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Großpötzl M, Riedl R, Schließleder G, Hu ZJ, Michaelides M, Sadda S, Birch D, Charbel Issa P, Wedrich A, Seidel G, Scholl HPN, Strauss RW. Progression of PROM1-Associated Retinal Degeneration as Determined by Spectral-Domain Optical Coherence Tomography Over a 24-Month Period. Am J Ophthalmol 2024; 259:109-116. [PMID: 37979600 DOI: 10.1016/j.ajo.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 11/06/2023] [Accepted: 11/10/2023] [Indexed: 11/20/2023]
Abstract
PURPOSE To evaluate the progression of atrophy as determined by spectral-domain optical coherence tomography (SD-OCT) in patients with molecularly confirmed PROM1-associated retinal degeneration (RD) over a 24-month period. DESIGN International, multicenter, prospective case series. METHODS A total of 13 eyes (13 patients) affected with PROM1-associated RD were enrolled at 5 sites and SD-OCT images were obtained at baseline and after 24 months. Loss of mean thickness (MT) and intact area were estimated after semi-automated segmentation for the following individual retinal layers in the central subfield (CS), inner ring, and outer ring of the ETDRS grid: retinal pigment epithelium (RPE), outer segments (OS), inner segments (IS), outer nuclear layer (ONL), inner retina (IR), and total retina (TR). RESULTS Statistically significant losses of thickness of RPE and TR were detected in the CS and inner ring and of ONL and IS in the outer ring (all P < .05); a statistically significant decrease in the intact area of RPE and IS was observed in the inner ring, and of ONL in the outer ring (all P < .05); the change in MT and the intact area of the other layers showed a trend of decline over an observational period of 24 months. CONCLUSIONS Significant thickness losses could be detected in outer retinal layers by SD-OCT over a 24-month period in patients with PROM1-associated retinal degeneration. Loss of thickness and/or intact area of such layers may serve as potential endpoints for clinical trials that aim to slow down the disease progression of PROM1-associated retinal degeneration.
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Affiliation(s)
- Manuel Großpötzl
- Department of Ophthalmology (M.G., G.S., A.W., G.S., R.W.S), Medical University Graz, Graz, Austria
| | - Regina Riedl
- Institute for Medical Informatics, Statistics and Documentation (R.R.), Medical University Graz, Graz, Austria
| | - Gernot Schließleder
- Department of Ophthalmology (M.G., G.S., A.W., G.S., R.W.S), Medical University Graz, Graz, Austria
| | - Zhihong Jewel Hu
- Doheny Eye Institute (Z.J.H., S.V.S.), David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - Michel Michaelides
- Moorfields Eye Hospital (M.M., R.W.S.), NHS Foundation Trust, London, United Kingdom; UCL Institute of Ophthalmology (M.M., R.W.S.), University College London, London, United Kingdom
| | - SriniVas Sadda
- Doheny Eye Institute (Z.J.H., S.V.S.), David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - David Birch
- Retina Foundation of the Southwest (D.B.), Dallas, Texas, USA
| | - Peter Charbel Issa
- Department of Ophthalmology (P.C.I.), University of Bonn, Bonn, Germany; Oxford Eye Hospital (P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (P.C.I.), Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Andreas Wedrich
- Department of Ophthalmology (M.G., G.S., A.W., G.S., R.W.S), Medical University Graz, Graz, Austria
| | - Gerald Seidel
- Department of Ophthalmology (M.G., G.S., A.W., G.S., R.W.S), Medical University Graz, Graz, Austria
| | - Hendrik P N Scholl
- Institute of Molecular and Clinical Ophthalmology Basel (H.P.N.S.), Basel, Switzerland; Department of Ophthalmology (R.W.S.), University of Basel, Basel, Switzerland
| | - Rupert W Strauss
- Department of Ophthalmology (M.G., G.S., A.W., G.S., R.W.S), Medical University Graz, Graz, Austria; Moorfields Eye Hospital (M.M., R.W.S.), NHS Foundation Trust, London, United Kingdom; UCL Institute of Ophthalmology (M.M., R.W.S.), University College London, London, United Kingdom; Institute of Molecular and Clinical Ophthalmology Basel (H.P.N.S.), Basel, Switzerland; Wilmer Eye Institute (R.W.S.), Johns Hopkins University, Baltimore, Maryland, USA.
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2
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Farnoodian M, Bose D, Barone F, Nelson LM, Boyle M, Jun B, Do K, Gordon W, Guerin MAK, Perera R, Ji JX, Cogliati T, Sharma R, Brooks BP, Bazan NG, Bharti K. Retina and RPE lipid profile changes linked with ABCA4 associated Stargardt's maculopathy. Pharmacol Ther 2023; 249:108482. [PMID: 37385300 PMCID: PMC10530239 DOI: 10.1016/j.pharmthera.2023.108482] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/20/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
Stargardt maculopathy, caused predominantly by mutations in the ABCA4 gene, is characterized by an accumulation of non-degradable visual pigment derivative, lipofuscin, in the retinal pigment epithelium (RPE) - resulting in RPE atrophy. RPE is a monolayer tissue located adjacent to retinal photoreceptors and regulates their health and functioning; RPE atrophy triggers photoreceptor cell death and vision loss in Stargardt patients. Previously, ABCA4 mutations in photoreceptors were thought to be the major contributor to lipid homeostasis defects in the eye. Recently, we demonstrated that ABCA4 loss of function in the RPE leads to cell-autonomous lipid homeostasis defects. Our work underscores that an incomplete understanding of lipid metabolism and lipid-mediated signaling in the retina and RPE are potential causes for lacking treatments for this disease. Here we report altered lipidomic in mouse and human Stargardt models. This work provides the basis for therapeutics that aim to restore lipid homeostasis in the retina and the RPE.
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Affiliation(s)
- Mitra Farnoodian
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Devika Bose
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Francesca Barone
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Luke Mathew Nelson
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Marisa Boyle
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Khanh Do
- Faculty of Medicine, Phenikaa University, Hanoi, Viet Nam
| | - William Gordon
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Marie-Audrey Kautzmann Guerin
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Rasangi Perera
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Jeff X Ji
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Tiziana Cogliati
- Division of Aging Biology, National Institute on Aging, National Institute of Health, Bethesda, MD, USA
| | - Ruchi Sharma
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Kapil Bharti
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA.
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3
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Paavo M, Lee W, Parmann R, Lima de Carvalho JR, Zernant J, Tsang SH, Allikmets R, Sparrow JR. Insights Into PROM1-Macular Disease Using Multimodal Imaging. Invest Ophthalmol Vis Sci 2023; 64:27. [PMID: 37093133 PMCID: PMC10148657 DOI: 10.1167/iovs.64.4.27] [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: 11/17/2022] [Accepted: 03/15/2023] [Indexed: 04/25/2023] Open
Abstract
Purpose To describe the features of genetically confirmed PROM1-macular dystrophy in multimodal images. Methods Thirty-six (36) eyes of 18 patients (5-66 years; mean age, 42.4 years) were prospectively studied by clinical examination and multimodal imaging. Short-wavelength autofluorescence (SW-AF) and quantitative fundus autofluorescence (qAF) images were acquired with a scanning laser ophthalmoscope (HRA+OCT, Heidelberg Engineering) modified by insertion of an internal autofluorescent reference. Further clinical testing included near-infrared autofluorescence (NIR-AF; HRA2, Heidelberg Engineering) with semiquantitative analysis, spectral domain-optical coherence tomography (HRA+OCT) and full-field electroretinography. All patients were genetically confirmed by exome sequencing. Results All 18 patients presented with varying degrees of maculopathy. One family with individuals affected across two generations exhibited granular fleck-like deposits across the posterior pole. Areas of granular deposition in SW-AF and NIR-AF corresponded to intermittent loss of the ellipsoid zone, whereas discrete regions of hypoautofluorescence corresponded with a loss of outer retinal layers in spectral-domain optical coherence tomography scans. For 18 of the 20 eyes, qAF levels within the macula were within the 95% confidence intervals of healthy age-matched individuals; nor was the mean NIR-AF signal increased relative to healthy eyes. Conclusions Although PROM1-macular dystrophy (Stargardt disease 4) can exhibit phenotypic overlap with recessive Stargardt disease, significantly increased SW-AF levels were not detected. As such, elevated bisretinoid lipofuscin may not be a feature of the pathophysiology of PROM1 disease. The qAF approach could serve as a method of early differential diagnosis and may help to identify appropriate disease targets as therapeutics become available to treat inherited retinal disease.
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Affiliation(s)
- Maarjaliis Paavo
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
- Helsinki University Eye Hospital, Helsinki, Finland
| | - Winston Lee
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
| | - Rait Parmann
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
| | | | - Jana Zernant
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
| | - Stephen H. Tsang
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
| | - Rando Allikmets
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
| | - Janet R. Sparrow
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, United States
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
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4
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Sajovic J, Meglič A, Volk M, Maver A, Jarc-Vidmar M, Hawlina M, Fakin A. Stargardt-like Clinical Characteristics and Disease Course Associated with Variants in the WDR19 Gene. Genes (Basel) 2023; 14:genes14020291. [PMID: 36833218 PMCID: PMC9957452 DOI: 10.3390/genes14020291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
Variants in WDR19 (IFT144) have been implicated as another possible cause of Stargardt disease. The purpose of this study was to compare longitudinal multimodal imaging of a WDR19-Stargardt patient, harboring p.(Ser485Ile) and a novel c.(3183+1_3184-1)_(3261+1_3262-1)del variant, with 43 ABCA4-Stargardt patients. Age at onset, visual acuity, Ishihara color vision, color fundus, fundus autofluorescence (FAF), spectral-domain optical coherence tomography (OCT) images, microperimetry and electroretinography (ERG) were evaluated. First symptom of WDR19 patient was nyctalopia at the age of 5 years. After the age of 18 years, OCT showed hyper-reflectivity at the level of the external limiting membrane/outer nuclear layer. There was abnormal cone and rod photoreceptor function on ERG. Widespread fundus flecks appeared, followed by perifoveal photoreceptor atrophy. Fovea and peripapillary retina remained preserved until the latest exam at 25 years of age. ABCA4 patients had median age of onset at 16 (range 5-60) years and mostly displayed typical Stargardt triad. A total of 19% had foveal sparing. In comparison to ABCA4 patients, the WDR19 patient had a relatively large foveal preservation and severe rod photoreceptor impairment; however, it was still within the ABCA4 disease spectrum. Addition of WDR19 in the group of genes producing phenocopies of Stargardt disease underlines the importance of genetic testing and may help to understand its pathogenesis.
