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Conway MP, Stephenson KAJ, Zhu J, Dockery A, Burke T, Turner J, Le FT, O’Byrne JJ, Keegan DJ. The Role of the Ophthalmic Genetics Multidisciplinary Team in the Management of Inherited Retinal Degenerations-A Case-Based Review. Life (Basel) 2024; 14:107. [PMID: 38255722 PMCID: PMC10817299 DOI: 10.3390/life14010107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/03/2024] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
(1) Background: Inherited retinal degenertions are rare conditions which may have a dramatic impact on the daily life of those affected and how they interact with their environment. Coordination of clinical services via an ophthalmic genetics multidisciplinary team (OG-MDT) allows better efficiency of time and resources to reach diagnoses and facilitate patient needs. (2) Methods: This clinical case series was conducted by a retrospective review of patient records for patients enrolled in the Target 5000 programme and managed by the OG-MDT, at the Mater Hospital Dublin, Ireland (n = 865) (3) Results: Herein we describe clinical cases and how the use of the OG-MDT optimizes care for isolated and syndromic IRD pedigrees. (4) Conclusions: this paper demonstrates the benefits of an OG-MDT to patients with IRDs resulting in the holistic resolution of complex and syndromic cases. Furthermore, we demonstrate that this format can be adopted/developed by similar centres around the world, bringing with it the myriad benefits.
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Affiliation(s)
- Marcus P. Conway
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Kirk A. J. Stephenson
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Julia Zhu
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Adrian Dockery
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Tomas Burke
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Jacqueline Turner
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - Francois Thai Le
- Eye Clinic Liasson Officer, Vision Ireland, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland;
| | - James J. O’Byrne
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
| | - David J. Keegan
- Mater Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, D07 AX57 Dublin, Ireland (D.J.K.)
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Stepanova A, Ogorodova N, Kadyshev V, Shchagina O, Kutsev S, Polyakov A. A Molecular Genetic Analysis of RPE65-Associated Forms of Inherited Retinal Degenerations in the Russian Federation. Genes (Basel) 2023; 14:2056. [PMID: 38002999 PMCID: PMC10671290 DOI: 10.3390/genes14112056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
Pathogenic variants in the RPE65 gene cause the only known form of inherited retinal degenerations (IRDs) that are prone to gene therapy. The current study is aimed at the evaluation of the prevalence of RPE65-associated retinopathy in the Russian Federation, the characterization of known variants in the RPE65 gene, and the establishment of the specificities of the mutation spectrum in Russian patients. METHODS The analysis was carried out on blood samples obtained from 1053 non-related IRDs patients. The analysis, which consisted of 211 genes, was carried out based on the method of massive parallel sequencing (MPS) for all probands. Variant validation, as well as biallelic status verification, were carried out using direct automated Sanger sequencing. The number of copies of RPE65 exons 1-14 was analyzed with quantitative MLPA using an MRC-Holland SALSA MLPA probemix. RESULTS Out of 1053 non-related patients, a molecular genetic diagnosis of IRDs has been confirmed in 474 cases, including 25 (5.3%) patients with RPE65-associated retinopathy. We detected 26 variants in the RPE65 gene, nine of which have not been previously described in the literature. The most common mutations in the Russian population were c.304G>T/p.(Glu102*), c.370C>T/p.(Arg124*), and c.272G>A/p.(Arg91Gln), which comprised 41.8% of all affected chromosomes. CONCLUSIONS The current study shows that pathogenic variants in the RPE65 gene contribute significantly to the pathogenesis of IRDs and comprise 5.3% of all patients with a confirmed molecular genetic diagnosis. This study allowed for the formation of a cohort for target therapy of the disorder; such therapy has already been carried out for some patients.
