France
| | - R Rossignol
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France.
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35
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Mitochondrial disorders and the eye. Surv Ophthalmol 2019; 65:294-311. [PMID: 31783046 DOI: 10.1016/j.survophthal.2019.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 11/16/2019] [Accepted: 11/18/2019] [Indexed: 01/27/2023]
Abstract
Mitochondria are cellular organelles that play a key role in energy metabolism and oxidative phosphorylation. Malfunctioning of mitochondria has been implicated as the cause of many disorders with variable inheritance, heterogeneity of systems involved, and varied phenotype. Metabolically active tissues are more likely to be affected, causing an anatomic and physiologic disconnect in the treating physicians' mind between presentation and underlying pathophysiology. We shall focus on disorders of mitochondrial metabolism relevant to an ophthalmologist. These disorders can affect all parts of the visual pathway (crystalline lens, extraocular muscles, retina, optic nerve, and retrochiasm). After the introduction reviewing mitochondrial structure and function, each disorder is reviewed in detail, including approaches to its diagnosis and most current management guidelines.
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36
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A Missense Mutation in OPA1 Causes Dominant Optic Atrophy in a Chinese Family. J Ophthalmol 2019; 2019:1424928. [PMID: 31781369 PMCID: PMC6875404 DOI: 10.1155/2019/1424928] [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: 01/25/2019] [Revised: 07/23/2019] [Accepted: 09/13/2019] [Indexed: 11/21/2022] Open
Abstract
Background To investigate the genetic causes and clinical characteristics of dominant optic atrophy (DOA) in a Chinese family. Methods A 5-generation pedigree of 35 family members including 12 individuals affected with DOA was recruited from Shenzhen Eye Hospital, China. Four affected family members and one unaffected family member were selected for whole exome sequencing. Sanger sequencing was used to confirm and screen the identified mutation in 18 members of the family. The disease-causing mutation was identified by bioinformatics analysis and confirmed by segregation analysis. The clinical characteristics of the family members were analyzed. Results A heterozygous missense mutation (c.1313A>G, p.D438G) in optic atrophy 1 (OPA1) was identified in 10 individuals affected with DOA in this family. None of the unaffected family members had the mutation. Patients in this family had vision loss since they were children or adolescence. The visual acuity decreased progressively to hand movement, except for one patient (IV-12) who had relatively good vision of 20/30 and 20/28. The fundus typically manifested as optic disc pallor. The visual fields, optical coherence tomography, and visual evoked potential suggested variable degree of abnormality in patients. Patients who had a history of cigarette smoking and alcohol drinking had more severe clinical manifestations. Conclusions Our results suggest that the p.D438G mutation in OPA1 causes optic atrophy in this family. The patients who carried the mutation demonstrated heterogeneous clinical manifestations in this family. This is the first report on the c.1313A>G (p.D438G) mutation of OPA1 in a Chinese family affected with DOA.
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37
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Abstract
PURPOSE OF REVIEW The diagnosis of visual loss from toxic-metabolic and hereditary optic neuropathies may be delayed in some cases because of a failure to elicit important information in the clinical history or to recognize typical examination findings. An understanding of the features specific to each type of toxic-metabolic and hereditary optic neuropathy, and of the underlying mechanism of insult to the optic nerve, could lead to earlier recognition, diagnosis, and treatment (when available). RECENT FINDINGS Understanding of the role of mitochondria in toxic-metabolic and hereditary optic neuropathies is growing, particularly regarding the mechanism of insult of certain agents (medications and toxins) and of vitamin B12 deficiency. New developments in the quest for treatment for hereditary optic neuropathy, specifically Leber hereditary optic neuropathy, are being seen. SUMMARY Toxic-metabolic and hereditary optic neuropathies present in a similar fashion, with painless, progressive, bilateral visual loss with dyschromatopsia and cecocentral visual field defects. The associated retinal ganglion cell and axonal loss is typically due to mitochondrial dysfunction caused by an exogenous agent (toxic), by insufficient or deficient substrate (metabolic or nutritional), or by abnormal proteins or mitochondrial structure determined by a genetic mutation (hereditary).