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Affiliation(s)
- Jana Sajovic
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia
| | - Andrej Meglič
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia
| | - Marija Volk
- Clinical Institute of Genomic Medicine, University Medical Centre Ljubljana, Šlajmerjeva 4, 1000 Ljubljana, Slovenia
| | - Aleš Maver
- Clinical Institute of Genomic Medicine, University Medical Centre Ljubljana, Šlajmerjeva 4, 1000 Ljubljana, Slovenia
| | - Martina Jarc-Vidmar
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Marko Hawlina
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Ana Fakin
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
- Correspondence:
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5
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Mc Clinton B, Corradi Z, McKibbin M, Panneman DM, Roosing S, Boonen EGM, Ali M, Watson CM, Steel DH, Cremers FPM, Inglehearn CF, Hitti-Malin RJ, Toomes C. Effective smMIPs-Based Sequencing of Maculopathy-Associated Genes in Stargardt Disease Cases and Allied Maculopathies from the UK. Genes (Basel) 2023; 14:191. [PMID: 36672932 PMCID: PMC9859292 DOI: 10.3390/genes14010191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 01/13/2023] Open
Abstract
Macular dystrophies are a group of individually rare but collectively common inherited retinal dystrophies characterised by central vision loss and loss of visual acuity. Single molecule Molecular Inversion Probes (smMIPs) have proved effective in identifying genetic variants causing macular dystrophy. Here, a previously established smMIPs panel tailored for genes associated with macular diseases has been used to examine 57 UK macular dystrophy cases, achieving a high solve rate of 63.2% (36/57). Among 27 bi-allelic STGD1 cases, only three novel ABCA4 variants were identified, illustrating that the majority of ABCA4 variants in Caucasian STGD1 cases are currently known. We examined cases with ABCA4-associated disease in detail, comparing our results with a previously reported variant grading system, and found this model to be accurate and clinically useful. In this study, we showed that ABCA4-associated disease could be distinguished from other forms of macular dystrophy based on clinical evaluation in the majority of cases (34/36).
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Affiliation(s)
- Benjamin Mc Clinton
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
| | - Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Martin McKibbin
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
- Department of Ophthalmology, St. James’s University Hospital, Leeds LS9 7TF, UK
| | - Daan M. Panneman
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Erica G. M. Boonen
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Manir Ali
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
| | - Christopher M. Watson
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
- North East and Yorkshire Genomic Laboratory Hub, Central Lab, St. James’s University Hospital, Leeds LS9 7TF, UK
| | - David H. Steel
- Sunderland Eye Infirmary, Sunderland SR2 9HP, UK
- The Bioscience Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Frans P. M. Cremers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Chris F. Inglehearn
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
| | - Rebekkah J. Hitti-Malin
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Carmel Toomes
- Leeds Institute of Medical Research, University of Leeds, St James’s University Hospital, Leeds LS9 7TF, UK
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Lee IJ, Abbey C, Leys M. Clinical Characterization of Autosomal Dominant and Autosomal Recessive PROM1 Mutation With a Report of Novel Mutation. Ophthalmic Surg Lasers Imaging Retina 2022; 53:422-428. [PMID: 35951719 DOI: 10.3928/23258160-20220723-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND OBJECTIVE This study aims to provide clinical characterization of PROM1 mutation with a report of novel mutation. PATIENTS AND METHODS This study is a retrospective case series of six patients from a single institution with multimodal imaging, electroretinography, and genetic testing. RESULTS Six patients aged 12 to 47 years were identified. Patients with autosomal recessive (AR) variants showed more severe panretinal dystrophy with symmetrical macular involvement and peripheral retinal pigment epithelium atrophy. The autosomal dominant (AD) variants, on the other hand, showed milder macular involvement with bull's eye maculopathy phenotype with minimal peripheral involvement. Among patients with AR variants, a younger patient with aberrant splicing showed a milder phenotype compared with patients with a nonsense mutation and an additional ABCA4 mutation. CONCLUSION The authors describe patients with PROM1 retinopathy inherited AD and AR inherited patterns. Novel mutations of c.1909C>T and c.2050C>T were identified, leading to truncation of the protein at sequence p.Gln637* and p.Arg684*, respectively. [Ophthalmic Surg Lasers Imaging Retina 2022;53:422-428.].
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Choi H, Cloutier A, Lally D. PRPH2-Associated Macular Dystrophy in 4 Family Members with a Novel Mutation. Ophthalmic Genet 2021; 43:235-239. [PMID: 34906036 DOI: 10.1080/13816810.2021.2015790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Peripherin-2 (PRPH2) gene variants are a well-established cause of multiple inherited maculopathies including central areolar choroidal dystrophy (CACD) and pattern dystrophy. In this familial case study, we present a 63-year-old proband who presented with visual acuity of 20/63 right eye and 20/100 left eye with a complaint of lowered visual acuity in the left eye for unknown duration. Fundus examination presented with unifocal atrophic lesions bilaterally. Multi-modal imaging was obtained and genetic testing (My Retina Tracker; Blueprint Genetics) was performed. The proband was monoallelic for a novel missense mutation within the PRPH2 gene (Arg203Pro) not previously found in the literature or large databases (gnomAD, ClinVar, and HGMD). Subsequent examination of the proband's mother, older sister (65 years old), younger sister (53), and daughter (35) found the novel mutation to segregate with maculopathy ranging from speckled fundus autofluorescence with EZ disruption and RPE attenuation on spectral domain optical coherence tomography to large unifocal atrophic lesions throughout the macula bilaterally. The purpose of this case report is to add to the literature of PRPH2-associated disease by providing a comprehensive fundus examination of a family with autosomal dominant PRPH2-associated maculopathy diagnosed as central areolar choroidal dystrophy and pattern dystrophy.
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Affiliation(s)
- Hanna Choi
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, USA.,New England Retina Consultants, Springfield, Massachusetts, USA
| | - Alan Cloutier
- New England Retina Consultants, Springfield, Massachusetts, USA
| | - David Lally
- New England Retina Consultants, Springfield, Massachusetts, USA.,Department of Surgery, University of Massachusetts Medical School-Baystate, Springfield, Massachusetts, USA
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8
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Al-Khuzaei S, Broadgate S, Foster CR, Shah M, Yu J, Downes SM, Halford S. An Overview of the Genetics of ABCA4 Retinopathies, an Evolving Story. Genes (Basel) 2021; 12:1241. [PMID: 34440414 PMCID: PMC8392661 DOI: 10.3390/genes12081241] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/16/2022] Open
Abstract
Stargardt disease (STGD1) and ABCA4 retinopathies (ABCA4R) are caused by pathogenic variants in the ABCA4 gene inherited in an autosomal recessive manner. The gene encodes an importer flippase protein that prevents the build-up of vitamin A derivatives that are toxic to the RPE. Diagnosing ABCA4R is complex due to its phenotypic variability and the presence of other inherited retinal dystrophy phenocopies. ABCA4 is a large gene, comprising 50 exons; to date > 2000 variants have been described. These include missense, nonsense, splicing, structural, and deep intronic variants. Missense variants account for the majority of variants in ABCA4. However, in a significant proportion of patients with an ABCA4R phenotype, a second variant in ABCA4 is not identified. This could be due to the presence of yet unknown variants, or hypomorphic alleles being incorrectly classified as benign, or the possibility that the disease is caused by a variant in another gene. This underlines the importance of accurate genetic testing. The pathogenicity of novel variants can be predicted using in silico programs, but these rely on databases that are not ethnically diverse, thus highlighting the need for studies in differing populations. Functional studies in vitro are useful towards assessing protein function but do not directly measure the flippase activity. Obtaining an accurate molecular diagnosis is becoming increasingly more important as targeted therapeutic options become available; these include pharmacological, gene-based, and cell replacement-based therapies. The aim of this review is to provide an update on the current status of genotyping in ABCA4 and the status of the therapeutic approaches being investigated.
