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Awadh Hashem S, Georgiou M, Ali RR, Michaelides M. RPGR-Related Retinopathy: Clinical Features, Molecular Genetics, and Gene Replacement Therapy. Cold Spring Harb Perspect Med 2023; 13:a041280. [PMID: 37188525 PMCID: PMC10626266 DOI: 10.1101/cshperspect.a041280] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Retinitis pigmentosa GTPase regulator (RPGR) gene variants are the predominant cause of X-linked retinitis pigmentosa (XLRP) and a common cause of cone-rod dystrophy (CORD). XLRP presents as early as the first decade of life, with impaired night vision and constriction of peripheral visual field and rapid progression, eventually leading to blindness. In this review, we present RPGR gene structure and function, molecular genetics, animal models, RPGR-associated phenotypes and highlight emerging potential treatments such as gene-replacement therapy.
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Affiliation(s)
- Shaima Awadh Hashem
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, United Kingdom
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, United Kingdom
- Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Robin R Ali
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, United Kingdom
- Centre for Cell and Gene Therapy, King's College London, London WC2R 2LS, United Kingdom
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, United Kingdom
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2
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Wongchaisuwat N, Amato A, Lamborn AE, Yang P, Everett L, Pennesi ME. Retinitis pigmentosa GTPase regulator-related retinopathy and gene therapy. Saudi J Ophthalmol 2023; 37:276-286. [PMID: 38155670 PMCID: PMC10752277 DOI: 10.4103/sjopt.sjopt_168_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/14/2023] [Accepted: 08/16/2023] [Indexed: 12/30/2023] Open
Abstract
Retinitis pigmentosa GTPase regulator (RPGR)-related retinopathy is a retinal dystrophy inherited in a X-linked recessive manner that typically causes progressive visual loss starting in childhood with severe visual impairment by the fourth decade of life. It manifests as an early onset and severe form of retinitis pigmentosa. There are currently no effective treatments for RPGR-related retinopathy; however, there are multiple clinical trials in progress exploring gene augmentation therapy aimed at slowing down or halting the progression of disease and possibly restoring visual function. This review focuses on the molecular biology, clinical manifestations, and the recent progress of gene therapy clinical trials.
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Affiliation(s)
- Nida Wongchaisuwat
- Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Alessia Amato
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Andrew E. Lamborn
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Paul Yang
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Lesley Everett
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon, USA
| | - Mark E. Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon, USA
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3
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Birch DG, Cheetham JK, Daiger SP, Hoyng C, Kay C, MacDonald IM, Pennesi ME, Sullivan LS. Overcoming the Challenges to Clinical Development of X-Linked Retinitis Pigmentosa Therapies: Proceedings of an Expert Panel. Transl Vis Sci Technol 2023; 12:5. [PMID: 37294701 PMCID: PMC10270308 DOI: 10.1167/tvst.12.6.5] [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: 01/31/2023] [Accepted: 04/24/2023] [Indexed: 06/11/2023] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is a rare inherited retinal disease manifesting as impaired night vision and peripheral vision loss that progresses to legal blindness. Although several trials of ocular gene therapy for XLRP have been conducted or are in progress, there is currently no approved treatment. In July 2022, the Foundation Fighting Blindness convened an expert panel to examine relevant research and make recommendations for overcoming the challenges and capitalizing on the opportunities in conducting clinical trials of RPGR-targeted therapy for XLRP. Data presented concerned RPGR structure and mutation types known to cause XLRP, RPGR mutation-associated retinal phenotype diversity, patterns in genotype/phenotype relationships, disease onset and progression from natural history studies, and the various functional and structural tests used to monitor disease progression. Panel recommendations include considerations, such as genetic screening and other factors that can impact clinical trial inclusion criteria, the influence of age on defining and stratifying participant cohorts, the importance of conducting natural history studies early in clinical development programs, and the merits and drawbacks of available tests for measuring treatment outcomes. We recognize the need to work with regulators to adopt clinically meaningful end points that would best determine the efficacy of a trial. Given the promise of RPGR-targeted gene therapy for XLRP and the difficulties encountered in phase III clinical trials to date, we hope these recommendations will help speed progress to finding a cure. Translational Relevance Examination of relevant data and recommendations for the successful clinical development of gene therapies for RPGR-associated XLRP.
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Affiliation(s)
| | | | - Stephen P. Daiger
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, TX, USA
| | - Carel Hoyng
- Radboud University, Nijmegen, The Netherlands
| | | | | | - Mark E. Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Lori S. Sullivan
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, TX, USA
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4
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Nguyen XTA, Moekotte L, Plomp AS, Bergen AA, van Genderen MM, Boon CJF. Retinitis Pigmentosa: Current Clinical Management and Emerging Therapies. Int J Mol Sci 2023; 24:ijms24087481. [PMID: 37108642 PMCID: PMC10139437 DOI: 10.3390/ijms24087481] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/01/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies characterized by the degeneration of rod photoreceptors, followed by the degeneration of cone photoreceptors. As a result of photoreceptor degeneration, affected individuals experience gradual loss of visual function, with primary symptoms of progressive nyctalopia, constricted visual fields and, ultimately, central vision loss. The onset, severity and clinical course of RP shows great variability and unpredictability, with most patients already experiencing some degree of visual disability in childhood. While RP is currently untreatable for the majority of patients, significant efforts have been made in the development of genetic therapies, which offer new hope for treatment for patients affected by inherited retinal dystrophies. In this exciting era of emerging gene therapies, it remains imperative to continue supporting patients with RP using all available options to manage their condition. Patients with RP experience a wide variety of physical, mental and social-emotional difficulties during their lifetime, of which some require timely intervention. This review aims to familiarize readers with clinical management options that are currently available for patients with RP.