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38
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Le Roux B, Lenaers G, Zanlonghi X, Amati-Bonneau P, Chabrun F, Foulonneau T, Caignard A, Leruez S, Gohier P, Procaccio V, Milea D, den Dunnen JT, Reynier P, Ferré M. OPA1: 516 unique variants and 831 patients registered in an updated centralized Variome database. Orphanet J Rare Dis 2019; 14:214. [PMID: 31500643 PMCID: PMC6734442 DOI: 10.1186/s13023-019-1187-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/30/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The dysfunction of OPA1, a dynamin GTPase involved in mitochondrial fusion, is responsible for a large spectrum of neurological disorders, each of which includes optic neuropathy. The database dedicated to OPA1 ( https://www.lovd.nl/OPA1 ), created in 2005, has now evolved towards a centralized and more reliable database using the Global Variome shared Leiden Open-source Variation Database (LOVD) installation. RESULTS The updated OPA1 database, which registers all the patients from our center as well as those reported in the literature, now covers a total of 831 patients: 697 with isolated dominant optic atrophy (DOA), 47 with DOA "plus", and 83 with asymptomatic or unclassified DOA. It comprises 516 unique OPA1 variants, of which more than 80% (414) are considered pathogenic. Full clinical data for 118 patients are documented using the Human Phenotype Ontology, a standard vocabulary for referencing phenotypic abnormalities. Contributors may now make online submissions of phenotypes related to OPA1 mutations, giving clinical and molecular descriptions together with detailed ophthalmological and neurological data, according to an international thesaurus. CONCLUSIONS The evolution of the OPA1 database towards the LOVD, using unified nomenclature, should ensure its interoperability with other databases and prove useful for molecular diagnoses based on gene-panel sequencing, large-scale mutation statistics, and genotype-phenotype correlations.
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Affiliation(s)
- Bastien Le Roux
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Guy Lenaers
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
| | - Xavier Zanlonghi
- Centre de Compétence Maladie Rare, Clinique Jules Verne, Nantes, France
| | - Patrizia Amati-Bonneau
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.,Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Floris Chabrun
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.,Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Thomas Foulonneau
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
| | - Angélique Caignard
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Stéphanie Leruez
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Philippe Gohier
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Vincent Procaccio
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.,Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Dan Milea
- Singapore National Eye Center, Singapore Eye Research Institute, Duke-NUS, Singapore, Singapore
| | - Johan T den Dunnen
- Human Genetics and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Pascal Reynier
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.,Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Marc Ferré
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.
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Zou XH, Guo XX, Su HZ, Wang C, Dong EL, Wang N, Chen WJ, Zhang QJ. Whole Exome Sequencing Identifies Two Novel Mutations in the Reticulon 4-Interacting Protein 1 Gene in a Chinese Family with Autosomal Recessive Optic Neuropathies. J Mol Neurosci 2019; 68:640-646. [PMID: 31077085 DOI: 10.1007/s12031-019-01319-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 04/16/2019] [Indexed: 10/26/2022]
Abstract
Autosomal recessive optic neuropathies (IONs) are extremely rare disorders affecting retinal ganglion cells and the nervous system. RTN4IP1 has recently been identified as the third known gene associated with the autosomal recessive ION optic atrophy 10 (OPA10). Patients with RTN4IP1 mutations show early-onset optic neuropathy that can be followed by additional neurological symptoms such as seizures, ataxia, mental retardation, or even severe encephalopathy. Here, we report two siblings from a Chinese family who presented with early-onset optic neuropathy, epilepsy, and mild intellectual disability. Using whole exome sequencing combined with Sanger sequencing, we identified novel compound heterozygous RTN4IP1 mutations (c.646G > A, p.G216R and c.1162C > T, p.R388X) which both co-segregated with the disease phenotype and were predicted to be disease-causing by prediction software. An in vitro functional study in urine cells obtained from one of the patients revealed low expression of the RTN4IP1 protein. Our results identify novel compound heterozygous mutations in RTN4IP1 which are associated with OPA10, highlighting the frequency of RTN4IP1 mutations in human autosomal recessive IONs. To our knowledge, this is the first report of RTN4IP1 carriers from China.
