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Balfoort BM, Pampalone G, Ruiter JPN, Denis SW, Brands MM, Timmer C, Wagenmakers MAEM, Wanders RJA, van Karnebeek CD, Cellini B, Houtkooper RH, Ferdinandusse S. Extending diagnostic practices in gyrate atrophy: Enzymatic characterization and the development of an in vitro pyridoxine responsiveness assay. Mol Genet Metab 2024; 143:108542. [PMID: 39053126 DOI: 10.1016/j.ymgme.2024.108542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 07/17/2024] [Accepted: 07/17/2024] [Indexed: 07/27/2024]
Abstract
Gyrate atrophy of the choroid and retina (GACR) is caused by pathogenic biallelic variants in the gene encoding ornithine-δ-aminotransferase (OAT), and is characterized by progressive vision loss leading to blindness. OAT is a pyridoxal-5'-phosphate (PLP) dependent enzyme that is mainly involved in ornithine catabolism, and patients with a deficiency develop profound hyperornithinemia. Therapy is aimed at lowering ornithine levels through dietary arginine restriction and, in some cases, through enhancement of OAT activity via supraphysiological dosages of pyridoxine. In this study, we aimed to extend diagnostic practices in GACR by extensively characterizing the consequences of pathogenic variants on the enzymatic function of OAT, both at the level of the enzyme itself as well as the flux through the ornithine degradative pathway. In addition, we developed an in vitro pyridoxine responsiveness assay. We identified 14 different pathogenic variants, of which one variant was present in all patients of Dutch ancestry (p.(Gly353Asp)). In most patients the enzymatic activity of OAT as well as the rate of [14C]-ornithine flux was below the limit of quantification (LOQ). Apart from our positive control, only one patient cell line showed responsiveness to pyridoxine in vitro, which is in line with the reported in vivo pyridoxine responsiveness in this patient. None of the patients harboring the p.(Gly353Asp) substitution were responsive to pyridoxine in vivo or in vitro. In silico analysis and small-scale expression experiments showed that this variant causes a folding defect, leading to increased aggregation properties that could not be rescued by PLP. Using these results, we developed a diagnostic pipeline for new patients suspected of having GACR. Adding OAT enzymatic analyses and in vitro pyridoxine responsiveness to diagnostic practices will not only increase knowledge on the consequences of pathogenic variants in OAT, but will also enable expectation management for therapeutic modalities, thus eventually improving clinical care.
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Affiliation(s)
- Berith M Balfoort
- Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Gastroenterology, Endocrinology and Metabolism, Amsterdam, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Gioena Pampalone
- Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Jos P N Ruiter
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Simone W Denis
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Marion M Brands
- Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Corrie Timmer
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Margreet A E M Wagenmakers
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Erasmus University Medical Center Rotterdam, Rotterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Clara D van Karnebeek
- Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands; Amsterdam Gastroenterology, Endocrinology and Metabolism, Amsterdam, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Barbara Cellini
- Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Riekelt H Houtkooper
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands; Amsterdam Gastroenterology, Endocrinology and Metabolism, Amsterdam, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Gastroenterology, Endocrinology and Metabolism, Amsterdam, University of Amsterdam, Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands.
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2
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Merino Diez MT, Soria Prada C, Zamorano Aleixandre M, Gonzalez-Lopez JJ. Gyrate atrophy of the choroid and retina: Update on diagnosis and treatment. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2024; 99:392-399. [PMID: 38663712 DOI: 10.1016/j.oftale.2024.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/12/2024] [Indexed: 04/30/2024]
Abstract
Gyrate atrophy of the choroid and retina (GACR) is a rare autosomal recessive disease characterised by elevated plasma ornithine levels due to deficiency of the enzyme ornithine aminotransferase (OAT). The accumulation of this amino acid in plasma leads to the development of patches of chorioretinal atrophy in the peripheral retina extending into the macular area. Patients usually present with night blindness followed by constriction of the visual field and, finally, decreased central vision and blindness. The disease is diagnosed by the presence of the characteristic clinical picture, the presence of hyperornithinaemia in plasma and the detection of mutations in the OAT enzyme gene. There is currently no effective gene therapy and the most common therapeutic intervention mainly involves dietary modifications with arginine restriction. This article aims to summarise the pathogenesis, clinical and diagnostic findings and treatment options in patients with GACR.