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Affiliation(s)
- Xuan-Thanh-An Nguyen
- Department of Ophthalmology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Lude Moekotte
- Department of Ophthalmology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - Astrid S Plomp
- Department of Clinical Genetics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Arthur A Bergen
- Department of Clinical Genetics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Maria M van Genderen
- Department of Ophthalmology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
- Bartiméus, Diagnostic Center for Complex Visual Disorders, 3703 AJ Zeist, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
- Department of Ophthalmology, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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Cehajic-Kapetanovic J, Martinez-Fernandez de la Camara C, Birtel J, Rehman S, McClements ME, Charbel Issa P, Lotery AJ, MacLaren RE. Impaired glutamylation of RPGR ORF15 underlies the cone-dominated phenotype associated with truncating distal ORF15 variants. Proc Natl Acad Sci U S A 2022; 119:e2208707119. [PMID: 36445968 PMCID: PMC9897430 DOI: 10.1073/pnas.2208707119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pathogenic variants in the Retinitis pigmentosa GTPase regulator (RPGR) gene lead to a clinically severe form of X-linked retinal dystrophy. However, it remains unclear why some variants cause a predominant rod, while others result in a cone-dominated phenotype. Post-translational glutamylation of the photoreceptor-specific RPGRORF15 isoform by the TTLL5 enzyme is essential for its optimal function in photoreceptors, and loss of TTLL5 leads to retinal dystrophy with a cone phenotype. Here we show that RPGR retinal disease, studied in a single cohort of 116 male patients, leads to a clear progressive shift from rod- to cone-dominating phenotype as the RPGRORF15 variant location approaches the distal part of the Open Reading Frame 15 (ORF15) region. The rod photoreceptor involvement on the contrary diminishes along the RGPR sequence, and the variants associated with the cone only phenotype are located predominantly in the very distal part, including the C-terminal basic domain. Moreover, these distal truncating RPGRORF15 variants disrupt the interaction with TTLL5 and lead to a significant impairment of RPGR glutamylation. Thus, consistent with the phenotype of TTLL5 pathogenic variants, our study shows that RPGRORF15 variants, which disrupt its basic domain and the interaction with TTLL5, also impair RPGR glutamylation and lead to the cone phenotype. This has implications for ongoing gene therapy clinical trials where the application of RPGR with impaired glutamylation may be less effective in treating RGPR dystrophies and may even convert a rod-cone dystrophy into a cone dystrophy phenotype.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
| | - Cristina Martinez-Fernandez de la Camara
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
| | - Johannes Birtel
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- cDepartment of Ophthalmology, University of Bonn, 53127Bonn, Germany
| | - Salwah Rehman
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Michelle E. McClements
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Peter Charbel Issa
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Andrew J Lotery
- dClinical Neurosciences Research Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SO16 6YDSouthampton, United Kingdom
- eUniversity Hospital Southampton NHS Foundation Trust, SO16 6YDSouthampton, United Kingdom
| | - Robert E. MacLaren
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
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Martinez-Fernandez de la Camara C, Cehajic-Kapetanovic J, MacLaren RE. Emerging gene therapy products for RPGR-associated X-linked retinitis pigmentosa. Expert Opin Emerg Drugs 2022; 27:431-443. [PMID: 36562395 DOI: 10.1080/14728214.2022.2152003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 11/22/2022] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Mutations in the RPGR gene are responsible for one of the most prevalent and severe types of retinitis pigmentosa. Gene therapy has shown great promise to treat inherited retinal diseases, and currently, four RPGR gene therapy vectors are being evaluated in clinical trials. AREAS COVERED This manuscript reviews the gene therapy products that are in development for X-linked retinitis pigmentosa caused by mutations in RPGR, and the challenges that scientists and clinicians have faced. EXPERT OPINION The development of a gene therapy product for RPGR-associated retinal degeneration has been a great challenge due to the incomplete understanding of the underlying genetics and mechanism of action of RPGR, and on the other hand, due to the instability of the RPGR gene. Three of the four gene therapy vectors currently in clinical trials include a codon-optimized version of the human RPGR sequence, and the other vector contains a shortened version of the human RPGR. To date, the only Phase I/II results published in a peer-reviewed journal demonstrate a good safety profile and an improvement in the visual field using a codon optimized version of RPGRORF15.
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Affiliation(s)
- Cristina Martinez-Fernandez de la Camara
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
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7
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Mansouri V. X-Linked Retinitis Pigmentosa Gene Therapy: Preclinical Aspects. Ophthalmol Ther 2022; 12:7-34. [PMID: 36346573 PMCID: PMC9641696 DOI: 10.1007/s40123-022-00602-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/17/2022] [Indexed: 11/11/2022] Open
Abstract
The most common inherited eye disease is retinitis pigmentosa (RP). X-linked RP (XLRP) is one of the most severe types of RP, with a considerable disease burden. Patients with XLRP experience a decrease in their vision and become blind in their 4th decade of life, causing much morbidity after starting a rather normal life. Treatment of XLRP remains challenging, and current treatments are not effective enough in restoring vision. Gene therapy of XLRP, capable of restoring the functional RPGR gene, showed promising results in preclinical studies and clinical trials; however, to date, no approved product has entered the market. The development of a gene therapy product needs through preliminary assessment of the drug in animal models before administration to humans. In this article, we reviewed the genetic pathology of XLRP, along with the preclinical aspects of the XLRP gene therapy, animal models, associated assessments, and future challenges and directions.
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Affiliation(s)
- Vahid Mansouri
- Gene Therapy Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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8
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Vinikoor-Imler LC, Simpson C, Narayanan D, Abbasi S, Lally C. Prevalence of RPGR-mutated X-linked retinitis pigmentosa among males. Ophthalmic Genet 2022; 43:581-588. [PMID: 36004681 DOI: 10.1080/13816810.2022.2109686] [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 X-linked retinitis pigmentosa (XLRP) is a rare inherited retinal disease predominantly affecting males. MATERIALS AND METHODS A comprehensive literature review was conducted to determine the prevalence of retinitis pigmentosa GTPase regulator (RPGR)-mutated XLRP. Identified studies were used to estimate four components among males: the prevalence of retinitis pigmentosa (RP), the proportion of RP that was X-linked, the proportion of misclassified inheritance type among RP cases, and the proportion of XLRP that was RPGR-mutated. Studies providing a direct estimate of XLRP prevalence were also included. The components' sample size-weighted averages were combined to determine an overall prevalence estimate. RESULTS The prevalence of XLRP was estimated to be between 2.7-3.5 per 100,000 males in the US, Europe, and Australia. After correction for misclassification, the prevalence increased to 4.0-5.2 per 100,000 males. Finally, the proportion of XLRP cases due to RPGR mutations was applied, resulting in an RPGR-mutated XLRP estimate of 3.4-4.4 per 100,000 males. Studies from other countries were consistent with the results for the overall XLRP prevalence but were not included in the final calculation because of regional variations and lack of detailed information. CONCLUSIONS These findings address an important gap in the understanding of RPGR-mutated XLRP by summarizing the global burden of this condition.