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Affiliation(s)
- Xiao-Huan Zou
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - Xin-Xin Guo
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - Hui-Zhen Su
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - Chong Wang
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - En-Lin Dong
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - Ning Wang
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China.,Department of Neurology and Institute of Neurology, Fujian Medical University, 20 Chazhong Road, Fuzhou, 350005, China
| | - Wan-Jin Chen
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China. .,Department of Neurology and Institute of Neurology, Fujian Medical University, 20 Chazhong Road, Fuzhou, 350005, China.
| | - Qi-Jie Zhang
- Fujian Key Laboratory of Molecular Neurology, Fuzhou, China. .,Department of Neurology and Institute of Neurology, Fujian Medical University, 20 Chazhong Road, Fuzhou, 350005, China.
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40
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Guo H, Li S, Dai L, Huang X, Yu T, Yin Z, Bai Y. Genetic analysis in a cohort of patients with hereditary optic neuropathies in Southwest of China. Mitochondrion 2018; 46:327-333. [PMID: 30201499 DOI: 10.1016/j.mito.2018.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 02/25/2018] [Accepted: 09/04/2018] [Indexed: 11/16/2022]
Abstract
We report the results of molecular screening in 121 patients with suspected hereditary optic neuropathies. The 34 primary and 9 secondary LHON mutations were screened in all the patients. In the familial cases, OPA1 was also tested when negative finding for the mtDNA mutations screening. Molecular defects were identified in 35 patients (28.9% of screened patients). Among these, 33 patients (94.3%) had an mtDNA mutation, including m.11778G > A (69.7%), m.14484 T > C, m.3460G > A, m.3635G > A, m.14502 T > C and three secondary mutations m.3316G > A, m.3394 T > C, m.3497C > T. Two novel OPA1 mutations, c.1301 T > G (p.Leu434Arg) and c.985-1G > A (IVS9-1G > A), were also detected in families with the evidence of father-to-son transmission. In conclusion, we reported the results of the molecular screening of 121 patients with hereditary optic neuropathies from southwest of China. Our results highlight the importance of investigating LHON-causing mtDNA mutations and OPA1 mutations in cases of suspected hereditary optic neuropathy.
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Affiliation(s)
- Hong Guo
- Department of Medical Genetics, Army Medical University, 30#, Gaotanyan St., Shapingba District, Chongqing 400038, PR China
| | - Shiying Li
- Southwest Eye Hospital, Southwest Hospital, Army Medical University, 30#, Gaotanyan St., Shapingba District 400038, Chongqing, PR China
| | - Limeng Dai
- Department of Medical Genetics, Army Medical University, 30#, Gaotanyan St., Shapingba District, Chongqing 400038, PR China
| | - Xiaoyong Huang
- Southwest Eye Hospital, Southwest Hospital, Army Medical University, 30#, Gaotanyan St., Shapingba District 400038, Chongqing, PR China
| | - Tao Yu
- Southwest Eye Hospital, Southwest Hospital, Army Medical University, 30#, Gaotanyan St., Shapingba District 400038, Chongqing, PR China
| | - Zhengqin Yin
- Southwest Eye Hospital, Southwest Hospital, Army Medical University, 30#, Gaotanyan St., Shapingba District 400038, Chongqing, PR China.
| | - Yun Bai
- Department of Medical Genetics, Army Medical University, 30#, Gaotanyan St., Shapingba District, Chongqing 400038, PR China.