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Affiliation(s)
| | - C Soria Prada
- Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
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3
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Bergen AA, Buijs MJ, Ten Asbroek AL, Balfoort BM, Boon CJ, Brands MM, Wanders RJ, van Karnebeek CD, Houtkooper RH. Vision on gyrate atrophy: why treat the eye? EMBO Mol Med 2024; 16:4-7. [PMID: 38177529 PMCID: PMC10883273 DOI: 10.1038/s44321-023-00001-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/29/2023] [Accepted: 10/09/2023] [Indexed: 01/06/2024] Open
Abstract
In the April issue of this Journal, Boffa and coworkers put forward a new therapeutic approach for Gyrate Atrophy of the Choroid and Retina (GACR; OMIM 258870) (Boffa et al, 2023). The authors propose to apply gene therapy to the liver for GACR, a metabolic disease primarily affecting eyesight due to retinal degeneration. Their vision is enthusiastically supported by a News and Views comment in the same issue (Seker Yilmaz and Gissen, 2023). However, based on disease pathology, patient's needs, ethical considerations, therapeutic developmental time lines, and current state of the art of gene therapy for liver and eye, we have a different view on this issue: We argue below that local treatment of the eye is the preferred option for GACR.
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Affiliation(s)
- Arthur A Bergen
- Department of Human Genetics, Section Ophthalmogenetics, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands
| | - Mark Jn Buijs
- Department of Human Genetics, Section Ophthalmogenetics, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Anneloor Lma Ten Asbroek
- Department of Human Genetics, Section Ophthalmogenetics, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Berith M Balfoort
- Department of Paediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Camiel Jf Boon
- Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- Department of Ophthalmology, Leiden UMC, Leiden, the Netherlands
| | - Marion M Brands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands
- Department of Paediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- United for Metabolic Diseases, Amsterdam, The Netherlands
| | - Ronald Ja Wanders
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- United for Metabolic Diseases, Amsterdam, The Netherlands
| | - Clara Dm van Karnebeek
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands
- Department of Paediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
- United for Metabolic Diseases, Amsterdam, The Netherlands
| | - Riekelt H Houtkooper
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, the Netherlands.
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam UMC, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands.
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4
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Pauleikhoff L, Weisschuh N, Lentzsch A, Spital G, Krohne TU, Agostini H, Lange CAK. Clinical characteristics of gyrate atrophy compared with a gyrate atrophy-like retinal phenotype. Eur J Ophthalmol 2024; 34:79-88. [PMID: 37218157 DOI: 10.1177/11206721231178147] [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] [Indexed: 05/24/2023]
Abstract
INTRODUCTION Gyrate atrophy (GA) is a rare retinal dystrophy due to biallelic pathogenic variants in the ornithine aminotransferase (OAT) gene, causing a 10-fold increase in plasma ornithine levels. It is characterized by circular patches of chorioretinal atrophy. However, a GA-like retinal phenotype (GALRP) without elevated ornithine levels has also been reported. The aim of this study is to compare the clinical characteristics of GA and GALRP and to identify possible discriminators. METHODS A multicenter, retrospective chart review was performed at three German referral centres on patient records between 01/01/2009 and 31/12/2021. Records were screened for patients affected by GA or GALRP. Only patients with examination results for plasma ornithine levels and / or genetic testing of the OAT gene were included. Further clinical data was gathered where available. RESULTS Ten patients (5 female) were included in the analysis. Three suffered from GA, while seven had a GALRP. Mean age (± SD) at onset of symptoms was 12.3 (± 3.5) years for GA compared with 46.7 (± 14.0) years for GALRP patients (p = 0.002). Mean degree of myopia was higher in GA (-8.0 dpt. ± 3.6) compared to GALRP patients (-3.8 dpt. ± 4.8, p = 0.04). Interestingly, all GA patients showed macular oedema, while only one GALRP patient did. Only one patient with GALRP had a positive family history, while two were immunosuppressed. DISCUSSION Age of onset, refraction and presence of macular cystoid cavities appear to be discriminators between GA and GALRP. GALRP may encompass both genetic and non-genetic subtypes.