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Affiliation(s)
| | | | - Divya Narayanan
- Global Medical Affairs, Biogen, Cambridge, Massachusetts, USA
| | - Saad Abbasi
- Global Medical Affairs, Biogen, Cambridge, Massachusetts, USA
| | - Cathy Lally
- Epidemiologic Research & Methods, LLC, Atlanta, Georgia, USA
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Battu R, Ratra D, Gopal L. Newer therapeutic options for inherited retinal diseases: Gene and cell replacement therapy. Indian J Ophthalmol 2022; 70:2316-2325. [PMID: 35791112 PMCID: PMC9426045 DOI: 10.4103/ijo.ijo_82_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inherited retinal diseases (IRD) are genotypically and phenotypically varied disorders that lead to progressive degeneration of the outer retina and the retinal pigment epithelium (RPE) eventually resulting in severe vision loss. Recent research and developments in gene therapy and cell therapy have shown therapeutic promise in these hitherto incurable diseases. In gene therapy, copies of a healthy gene are introduced into the host cells via a viral vector. Clinical trials for several genes are underway while treatment for RPE65 called voretigene neparvovec, is already approved and commercially available. Cell therapy involves the introduction of stem cells that can replace degenerated cells. These therapies are delivered to the target tissues, namely the photoreceptors (PR) and RPE via subretinal, intravitreal, or suprachoroidal delivery systems. Although there are several limitations to these therapies, they are expected to slow the disease progression and restore some visual functions. Further advances such as gene editing technologies are likely to result in more precise and personalized treatments. Currently, several IRDs such as retinitis pigmentosa, Stargardt disease, Leber congenital amaurosis, choroideremia, achromatopsia, and Usher syndrome are being evaluated for possible gene therapy or cell therapy. It is important to encourage patients to undergo gene testing and maintain a nationwide registry of IRDs. This article provides an overview of the basics of these therapies and their current status.
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Affiliation(s)
- Rajani Battu
- Aster CMI Hospital; Centre for Eye Genetics and Research, Bengaluru, Karnataka, India
| | - Dhanashree Ratra
- Department of Vitreoretinal Diseases, Sankara Nethralaya, Chennai, Tamil Nadu, India
| | - Lingam Gopal
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Eye Research, Singapore
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Mihailovic N, Schimpf-Linzenbold S, Sattler I, Eter N, Heiduschka P. The first reported case of a deletion of the entire RPGR gene in a family with X-linked retinitis pigmentosa. Ophthalmic Genet 2022; 43:679-684. [PMID: 35652150 DOI: 10.1080/13816810.2022.2083181] [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: 10/18/2022]
Abstract
Clinical phenotypes of a patient with a deletion of the entire RPGR gene have not been described in the literature yet. We hereby report a new mutation in a family of X-linked retinitis pigmentosa (×lRP), showing the deletion of the entire RPGR gene. Gene therapy for inherited retinal diseases holds great promise; however, so far there has been no approved treatment of RPGR-mediated retinitis pigmentosa. The presented evidence of genotype-phenotype correlation may be useful for genetic diagnosis or even genetic treatment in the near future.
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Affiliation(s)
- Nataša Mihailovic
- Department of Ophthalmology, University of Muenster Medical Center, Muenster, Germany.,Department of Ophthalmology, Klinikum Fulda, University of Marburg Campus Fulda, Fulda, Germany
| | | | - Inga Sattler
- Zentrum für Humangenetik Tübingen, Praxis fuer Humangenetik und CeGaT GmbH, Tuebingen, Germany
| | - Nicole Eter
- Department of Ophthalmology, University of Muenster Medical Center, Muenster, Germany
| | - Peter Heiduschka
- Department of Ophthalmology, University of Muenster Medical Center, Muenster, Germany
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11
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Stem cell transplantation as a progressing treatment for retinitis pigmentosa. Cell Tissue Res 2022; 387:177-205. [PMID: 35001210 DOI: 10.1007/s00441-021-03551-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/27/2021] [Indexed: 11/02/2022]
Abstract
Retinal degenerative diseases such as retinitis pigmentosa (RP) are of the major causes of vision loss in developed countries. Despite the unclear pathophysiology, treatment methods have been investigated vastly in the past decades. This review article mainly discusses the advances in application of stem cell and progenitor transplantation for retinitis pigmentosa. Stem cell sources such as mesenchymal stem cells, embryonic stem cells, induced pluripotent stem cells, neural stem cells, retinal progenitor cells, and olfactory ensheathing cells are discussed separately in addition to a brief description of two approaches for treatment of early-stage RP, including gene therapy and nutritional therapy.
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12
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Tuupanen S, Gall K, Sistonen J, Saarinen I, Kämpjärvi K, Wells K, Merkkiniemi K, von Nandelstadh P, Sarantaus L, Känsäkoski J, Mårtenson E, Västinsalo H, Schleit J, Sankila EM, Kere A, Junnila H, Siivonen P, Andreevskaya M, Kytölä V, Muona M, Salmenperä P, Myllykangas S, Koskenvuo J, Alastalo TP. Prevalence of RPGR-Mediated Retinal Dystrophy in an Unselected Cohort of Over 5000 Patients. Transl Vis Sci Technol 2022; 11:6. [PMID: 34985506 PMCID: PMC8742508 DOI: 10.1167/tvst.11.1.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Comprehensive genetic testing for inherited retinal dystrophy (IRD) is challenged by difficult-to-sequence genomic regions, which are often mutational hotspots, such as RPGR ORF15. The purpose of this study was to evaluate the diagnostic contribution of RPGR variants in an unselected IRD patient cohort referred for testing in a clinical diagnostic laboratory. Methods A total of 5201 consecutive patients were analyzed with a clinically validated next-generation sequencing (NGS)–based assay, including the difficult-to-sequence RPGR ORF15 region. Copy number variant (CNV) detection from NGS data was included. Variant interpretation was performed per the American College of Medical Genetics and Genomics guidelines. Results A confirmed molecular diagnosis in RPGR was found in 4.5% of patients, 24.0% of whom were females. Variants in ORF15 accounted for 74% of the diagnoses; 29% of the diagnostic variants were in the most difficult-to-sequence central region of ORF15 (c.2470-3230). Truncating variants made up the majority (91%) of the diagnostic variants. CNVs explained 2% of the diagnostic cases, of which 80% were one- or two-exon deletions outside of ORF15. Conclusions Our findings indicate that high-throughput, clinically validated NGS-based testing covering the difficult-to-sequence region of ORF15, in combination with high-resolution CNV detection, can help to maximize the diagnostic yield for patients with IRD. Translational Relevance These results demonstrate an accurate and scalable method for the detection of RPGR-related variants, including the difficult-to-sequence ORF15 hotspot, which is relevant given current and emerging therapeutic opportunities.