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Affiliation(s)
- Saoud Al-Khuzaei
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | | | - Mital Shah
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Susan M. Downes
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
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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: 15] [Impact Index Per Article: 5.0] [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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Camp DA, Gemayel MC, Ciulla TA. Understanding the genetic pathology of Stargardt disease: a review of current findings and challenges. Expert Opin Orphan Drugs 2021. [DOI: 10.1080/21678707.2021.1898373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- David A. Camp
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Michael C. Gemayel
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
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11
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Yeboah GK, Lobanova ES, Brush RS, Agbaga MP. Very long chain fatty acid-containing lipids: a decade of novel insights from the study of ELOVL4. J Lipid Res 2021; 62:100030. [PMID: 33556440 PMCID: PMC8042400 DOI: 10.1016/j.jlr.2021.100030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/12/2021] [Accepted: 01/27/2021] [Indexed: 11/18/2022] Open
Abstract
Lipids play essential roles in maintaining cell structure and function by modulating membrane fluidity and cell signaling. The fatty acid elongase-4 (ELOVL4) protein, expressed in retina, brain, Meibomian glands, skin, testes and sperm, is an essential enzyme that mediates tissue-specific biosynthesis of both VLC-PUFA and VLC-saturated fatty acids (VLC-SFA). These fatty acids play critical roles in maintaining retina and brain function, neuroprotection, skin permeability barrier maintenance, and sperm function, among other important cellular processes. Mutations in ELOVL4 that affect biosynthesis of these fatty acids cause several distinct tissue-specific human disorders that include blindness, age-related cerebellar atrophy and ataxia, skin disorders, early-childhood seizures, mental retardation, and mortality, which underscores the essential roles of ELOVL4 products for life. However, the mechanisms by which one tissue makes VLC-PUFA and another makes VLC-SFA, and how these fatty acids exert their important functional roles in each tissue, remain unknown. This review summarizes research over that last decade that has contributed to our current understanding of the role of ELOVL4 and its products in cellular function. In the retina, VLC-PUFA and their bioactive "Elovanoids" are essential for retinal function. In the brain, VLC-SFA are enriched in synaptic vesicles and mediate neuronal signaling by determining the rate of neurotransmitter release essential for normal neuronal function. These findings point to ELOVL4 and its products as being essential for life. Therefore, mutations and/or age-related epigenetic modifications of fatty acid biosynthetic gene activity that affect VLC-SFA and VLC-PUFA biosynthesis contribute to age-related dysfunction of ELOVL4-expressing tissues.
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Affiliation(s)
- Gyening Kofi Yeboah
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Ekaterina S Lobanova
- Department of Ophthalmology Research, University of Florida, Gainesville, FL, USA
| | - Richard S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA.
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12
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Carr BJ, Stanar P, Moritz OL. Distinct roles for prominin-1 and photoreceptor cadherin in outer segment disc morphogenesis in CRISPR-altered X. laevis. J Cell Sci 2021; 134:jcs253906. [PMID: 33277376 DOI: 10.1242/jcs.253906] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/23/2020] [Indexed: 12/30/2022] Open
Abstract
Mutations in prominin-1 (prom1) and photoreceptor cadherin (cdhr1) are associated with inherited retinal degenerative disorders but their functions remain unknown. Here, we used CRISPR-Cas9 to generate prom1-null, cdhr1-null, and prom1 plus cdhr1 double-null Xenopuslaevis and then documented the effects of these mutations on photoreceptor structure and function. Prom1-null mutations resulted in severely dysmorphic photoreceptors comprising overgrown and disorganized disc membranes. Cone outer segments were more severely affected than rods and had an impaired electroretinogram response. Cdhr1-null photoreceptors did not appear grossly dysmorphic, but ultrastructural analysis revealed that some disc membranes were overgrown or oriented vertically within the plasma membrane. Double-null mutants did not differ significantly from prom1-null mutants. Our results indicate that neither prom1 nor cdhr1 are necessary for outer segment disc membrane evagination or the fusion event that controls disc sealing. Rather, they are necessary for the higher-order organization of the outer segment. Prom1 may align and reinforce interactions between nascent disc leading edges, a function more critical in cones for structural support. Cdhr1 may secure discs in a horizontal orientation prior to fusion and regulate cone lamellae size.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Brittany J Carr
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, University of British Columbia, 330-2550 Willow St., Vancouver, British Columbia V5Z 3N9, Canada
| | - Paloma Stanar
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, University of British Columbia, 330-2550 Willow St., Vancouver, British Columbia V5Z 3N9, Canada
| | - Orson L Moritz
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, University of British Columbia, 330-2550 Willow St., Vancouver, British Columbia V5Z 3N9, Canada
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13
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Al-Khuzaei S, Shah M, Foster CR, Yu J, Broadgate S, Halford S, Downes SM. The role of multimodal imaging and vision function testing in ABCA4-related retinopathies and their relevance to future therapeutic interventions. Ther Adv Ophthalmol 2021; 13:25158414211056384. [PMID: 34988368 PMCID: PMC8721514 DOI: 10.1177/25158414211056384] [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] [Received: 06/19/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
The aim of this review article is to describe the specific features of Stargardt disease and ABCA4 retinopathies (ABCA4R) using multimodal imaging and functional testing and to highlight their relevance to potential therapeutic interventions. Standardised measures of tissue loss, tissue function and rate of change over time using formal structured deep phenotyping in Stargardt disease and ABCA4R are key in diagnosis, and prognosis as well as when selecting cohorts for therapeutic intervention. In addition, a meticulous documentation of natural history will be invaluable in the future to compare treated with untreated retinas. Despite the familiarity with the term Stargardt disease, this eponymous classification alone is unhelpful when evaluating ABCA4R, as the ABCA4 gene is associated with a number of phenotypes, and a range of severity. Multimodal imaging, psychophysical and electrophysiologic measurements are necessary in diagnosing and characterising these differing retinopathies. A wide range of retinal dystrophy phenotypes are seen in association with ABCA4 mutations. In this article, these will be referred to as ABCA4R. These different phenotypes and the existence of phenocopies present a significant challenge to the clinician. Careful phenotypic characterisation coupled with the genotype enables the clinician to provide an accurate diagnosis, associated inheritance pattern and information regarding prognosis and management. This is particularly relevant now for recruiting to therapeutic trials, and in the future when therapies become available. The importance of accurate genotype-phenotype correlation studies cannot be overemphasised. This approach together with segregation studies can be vital in the identification of causal mutations when variants in more than one gene are being considered as possible. In this article, we give an overview of the current imaging, psychophysical and electrophysiological investigations, as well as current therapeutic research trials for retinopathies associated with the ABCA4 gene.
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Affiliation(s)
- Saoud Al-Khuzaei
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mital Shah
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | | | | | | | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Susan M. Downes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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14
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Novel variants associated with Stargardt disease in Chinese patients. Gene 2020; 754:144890. [DOI: 10.1016/j.gene.2020.144890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 12/11/2022]
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15
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Fujinami K, Oishi A, Yang L, Arno G, Pontikos N, Yoshitake K, Fujinami-Yokokawa Y, Liu X, Hayashi T, Katagiri S, Mizobuchi K, Mizota A, Shinoda K, Nakamura N, Kurihara T, Tsubota K, Miyake Y, Iwata T, Tsujikawa A, Tsunoda K. Clinical and genetic characteristics of 10 Japanese patients with PROM1-associated retinal disorder: A report of the phenotype spectrum and a literature review in the Japanese population. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:656-674. [PMID: 32820593 DOI: 10.1002/ajmg.c.31826] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 01/14/2023]
Abstract
Variants in the PROM1 gene are associated with cone (-rod) dystrophy, macular dystrophy, and other phenotypes. We describe the clinical and genetic characteristics of 10 patients from eight Japanese families with PROM1-associated retinal disorder (PROM1-RD) in a nationwide cohort. A literature review of PROM1-RD in the Japanese population was also performed. The median age at onset/examination of 10 patients was 31.0 (range, 10-45)/44.5 (22-73) years. All 10 patients showed atrophic macular changes. Seven patients (70.0%) had spared fovea to various degrees, approximately half of whom had maintained visual acuity. Generalized cone (-rod) dysfunction was demonstrated in all nine subjects with available electrophysiological data. Three PROM1 variants were identified in this study: one recurrent disease-causing variant (p.Arg373Cys), one novel putative disease-causing variant (p.Cys112Arg), and one novel variant of uncertain significance (VUS; p.Gly53Asp). Characteristic features of macular atrophy with generalized cone-dominated retinal dysfunction were shared among all 10 subjects with PROM1-RD, and the presence of foveal sparing was crucial in maintaining visual acuity. Together with the three previously reported variants [p.R373C, c.1551+1G>A (pathogenic), p.Asn580His (likely benign)] in the literature of Japanese patients, one prevalent missense variant (p.Arg373Cys, 6/9 families, 66.7%) detected in multiple studies was determined in the Japanese population, which was also frequently detected in the European population.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Akio Oishi
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Lizhu Yang
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Gavin Arno
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,North East Thames Regional Genetics Service, UCL Great Ormond Street Institute of Child Health, Great Ormond Street NHS Foundation Trust, London, UK
| | - Nikolas Pontikos
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Kazutoshi Yoshitake
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Yu Fujinami-Yokokawa
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan.,Division of Public Health, Yokokawa Clinic, Suita, Japan
| | - Xiao Liu
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Takaaki Hayashi
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
| | - Satoshi Katagiri
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
| | - Kei Mizobuchi
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
| | - Atsushi Mizota
- Department of Ophthalmology, Teikyo University, Tokyo, Japan
| | - Kei Shinoda
- Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, Saitama Medical University, Saitama, Japan
| | - Natsuko Nakamura
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Toshihide Kurihara
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Yozo Miyake
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Aichi Medical University, Nagakute, Japan.,Next vision, Kobe Eye Center, Hyogo, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Akitaka Tsujikawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
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16
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Cremers FPM, Lee W, Collin RWJ, Allikmets R. Clinical spectrum, genetic complexity and therapeutic approaches for retinal disease caused by ABCA4 mutations. Prog Retin Eye Res 2020; 79:100861. [PMID: 32278709 PMCID: PMC7544654 DOI: 10.1016/j.preteyeres.2020.100861] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/18/2022]
Abstract
The ABCA4 protein (then called a “rim protein”) was first
identified in 1978 in the rims and incisures of rod photoreceptors. The
corresponding gene, ABCA4, was cloned in 1997, and variants
were identified as the cause of autosomal recessive Stargardt disease (STGD1).