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Affiliation(s)
- Anna Stepanova
- Research Centre for Medical Genetics, Moscow 115478, Russia
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3
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Chew LA, Iannaccone A. Gene-agnostic approaches to treating inherited retinal degenerations. Front Cell Dev Biol 2023; 11:1177838. [PMID: 37123404 PMCID: PMC10133473 DOI: 10.3389/fcell.2023.1177838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/31/2023] [Indexed: 05/02/2023] Open
Abstract
Most patients with inherited retinal degenerations (IRDs) have been waiting for treatments that are "just around the corner" for decades, with only a handful of seminal breakthroughs happening in recent years. Highlighting the difficulties in the quest for curative therapeutics, Luxturna required 16 years of development before finally obtaining United States Food and Drug Administration (FDA) approval and its international equivalents. IRDs are both genetically and phenotypically heterogeneous. While this diversity offers many opportunities for gene-by-gene precision medicine-based approaches, it also poses a significant challenge. For this reason, alternative (or parallel) strategies to identify more comprehensive, across-the-board therapeutics for the genetically and phenotypically diverse IRD patient population are very appealing. Even when gene-specific approaches may be available and become approved for use, many patients may have reached a disease stage whereby these approaches may no longer be viable. Thus, alternate visual preservation or restoration therapeutic approaches are needed at these stages. In this review, we underscore several gene-agnostic approaches that are being developed as therapeutics for IRDs. From retinal supplementation to stem cell transplantation, optogenetic therapy and retinal prosthetics, these strategies would bypass at least in part the need for treating every individual gene or mutation or provide an invaluable complement to them. By considering the diverse patient population and treatment strategies suited for different stages and patterns of retinal degeneration, gene agnostic approaches are very well poised to impact favorably outcomes and prognosis for IRD patients.
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Affiliation(s)
- Lindsey A. Chew
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States
| | - Alessandro Iannaccone
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
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Scruggs BA, Vasconcelos HM, Matioli da Palma M, Kogachi K, Pennesi ME, Yang P, Bailey ST, Lauer AK. Injection pressure levels for creating blebs during subretinal gene therapy. Gene Ther 2022; 29:601-607. [PMID: 34580433 PMCID: PMC8958181 DOI: 10.1038/s41434-021-00294-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 09/07/2021] [Accepted: 09/15/2021] [Indexed: 01/09/2023]
Abstract
Retinal damage has been associated with increased injection pressure during subretinal gene therapy delivery in various animal models, yet there are no human clinical data regarding the pressures required to initiate and propagate subretinal blebs. This study characterized the intraoperative pressure levels for subretinal gene therapy delivery across eight retinal conditions. A total of 116 patients with retinal degenerative diseases have been treated with subretinal gene therapy at OHSU-Casey Eye Institute as of June 2020; seventy patients (60.3%) were treated using a pneumatic-assisted subretinal delivery system. All retinal blebs were performed using a 41-gauge injection cannula, and use of a balanced salt solution (BSS) "pre-bleb" prior to gene therapy delivery was performed at the discretion of the surgeon. Patient age and intraoperative data for BSS and vector injections were analyzed in a masked fashion for all patients who received pneumatic-assisted subretinal gene therapy. The median age of the patients was 35 years (range 4-70). No significant differences in injection pressures were found across the eight retinal conditions. In this study, patient age was shown to affect maximum injection pressures required for bleb propagation, and the relationship between age and pressure varied based on retinal condition. These data have important implications in optimizing surgical protocols for subretinal injections.
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Affiliation(s)
- Brittni A Scruggs
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA
| | - Huber Martins Vasconcelos
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Mariana Matioli da Palma
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Katie Kogachi
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Mark E Pennesi
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Paul Yang
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Steven T Bailey
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Andreas K Lauer
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA.
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De Silva SR, Moore AT. Optogenetic approaches to therapy for inherited retinal degenerations. J Physiol 2022; 600:4623-4632. [PMID: 35908243 DOI: 10.1113/jp282076] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/18/2022] [Indexed: 01/07/2023] Open
Abstract
Inherited retinal degenerations such as retinitis pigmentosa (RP) affect around one in 4000 people and are the leading cause of blindness in working age adults in several countries. In these typically monogenic conditions, there is progressive degeneration of photoreceptors; however, inner retinal neurons such as bipolar cells and ganglion cells remain largely structurally intact, even in end-stage disease. Therapeutic approaches aiming to stimulate these residual cells, independent of the underlying genetic cause, could potentially restore visual function in patients with advanced vision loss, and benefit many more patients than therapies directed at the specific gene implicated in each disorder. One approach investigated for this purpose is that of optogenetics, a method of neuromodulation that utilises light to activate neurons engineered to ectopically express a light-sensitive protein. Using gene therapy via adeno-associated viral vectors, a range of photosensitive proteins have been expressed in remaining retinal cells in advanced retinal degeneration with in vivo studies demonstrating restoration of visual function. Developing an effective optogenetic strategy requires consideration of multiple factors, including the light-sensitive protein that is used, the vector and method for gene delivery, and the target cell for expression because these in turn may affect the quality of vision that can be restored. Currently, at least four clinical trials are ongoing to investigate optogenetic therapies in patients, with the ultimate aim of reversing visual loss in end-stage disease.