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Affiliation(s)
| | | | | | | | | | - Kirsty Wells
- Blueprint Genetics OY, Keilaranta, Espoo, Finland
| | | | | | | | | | | | | | | | - Eeva-Marja Sankila
- Helsinki University Eye Hospital, Outpatient Clinic for Hereditary Eye Diseases, Helsinki, Finland
| | | | | | | | | | - Ville Kytölä
- Blueprint Genetics OY, Keilaranta, Espoo, Finland
| | - Mikko Muona
- Blueprint Genetics OY, Keilaranta, Espoo, Finland
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13
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Buckley TM, Jolly JK, Josan AS, Wood LJ, Cehajic‐Kapetanovic J, MacLaren RE. Clinical applications of microperimetry in RPGR-related retinitis pigmentosa: a review. Acta Ophthalmol 2021; 99:819-825. [PMID: 33783139 DOI: 10.1111/aos.14816] [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: 07/13/2020] [Revised: 12/16/2020] [Accepted: 02/02/2021] [Indexed: 01/05/2023]
Abstract
Microperimetry, or fundus-tracked perimetry, is a precise static-automated perimetric technique to assess central retinal function. As visual acuity only deteriorates at a late disease stage in RPGR-related retinitis pigmentosa (RP), alternative markers for disease progression are of great utility. Microperimetry assessment has been of critical value as an outcome measure in a recently reported phase I/II gene therapy trial for RPGR-related RP, both in terms of detecting safety and efficacy signals. Here, we performed a review of the literature. We describe the principles of microperimetry before outlining specific parameters that may be useful as outcome measures in clinical trial settings. The current state of structure-function correlations between short-wavelength autofluorescence, optical coherence tomography and adaptive optics in RPGR-related retinitis pigmentosa are also summarized.
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Affiliation(s)
| | - Jasleen K. Jolly
- Oxford Eye Hospital Oxford University Hospitals NHS Trust Oxford UK
- Nuffield Laboratory of Ophthalmology Nuffield Department of Clinical Neurosciences Oxford Biomedical Research Centre University of Oxford Oxford UK
| | - Amandeep Singh Josan
- Oxford Eye Hospital Oxford University Hospitals NHS Trust Oxford UK
- Nuffield Laboratory of Ophthalmology Nuffield Department of Clinical Neurosciences Oxford Biomedical Research Centre University of Oxford Oxford UK
| | - Laura J. Wood
- Oxford Eye Hospital Oxford University Hospitals NHS Trust Oxford UK
- Nuffield Laboratory of Ophthalmology Nuffield Department of Clinical Neurosciences Oxford Biomedical Research Centre University of Oxford Oxford UK
| | - Jasmina Cehajic‐Kapetanovic
- Oxford Eye Hospital Oxford University Hospitals NHS Trust Oxford UK
- Nuffield Laboratory of Ophthalmology Nuffield Department of Clinical Neurosciences Oxford Biomedical Research Centre University of Oxford Oxford UK
| | - Robert E. MacLaren
- Oxford Eye Hospital Oxford University Hospitals NHS Trust Oxford UK
- Nuffield Laboratory of Ophthalmology Nuffield Department of Clinical Neurosciences Oxford Biomedical Research Centre University of Oxford Oxford UK
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14
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Analysis of imaging biomarkers and retinal nerve fiber layer thickness in RPGR-associated retinitis pigmentosa. Graefes Arch Clin Exp Ophthalmol 2021; 259:3597-3604. [PMID: 34287692 PMCID: PMC8589744 DOI: 10.1007/s00417-021-05233-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 03/22/2021] [Accepted: 05/03/2021] [Indexed: 01/23/2023] Open
Abstract
Purpose To investigate multimodal retinal imaging characteristics including the retinal nerve fiber layer (RNFL) thickness in patients with RPGR-associated retinitis pigmentosa (RP). Methods This cross-sectional case–control study included 17 consecutive patients (median age, 21 years) with RPGR-associated RP who underwent retinal imaging including optical coherence tomography (OCT), short-wavelength fundus autofluorescence (AF) imaging, and RNFL scans centered on the optic disc. RNFL thickness was manually segmented and compared to clinical and imaging parameters including the transfoveal ellipsoid zone (EZ) width, the horizontal diameter of the macular hyperautofluorescent ring. RNFL thickness was compared to 17 age- and sex-matched controls. Results In patients with RPGR-associated RP, the EZ width (R2 = 0.65), the central hyperautofluorescent ring on AF images (R2 = 0.72), and visual acuity (R2 = 0.68) were negatively correlated with age. In comparison to controls, a significantly (p < 0.0001) increased global RNFL thickness was identified in RPGR-associated RP, which was, however, less pronounced in progressed disease as indicated by the EZ width or the diameter of the central hyperautofluorescent ring. Conclusions This study describes retinal characteristics in patients with RPGR-associated RP including a pronounced peripapillary RNFL thickness compared to healthy controls. These results contribute to the knowledge about imaging biomarkers in RP, which might be of interest for therapeutic approaches such as gene replacement therapies.
![]() Supplementary Information The online version contains supplementary material available at 10.1007/s00417-021-05233-w.