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41
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Li H, Jones EM, Li H, Yang L, Sun Z, Yuan Z, Chen R, Dong F, Sui R. Clinical and genetic features of eight Chinese autosomal-dominant optic atrophy pedigrees with six novel OPA1 pathogenic variants. Ophthalmic Genet 2018; 39:569-576. [PMID: 29952689 DOI: 10.1080/13816810.2018.1466337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Autosomal-dominant optic atrophy (ADOA) is one of the most common types of inherited optic atrophy. We identify OPA1 pathogenic variants and assess the clinical features of a cohort of Chinese ADOA patients Materials and Methods: Detailed clinical evaluations were performed and genomic DNA was extracted from peripheral blood for all the participants. Sanger sequencing was used to analyze all exons and exon/intron junctions of OPA1 for eight pedigrees. Target exome capture plus next-generation sequencing (NGS) were applied for one atypical family with photophobia. Reverse transcription polymerase chain reaction was carried out to further characterize the mRNA change of selected splicing alteration. RESULTS All 17 patients had impaired vision and optic-disk pallor; however, the clinical severity varied markedly. Two patients complicated with hearing loss. Six novel and two reported pathogenic variants in OPA1 (GenBank Accession No. NM_130837.2) were identified including four nonsynonymous variants (c.2400T > G, c.1468T > C, c.1567A > G and c.1466T > C), two splicing variants (c.2984-1_2986delGAGA and c.2983 + 5G > A), one small deletion (c.2960_2968delGCGTTCAAC), and one small insertion (c.3009_3010insA). RNA analysis revealed the splicing variant c.2984-1_2986delGAGA caused small deletion of mRNA (r.2983_2988del). CONCLUSIONS ADOA patients presented variable clinical manifestations. Novel OPA1 pathogenic variants are the main genetic defect for Chinese ADOA cases. NGS may be a useful molecular testing tool for atypical ADOA.
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Affiliation(s)
- Huajin Li
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Evan M Jones
- b Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA
| | - Hui Li
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Lizhu Yang
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Zixi Sun
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Zhisheng Yuan
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Rui Chen
- b Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA
| | - Fangtian Dong
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Ruifang Sui
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
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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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Ścieżyńska A, Ruszkowska E, Szulborski K, Rydz K, Wierzbowska J, Kosińska J, Rękas M, Płoski R, Szaflik JP, Ołdak M. Processing of OPA1 with a novel N-terminal mutation in patients with autosomal dominant optic atrophy: Escape from nonsense-mediated decay. PLoS One 2017; 12:e0183866. [PMID: 28841713 PMCID: PMC5571936 DOI: 10.1371/journal.pone.0183866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 08/11/2017] [Indexed: 12/02/2022] Open
Abstract
Autosomal Dominant Optic Atrophy (ADOA) is the most common dominantly inherited optic neuropathy. In the majority of patients it is caused by OPA1 mutations and those predicted to introduce a premature termination codon (PTC) are frequently detected. Transcripts containing PTC may be degraded by nonsense-mediated mRNA decay (NMD), however very little is known about an effect of OPA1 mutations on NMD activation. Here, using a combination of linkage analysis and DNA sequencing, we have identified a novel c.91C>T OPA1 mutation with a putative premature stop codon (Q31*), which segregated with ADOA in two Polish families. At the mRNA level we found no changes in the amount of OPA1 transcript among mutation carriers vs. non-carriers. Specific allele quantification revealed a considerable level of the OPA1 mutant transcript. Our study identifies a novel pathogenic OPA1 mutation and shows that it is located in the transcript region not prone for NMD activation. The data emphasizes the importance of analyzing how mutated genes are being processed in the cell. This gives an insight into the molecular mechanism of a genetic disease and promotes development of innovative therapeutic approaches.