Over the next two decades, variation in ABCA4 has been
attributed to phenotypes other than the classically defined STGD1 or fundus
flavimaculatus, ranging from early onset and fast progressing cone-rod dystrophy
and retinitis pigmentosa-like phenotypes to very late onset cases of mostly mild
disease sometimes resembling, and confused with, age-related macular
degeneration. Similarly, analysis of the ABCA4 locus uncovered
a trove of genetic information, including >1200 disease-causing mutations
of varying severity, and of all types – missense, nonsense, small
deletions/insertions, and splicing affecting variants, of which many are located
deep-intronic. Altogether, this has greatly expanded our understanding of
complexity not only of the diseases caused by ABCA4 mutations,
but of all Mendelian diseases in general. This review provides an in depth
assessment of the cumulative knowledge of ABCA4-associated retinopathy –
clinical manifestations, genetic complexity, pathophysiology as well as current
and proposed therapeutic approaches.
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands.
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, 10032, USA.
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Cehajic-Kapetanovic J, Birtel J, McClements ME, Shanks ME, Clouston P, Downes SM, Charbel Issa P, MacLaren RE. Clinical and Molecular Characterization of PROM1-Related Retinal Degeneration. JAMA Netw Open 2019; 2:e195752. [PMID: 31199449 PMCID: PMC6575153 DOI: 10.1001/jamanetworkopen.2019.5752] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
IMPORTANCE The PROM1 gene, commonly associated with cone-rod dystrophies, may have dominant or recessive phenotypes that influence disease onset and severity. OBJECTIVE To characterize the clinical phenotype and molecular genetic variations in patients with PROM1 variants. DESIGN, SETTING, AND PARTICIPANTS This case-series study was conducted at 2 specialist retinal genetics clinics and examined 19 consecutively enrolled patients with PROM1-related retinal degeneration. Data were collected and analyzed from May 2018 to December 2018. MAIN OUTCOMES AND MEASURES Results of ophthalmic examination, retinal imaging, and molecular genetic analysis by next-generation sequencing. RESULTS Of 19 patients, 13 (68%) were women, and age ranged from 11 to 70 years. All patients presented with central visual loss, with or without photophobia. Individuals with recessive variants commonly had severe loss of visual acuity by their 20s, whereas the dominant variant was associated with a milder phenotype, with most patients retaining good vision into late adulthood. The recessive cases were associated with a panretinal dystrophy of cone-rod phenotype with early macular involvement, whereas the dominant variants were associated with a cone-rod phenotype that was restricted to the macula with predominantly cone dysfunction. Next-generation sequencing identified 3 novel and 9 previously reported variants in PROM1. Recessive mutations included 6 truncating variants (3 nonsense and 3 frameshift), 4 splice site variants, and 1 missense variant. All 6 dominant variants were associated with a c.1117C>T missense variant. The variants were distributed throughout the PROM1 genomic sequence with no specific clustering on protein domains. CONCLUSIONS AND RELEVANCE In this case-series study, PROM1 recessive variants were associated with early-onset, severe panretinal degeneration. The similar phenotypes observed in patients with homozygous missense variants and splice site variants compared with similarly aged patients with truncating variants suggests that all recessive variants have a null (or loss of function close to null) outcome on PROM1 function. In contrast, the dominant missense cases were associated with a milder, cone-driven phenotype, suggesting that the dominant disease is preferentially associated with cones. This has implications for the development of treatments for this severely blinding disease, and adeno-associated viral vector-based gene therapy and optogenetics could become successful treatment options.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Johannes Birtel
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
| | - Morag E. Shanks
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Penny Clouston
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Susan M. Downes
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Peter Charbel Issa
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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18
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A case-control collapsing analysis identifies retinal dystrophy genes associated with ophthalmic disease in patients with no pathogenic ABCA4 variants. Genet Med 2019; 21:2336-2344. [PMID: 30926958 DOI: 10.1038/s41436-019-0495-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 03/12/2019] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Variants in the ABCA4 gene are causal for a variety of retinal dystrophy phenotypes, including Stargardt disease (STGD1). However, 15% of patients who present with symptoms compatible with STGD1/ABCA4 disease do not have identifiable causal ABCA4 variants. We hypothesized that a case-control collapsing analysis in ABCA4-negative patients with compatible symptoms would provide an objective measure to identify additional disease genes. METHODS We performed a genome-wide enrichment analysis of "qualifying variants"-ultrarare variants predicted to impact protein function-in protein-coding genes in 79 unrelated cases and 9028 unrelated controls. RESULTS Despite modest sample size, two known retinal dystrophy genes, PRPH2 and CRX, achieved study-wide significance (p < 1.33 × 10-6) under a dominant disease model, and eight additional known retinal dystrophy genes achieved nominal significance (p < 0.05). Across these ten genes, the excess of qualifying variants explained up to 36.8% of affected individuals. Furthermore, under a recessive model, the cone-rod dystrophy gene CERKL approached study-wide significance. CONCLUSION Our results indicate that case-control collapsing analyses can efficiently identify pathogenic variants in genes in non-ABCA4 retinal dystrophies. The genome-wide collapsing analysis framework is an objective discovery method particularly suitable in settings with overlapping disease phenotypes.
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Identification of novel pathogenic ABCA4 variants in a Han Chinese family with Stargardt disease. Biosci Rep 2019; 39:BSR20180872. [PMID: 30563929 PMCID: PMC6331664 DOI: 10.1042/bsr20180872] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 12/16/2022] Open
Abstract
Stargardt disease (STGD1, OMIM 248200) is a common hereditary juvenile or early adult onset macular degeneration. It ultimately leads to progressive central vision loss. Here, we sought to identify gene mutations associated with STGD1 in a three-generation Han Chinese pedigree by whole exome sequencing and Sanger sequencing. Two novel potentially pathogenic variants in a compound heterozygous state, c.3607G>T (p.(Gly1203Trp)) and c.6722T>C (p.(Leu2241Pro)), in the ATP binding cassette subfamily A member 4 gene (ABCA4) were identified as contributing to the family’s STGD1 phenotype. These variants may impact the ABCA4 protein structure and reduce the retinal-activated ATPase activity, leading to abnormal all-trans retinal accumulation in photoreceptor outer segments and in retinal pigment epithelium cells. The present study broadens the mutational spectrum of the ABCA4 responsible for STGD1. A combination of whole exome sequencing and Sanger sequencing is likely to be a time-saving and cost-efficient approach to screen pathogenic variants in genetic disorders caused by sizable genes, as well as avoiding misdiagnosis. These results perhaps refine genetic counseling and ABCA4-targetted treatments for families affected by STGD1.
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20
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Motta FL, Martin RP, Filippelli-Silva R, Salles MV, Sallum JMF. Relative frequency of inherited retinal dystrophies in Brazil. Sci Rep 2018; 8:15939. [PMID: 30374144 PMCID: PMC6206004 DOI: 10.1038/s41598-018-34380-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/15/2018] [Indexed: 11/09/2022] Open
Abstract
Among the Brazilian population, the frequency rates of inherited retinal dystrophies and their causative genes are underreported. To increase the knowledge about these dystrophies in our population, we retrospectively studied the medical records of 1,246 Brazilian patients with hereditary retinopathies during 20 years of specialized outpatient clinic care. Of these patients, 559 had undergone at least one genetic test. In this cohort, the most prevalent dystrophies were non-syndromic retinitis pigmentosa (35%), Stargardt disease (21%), Leber congenital amaurosis (9%), and syndromic inherited retinal dystrophies (12%). Most patients had never undergone genetic testing (55%), and among the individuals with molecular test results, 28.4% had negative or inconclusive results compared to 71.6% with a conclusive molecular diagnosis. ABCA4 was the most frequent disease-causing gene, accounting for 20% of the positive cases. Pathogenic variants also occurred frequently in the CEP290, USH2A, CRB1, RPGR, and CHM genes. The relative frequency rates of different inherited retinal dystrophies in Brazil are similar to those found globally. Although mutations in more than 250 genes lead to hereditary retinopathies, only 66 genes were responsible for 70% of the cases, which indicated that smaller and cheaper gene panels can be just as effective and provide more affordable solutions for implementation by the Brazilian public health system.
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Affiliation(s)
- Fabiana Louise Motta
- Department of Ophthalmology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Renan Paulo Martin
- Department of Biophysics, Universidade Federal de São Paulo, São Paulo, Brazil.,Institute of Genetic Medicine, Johns Hopkins Medicine, Baltimore, USA
| | | | | | - Juliana Maria Ferraz Sallum
- Department of Ophthalmology, Universidade Federal de São Paulo, São Paulo, Brazil. .,Instituto de Genética Ocular, Sao Paulo, Brazil.
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21
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Kim JM, Lee C, Lee GI, Kim NKD, Ki CS, Park WY, Kim BJ, Kim SJ. Identification of the PROM1 Mutation p.R373C in a Korean Patient With Autosomal Dominant Stargardt-like Macular Dystrophy. Ann Lab Med 2018; 37:536-539. [PMID: 28840994 PMCID: PMC5587829 DOI: 10.3343/alm.2017.37.6.536] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/21/2017] [Accepted: 07/12/2017] [Indexed: 01/11/2023] Open
Abstract
Stargardt-like macular dystrophy 4 (STGD4) is a rare macular dystrophy characterized by bull's eye atrophy of the macula and the underlying retinal pigment epithelium. Patients with STGD4 show decreased central vision, which often progresses to severe vision loss. The PROM1 gene encodes prominin-1, which is a 5-transmembrane glycoprotein also known as CD133 and is involved in photoreceptor disk morphogenesis. PROM1 mutations have been identified as genetic causes for STGD4 and other retinal degenerations such as retinitis pigmentosa. We report a case of STGD4 with a PROM1 p.R373C mutation in a Korean patient. Ophthalmic examinations of a 38-yr old man complaining of decreased visual acuity revealed bilateral atrophic macular lesions consistent with STGD4. Targeted exome sequencing of known inherited retinal degeneration genes revealed a heterozygous missense mutation c.1117C>T (p.R373C) of PROM1, which was confirmed by Sanger sequencing. To the best of our knowledge, this is the first case of a PROM1 mutation causing STGD4 in Koreans.