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15
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Michalakis S, Gerhardt M, Rudolph G, Priglinger S, Priglinger C. Gene Therapy for Inherited Retinal Disorders: Update on Clinical Trials. Klin Monbl Augenheilkd 2021; 238:272-281. [PMID: 33784790 DOI: 10.1055/a-1384-0818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Within the last decade, continuous advances in molecular biological techniques have made it possible to develop causative therapies for inherited retinal disorders (IRDs). Some of the most promising options are gene-specific approaches using adeno-associated virus-based vectors to express a healthy copy of the disease-causing gene in affected cells of a patient. This concept of gene supplementation therapy is already advocated for the treatment of retinal dystrophy in RPE65-linked Leber's congenital amaurosis (LCA) patients. While the concept of gene supplementation therapy can be applied to treat autosomal recessive and X-linked forms of IRD, it is not sufficient for autosomal dominant IRDs, where the pathogenic gene product needs to be removed. Therefore, for autosomal dominant IRDs, alternative approaches that utilize CRISPR/Cas9 or antisense oligonucleotides to edit or deplete the mutant allele or gene product are needed. In recent years, research retinal gene therapy has intensified and promising approaches for various forms of IRD are currently in preclinical and clinical development. This review article provides an overview of current clinical trials for the treatment of IRDs.
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Affiliation(s)
| | - Maximilian Gerhardt
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
| | - Günter Rudolph
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
| | | | - Claudia Priglinger
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
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16
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Birtel J, Yusuf IH, Priglinger C, Rudolph G, Charbel Issa P. Diagnosis of Inherited Retinal Diseases. Klin Monbl Augenheilkd 2021; 238:249-259. [PMID: 33784788 DOI: 10.1055/a-1388-7236] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inherited retinal diseases are a frequent cause of severe visual impairment or blindness in children and adults of working age. Across this group of diseases, there is great variability in the degree of visual impairment, the impact on everyday life, disease progression, and the suitability to therapeutic intervention. Therefore, an early and precise diagnosis is crucial for patients and their families. Characterizing inherited retinal diseases involves a detailed medical history, clinical examination with testing of visual function, multimodal retinal imaging as well as molecular genetic testing. This may facilitate a distinction between different inherited retinal diseases, as well as a differentiation from monogenic systemic diseases with retinal involvement, and from mimicking diseases.
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Affiliation(s)
- Johannes Birtel
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom.,Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Imran H Yusuf
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom.,Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Claudia Priglinger
- Department of Ophthalmology, University Hospital, LMU Munich, Munich, Germany
| | - Günter Rudolph
- Department of Ophthalmology, University Hospital, LMU Munich, Munich, Germany
| | - Peter Charbel Issa
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom.,Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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17
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Wood LJ, Jolly JK, Josan AS, Buckley TMW, MacLaren RE. Low Luminance Visual Acuity and Low Luminance Deficit in Choroideremia and RPGR-Associated Retinitis Pigmentosa. Transl Vis Sci Technol 2021; 10:28. [PMID: 34003913 PMCID: PMC7900861 DOI: 10.1167/tvst.10.2.28] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 01/07/2021] [Indexed: 11/24/2022] Open
Abstract
Introduction Choroideremia and RPGR-associated retinitis pigmentosa (RP) are two distinct inherited rod-cone degenerations, where good visual acuity (VA) is maintained until late disease stages, limiting its usefulness as a disease marker. Low luminance VA and low luminance deficit (standard VA minus low luminance VA) may be more sensitive visual function measures. Methods Standard VA was obtained using Early Treatment Diabetic Retinopathy Study letter charts (Precision Vision, Bloomington, IL, USA). Low luminance VA was assessed using a 2.0-log unit neutral density filter, with the same chart setup, without formal dark adaptation. Mean central retinal sensitivity was assessed using MAIA microperimetry (Centervue SpA, Padova, Italy). Optical coherence tomography imaging was attained with Heidelberg Eye Explorer software (Heidelberg Engineering, Heidelberg, Germany). Results Twenty-four male participants with confirmed pathogenic RPGR mutations, 44 male participants with confirmed pathogenic CHM mutations, and 62 age-matched controls underwent clinical assessment prior to clinical trial recruitment. Low luminance VA was significantly reduced in both disease groups compared to controls. The low luminance deficit correlated with microperimetry retinal sensitivity and ellipsoid zone width. Eleven participants with moderate VA had poor low luminance VA (subsequently a large low luminance deficit), no detectable microperimetry sensitivity, and severely constricted ellipsoid zone widths. Conclusions Low luminance VA and subsequently low luminance deficit are useful markers of central macular visual function in both choroideremia and RPGR-associated RP, when standard VA is preserved. Translational Relevance Low luminance visual acuity and low luminance deficit are useful vision measures in two distinct rod-cone degenerations and may be useful in other retinal degenerations.
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Affiliation(s)
- Laura J. Wood
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jasleen K. Jolly
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Amandeep S. Josan
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Thomas M. W. Buckley
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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18
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Koyanagi Y, Ueno S, Ito Y, Kominami T, Komori S, Akiyama M, Murakami Y, Ikeda Y, Sonoda KH, Terasaki H. Relationship Between Macular Curvature and Common Causative Genes of Retinitis Pigmentosa in Japanese Patients. Invest Ophthalmol Vis Sci 2021; 61:6. [PMID: 32749464 PMCID: PMC7441377 DOI: 10.1167/iovs.61.10.6] [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] [Indexed: 11/24/2022] Open
Abstract
Purpose To determine the relationship between the macular curvature and the causative genes of retinitis pigmentosa (RP). Methods We examined the medical records of the right eyes of 65 cases with RP (31 men and 34 women; average age, 47.6 years). There were 31 cases with the EYS variants, 11 cases with the USH2A variants, six cases with the RPGR variants, 13 cases with the RP1 variants, and four cases with the RP1L1 variants. The mean curvature of Bruch's membrane was calculated within 6 mm of the fovea as the mean macular curvature index (MMCI, 1/µm). We used multiple linear regression analysis to determine the independence of the causative genes contributing to the MMCIs after adjustments for age, sex, axial length, and width of the ellipsoid zone. Results The median MMCI was −31.2 × 10−5/µm for the RPGR eyes, −16.5 × 10−5/µm for the RP1L1 eyes, −13.0 × 10−5/µm for the RP1 eyes, −9.8 × 10−5/µm for the EYS eyes, and −9.0 × 10−5/µm for the USH2A eyes. Compared with the EYS gene as the reference gene, the RPGR gene was significantly related to the MMCI values after adjusting for the other parameters (P = 5.30 × 10−6). In contrast, the effects of the other genes, USH2A, RP1, and RP1L1, were not significantly different from that of the EYS gene (P = 0.26, P = 0.49, and P = 0.92, respectively). Conclusions The RPGR gene had a stronger effect on the steep macular curvature than the other ciliopathy-related genes.