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Affiliation(s)
- Samantha R De Silva
- Oxford Eye Hospital, Oxford, UK.,UCL Institute of Ophthalmology, London, UK.,Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, London, UK.,Ophthalmology Department, University of California, San Francisco, CA, USA
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Gilhooley MJ, Lindner M, Palumaa T, Hughes S, Peirson SN, Hankins MW. A systematic comparison of optogenetic approaches to visual restoration. Mol Ther Methods Clin Dev 2022; 25:111-123. [PMID: 35402632 PMCID: PMC8956963 DOI: 10.1016/j.omtm.2022.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/04/2022] [Indexed: 02/06/2023]
Abstract
During inherited retinal degenerations (IRDs), vision is lost due to photoreceptor cell death; however, a range of optogenetic tools have been shown to restore light responses in animal models. Restored response characteristics vary between tools and the neuronal cell population to which they are delivered: the interplay between these is complex, but targeting upstream neurons (such as retinal bipolar cells) may provide functional benefit by retaining intraretinal signal processing. In this study, our aim was to compare two optogenetic tools: mammalian melanopsin (hOPN4) and microbial red-shifted channelrhodopsin (ReaChR) expressed within two subpopulations of surviving cells in a degenerate retina. Intravitreal adeno-associated viral vectors and mouse models utilising the Cre/lox system restricted expression to populations dominated by bipolar cells or retinal ganglion cells and was compared with non-targeted delivery using the chicken beta actin (CBA) promoter. In summary, we found bipolar-targeted optogenetic tools produced faster kinetics and flatter intensity-response relationships compared with non-targeted or retinal-ganglion-cell-targeted hOPN4. Hence, optogenetic tools of both mammalian and microbial origins show advantages when targeted to bipolar cells. This demonstrates the advantage of bipolar-cell-targeted optogenetics for vision restoration in IRDs. We therefore developed a bipolar-cell-specific gene delivery system employing a compressed promoter with the potential for clinical translation.
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Affiliation(s)
- Michael J. Gilhooley
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- The Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital, 162, City Road, London EC1V 2PD, UK
| | - Moritz Lindner
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps University, Deutschhausstrasse 1-2, Marburg 35037, Germany
| | - Teele Palumaa
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- East Tallinn Central Hospital Eye Clinic, Ravi 18, 10138 Tallinn, Estonia
| | - Steven Hughes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
| | - Stuart N. Peirson
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
| | - Mark W. Hankins
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Jules Thorne SCNi, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK
- Corresponding author Mark W. Hankins, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX1 3QU, UK.
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Stephenson KAJ, Zhu J, Dockery A, Whelan L, Burke T, Turner J, O'Byrne JJ, Farrar GJ, Keegan DJ. Clinical and Genetic Re-Evaluation of Inherited Retinal Degeneration Pedigrees following Initial Negative Findings on Panel-Based Next Generation Sequencing. Int J Mol Sci 2022; 23:995. [PMID: 35055178 DOI: 10.3390/ijms23020995] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/03/2022] [Accepted: 01/12/2022] [Indexed: 02/06/2023] Open
Abstract
Although rare, inherited retinal degenerations (IRDs) are the most common reason for blind registration in the working age population. They are highly genetically heterogeneous (>300 known genetic loci), and confirmation of a molecular diagnosis is a prerequisite for many therapeutic clinical trials and approved treatments. First-tier genetic testing of IRDs with panel-based next-generation sequencing (pNGS) has a diagnostic yield of ≈70-80%, leaving the remaining more challenging cases to be resolved by second-tier testing methods. This study describes the phenotypic reassessment of patients with a negative result from first-tier pNGS and the rationale, outcomes, and cost of second-tier genetic testing approaches. Removing non-IRD cases from consideration and utilizing case-appropriate second-tier genetic testing techniques, we genetically resolved 56% of previously unresolved pedigrees, bringing the overall resolve rate to 92% (388/423). At present, pNGS remains the most cost-effective first-tier approach for the molecular assessment of diverse IRD populations Second-tier genetic testing should be guided by clinical (i.e., reassessment, multimodal imaging, electrophysiology), and genetic (i.e., single alleles in autosomal recessive disease) indications to achieve a genetic diagnosis in the most cost-effective manner.