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Affiliation(s)
- L Pauleikhoff
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Ophthalmology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - N Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - A Lentzsch
- Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - G Spital
- St. Franziskus Eye Center, Münster, Germany
| | - T U Krohne
- Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - H Agostini
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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5
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Palmer E, Stepien KM, Campbell C, Barton S, Iosifidis C, Ghosh A, Broomfield A, Woodall A, Wilcox G, Sergouniotis PI, Black GC. Clinical, biochemical and molecular analysis in a cohort of individuals with gyrate atrophy. Orphanet J Rare Dis 2023; 18:265. [PMID: 37667371 PMCID: PMC10476330 DOI: 10.1186/s13023-023-02840-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 07/21/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Gyrate atrophy of the choroid and retina is a rare autosomal recessive metabolic disorder caused by biallelic variants in the OAT gene, encoding the enzyme ornithine δ-aminotransferase. Impaired enzymatic activity leads to systemic hyperornithinaemia, which in turn underlies progressive chorioretinal degeneration. In this study, we describe the clinical and molecular findings in a cohort of individuals with gyrate atrophy. METHODS Study participants were recruited through a tertiary UK clinical ophthalmic genetic service. All cases had a biochemical and molecular diagnosis of gyrate atrophy. Retrospective phenotypic and biochemical data were collected using electronic healthcare records. RESULTS 18 affected individuals from 12 families (8 male, 10 female) met the study inclusion criteria. The median age at diagnosis was 8 years (range 10 months - 33 years) and all cases had hyperornithinaemia (median: 800 micromoles/L; range: 458-1244 micromoles/L). Common features at presentation included high myopia (10/18) and nyctalopia (5/18). Ophthalmic findings were present in all study participants who were above the age of 6 years. One third of patients had co-existing macular oedema and two thirds developed pre-senile cataracts. Compliance with dietary modifications was suboptimal in most cases. A subset of participants had extraocular features including a trend towards reduced fat-free mass and developmental delay. CONCLUSIONS Our findings highlight the importance of multidisciplinary care in families with gyrate atrophy. Secondary ophthalmic complications such as macular oedema and cataract formation are common. Management of affected individuals remains challenging due to the highly restrictive nature of the recommended diet and the limited evidence-base for current strategies.
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Affiliation(s)
- Eleanor Palmer
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Karolina M Stepien
- Adult Inherited Metabolic Disorders, Salford Royal NHS Foundation Trust, Salford, Greater Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Christopher Campbell
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Stephanie Barton
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Christos Iosifidis
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Arunabha Ghosh
- Willink Biochemical Genetics, Royal Manchester Children's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Alexander Broomfield
- Willink Biochemical Genetics, Royal Manchester Children's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Alison Woodall
- Adult Inherited Metabolic Disorders, Salford Royal NHS Foundation Trust, Salford, Greater Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Gisela Wilcox
- Adult Inherited Metabolic Disorders, Salford Royal NHS Foundation Trust, Salford, Greater Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Panagiotis I Sergouniotis
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
| | - Graeme C Black
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
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6
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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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7
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Molecular and Cellular Regulations in the Development of the Choroidal Circulation System. Int J Mol Sci 2023; 24:ijms24065371. [PMID: 36982446 PMCID: PMC10048934 DOI: 10.3390/ijms24065371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/09/2023] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
Disorders in the development and regulation of blood vessels are involved in various ocular disorders, such as persistent hyperplastic primary vitreous, familial exudative vitreoretinopathy, and choroidal dystrophy. Thus, the appropriate regulation of vascular development is essential for healthy ocular functions. However, regulation of the developing choroidal circulation system has not been well studied compared with vascular regulation in the vitreous and the retina. The choroid is a vascular-rich and uniquely structured tissue supplying oxygen and nutrients to the retina, and hypoplasia and the degeneration of the choroid are involved in many ocular disorders. Therefore, understanding the developing choroidal circulation system expands our knowledge of ocular development and supports our understanding of ocular disorders. In this review, we examine studies on regulating the developing choroidal circulation system at the cellular and molecular levels and discuss the relevance to human diseases.
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8
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Large Benefit from Simple Things: High-Dose Vitamin A Improves RBP4-Related Retinal Dystrophy. Int J Mol Sci 2022; 23:ijms23126590. [PMID: 35743034 PMCID: PMC9223508 DOI: 10.3390/ijms23126590] [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] [Received: 04/22/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal diseases (IRD) are a group of heterogeneous disorders, most of which lead to blindness with limited therapeutic options. Pathogenic variants in RBP4, coding for a major blood carrier of retinol, retinol-binding protein 4, are responsible for a peculiar form of IRD. The aim of this study was to investigate if retinal function of an RBP4-related IRD patient can be improved by retinol administration. Our patient presented a peculiar white-dot retinopathy, reminiscent of vitamin A deficient retinopathy. Using a customized next generation sequencing (NGS) IRD panel we discovered a novel loss-of-function homozygous pathogenic variant in RBP4: c.255G >A, p.(Trp85*). Western blotting revealed the absence of RBP4 protein in the patient’s serum. Blood retinol levels were undetectable. The patient was put on a high-dose oral retinol regimen (50,000 UI twice a week). Subjective symptoms and retinal function markedly and sustainably improved at 5-months and 1-year follow-up. Here we show that this novel IRD case can be treated by oral retinol administration.