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19
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Mahroo OA, Arno G, Ba-Abbad R, Downes SM, Bird A, Webster AR. Reanalysis of Association of Pro50Leu Substitution in Guanylate Cyclase Activating Protein-1 With Dominant Retinal Dystrophy. JAMA Ophthalmol 2020; 138:200-203. [PMID: 31804667 PMCID: PMC6902164 DOI: 10.1001/jamaophthalmol.2019.4959] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Question Is there evidence that the Pro50Leu substitution in guanylate cyclase activating protein-1 (encoded by the gene GUCA1A) is associated with a dominant retinal dystrophy? Findings In this cross-sectional study reevaluating the original published study of a family after examination of another family member and further genetic testing, a pathogenic variant in the X chromosome–linked RPGR gene was found. Also, publicly available genomic data show that the variant in GUCA1A is too common to cause a dominant retinal dystrophy. Meaning The p.(Pro50Leu) variant in GUCA1A should not be considered a pathogenic variant. Importance As genetic and genomic screening is becoming more widely accessed, correctly distinguishing pathogenic from nonpathogenic variants is of increasing relevance. Objective To reevaluate a previously reported family in whom the p.(Pro50Leu) variant in the gene GUCA1A was associated with a dominant retinal dystrophy, in light of new examination findings in the proband’s daughter. Design, Setting, and Participants A genetic study relating to a family with an inherited retinal dystrophy was performed at the retinal genetics service of Moorfields Eye Hospital from October 27, 2009, to May 23, 2019, after the proband’s daughter underwent fundus examination. Main Outcomes and Measures Results of sequencing of X chromosome–linked retinitis pigmentosa genes in the proband and specific analysis of the repetitive ORF15 region of the RPGR gene. Results A frame-shifting single-nucleotide deletion was found in the ORF15 exon of RPGR (GRCh37 [hg19] x:38145160delT; NM_001034853.1: c.3092delA p.[Glu1031Glyfs*58]), which may be associated with the loss of 121 amino acid residues at the carboxyl terminus of the protein. The p.(Pro50Leu) variant in GUCA1A was also found to be too common in a publicly available genome database to be a fully penetrant cause of a dominant retinal dystrophy. Conclusions and Relevance The phenotype in the family is now associated with the variant in RPGR. The findings suggest that the p.(Pro50Leu) variant in GUCA1A should not be regarded as pathogenic. This report also highlights the relevance of examining relatives, of reevaluating diagnoses in light of new data, and of considering X chromosome–linked inheritance in apparently autosomal dominant pedigrees unless there is clear male-to-male transmission.
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Affiliation(s)
- Omar A Mahroo
- Genetics Service, Moorfields Eye Hospital, London, United Kingdom.,Institute of Ophthalmology, University College London, United Kingdom.,Section of Ophthalmology, King's College London, St Thomas' Hospital Campus, London, United Kingdom.,Department of Physiology, Development and Neuroscience, University of Cambridge, United Kingdom
| | - Gavin Arno
- Genetics Service, Moorfields Eye Hospital, London, United Kingdom.,Institute of Ophthalmology, University College London, United Kingdom
| | - Rola Ba-Abbad
- Genetics Service, Moorfields Eye Hospital, London, United Kingdom.,Institute of Ophthalmology, University College London, United Kingdom
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals National Health Service Foundation Trust, Oxford, United Kingdom.,Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Alan Bird
- Genetics Service, Moorfields Eye Hospital, London, United Kingdom.,Institute of Ophthalmology, University College London, United Kingdom
| | - Andrew R Webster
- Genetics Service, Moorfields Eye Hospital, London, United Kingdom.,Institute of Ophthalmology, University College London, United Kingdom
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20
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Cehajic-Kapetanovic J, McClements ME, Whitfield J, Shanks M, Clouston P, MacLaren RE. Association of a Novel Intronic Variant in RPGR With Hypomorphic Phenotype of X-Linked Retinitis Pigmentosa. JAMA Ophthalmol 2020; 138:1151-1158. [PMID: 32970112 PMCID: PMC7516822 DOI: 10.1001/jamaophthalmol.2020.3634] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Importance Pathogenic variants in retinitis pigmentosa GTPase regulator (RPGR) gene typically lead to a severe form of X-linked retinitis pigmentosa, which is associated with early severe vision loss. Objective To investigate an X-linked retinal degeneration family with atypical preservation of visual acuity in the presence of a novel deep intronic splice site RPGR c.779-5T>G variant. Design, Setting, and Participants In this case series, 3 members of an X-linked retinal degeneration family were studied by in-depth phenotyping and genetic screening at a single center. Data were collected and analyzed from November 2018 to March 2020. Main Outcomes and Measures Data were collected on full ophthalmic history, examination, and retinal imaging. A full retinitis pigmentosa gene panel was analyzed by next-generation sequencing. The pathogenicity of the RPGR c.779-5T>G variant was assessed by in silico splice prediction tools and by purpose-designed in vitro splicing assay. Results An 84-year-old man was referred with clinical diagnosis of choroideremia and possible inclusion into a gene therapy trial. He presented with late-stage retinal degeneration and unusually preserved visual acuity (78 and 68 ETRDS letters) that clinically resembled choroideremia. His 23-year-old grandson was still in early stages of degeneration but showed a very different clinical picture, typical of retinitis pigmentosa. Next-generation sequencing identified a sole RPGR c.779-5T>G variant of undetermined pathogenicity in both cases. The daughter of the proband showed an RPGR carrier phenotype and was confirmed to carry the same variant. The molecular analysis confirmed that the RPGR c.779-5T>G variation reduced the efficiency of intron splicing compared with wild type, leading to a population of mutant and normal transcripts. The predicted consequences of the pathogenic variant are potential use of an alternative splice acceptor site or complete skipping of exon 8, resulting in truncated forms of the RPGR protein with different levels of glutamylation. Conclusions and Relevance These results support the importance of careful interpretation of inconsistent clinical phenotypes between family members. Using a molecular splicing assay, a new pathogenic variant in a noncoding region of RPGR was associated with a proportion of normal and hypomorphic RPGR, where cones are likely to survive longer than expected, potentially accounting for the preserved visual acuity observed in this family.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, England
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, England