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Passaro ML, Magno L, Mazzucco A, Attaguile M, Montorio D, Cennamo G. An unusual association of macular retinoschisis with progressive familiar intrahepatic cholestasis: A multimodal imaging study. Eur J Ophthalmol 2021; 33:11206721211060141. [PMID: 34751049 DOI: 10.1177/11206721211060141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate a case of macular retinoschisis associated with a TJP2 mutation in a young woman affected by a Progressive Familiar Intrahepatic Cholestasis (PFIC) using multimodal imaging. METHODS Observational case report. RESULTS A 35-year-old woman, undergone a liver transplant for PFIC, was referred to Eye Clinic for complete ophthalmological examination and multimodal imaging. Fundus examination showed no significant alterations in both eyes while multicolor image revealed the presence of several cystes in macular region. The autofluorescence image highlighted small areas of iperautofluorescence in macular region. En-face image showed a "coral shape pattern" and structural optical coherence tomography (OCT) revealed foveal hyporeflective cystic spaces in outer and inner nuclear layers, areas of splitting within the nerve fiber layer (schisis areas) and an initial preretinal fibrosis. Lastly, OCT-angiography (OCT-A) demonstrated small perifoveal teleangectasias and slight reduction of the foveal avascular zone area. CONCLUSION Multimodal imaging could help to highlight the presence of a rare retinal disorder associated with a gene related systemic disease.
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Affiliation(s)
- Maria Laura Passaro
- Department of Neurosciences, Reproductive Sciences and Dentistry, 9307University of Naples Federico II, Naples, Italy
| | - Luigifilippo Magno
- Department of Neurosciences, Reproductive Sciences and Dentistry, 9307University of Naples Federico II, Naples, Italy
| | - Alberto Mazzucco
- Department of Neurosciences, Reproductive Sciences and Dentistry, 9307University of Naples Federico II, Naples, Italy
| | - Michele Attaguile
- Department of Neurosciences, Reproductive Sciences and Dentistry, 9307University of Naples Federico II, Naples, Italy
| | - Daniela Montorio
- Department of Neurosciences, Reproductive Sciences and Dentistry, 9307University of Naples Federico II, Naples, Italy
| | - Gilda Cennamo
- Eye Clinic, Public Health Department, 165474University's of Naples Federico II, Naples, Italy
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Abstract
PURPOSE To investigate, using multimodal imaging, the anatomy of neovascularization in eyes with enhanced S-cone syndrome. METHODS Three eyes with neovascularization, from two patients with enhanced S-cone syndrome, were analyzed using fluorescein angiography, indocyanine-green and optical coherence tomography angiography imaging. RESULTS The eyes reported had a demonstrable Type 3 neovascularization with evidence of retinal-retinal anastomoses on fluorescein angiography, indocyanine-green and optical coherence tomography angiography imaging. One eye that was initially without neovascularization, but with chronic macular edema developed a macular hemorrhage. This eye was treated with 8 injections of intravitreal bevacizumab over 29-months resulting in a final fibrovascular lesion. The characteristics of this final lesion share similarities to the two other eyes described. In all eyes and all exams, retinal vessels are observed to communicate with the subretinal fibrovascular lesion. CONCLUSION We provide evidence of retinal arteriovenous anastomosis of the superficial retinal plexus to a subretinal neovascular complex in patients with enhanced S-cone syndrome and point to similarities with Type 3 neovascularization in macular telengiectasia Type 2 (MacTel2) and age-related macular degeneration. These findings provide insights into the anatomy of neovascularization in these pathologies and may lead to hypotheses of their etiologies.