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Affiliation(s)
- Jong Min Kim
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chung Lee
- Samsung Genome Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.,Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, Korea
| | - Ga In Lee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Nayoung K D Kim
- Samsung Genome Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chang Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Woong Yang Park
- Samsung Genome Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.,Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Byoung Joon Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sang Jin Kim
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
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22
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Sheremet NL, Zhorzholadze NV, Ronzina IA, Grushke IG, Kurbatov SA, Chukhrova AL, Loginova AN, Shcherbakova PO, Tanas AS, Polyakov AV, Strel'nikov VV. [Molecular genetic diagnosis of Stargardt disease]. Vestn Oftalmol 2018; 133:4-11. [PMID: 28980559 DOI: 10.17116/oftalma201713344-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
AIM To comparatively evaluate the efficacy of genetic screening in patients with Stargardt disease (SD) by using an express panel of 5 most common ABCA4 mutations and performing massive parallel sequencing of all coding regions of the ABCA4, ELOVL4, PROM1, and CNGB3 genes. MATERIAL AND METHODS MLPA analysis for 5 ABCA4 mutations, namely p.G863A, p.L541P, p.A1038V, p.G1961E, and p.P1380L, was done in 54 patients with SD. In 25 patients, massive parallel sequencing of coding regions (exons) and neighboring introns of the ABCA4, ELOVL4, PROM1, and CNGB3 genes was also performed. RESULTS Gene testing for 5 ABCA4 mutations showed that 50% of patients (27 patients) harbored one mutation and 13% - two mutations. At massive parallel sequencing (25 patients), two pathogenic alleles were found in 21 patients (84%), one mutation - in 23 patients (91.7%). The majority of mutations was accounted for by the ABCA4 gene (83% of all mutation-positive patients). CONCLUSION Sequencing of exons and neighboring introns of the ABCA4, ELOVL4, PROM1, and CNGB3 genes with the new molecular genetic diagnostic system enabled confirmation of the diagnosis of SD in 84% of patients. High prevalence of p.L541P, p.A1038V, and p.G1961E mutations of the ABCA4 gene has been established.
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Affiliation(s)
- N L Sheremet
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russia, 119021
| | - N V Zhorzholadze
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russia, 119021
| | - I A Ronzina
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russia, 119021
| | - I G Grushke
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russia, 119021
| | - S A Kurbatov
- Voronezh Regional Clinical Consultative and Diagnostic Center, 5a Lenina Sq., Voronezh, Russia, 394018
| | - A L Chukhrova
- Research Centre of Medical Genetics, 1 Moskvorech'e St., Moscow, Russia, 115478
| | - A N Loginova
- Research Centre of Medical Genetics, 1 Moskvorech'e St., Moscow, Russia, 115478
| | - P O Shcherbakova
- Pirogov Russian National Research Medical University, 1 Ostrovityanova St., Moscow, Russia, 117997
| | - A S Tanas
- Research Centre of Medical Genetics, 1 Moskvorech'e St., Moscow, Russia, 115478
| | - A V Polyakov
- Research Centre of Medical Genetics, 1 Moskvorech'e St., Moscow, Russia, 115478
| | - V V Strel'nikov
- Research Centre of Medical Genetics, 1 Moskvorech'e St., Moscow, Russia, 115478
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23
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Novel ABCA4 mutation leads to loss of a conserved C-terminal motif: implications for predicting pathogenicity based on genetic testing. Eur J Ophthalmol 2018; 28:123-126. [DOI: 10.5301/ejo.5001019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Purpose: Mutations in the ABCA4 gene result in a broad spectrum of severe retinal degeneration, including Stargardt macular dystrophy, fundus flavimaculatus, autosomal recessive retinitis pigmentosa, and cone-rod dystrophy. In addition to the detection of well-characterized mutations, genetic testing frequently yields novel variants of unknown significance. The purpose of this report is to describe an approach to aid in the assessment of genetic variants of unknown significance. Case report: We report an 11-year-old girl with Stargardt disease harboring novel compound heterozygous deletions of ABCA4 (c.850_857delATTCAAGA and c.6184_6187delGTCT). The pathogenicity of these variants was otherwise unknown. Both deletions introduce premature stop codons and are localized within the open reading frame of ABCA4. The c.850_857delATTCAAGA occurs early in the gene and leads to a significantly truncated protein of only 317 amino acids. The c.6184_6187delGTCT, is localized to the 3’ terminus of the ORF and results in removal of the last 161 out of 2,273 amino acids of ABCA4, including the VFVNFA motif, which has been shown to be critical in ABCA4 protein function. Homology-based protein modeling of ABCA4 harboring this deletion suggests significant alterations in the protein structure and function. Conclusions: Our analyses allowed us to classify novel variants in ABCA4 as being clearly loss-of-function mutations, and thus pathogenic variants. In cases of variants of unknown significance, appraising the protein structure-function consequences of genetic mutations using in silico tools may help to predict the clinical importance of variants of uncertain pathogenicity.
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24
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Imani S, Cheng J, Shasaltaneh MD, Wei C, Yang L, Fu S, Zou H, Khan MA, Zhang X, Chen H, Zhang D, Duan C, Lv H, Li Y, Chen R, Fu J. Genetic identification and molecular modeling characterization reveal a novel PROM1 mutation in Stargardt4-like macular dystrophy. Oncotarget 2017; 9:122-141. [PMID: 29416601 PMCID: PMC5787432 DOI: 10.18632/oncotarget.22343] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/26/2017] [Indexed: 01/01/2023] Open
Abstract
Stargardt disease-4 (STGD4) is an autosomal dominant complex, genetically heterogeneous macular degeneration/dystrophy (MD) disorder. In this paper, we used targeted next generation sequencing and multiple molecular dynamics analyses to identify and characterize a disease-causing genetic variant in four generations of a Chinese family with STGD4-like MD. We found a novel heterozygous missense mutation, c.734T>C (p.L245P) in the PROM1 gene. Structurally, this mutation most likely impairs PROM1 protein stability, flexibility, and amino acid interaction network after changing the amino acid residue Leucine into Proline in the basic helix-loop-helix leucine zipper domain. Molecular dynamic simulation and principal component analysis provide compelling evidence that this PROM1 mutation contributes to disease causativeness or susceptibility variants in patients with STGD4-like MD. Thus, this finding defines new approaches in genetic characterization, accurate diagnosis, and prevention of STGD4-like MD.
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Affiliation(s)
- Saber Imani
- Hunan Normal University Medical College, Changsha, Hunan, China.,Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.,Chemical Injuries Research Center, Baqiyatallah Medical Sciences University, Tehran, Iran
| | - Jingliang Cheng
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Marzieh Dehghan Shasaltaneh
- Laboratory of Neuro-organic Chemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.,Laboratory of Systems Biology and Bioinformatics, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Chunli Wei
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.,State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
| | - Lisha Yang
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Shangyi Fu
- The Honors College, University of Houston, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Hui Zou
- Hunan Normal University Medical College, Changsha, Hunan, China.,Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Md Asaduzzaman Khan
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Xianqin Zhang
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Hanchun Chen
- Department of Biochemistry, School of Life Sciences & the State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
| | - Dianzheng Zhang
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, USA
| | - Chengxia Duan
- Department of Ophthalmology, First Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Hongbin Lv
- Department of Ophthalmology, First Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Junjiang Fu
- Hunan Normal University Medical College, Changsha, Hunan, China.,Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.,State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
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25
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Randhawa S, Sharma M. A NEW MACULAR DYSTROPHY SECONDARY TO A NOVEL MUTATION IN THE PROMININ 1 (PROM1) GENE. Retin Cases Brief Rep 2017; 11 Suppl 1:S62-S64. [PMID: 27571428 DOI: 10.1097/icb.0000000000000405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
PURPOSE To report a case of a new macular dystrophy caused by a novel mutation in the PROM1 gene. METHODS History and clinical examination, fluorescein angiography, optical coherence tomography, autofluorescence, electrophysiology, and genetics. RESULTS We report a case of a 51-year-old man with progressive central visual loss in both his eyes. On fundus examination and imaging, there were asymmetric atrophic macular lesions in both his eyes. Electrophysiology revealed a bilateral macular atrophy; genetic testing revealed a novel PROM1 mutation as the probable cause. CONCLUSION A novel PROM1 mutation as the cause of a new bilateral macular atrophy is revealed.