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
| | - Jennifer Whitfield
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
| | - Morag Shanks
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
| | - Penny Clouston
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, England
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, England
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21
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Woodburn KW, Vijay S, Blumenkranz MS. Sight of Action: the Rationale and Evolution of Gene Therapy Approaches to the Treatment of Retinal Diseases. CURRENT OPHTHALMOLOGY REPORTS 2020. [DOI: 10.1007/s40135-020-00255-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Liu YS, Pan JQ, Wan JF, Ren CY, Xu ZH, Pan XB, Gao RN, Liu SQ, Zhang JL, Yao QH, Wang JH, Li EM, Rao JH, Hou P, Chen JH. A novel missense mutation of RPGR identified from retinitis pigmentosa affects splicing of the ORF15 region and causes loss of transcript heterogeneity. Biochem Biophys Res Commun 2020; 531:172-179. [PMID: 32788070 DOI: 10.1016/j.bbrc.2020.06.109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 06/22/2020] [Indexed: 02/05/2023]
Abstract
Mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene, are the major cause of X-linked retinitis pigmentosa (RP), in which exon open reading frame 15 (ORF15) of RPGR has been implicated to play a substantial role. We identified a novel hemizygous missense mutation E585K of RPGR from whole-exome sequencing of RP. RNA-Seq analysis and functional study were conducted to investigate the underlying pathogenic mechanism of the mutation. Our results showed that the mutation actually affected RPGR ORF15 splicing. RNA-Seq analysis of the human retina followed by validation in cells revealed a complex splicing pattern near the 3' boundary of RPGR exon 14 in the ORF15 region, resulting from a variety of alternative splicing events (ASEs). The wildtype RPGR mini-gene expressed in human 293T cells confirmed these ASEs in vitro. In contrast, without new RNA species detected, the mutant mini-gene disrupted the splicing pattern of the ORF15 region, and caused loss of RPGR transcript heterogeneity. The RNA species derived from the mutant mini-gene were predominated by a minor out-of-frame transcript that was also observed in wildtype RPGR, resulting from an upstream alternative 5' splice site in exon 14. Our findings therefore provide insights into the influence of RPGR exonic mutations on alternative splicing of the ORF15 region, and the underlying molecular mechanism of RP.
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Affiliation(s)
- Yan-Shan Liu
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China; Joint Primate Research Center for Chronic Diseases, Jiangnan University and Guangdong Institute of Applied Biological Resources, Jiangnan University, Wuxi, Jiangsu, China; Guangdong Institute of Applied Biological Resources, Guangzhou, Guangdong, China
| | - Jia-Qi Pan
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China; Joint Primate Research Center for Chronic Diseases, Jiangnan University and Guangdong Institute of Applied Biological Resources, Jiangnan University, Wuxi, Jiangsu, China; Guangdong Institute of Applied Biological Resources, Guangzhou, Guangdong, China
| | - Ji-Feng Wan
- Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China
| | - Chun-Yan Ren
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China; Joint Primate Research Center for Chronic Diseases, Jiangnan University and Guangdong Institute of Applied Biological Resources, Jiangnan University, Wuxi, Jiangsu, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
| | - Zhou-Heng Xu
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Xu-Bin Pan
- Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Ruo-Nan Gao
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Shao-Qiang Liu
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Jia-Li Zhang
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | | | - Ji-Hong Wang
- Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - En-Min Li
- Shantou University Medical College, Shantou, Guangdong, China
| | - Jun-Hua Rao
- Joint Primate Research Center for Chronic Diseases, Jiangnan University and Guangdong Institute of Applied Biological Resources, Jiangnan University, Wuxi, Jiangsu, China; Guangdong Institute of Applied Biological Resources, Guangzhou, Guangdong, China
| | - Ping Hou
- Jinhua Eye Hospital, Jinhua, Zhejiang, China.
| | - Jian-Huan Chen
- Laboratory of Genomic and Precision Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China; Joint Primate Research Center for Chronic Diseases, Jiangnan University and Guangdong Institute of Applied Biological Resources, Jiangnan University, Wuxi, Jiangsu, China; Guangdong Institute of Applied Biological Resources, Guangzhou, Guangdong, China.
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23
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Cehajic-Kapetanovic J, Jasani KM, Shanks M, Clouston P, MacLaren RE. A novel homozygous c.67C>T variant in retinol binding protein 4 (RBP4) associated with retinitis pigmentosa and childhood acne vulgaris. Ophthalmic Genet 2020; 41:288-292. [PMID: 32323592 DOI: 10.1080/13816810.2020.1755985] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND The retinol binding protein 4 (RBP4) is essential in delivering retinol to the retinal pigment epithelium and normal functioning of the visual cycle. Homozygous mutations in the RBP4 gene lead to severe retinitis pigmentosa that is phenotypically indistinguishable from retinitis pigmentosa caused by other recessive mutations. METHODS Case Report. PURPOSE To report a novel homozygous RBP4 c.67 C > T variant in a case of retinitis pigmentosa associated with severe childhood acne vulgaris. RESULTS A 49-year old Caucasian man with a family history of retinitis pigmentosa, presented with low vision and night blindness from early childhood. Fundus examination showed findings typical of recessive retinitis pigmentosa. Next generation sequencing analysis revealed a novel homozygous RBP4 c.67 C > T variant. Examination of patient's back showed widespread scaring and hyperpigmentation secondary to severe childhood-onset acne vulgaris. Patient's affected brother, positive for the same homozygous variant, also had a history of severe acne vulgaris whereas the unaffected brother did not, confirming that mutations in RBP4 segregated with the acne vulgaris phenotype in this family. CONCLUSIONS We describe a case of retinitis pigmentosa associated with acne vulgaris and highlight the role of this systemic manifestation of retinol deficiency in confirming pathogenicity of the novel variant. Given the small size of the genomic RBP4 DNA (0.6kb), gene therapy using an adeno-associated viral vector with subretinal delivery has great potential to treat this severe childhood-onset blinding retinal disease. In addition, ubiquitous expression of RBP4 supports the development of in vitro functional assays to test the vector potency for clinical use.