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Affiliation(s)
- Ramiro S Maldonado
- National Eye Institute, National Institutes of Health, Bethesda, Maryland
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Andreazzoli M, Barravecchia I, De Cesari C, Angeloni D, Demontis GC. Inducible Pluripotent Stem Cells to Model and Treat Inherited Degenerative Diseases of the Outer Retina: 3D-Organoids Limitations and Bioengineering Solutions. Cells 2021; 10:cells10092489. [PMID: 34572137 PMCID: PMC8471616 DOI: 10.3390/cells10092489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/12/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal degenerations (IRD) affecting either photoreceptors or pigment epithelial cells cause progressive visual loss and severe disability, up to complete blindness. Retinal organoids (ROs) technologies opened up the development of human inducible pluripotent stem cells (hiPSC) for disease modeling and replacement therapies. However, hiPSC-derived ROs applications to IRD presently display limited maturation and functionality, with most photoreceptors lacking well-developed outer segments (OS) and light responsiveness comparable to their adult retinal counterparts. In this review, we address for the first time the microenvironment where OS mature, i.e., the subretinal space (SRS), and discuss SRS role in photoreceptors metabolic reprogramming required for OS generation. We also address bioengineering issues to improve culture systems proficiency to promote OS maturation in hiPSC-derived ROs. This issue is crucial, as satisfying the demanding metabolic needs of photoreceptors may unleash hiPSC-derived ROs full potential for disease modeling, drug development, and replacement therapies.
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Affiliation(s)
| | - Ivana Barravecchia
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | | | - Debora Angeloni
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | - Gian Carlo Demontis
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Correspondence: (M.A.); (G.C.D.)
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Abstract
Inherited retinal degenerations (IRDs) are a leading cause of blindness. Although gene-supplementation therapies have been developed, they are only available for a small proportion of recessive IRD mutations. In contrast, genome editing using clustered-regularly interspaced short palindromic repeats (CRISPR) CRISPR-associated (Cas) systems could provide alternative therapeutic avenues for treating a wide range of genetic retinal diseases through targeted knockdown or correction of mutant alleles. Progress in this rapidly evolving field has been highlighted by recent Food and Drug Administration clinical trial approval for EDIT-101 (Editas Medicine, Inc., Cambridge, MA), which has demonstrated efficacious genome editing in a mouse model of CEP290-associated Leber congenital amaurosis and safety in nonhuman primates. Nonetheless, there remains a significant number of challenges to developing clinically viable retinal genome-editing therapies. In particular, IRD-causing mutations occur in more than 200 known genes, with considerable heterogeneity in mutation type and position within each gene. Additionally, there are remaining safety concerns over long-term expression of Cas9 in vivo. This review highlights (i) the technological advances in gene-editing technology, (ii) major safety concerns associated with retinal genome editing, and (iii) potential strategies for overcoming these challenges to develop clinical therapies.
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Affiliation(s)
- Joel Quinn
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Ayesha Musa
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Ariel Kantor
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
- Correspondence: Dr. Kanmin Xue, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
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Chiou GJ, Huang DS, Hu FR, Yang CM, Yang CH, Huang CW, Lin JW, Lin CW, Ho TC, Hsieh YT, Lai TT, Chen HM, Chen PL, Hsiao CK, Chen TC. Metabolic Syndromes as Important Comorbidities in Patients of Inherited Retinal Degenerations: Experiences from the Nationwide Health Database and a Large Hospital-Based Cohort. Int J Environ Res Public Health 2021; 18:2065. [PMID: 33672521 PMCID: PMC7923804 DOI: 10.3390/ijerph18042065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/15/2021] [Accepted: 02/15/2021] [Indexed: 01/05/2023]
Abstract
This study aimed to evaluate the medical and socioeconomic impacts of IRDs using the nationwide health database and a large hospital-based cohort. This retrospective cross-sectional cohort study used data from the nationwide National Health Insurance Research Database (NHIRD). All patients with IRD from January 2012 to December 2016 were selected from the NHIRD and matched with the general population at a ratio of 1:4. All variables, including comorbidities, medications, service utilization, and medical costs, within 1 year from the date of the IRD diagnosis, were analyzed. Disability data were retrieved from the Taiwan Inherited retinal degeneration Project (TIP), a medical center-based database. A total of 4447 and 17,788 subjects from the nationwide database were included in the IRD and control groups, respectively. The Charlson comorbidity index score was higher in the IRD group (0.74:0.52, p < 0.001). Yearly visits to the ophthalmology clinic were more frequent in the IRD group (6.80:1.06, p < 0.001), particularly to tertiary medical centers (p < 0.001). The IRD group showed greater odds ratios (OR) for metabolic syndrome-related comorbidities, including hypertension (OR = 1.18, 95% confidence interval (CI) 1.10 to 1.26) and diabetes (OR = 1.32, 95% CI 1.21 to 1.45), and double the average yearly medical cost (2104.3 vs. 1084.6 USD, p < 0.001) and ten times the yearly ophthalmology cost (369.1 vs. 36.1 USD, p < 0.001). The average disability level was 54.17% for all subjects. This study revealed the large medical and socioeconomic impacts of IRD on not only patients with IRD, but also their family members and the whole society.