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9
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Garanto A, Ferreira CR, Boon CJF, van Karnebeek CDM, Blau N. Clinical and biochemical footprints of inherited metabolic disorders. VII. Ocular phenotypes. Mol Genet Metab 2022; 135:311-319. [PMID: 35227579 PMCID: PMC10518078 DOI: 10.1016/j.ymgme.2022.02.002] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 01/19/2022] [Accepted: 02/11/2022] [Indexed: 12/11/2022]
Abstract
Ocular manifestations are observed in approximately one third of all inherited metabolic disorders (IMDs). Although ocular involvement is not life-threatening, it can result in severe vision loss, thereby leading to an additional burden for the patient. Retinal degeneration with or without optic atrophy is the most frequent phenotype, followed by oculomotor problems, involvement of the cornea and lens, and refractive errors. These phenotypes can provide valuable clues that contribute to its diagnosis. In this issue we found 577 relevant IMDs leading to ophthalmologic manifestations. This article is the seventh of a series attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.
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Affiliation(s)
- Alejandro Garanto
- Department of Pediatrics, Amalia Children's Hospital Radboud Center for Mitochondrial and Metabolic Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands.
| | - Carlos R Ferreira
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands and Amsterdam University Medical Centers, Academic Medical Center, Department of Ophthalmology, University of Amsterdam, Amsterdam, the Netherlands.
| | - Clara D M van Karnebeek
- Department of Pediatrics, Amalia Children's Hospital Radboud Center for Mitochondrial and Metabolic Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands; Departments of Pediatrics and Human Genetics, Emma Children's Hospital, Amsterdam Reproduction and Development, Amsterdam University Medical Centers, Amsterdam, the Netherlands.
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital, Zürich, Switzerland.
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10
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Fenner BJ, Tan TE, Barathi AV, Tun SBB, Yeo SW, Tsai ASH, Lee SY, Cheung CMG, Chan CM, Mehta JS, Teo KYC. Gene-Based Therapeutics for Inherited Retinal Diseases. Front Genet 2022; 12:794805. [PMID: 35069693 PMCID: PMC8782148 DOI: 10.3389/fgene.2021.794805] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a heterogenous group of orphan eye diseases that typically result from monogenic mutations and are considered attractive targets for gene-based therapeutics. Following the approval of an IRD gene replacement therapy for Leber's congenital amaurosis due to RPE65 mutations, there has been an intensive international research effort to identify the optimal gene therapy approaches for a range of IRDs and many are now undergoing clinical trials. In this review we explore therapeutic challenges posed by IRDs and review current and future approaches that may be applicable to different subsets of IRD mutations. Emphasis is placed on five distinct approaches to gene-based therapy that have potential to treat the full spectrum of IRDs: 1) gene replacement using adeno-associated virus (AAV) and nonviral delivery vectors, 2) genome editing via the CRISPR/Cas9 system, 3) RNA editing by endogenous and exogenous ADAR, 4) mRNA targeting with antisense oligonucleotides for gene knockdown and splicing modification, and 5) optogenetic approaches that aim to replace the function of native retinal photoreceptors by engineering other retinal cell types to become capable of phototransduction.
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Affiliation(s)
- Beau J Fenner
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Tien-En Tan
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | | | - Sai Bo Bo Tun
- Singapore Eye Research Institute, Singapore, Singapore
| | - Sia Wey Yeo
- Singapore Eye Research Institute, Singapore, Singapore
| | - Andrew S H Tsai
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Shu Yen Lee
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Chui Ming Gemmy Cheung
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Choi Mun Chan
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Jodhbir S Mehta
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore.,School of Material Science and Engineering, Nanyang Technological University, Singapore, Singapore.,Yong Loo Lin School of Medicine, Department of Ophthalmology, National University of Singapore, Singapore, Singapore
| | - Kelvin Y C Teo
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
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