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Affiliation(s)
- Sandeep Randhawa
- *Associated Retinal Consultants, PC, Royal Oak, MI, Department of Ophthalmology, Oakland University William Beaumont School of Medicine, Michigan; and †Department of Ophthalmology, The Permanente Medical Group, Roseville, California
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26
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Salles MV, Motta FL, Dias da Silva E, Varela Lima Teixeira P, Antunes Costa K, Filippelli-Silva R, Martin R, Pesquero JB, Ferraz Sallum JM. PROM1 gene variations in Brazilian patients with macular dystrophy. Ophthalmic Genet 2017; 38:39-42. [DOI: 10.1080/13816810.2016.1275022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Mariana Vallim Salles
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Fabiana Louise Motta
- Biophysics Laboratory, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Elton Dias da Silva
- Biophysics Laboratory, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | | | - Kárita Antunes Costa
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | | | - Renan Martin
- Biophysics Laboratory, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - João Bosco Pesquero
- Biophysics Laboratory, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Juliana Maria Ferraz Sallum
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
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27
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Zhang J, Qi A, Wang X, Pan H, Mo H, Huang J, Li H, Chen Z, Wei M, Wang B. Novel compound heterozygous mutations in ABCA4 in a Chinese pedigree with Stargardt disease. Mol Vis 2016; 22:1514-1521. [PMID: 28050124 PMCID: PMC5204459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 12/28/2016] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Stargardt disease (STGD) is a common macular dystrophy in juveniles that is commonly inherited as an autosomal recessive trait. Mutations in five genes (ABCA4, PROM1, ELOVL4, BEST1, and PRPH2) have been reported to be associated with STGD. In the present study, we aimed to identify the pathogenic mutations in affected members in a Chinese STGD pedigree. METHODS One patient was selected for whole-exome sequencing. Variants in five candidate genes were identified initially, followed by several filtering steps against public and private variation databases (1000Genomes, ESP6500si, ExAC, and in-house database), as well as bioinformatic analysis of the putative pathogenic roles. Sanger sequencing was used for cosegregation analysis among all members with available DNA. RESULTS Two mutations in ABCA4 (NM_000350.2; c.5646G>A; p.Met1882Ile and NM_000350.2; c.3523-2A>G) were found using whole-exome sequencing. Cosegregation analysis confirmed all the affected members carried the compound heterozygous mutations while the other healthy members had at most one. The missense mutation was extremely rare in public databases and predicted to be deleterious. The splice-site mutation was absent from all public and private databases and was predicted to alter the splice pattern, resulting in an exon skip and a frameshift. CONCLUSIONS Using whole-exome sequencing, we found novel compound heterozygous mutations in ABCA4 in a Chinese STGD pedigree. These mutations are reported for the first time, therefore widening the mutation spectrum of Stargardt disease. The present study also illustrates the potential of whole-exome sequencing in determining the genetic cause of STGD.
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Affiliation(s)
- Jianping Zhang
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Anhui Qi
- Graduate School of Peking Union Medical College, Beijing, China,National Research Institute of Family Planning, Beijing, China
| | - Xi Wang
- National Research Institute of Family Planning, Beijing, China
| | - Hong Pan
- Graduate School of Peking Union Medical College, Beijing, China,National Research Institute of Family Planning, Beijing, China
| | - Haiming Mo
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Jiwei Huang
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Honghui Li
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Zhenwen Chen
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Meirong Wei
- Department of Ophthalmology, Liuzhou Maternal and Child Healthcare Hospital, Liuzhou, Guangxi, China
| | - Binbin Wang
- National Research Institute of Family Planning, Beijing, China
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Twists and turns—How we stepped into and had fun in the “boring” lipid field. SCIENCE CHINA-LIFE SCIENCES 2015; 58:1073-83. [DOI: 10.1007/s11427-015-4949-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 09/28/2015] [Indexed: 11/25/2022]
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29
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Xin W, Xiao X, Li S, Jia X, Guo X, Zhang Q. Identification of Genetic Defects in 33 Probands with Stargardt Disease by WES-Based Bioinformatics Gene Panel Analysis. PLoS One 2015; 10:e0132635. [PMID: 26161775 PMCID: PMC4498695 DOI: 10.1371/journal.pone.0132635] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 06/16/2015] [Indexed: 11/19/2022] Open
Abstract
Stargardt disease (STGD) is the most common hereditary macular degeneration in juveniles, with loss of central vision occurring in the first or second decade of life. The aim of this study is to identify the genetic defects in 33 probands with Stargardt disease. Clinical data and genomic DNA were collected from 33 probands from unrelated families with STGD. Variants in coding genes were initially screened by whole exome sequencing. Candidate variants were selected from all known genes associated with hereditary retinal dystrophy and then confirmed by Sanger sequencing. Putative pathogenic variants were further validated in available family members and controls. Potential pathogenic mutations were identified in 19 of the 33 probands (57.6%). These mutations were all present in ABCA4, but not in the other four STGD-associated genes or in genes responsible for other retinal dystrophies. Of the 19 probands, ABCA4 mutations were homozygous in one proband and compound heterozygous in 18 probands, involving 28 variants (13 novel and 15 known). Analysis of normal controls and available family members in 12 of the 19 families further support the pathogenicity of these variants. Clinical manifestation of all probands met the diagnostic criteria of STGD. This study provides an overview of a genetic basis for STGD in Chinese patients. Mutations in ABCA4 are the most common cause of STGD in this cohort. Genetic defects in approximately 42.4% of STGD patients await identification in future studies.
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Affiliation(s)
- Wei Xin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiangming Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
- * E-mail:
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30
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Retinitis Pigmentosa with EYS Mutations Is the Most Prevalent Inherited Retinal Dystrophy in Japanese Populations. J Ophthalmol 2015; 2015:819760. [PMID: 26161267 PMCID: PMC4487330 DOI: 10.1155/2015/819760] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/19/2015] [Indexed: 11/18/2022] Open
Abstract
The aim of this study was to gain information about disease prevalence and to identify the responsible genes for inherited retinal dystrophies (IRD) in Japanese populations. Clinical and molecular evaluations were performed on 349 patients with IRD. For segregation analyses, 63 of their family members were employed. Bioinformatics data from 1,208 Japanese individuals were used as controls. Molecular diagnosis was obtained by direct sequencing in a stepwise fashion utilizing one or two panels of 15 and 27 genes for retinitis pigmentosa patients. If a specific clinical diagnosis was suspected, direct sequencing of disease-specific genes, that is, ABCA4 for Stargardt disease, was conducted. Limited availability of intrafamily information and decreasing family size hampered identifying inherited patterns. Differential disease profiles with lower prevalence of Stargardt disease from European and North American populations were obtained. We found 205 sequence variants in 159 of 349 probands with an identification rate of 45.6%. This study found 43 novel sequence variants. In silico analysis suggests that 20 of 25 novel missense variants are pathogenic. EYS mutations had the highest prevalence at 23.5%. c.4957_4958insA and c.8868C>A were the two major EYS mutations identified in this cohort. EYS mutations are the most prevalent among Japanese patients with IRD.
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Abstract
Stargardt disease is the most common form of autosomal recessive macular dystrophy. Mutation in the ABCA4 gene (ABCR protein) is responsible for disease manifestation in more than 95% of Stargardt patients. ABCA4 codes for a member of the ATP binding cassette transmembrane protein involved in the transport of all-trans retinal. Dysfunction in this protein causes accumulation of lipofuscin, which is toxic to the RPE and photoreceptors. Presenting symptoms, fundus appearance, and progression of the disease are widely variable in this disease. Different imaging modalities have been utilized to study the presentation and evolution of fundus changes. Although there is ongoing research to better understand the disease process and ways to alternate its path, currently there is no treatment for Startgardt patients.
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Bennett LD, Hopiavuori BR, Brush RS, Chan M, Van Hook MJ, Thoreson WB, Anderson RE. Examination of VLC-PUFA-deficient photoreceptor terminals. Invest Ophthalmol Vis Sci 2014; 55:4063-72. [PMID: 24764063 DOI: 10.1167/iovs.14-13997] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Juvenile-onset autosomal dominant Stargardt-like macular dystrophy (STGD3) is caused by mutations in ELOVL4 (elongation of very long fatty acids-4), an elongase necessary for the biosynthesis of very long chain fatty acids (VLC-FAs ≥ C26). Photoreceptors are enriched with VLC polyunsaturated fatty acids (VLC-PUFAs), which are necessary for long-term survival of rod photoreceptors. The purpose of these studies was to determine the effect of deletion of VLC-PUFAs on rod synaptic function in retinas of mice conditionally depleted (KO) of Elovl4. METHODS Retina function was assessed in wild-type (WT) and KO by electroretinography. Outer plexiform structure was evaluated by immunofluorescence and transmission electron microscopy. Single-cell recordings measured rod ion channel operation and rod bipolar glutamate signaling. Sucrose gradient centrifugation was used to isolate synaptosomes from bovine retina. Proteins and lipids were analyzed by Western blotting and tandem mass spectroscopy, respectively. RESULTS Inner retinal responses (b-wave, oscillatory potentials, and scotopic threshold responses) of the ERG were decreased in the KO mice compared to controls. However the rod ion channel operation and bipolar glutamate responses were comparable between groups. Biochemical analysis revealed that conventional and ribbon synapses have VLC-PUFAs. Ultrastructural analysis showed that the outer plexiform layer was disorganized and the diameter of vesicles in rod terminals was smaller in the KO mice. CONCLUSIONS Very long chain PUFAs affect rod function by contributing to synaptic vesicle size, which may alter the dynamics of synaptic transmission, ultimately resulting in a loss of neuronal connectivity and death of rod photoreceptors.
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Affiliation(s)
- Lea D Bennett
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Blake R Hopiavuori
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Richard S Brush
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Michael Chan
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Robert E Anderson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Zhang X, Ge X, Shi W, Huang P, Min Q, Li M, Yu X, Wu Y, Zhao G, Tong Y, Jin ZB, Qu J, Gu F. Molecular diagnosis of putative Stargardt disease by capture next generation sequencing. PLoS One 2014; 9:e95528. [PMID: 24763286 PMCID: PMC3999032 DOI: 10.1371/journal.pone.0095528] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Accepted: 03/27/2014] [Indexed: 01/01/2023] Open
Abstract
Stargardt Disease (STGD) is the commonest genetic form of juvenile or early adult onset macular degeneration, which is a genetically heterogeneous disease. Molecular diagnosis of STGD remains a challenge in a significant proportion of cases. To address this, seven patients from five putative STGD families were recruited. We performed capture next generation sequencing (CNGS) of the probands and searched for potentially disease-causing genetic variants in previously identified retinal or macular dystrophy genes. Seven disease-causing mutations in ABCA4 and two in PROM1 were identified by CNGS, which provides a confident genetic diagnosis in these five families. We also provided a genetic basis to explain the differences among putative STGD due to various mutations in different genes. Meanwhile, we show for the first time that compound heterozygous mutations in PROM1 gene could cause cone-rod dystrophy. Our findings support the enormous potential of CNGS in putative STGD molecular diagnosis.