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Affiliation(s)
- Guann-Jye Chiou
- Department of Medical Education, National Taiwan University Hospital, Taipei 100, Taiwan;
| | - Ding-Siang Huang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Fung-Rong Hu
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chung-May Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chang-Hao Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Ching-Wen Huang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Jou-Wei Lin
- Cardiovascular Center, National Taiwan University Hospital (Yun-Lin Branch), Yunlin 632, Taiwan;
| | - Chao-Wen Lin
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Tzyy-Chang Ho
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Yi-Ting Hsieh
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Tso-Ting Lai
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
| | - Ho-Min Chen
- Health Data Research Center, National Taiwan University, Taipei 100, Taiwan;
| | - Pei-Lung Chen
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan;
- Graduate Institute of Medical Genomics and Proteomics, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Chuhsing Kate Hsiao
- Institute of Epidemiology and Preventive Medicine, National Taiwan University, Taipei 100, Taiwan;
| | - Ta-Ching Chen
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (D.-S.H.); (F.-R.H.); (C.-M.Y.); (C.-H.Y.); (C.-W.H.); (C.-W.L.); (T.-C.H.); (Y.-T.H.); (T.-T.L.)
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan;
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13
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Abstract
The retina is the light sensitive part of the eye and nervous tissue that have been used extensively to characterize the function of the central nervous system. The retina has a central position both in fundamental biology and in the physiopathology of neurodegenerative diseases. We address the contribution of functional genomics to the understanding of retinal biology by reviewing key events in their historical perspective as an introduction to major findings that were obtained through the study of the retina using genomics, transcriptomics and proteomics. We illustrate our purpose by showing that most of the genes of interest for retinal development and those involved in inherited retinal degenerations have a restricted expression to the retina and most particularly to photoreceptors cells. We show that the exponential growth of data generated by functional genomics is a future challenge not only in terms of storage but also in terms of accessibility to the scientific community of retinal biologists in the future. Finally, we emphasize on novel perspectives that emerge from the development of redox-proteomics, the new frontier in retinal biology.
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Affiliation(s)
- Frédéric Blond
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
| | - Thierry Léveillard
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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14
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Abstract
I was drawn into research in George Wald's laboratory at Harvard, where as an undergraduate and graduate student, I studied vitamin A deficiency and dark adaptation. A chance observation while an assistant professor at Harvard led to the major research of my career-to understand the functional organization of vertebrate retinas. I started with a retinal circuit analysis of the primate retina with Brian Boycott and intracellular retinal cell recordings in mudpuppies with Frank Werblin. Subsequent pharmacology studies with Berndt Ehinger primarily with fish focused on dopamine and neuromodulation. Using zebrafish, we studied retinal development, neuronal connectivity, and the effects of genetic mutations on retinal structure and function. Now semi-retired, I have returned to primate retinal circuitry, undertaking a connectomic analysis of the human fovea in Jeffrey Lichtman's laboratory.