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Affiliation(s)
- Aneta Ścieżyńska
- Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland
| | - Ewelina Ruszkowska
- Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland
| | - Kamil Szulborski
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | - Katarzyna Rydz
- Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland
| | - Joanna Wierzbowska
- Department of Ophthalmology, Military Institute of Medicine, Warsaw, Poland
| | - Joanna Kosińska
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Marek Rękas
- Department of Ophthalmology, Military Institute of Medicine, Warsaw, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | | | - Monika Ołdak
- Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland
- * E-mail:
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Caporali L, Maresca A, Capristo M, Del Dotto V, Tagliavini F, Valentino ML, La Morgia C, Carelli V. Incomplete penetrance in mitochondrial optic neuropathies. Mitochondrion 2017; 36:130-137. [PMID: 28716668 DOI: 10.1016/j.mito.2017.07.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 06/27/2017] [Accepted: 07/13/2017] [Indexed: 01/06/2023]
Abstract
Incomplete penetrance characterizes the two most frequent inherited optic neuropathies, Leber's Hereditary Optic Neuropathy (LHON) and dominant optic atrophy (DOA), due to genetic errors in the mitochondrial DNA (mtDNA) and the nuclear DNA (nDNA), respectively. For LHON, compelling evidence has accumulated on the complex interplay of mtDNA haplogroups and environmental interacting factors, whereas the nDNA remains essentially non informative. However, a compensatory mechanism of activated mitochondrial biogenesis and increased mtDNA copy number, possibly driven by a permissive nDNA background, is documented in LHON; when successful it maintains unaffected the mutation carriers, but in some individuals it might be hampered by tobacco smoking or other environmental factors, resulting in disease onset. In females, mitochondrial biogenesis is promoted and maintained within the compensatory range by estrogens, partially explaining the gender bias in LHON. Concerning DOA, none of the above mechanisms has been fully explored, thus mtDNA haplogroups, environmental factors such as tobacco and alcohol, and further nDNA variants may all participate as protective factors or, on the contrary, favor disease expression and severity. Next generation sequencing, complemented by transcriptomics and proteomics, may provide some answers in the next future, even if the multifactorial model that seems to apply to incomplete penetrance in mitochondrial optic neuropathies remains problematic, and careful stratification of patients will play a key role for data interpretation. The deep understanding of which factors impinge on incomplete penetrance may shed light on the pathogenic mechanisms leading to optic nerve atrophy, on their possible compensation and, thus, on development of therapeutic strategies.
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Affiliation(s)
- Leonardo Caporali
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Alessandra Maresca
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | | | - Valentina Del Dotto
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Francesca Tagliavini
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Maria Lucia Valentino
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
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Kamel K, Farrell M, O'Brien C. Mitochondrial dysfunction in ocular disease: Focus on glaucoma. Mitochondrion 2017; 35:44-53. [PMID: 28499981 DOI: 10.1016/j.mito.2017.05.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 03/08/2017] [Accepted: 05/08/2017] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction commonly presents with ocular findings as a part of a systemic disorder. These ophthalmic manifestations can be the first sign of a mitochondrial abnormality, which highlights the key role of a comprehensive ophthalmic assessment. On the other hand, a number of visually disabling genetic and acquired eye diseases with no curative treatment show abnormal mitochondrial function. Recent advances in mitochondrial research have improved our understanding of previously unexplained ocular disorders utilising better diagnostic approaches. Further studies on mitochondrial dysfunction and novel modalities of treatment will help to improve outcomes of these conditions. In this review article we discuss the clinical picture of common mitochondrial-related eye diseases, diagnostic approaches and possible treatment options including a very recent interesting report about gene therapy, with a particular focus on glaucoma.
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Affiliation(s)
- Khalid Kamel
- Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
| | | | - Colm O'Brien
- Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland.
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Chun BY, Rizzo JF. Dominant Optic Atrophy and Leber's Hereditary Optic Neuropathy: Update on Clinical Features and Current Therapeutic Approaches. Semin Pediatr Neurol 2017; 24:129-134. [PMID: 28941528 DOI: 10.1016/j.spen.2017.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dominant optic atrophy (DOA) and Leber hereditary optic neuropathy (LHON) are the two most common inherited optic neuropathies encountered in clinical practice. This review provides a summary of recent advances in the understanding of the clinical manifestations, current treatments, and ongoing clinical trials of these two optic neuropathies. Substantial progress has been made in the understanding of the clinical, genetic, and pathophysiological basis of DOA and LHON. Pathogenic OPA1 gene mutations in DOA and 3 primary mutations of mitochondrial DNA in LHON-induced mitochondrial dysfunction, which in turn leads to increased reactive oxygen species levels in mitochondria and possibly insufficient ATP production. The pathologic hallmark of these inherited optic neuropathies is primary degeneration of retinal ganglion cells, preferentially in the papillomacular bundle, which results in temporal optic disc pallor and central or cecocentral visual loss. There are no effective treatments for patients with LHON and DOA, although clinical trials are underway for the former. Translational research for these diseases is entering an accelerated phase with the availability of animal models, and a variety of pharmacological and genetic therapies are being developed.