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Affiliation(s)
- Xiao Zhang
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Xianglian Ge
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Wei Shi
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Ping Huang
- Department of Development and Planning, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qingjie Min
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Minghan Li
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Xinping Yu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Yaming Wu
- Department of Ophthalmology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | | | - Yi Tong
- Fuzhou Southeastern Eye Hospital, Fuzhou, China
| | - Zi-Bing Jin
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Jia Qu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
| | - Feng Gu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, China
- * E-mail:
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Bennett LD, Brush RS, Chan M, Lydic TA, Reese K, Reid GE, Busik JV, Elliott MH, Anderson RE. Effect of reduced retinal VLC-PUFA on rod and cone photoreceptors. Invest Ophthalmol Vis Sci 2014; 55:3150-7. [PMID: 24722693 DOI: 10.1167/iovs.14-13995] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Autosomal dominant Stargardt-like macular dystrophy (STGD3) is a juvenile-onset disease that is caused by mutations in Elovl4 (elongation of very long fatty acids-4). The Elovl4 catalyzes the first step in the conversion of C24 and longer fatty acids (FAs) to very long-chain FAs (VLC-FAs, ≥C26). Photoreceptors are particularly rich in VLC polyunsaturated FAs (VLC-PUFA). To explore the role of VLC-PUFAs in photoreceptors, we conditionally deleted Elovl4 in the mouse retina. METHODS Proteins were analyzed by Western blotting and lipids by gas chromatography (GC)-mass spectrometry, GC-flame ionization detection, and tandem mass spectrometry. Retina function was assessed by electroretinography (ERG), and structure was evaluated by bright field, immunofluorescence, and transmission electron microscopy. RESULTS Conditional deletion (KO) of retinal Elovl4 reduced RNA and protein levels by 91% and 96%, respectively. Total retina VLC-PUFAs were reduced by 88% compared to the wild type (WT) levels. Retinal VLC-PUFAs incorporated in phosphatidylcholine were less abundant at 12 months compared to 8-week-old levels. Amplitudes of the ERG a-wave were reduced by 22%, consistent with photoreceptor degeneration (11% loss of photoreceptors). Analysis of the rod a-wave responses gave no evidence of a role for VLC-PUFA in visual transduction. However, there were significant reductions in rod b-wave amplitudes (>30%) that could not be explained by loss of rod photoreceptors. There was no effect of VLC-PUFA reduction on cone ERG responses, and cone density was not different between the WT and KO mice at 12 months of age. CONCLUSIONS The VLC-PUFAs are important for rod, but not cone, function and for rod photoreceptor longevity.
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Affiliation(s)
- Lea D Bennett
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Richard S Brush
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Michael Chan
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Todd A Lydic
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States
| | - Kristen Reese
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States
| | - Gavin E Reid
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States
| | - Julia V Busik
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Michael H Elliott
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Robert E Anderson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Dawn of ocular gene therapy: implications for molecular diagnosis in retinal disease. SCIENCE CHINA-LIFE SCIENCES 2013; 56:125-33. [PMID: 23393028 DOI: 10.1007/s11427-013-4443-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/28/2012] [Indexed: 12/26/2022]
Abstract
Personalized medicine aims to utilize genomic information about patients to tailor treatment. Gene replacement therapy for rare genetic disorders is perhaps the most extreme form of personalized medicine, in that the patients' genome wholly determines their treatment regimen. Gene therapy for retinal disorders is poised to become a clinical reality. The eye is an optimal site for gene therapy due to the relative ease of precise vector delivery, immune system isolation, and availability for monitoring of any potential damage or side effects. Due to these advantages, clinical trials for gene therapy of retinal diseases are currently underway. A necessary precursor to such gene therapies is accurate molecular diagnosis of the mutation(s) underlying disease. In this review, we discuss the application of Next Generation Sequencing (NGS) to obtain such a diagnosis and identify disease causing genes, using retinal disorders as a case study. After reviewing ocular gene therapy, we discuss the application of NGS to the identification of novel Mendelian disease genes. We then compare current, array based mutation detection methods against next NGS-based methods in three retinal diseases: Leber's Congenital Amaurosis, Retinitis Pigmentosa, and Stargardt's disease. We conclude that next-generation sequencing based diagnosis offers several advantages over array based methods, including a higher rate of successful diagnosis and the ability to more deeply and efficiently assay a broad spectrum of mutations. However, the relative difficulty of interpreting sequence results and the development of standardized, reliable bioinformatic tools remain outstanding concerns. In this review, recent advances NGS based molecular diagnoses are discussed, as well as their implications for the development of personalized medicine.
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Molday RS, Zhang K. Defective lipid transport and biosynthesis in recessive and dominant Stargardt macular degeneration. Prog Lipid Res 2010; 49:476-92. [PMID: 20633576 DOI: 10.1016/j.plipres.2010.07.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Stargardt disease is a common inherited macular degeneration characterized by a significant loss in central vision in the first or second decade of life, bilateral atrophic changes in the central retina associated with degeneration of photoreceptors and underlying retinal pigment epithelial cells, and the presence of yellow flecks extending from the macula. Autosomal recessive Stargardt disease, the most common macular dystrophy, is caused by mutations in the gene encoding ABCA4, a photoreceptor ATP binding cassette (ABC) transporter. Biochemical studies together with analysis of abca4 knockout mice and Stargardt patients have implicated ABCA4 as a lipid transporter that facilitates the removal of potentially toxic retinal compounds from photoreceptors following photoexcitation. An autosomal dominant form of Stargardt disease also known as Stargardt-like dystrophy is caused by mutations in a gene encoding ELOVL4, an enzyme that catalyzes the elongation of very long-chain fatty acids in photoreceptors and other tissues. This review focuses on the molecular characterization of ABCA4 and ELOVL4 and their role in photoreceptor cell biology and the pathogenesis of Stargardt disease.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry and Molecular Biology, Centre of Macular Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada.
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Michaelides M, Gaillard MC, Escher P, Tiab L, Bedell M, Borruat FX, Barthelmes D, Carmona R, Zhang K, White E, McClements M, Robson AG, Holder GE, Bradshaw K, Hunt DM, Webster AR, Moore AT, Schorderet DF, Munier FL. The PROM1 mutation p.R373C causes an autosomal dominant bull's eye maculopathy associated with rod, rod-cone, and macular dystrophy. Invest Ophthalmol Vis Sci 2010; 51:4771-80. [PMID: 20393116 DOI: 10.1167/iovs.09-4561] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize in detail the phenotype of five unrelated families with autosomal dominant bull's eye maculopathy (BEM) due to the R373C mutation in the PROM1 gene. METHODS Forty-one individuals of five families of Caribbean (family A), British (families B, D, E), and Italian (family C) origin, segregating the R373C mutation in PROM1, were ascertained. Electrophysiological assessment, fundus autofluorescence (FAF) imaging, fundus fluorescein angiography (FFA), and optical coherence tomography (OCT) were performed in available subjects. Mutation screening of PROM1 was performed. RESULTS The R373C mutant was present heterozygously in all affected patients. The age at onset was variable and ranged between 9 and 58 years, with most of the individuals presenting with reading difficulties. Subjects commonly had a mild to moderate reduction in visual acuity except for members of family C who experienced markedly reduced central vision. The retinal phenotype was characterized by macular dystrophy, with retinal pigment epithelial mottling in younger subjects, progressing to typical BEM over time, with the development of macular atrophy in older patients. In addition, all members of family C had typical features of RP. The electrophysiological findings were variable both within and between families. CONCLUSIONS Mutations in PROM1 have been described to cause a severe form of autosomal recessive RP in two families of Indian and Pakistani descent. The results of this study have demonstrated that a distinct redundant PROM1 mutation (R373C) can also produce an autosomal dominant, fully penetrant retinopathy, characterized by BEM with little inter- and intrafamilial variability, and retinal dystrophy with variable rod or rod-cone dysfunction and marked intra- and interfamilial variability, ranging from isolated maculopathy without generalized photoreceptor dysfunction to maculopathy associated with very severe rod-cone dysfunction.
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Agbaga MP, Mandal MNA, Anderson RE. Retinal very long-chain PUFAs: new insights from studies on ELOVL4 protein. J Lipid Res 2010; 51:1624-42. [PMID: 20299492 DOI: 10.1194/jlr.r005025] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Compared with other mammalian tissues, retina is highly enriched in PUFA. Long-chain PUFA (LC-PUFA; C18-C24) are essential FAs that are enriched in the retina and are necessary for maintenance of normal retinal development and function. The retina, brain, and sperm also contain very LC-PUFA (VLC-PUFA; >C24). Although VLC-PUFA were discovered more than two decades ago, very little is known about their biosynthesis and functional roles in the retina. This is due mainly to intrinsic difficulties associated with working on these unusually long polyunsaturated hydrocarbon chains and their existence in small amounts. Recent studies on the FA elongase elongation of very long chain fatty acids-4 (ELOVL4) protein, however, suggest that VLC-PUFA probably play some uniquely important roles in the retina as well as the other tissues. Mutations in the ELOVL4 gene are found in patients with autosomal dominant Stargardt disease. Here, we review the recent literature on VLC-PUFA with special emphasis on the elongases responsible for their synthesis. We focus on a novel elongase, ELOVL4, involved in the synthesis of VLC-PUFA, and the importance of these FAs in maintaining the structural and functional integrity of retinal photoreceptors.
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Affiliation(s)
- Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Tong Z, Yang Z, Meyer JJ, McInnes AW, Xue L, Azimi AM, Baird J, Zhao Y, Pearson E, Wang C, Chen Y, Zhang K. A Novel Locus for X-linked Retinitis Pigmentosa. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2009. [DOI: 10.47102/annals-acadmedsg.v35n7p476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Introduction: Retinitis pigmentosa (RP) is the most prevalent group of inherited retinopathies and demonstrates considerable clinical and genetic heterogeneity, with wide variations in disease severity, progression, and gene involvement. We studied a large family with RP to determine the pattern of inheritance and to identify the disease-causing gene/locus.