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Affiliation(s)
- John E Dowling
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA;
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15
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Mustafi D, Arbabi A, Ameri H, Palczewski K. Retinal Gene Distribution and Functionality Implicated in Inherited Retinal Degenerations Can Reveal Disease-Relevant Pathways for Pharmacologic Intervention. Pharmaceuticals (Basel) 2019; 12:E74. [PMID: 31108889 DOI: 10.3390/ph12020074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/08/2019] [Accepted: 05/15/2019] [Indexed: 01/17/2023] Open
Abstract
The advent of genetic therapies for inherited retinal diseases (IRDs) has spurred the need for precise diagnosis and understanding of pathways for therapeutic targeting. The majority of IRDs that are clinically diagnosed, however, lack an identifiable mutation in established disease-causing loci and thus can be investigated with limited rational drug discovery methods. Transcriptome profiling of the retina can reveal the functional state of the tissue, and geographic profiling can uncover the various clinical phenotypic presentations of IRDs and aid in pharmaceutical intervention. In this investigation, we detail the retinal geographic expression of known retinal disease-causing genes in the primate retina and functional targetable pathways in specific IRDs. Understanding the genetic basis as well as the resulting functional consequences will assist in the discovery of future therapeutic interventions and provide novel insights to medicinal chemists. Herein, we report that, despite the genetic heterogeneity of retinal diseases, potential functional pathways can be elucidated for therapeutic targeting and be used for predictive phenotypic and genotypic modeling of novel IRD presentations.
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16
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Abalem MF, Musch DC, Birch DG, Pennesi ME, Heckenlively JR, Jayasundera T. Diurnal variations of foveoschisis by optical coherence tomography in patients with RS1 X-linked juvenile retinoschisis. Ophthalmic Genet 2018; 39:437-442. [PMID: 29902095 DOI: 10.1080/13816810.2018.1466340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND To evaluate diurnal variations in macular schisis cavities in patients with X-linked juvenile retinoschisis (XLRS) with pathogenic variants in the RS1 gene using spectral-domain optical coherence tomography (SD-OCT). METHODS Three consecutive patients with a clinical diagnosis of XLRS and pathogenic variants in the RS1, treated with carbonic anhydrase inhibitors (CAIs). Observational procedures: SD-OCT scans of the macula were acquired at 9 a.m., 1 p.m., and 4 p.m. within 24 h. RESULTS All patients demonstrated increased measures of central foveal thickness in the morning with gradual decrease through the day (9-43%). Major changes were observed between 9 a.m. and 1 p.m. in the central foveal thickness. CONCLUSION The central foveal thickness varies during daytime hours in patients with XLRS. This finding may explain the inconsistent and heterogeneous responses to treatment with CAIs and necessitate standardization of measurement times in treatment trials for XLRS as well as in the routine ophthalmic evaluation of these patients.
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Affiliation(s)
- Maria Fernanda Abalem
- a Department of Ophthalmology and Visual Sciences, Kellogg Eye Center , University of Michigan Medical School , Ann Arbor , MI , USA.,b Department of Ophthalmology and Otolaryngology , University of Sao Paulo Medical School , Sao Paulo , Brazil
| | - David C Musch
- a Department of Ophthalmology and Visual Sciences, Kellogg Eye Center , University of Michigan Medical School , Ann Arbor , MI , USA.,c Department of Epidemiology , University of Michigan School of Public Health , Ann Arbor , MI , USA
| | - David G Birch
- d Retina Foundation of the Southwest , Dallas , TX , USA
| | - Mark E Pennesi
- e Casey Eye Institute , Oregon Health & Science University , Portland , OR , USA
| | - John R Heckenlively
- a Department of Ophthalmology and Visual Sciences, Kellogg Eye Center , University of Michigan Medical School , Ann Arbor , MI , USA
| | - Thiran Jayasundera
- a Department of Ophthalmology and Visual Sciences, Kellogg Eye Center , University of Michigan Medical School , Ann Arbor , MI , USA
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17
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Soens ZT, Branch J, Wu S, Yuan Z, Li Y, Li H, Wang K, Xu M, Rajan L, Motta FL, Simões RT, Lopez-Solache I, Ajlan R, Birch DG, Zhao P, Porto FB, Sallum J, Koenekoop RK, Sui R, Chen R. Leveraging splice-affecting variant predictors and a minigene validation system to identify Mendelian disease-causing variants among exon-captured variants of uncertain significance. Hum Mutat 2017; 38:1521-1533. [PMID: 28714225 DOI: 10.1002/humu.23294] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/20/2017] [Accepted: 07/11/2017] [Indexed: 12/11/2022]
Abstract
The genetic heterogeneity of Mendelian disorders results in a significant proportion of patients that are unable to be assigned a confident molecular diagnosis after conventional exon sequencing and variant interpretation. Here, we evaluated how many patients with an inherited retinal disease (IRD) have variants of uncertain significance (VUS) that are disrupting splicing in a known IRD gene by means other than affecting the canonical dinucleotide splice site. Three in silico splice-affecting variant predictors were leveraged to annotate and prioritize variants for splicing functional validation. An in vitro minigene system was used to assay each variant's effect on splicing. Starting with 745 IRD patients lacking a confident molecular diagnosis, we validated 23 VUS as splicing variants that likely explain disease in 26 patients. Using our results, we optimized in silico score cutoffs to guide future variant interpretation. Variants that alter base pairs other than the canonical GT-AG dinucleotide are often not considered for their potential effect on RNA splicing but in silico tools and a minigene system can be utilized for the prioritization and validation of such splice-disrupting variants. These variants can be overlooked causes of human disease but can be identified using conventional exon sequencing with proper interpretation guidelines.