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Affiliation(s)
- J Cehajic-Kapetanovic
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University , Oxford, UK
| | - K M Jasani
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - M Shanks
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - P Clouston
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - R E MacLaren
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University , Oxford, UK
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24
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Talib M, Boon CJF. Retinal Dystrophies and the Road to Treatment: Clinical Requirements and Considerations. Asia Pac J Ophthalmol (Phila) 2020; 9:159-179. [PMID: 32511120 PMCID: PMC7299224 DOI: 10.1097/apo.0000000000000290] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/01/2020] [Indexed: 12/15/2022] Open
Abstract
: Retinal dystrophies (RDs) comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in the same gene may lead to different diagnoses, for example, retinitis pigmentosa or cone dystrophy. Conversely, mutations in different genes may lead to the same phenotype. The age at symptom onset, and the rate and characteristics of peripheral and central vision decline, may vary widely per disease group and even within families. For most RD cases, no effective treatment is currently available. However, preclinical studies and phase I/II/III gene therapy trials are ongoing for several RD subtypes, and recently the first retinal gene therapy has been approved by the US Food and Drug Administration for RPE65-associated RDs: voretigene neparvovec-rzyl (Luxturna). With the rapid advances in gene therapy studies, insight into the phenotypic spectrum and long-term disease course is crucial information for several RD types. The vast clinical heterogeneity presents another important challenge in the evaluation of potential efficacy in future treatment trials, and in establishing treatment candidacy criteria. This perspective describes these challenges, providing detailed clinical descriptions of several forms of RD that are caused by genes of interest for ongoing and future gene or cell-based therapy trials. Several ongoing and future treatment options will be described.
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Affiliation(s)
- Mays Talib
- Department of Ophthalmology, Leiden, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden, The Netherlands
- Department of Ophthalmology, Amsterdam UMC, Academic Medical Center, University of Amsterdam. Amsterdam, The Netherlands
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25
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Switonski M. Impact of gene therapy for canine monogenic diseases on the progress of preclinical studies. J Appl Genet 2020; 61:179-186. [PMID: 32189222 PMCID: PMC7148265 DOI: 10.1007/s13353-020-00554-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/24/2020] [Accepted: 03/09/2020] [Indexed: 12/31/2022]
Abstract
Rapid progress in knowledge of the organization of the dog genome has facilitated the identification of the mutations responsible for numerous monogenic diseases, which usually present a breed-specific distribution. The majority of these diseases have clinical and molecular counterparts in humans. The affected dogs have thus become valuable models for preclinical studies of gene therapy for problems such as eye diseases, immunodeficiency, lysosomal storage diseases, hemophilia, and muscular dystrophy. Successful gene therapies in dogs have significantly contributed to decisions to run clinical trials for several human diseases, such as Leber's congenital amaurosis 2-LCA2 (caused by a mutation of RPE65), X-linked retinitis pigmentosa-XLRP (caused by mutation RPGR), and achromatopsia (caused by mutation of CNGB3). Promising results were also obtained for canine as follows: hemophilia (A and B), mucopolysaccharidoses (MPS I, MPS IIIB, MPS VII), leukocyte adhesion deficiency (CLAD), and muscular dystrophy (a counterpart of human Duchenne dystrophy). Present knowledge on molecular background of canine monogenic diseases and their successful gene therapies prove that dogs have an important contribution to preclinical studies.
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Affiliation(s)
- Marek Switonski
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Poznan, Poland.
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Menghini M, Jolly JK, Nanda A, Wood L, Cehajic-Kapetanovic J, MacLaren RE. Early Cone Photoreceptor Outer Segment Length Shortening in RPGR X-Linked Retinitis Pigmentosa. Ophthalmologica 2020; 244:281-290. [PMID: 32209785 DOI: 10.1159/000507484] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/24/2020] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Introduction of retinal gene therapy requires established outcome measures along with thorough understanding of the pathophysiology. Evidence of early, thinned outer segments in RPGR X-linked retinitis pigmentosa could help understand how the level of cone photoreceptor involvement translates to visual potential. OBJECTIVE Analysis of foveal photoreceptor outer segment length in a young cohort of RPGR patients to help clarify the reason for absent maximal visual acuity seen. METHODS Case-control study of RPGR patients. Quantitative measurement of photoreceptor outer segment by OCT. RESULTS Eighteen male RPGR patients and 30 normal subjects were included. Outer segment thickness differed significantly between the RPGR and normal eyes (p < 0.0005). Mean outer segment values were 35.6 ± 2.3 µm and 35.4 ± 2.6 µm for RPGR right and left eyes, respectively. In normal eyes, the mean outer segment thickness was 61.4 ± 0.7 µm for right eyes and 62.4 ± 0.7 µm for left eyes. CONCLUSIONS Patients with RPGR X-linked retinitis pigmentosa show thinning of the foveal photoreceptor outer segment thickness early in the disease course, which could be an explanation for the lower maximum visual acuity seen. These findings must be taken into consideration when assessing efficacy outcome measures in retinal gene therapy trials.
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Affiliation(s)
- Moreno Menghini
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK,
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK,
| | - Jasleen K Jolly
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Anika Nanda
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Laura Wood
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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RPGR-Associated Dystrophies: Clinical, Genetic, and Histopathological Features. Int J Mol Sci 2020; 21:ijms21030835. [PMID: 32012938 PMCID: PMC7038140 DOI: 10.3390/ijms21030835] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/21/2020] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
This study describes the clinical, genetic, and histopathological features in patients with RPGR-associated retinal dystrophies. Nine male patients from eight unrelated families underwent a comprehensive ophthalmic examination. Additionally, the histopathology of the right eye from a patient with an end-stage cone-rod-dystrophy (CRD)/sector retinitis pigmentosa (RP) phenotype was examined. All RPGR mutations causing a CRD phenotype were situated in exon ORF15. The mean best-corrected visual acuity (BCVA, decimals) was 0.58 (standard deviation (SD)): 0.34; range: 0.05-1.13); and the mean spherical refractive error was -4.1 D (SD: 2.11; range: -1.38 to -8.19). Hyperautofluorescent rings were observed in six patients. Full-field electroretinography responses were absent in all patients. The visual field defects ranged from peripheral constriction to central islands. The mean macular sensitivity on microperimetry was 11.6 dB (SD: 7.8; range: 1.6-24.4) and correlated significantly with BCVA (r = 0.907; p = 0.001). A histological examination of the donor eye showed disruption of retinal topology and stratification, with a more severe loss found in the peripheral regions. Reactive gliosis was seen in the inner layers of all regions. Our study demonstrates the highly variable phenotype found in RPGR-associated retinal dystrophies. Therapies should be applied at the earliest signs of photoreceptor degeneration, prior to the remodeling of the inner retina.
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