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Affiliation(s)
- Bo Young Chun
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea; Brain Science & Engineering Institute, Kyungpook National University School of Medicine, Daegu, Korea
| | - Joseph F Rizzo
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
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Assessment of the retinal posterior pole in dominant optic atrophy by spectral-domain optical coherence tomography and microperimetry. PLoS One 2017; 12:e0174560. [PMID: 28358911 PMCID: PMC5373574 DOI: 10.1371/journal.pone.0174560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/11/2017] [Indexed: 11/24/2022] Open
Abstract
Background To assess posterior pole (PP) retinal structure in patients with genetically confirmed autosomal dominant optic atrophy (ADOA) using new spectral domain optical coherence tomography (SD-OCT) segmentation technology. To analyze retinal PP thickness in relation to retinal sensitivity data from microperimetry (MP) in ADOA patients. Methods and findings This prospective cross-sectional study included 11 patients with ADOA and 11 age-matched healthy subjects. All participants underwent both a “Posterior Pole” and “peripapillary RNFL (pRNFL)” scanning protocol using SD-OCT. Functional mapping of the PP was also performed using MP. A customized program was implemented in order to achieve accurate superimposition of MP sensitivity map onto SD-OCT map. The thickness of the PP different retinal layers and pRNFL was obtained and measured for each eye. Mean retinal sensitivity values and fixation stability were obtained and compared between ADOA patients and healthy subjects. Correlation analysis was performed on a point-to-point basis to evaluate the association between mean thickness and retinal sensitivity of each retinal layer. Total retinal thickness (TRT), Retinal Nerve Fiber Layer (RNFL), Ganglion Cell Layer (GCL), Inner Plexiform Layer (IPL), Inner Nuclear Layer (INL) and Inner Retinal Layers (IRL) at the posterior pole as well as pRNFL were significantly thinner in ADOA patients (P < 0.0001). On the contrary, the Outer Plexiform Layer (OPL) and the Outer Nuclear Layer (ONL) were significantly thicker in the ADOA group (P < 0.001). No significant differences were found in Retinal Pigment Epithelium (RPE) and Outer Retinal Layers (ORL) thickness between ADOA and controls. The average PP retinal sensitivity was significantly reduced in ADOA patients compared with controls (P < 0.001), as measured by microperimeter Nidek MP-1 (MP1). Fixation stability was significantly worse in the ADOA group (P = 0.01). The most severe sensitivity defects in ADOA patients were found at the level of the papillo-macular bundle (PMB). Conclusions Inner retinal layers showed pathological changes in ADOA patients. In addition, the whole retinal PP (not only the PMB) was significantly altered in ADOA, both in terms of retinal thickness and sensitivity.
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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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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: 124] [Impact Index Per Article: 15.5] [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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Dominant optic atrophy: updates on the pathophysiology and clinical manifestations of the optic atrophy 1 mutation. Curr Opin Ophthalmol 2016; 27:475-480. [PMID: 27585216 DOI: 10.1097/icu.0000000000000314] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE OF REVIEW Review recent advances in clinical and experimental studies of dominant optic atrophy (DOA) to better understand the complexities of pathophysiology caused by the optic atrophy 1 (OPA1) mutation. RECENT FINDINGS DOA is the most commonly diagnosed inherited optic atrophy, causing progressive bilateral visual loss that begins early in life. During the past 25 years, there has been substantial progress in the understanding of the clinical, genetic, and pathophysiological basis of this disease. The histopathological hallmark of DOA is the primary degeneration of retinal ganglion cells, preferentially in the papillomacular bundle, which results temporal optic disc pallor and cecocentral scotomata in patients with DOA. Loss of OPA1 protein function by OPA1 gene mutations causes mitochondrial dysfunction because of the loss of mitochondrial fusion, impaired mitochondrial oxidative phosphorylation, increases in reactive oxygen species, and altered calcium homeostasis. These factors lead to apoptosis of retinal ganglion cells by a haploinsufficiency mechanism. SUMMARY Improved understanding of the pathophysiology of DOA provides insights that can be used to develop therapeutic approaches to the DOA.
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