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Affiliation(s)
- Zachry T Soens
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Justin Branch
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Shijing Wu
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Zhisheng Yuan
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Hui Li
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Keqing Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Mingchu Xu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Lavan Rajan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Fabiana L Motta
- Department of Ophthalmology and Visual Sciences, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Renata T Simões
- Department of Retina and Vitreous, Ophthalmologic Center of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.,Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte Hospital - IEP/SCBH, Belo Horizonte, Minas Gerais, Brazil
| | - Irma Lopez-Solache
- McGill Ocular Genetics Laboratory and Centre, Department of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Radwan Ajlan
- McGill Ocular Genetics Laboratory and Centre, Department of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - David G Birch
- Retina Foundation of the Southwest and Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Peiquan Zhao
- Department of Ophthalmology, Xin Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fernanda B Porto
- Department of Retina and Vitreous, Ophthalmologic Center of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.,Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte Hospital - IEP/SCBH, Belo Horizonte, Minas Gerais, Brazil
| | - Juliana Sallum
- Department of Ophthalmology and Visual Sciences, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Robert K Koenekoop
- McGill Ocular Genetics Laboratory and Centre, Department of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas.,Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas.,Department of Structural and Computational Biology & Molecular Biophysics, Baylor College of Medicine, Houston, Texas
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18
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Bujakowska KM, Fernandez-Godino R, Place E, Consugar M, Navarro-Gomez D, White J, Bedoukian EC, Zhu X, Xie HM, Gai X, Leroy BP, Pierce EA. Copy-number variation is an important contributor to the genetic causality of inherited retinal degenerations. Genet Med 2017; 19:643-651. [PMID: 27735924 PMCID: PMC6377944 DOI: 10.1038/gim.2016.158] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/30/2016] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Despite substantial progress in sequencing, current strategies can genetically solve only approximately 55-60% of inherited retinal degeneration (IRD) cases. This can be partially attributed to elusive mutations in the known IRD genes, which are not easily identified by the targeted next-generation sequencing (NGS) or Sanger sequencing approaches. We hypothesized that copy-number variations (CNVs) are a major contributor to the elusive genetic causality of IRDs. METHODS Twenty-eight cases previously unsolved with a targeted NGS were investigated with whole-genome single-nucleotide polymorphism (SNP) and comparative genomic hybridization (CGH) arrays. RESULTS Deletions in the IRD genes were detected in 5 of 28 families, including a de novo deletion. We suggest that the de novo deletion occurred through nonallelic homologous recombination (NAHR) and we constructed a genomic map of NAHR-prone regions with overlapping IRD genes. In this article, we also report an unusual case of recessive retinitis pigmentosa due to compound heterozygous mutations in SNRNP200, a gene that is typically associated with the dominant form of this disease. CONCLUSIONS CNV mapping substantially increased the genetic diagnostic rate of IRDs, detecting genetic causality in 18% of previously unsolved cases. Extending the search to other structural variations will probably demonstrate an even higher contribution to genetic causality of IRDs.Genet Med advance online publication 13 October 2016.
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Affiliation(s)
- Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Rosario Fernandez-Godino
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Emily Place
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Mark Consugar
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel Navarro-Gomez
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Joseph White
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Emma C Bedoukian
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Xiaosong Zhu
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Hongbo M Xie
- Department of BioMedical Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Xiaowu Gai
- Center for Personalized Medicine, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Bart P Leroy
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Ophthalmology &Center for Medical Genetics, Ghent University Hospital &Ghent University, Ghent, Belgium
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
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