Materials and Methods: Ophthalmic examination was performed on 35 family members to identify affected individuals and carriers and to characterise the disease phenotype. Genetic linkage analysis was performed using short tandem repeat (STR) polymorphic markers encompassing the known loci for X-linked RP (xlRP) including RP2, RP3, RP6, RP23, and RP24. Mutation screening was performed by direct sequencing of PCR-amplified genomic DNA of the RP2 and RPGR genes of the affected individuals.
Results: A highly penetrant, X-linked form of RP was observed in this family. Age of onset was from 5 to 8 years and visual acuity ranged from 20/25 in children to light perception in older adults. Linkage analysis and direct sequencing showed that no known loci/genes were associated with the phenotype in this kindred.
Conclusion: A novel disease gene locus/loci is responsible for the xlRP phenotype in this family.
Key words: Genetic linkage, Mutation screening, Retinopathy
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Affiliation(s)
- Zongzhong Tong
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Zhenglin Yang
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Jay J Meyer
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Allen W McInnes
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Lai Xue
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Asif M Azimi
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Jenn Baird
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Yu Zhao
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Erik Pearson
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | | | - Yali Chen
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - Kang Zhang
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
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Xi Q, Li L, Traboulsi EI, Wang QK. Novel ABCA4 compound heterozygous mutations cause severe progressive autosomal recessive cone-rod dystrophy presenting as Stargardt disease. Mol Vis 2009; 15:638-45. [PMID: 19352439 PMCID: PMC2665199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Accepted: 03/21/2009] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To identify the gene causing a severe form of progressive autosomal recessive cone-rod dystrophy presenting as Stargardt disease and to characterize clinical features in a large American family. METHODS We characterized an American family who had an unusual retinal dystrophy with clinical features of Stargardt disease and severe progressive cone-rod dystrophy. Family members underwent complete ocular examinations with evaluation of visual acuity, visual fields, fundus examination, fluorescein angiography, and electroretinography. Genome-wide linkage analysis of the family was performed using 408 microsatellite markers spanning the entire human genome. Direct DNA sequence analysis was used for mutational analysis of the ABCA4 gene in all exons and exon-intron boundary regions and for testing cosegregation of the mutations with the disease in the family. DNA sequence analysis was used to determine the presence of the mutations in 200 unrelated controls. RESULTS The proband presented with a clinical phenotype that was initially compatible with Stargardt disease, only to progress to a severe cone-rod dystrophy over the course of a few years. The disease-causing gene in the family was linked to the ABCA4 locus on chromosomal 1p22. One novel mutation, c.655A>T, was identified in exon 6 and another novel splicing mutation, c.5312+3A>T, was identified in intron 37 of ABCA4. The mutations were not present in 200 controls. The two affected sisters in this pedigree were compound heterozygotes for the mutations. Unaffected family members either did not carry either or had only one of the two mutations. CONCLUSIONS We have identified two novel ABCA4 mutations, c.655A>T and c.5312+3A>T. When present as a compound heterozygous state, the mutations cause a phenotype of retinal dystrophy that initially manifests as Stargardt disease and slowly progresses to a severe cone-rod dystrophy. These results expand the wide range of clinical manifestations of ABCA4 mutations.
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Affiliation(s)
- Quansheng Xi
- Center for Cardiovascular Genetics and Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH
| | - Lin Li
- Center for Cardiovascular Genetics and Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH
| | | | - Qing Kenneth Wang
- Center for Cardiovascular Genetics and Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH,Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
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Abstract
Stargardt's disease is an autosomal recessive form of juvenile macular degeneration. The clinical presentation, relevant ancillary tests, and classic histologic features will be reviewed. The role of genetic mutations in the pathophysiology of Stargardt's disease will also be explored. Stargardt's disease is caused by mutations in the ABCR (ABCA4) gene on chromosome 1. Mutations in this gene have also been attributed to some cases of cone-rod dystrophy, retinitis pigmentosa, and age-related macular degeneration. The genetic and molecular pathways that produce Stargardt's disease will be discussed. Future diagnostic and therapeutic objectives for this visually disabling condition will also be presented.
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Affiliation(s)
- Corey Westerfeld
- Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA.
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Yang Z, Tong Z, Chorich LJ, Pearson E, Yang X, Moore A, Hunt DM, Zhang K. Clinical characterization and genetic mapping of North Carolina macular dystrophy. Vision Res 2007; 48:470-7. [PMID: 17976682 DOI: 10.1016/j.visres.2007.09.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/09/2007] [Accepted: 09/10/2007] [Indexed: 10/22/2022]
Abstract
North Carolina macular dystrophy (NCMD) is an autosomal dominant macular disease, was mapped to 6q14-q16.2, the disease-causing gene has yet not been identified. It shares phenotypic similarity with age-related macular degeneration including drusen and choroidal neovascularization. We collected six families with NCMD including 75 members, and conducted clinical characterization and genetic mapping for these families. Forty-five patients were diagnosed as NCMD; all six NCMD families were mapped to MCDR1 locus using genetic linkage analysis. MCDR1 interval was refined to 3 cM (1.8mb) between D6S1716 to D6S1671 via fine mapping using microsatellite markers in these six families, all eleven annotated genes within the interval were analyzed by mutation screening in coding regions, no mutation was found, suggesting a potential novel gene or a new pathological mechanism causing NCMD. The refinement of MCDR1 locus will aid the disease-causing gene identification. Functional studies of NCMD genes should provide important insights into pathogenetic mechanisms of NCMD and age-related macular degeneration.
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Affiliation(s)
- Zhenglin Yang
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
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Zhang Q, Zulfiqar F, Xiao X, Riazuddin SA, Ahmad Z, Caruso R, MacDonald I, Sieving P, Riazuddin S, Hejtmancik JF. Severe retinitis pigmentosa mapped to 4p15 and associated with a novel mutation in the PROM1 gene. Hum Genet 2007; 122:293-9. [PMID: 17605048 DOI: 10.1007/s00439-007-0395-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2007] [Accepted: 06/13/2007] [Indexed: 10/23/2022]
Abstract
Mutation in the PROM1 gene previously has been identified in one family with retinal degeneration for which neither ERG recordings nor detailed information about visual impairment is available. A large family with multiple individuals affected by retinal degeneration was ascertained in the Punjab province of Pakistan. The visual acuity of all affected patients in the family was severely compromised beginning in early childhood. The retinal disease in this family is a severe form of retinitis pigmentosa (RP) accompanied by macular degeneration. Fundus changes advanced with age. Choriocapillaris atrophy and posterior RPE atrophy were obvious allowing visualization of the large choroidal vessels in patients over 40 years of age. Rod and cone responses on ERG recordings were extinguished in patient's teens. A genome-wide scan mapped the disease to a 34.7 cM region of chromosome 4p14-p16 between D4S1599 and D4S405. A maximum lod score of 3.96 with D4S403 and D4S391 is seen at theta = 0. Sequence analysis of PROM1 located in the linkage interval identified a c.1726C>T homozygous transition in exon 15: resulting in p.Gln576X in the translated protein. This mutation is found in a homozygous state in all six affected individuals and was heterozygous in five of the six unaffected family members examined. The mutation was not detected in 192 chromosomes of unrelated control individuals of the same ethnicity and from the same region. This delineates the phenotypic characteristics of retinopathy caused by mutations in PROM1.
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Affiliation(s)
- Qingjiong Zhang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20982, USA.
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Boon CJF, van Schooneveld MJ, den Hollander AI, van Lith-Verhoeven JJC, Zonneveld-Vrieling MN, Theelen T, Cremers FPM, Hoyng CB, Klevering BJ. Mutations in the peripherin/RDS gene are an important cause of multifocal pattern dystrophy simulating STGD1/fundus flavimaculatus. Br J Ophthalmol 2007; 91:1504-11. [PMID: 17504850 PMCID: PMC2095453 DOI: 10.1136/bjo.2007.115659] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
AIM To describe the phenotype and to analyse the peripherin/RDS gene in 10 unrelated families with multifocal pattern dystrophy simulating Stargardt disease (STGD1). METHODS The probands of 10 families and 20 affected family members underwent an ophthalmic examination including dilated fundus examination, fundus autofluorescence imaging and optical coherence tomography (OCT). In all probands and in selected family members, fluorescein angiography, electrophysiological testing and visual field analysis were performed. Blood samples were obtained from affected and unaffected family members for analysis of the peripherin/RDS gene. RESULTS All 10 probands carried mutations in the peripherin/RDS gene. Nine different mutations were identified, including six mutations that were not described previously. All probands showed a pattern dystrophy with yellow-white flecks in the posterior pole that strongly resembled the flecks seen in STGD1, on ophthalmoscopy as well as on autofluorescence and OCT. Clinical findings in the family members carrying the same mutation as the proband were highly variable, ranging from no visible abnormalities to retinitis pigmentosa. CONCLUSIONS Mutations in the peripherin/RDS gene are the major cause of multifocal pattern dystrophy simulating STGD1/fundus flavimaculatus. This autosomal dominant disorder should be distinguished from autosomal recessive STGD1, in view of the different inheritance pattern and the overall better visual prognosis.
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Affiliation(s)
- Camiel J F Boon
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Yang Z, Kitsos G, Tong Z, Payne M, Gorezis S, Psilas K, Grigoriadou M, Zhao Y, Kamaya S, Aperis G, Petersen MB, Zhang K. A novel locus on 19q13 associated with autosomal-dominant macular dystrophy in a large Greek family. J Med Genet 2006; 43:e57. [PMID: 17142619 PMCID: PMC2563205 DOI: 10.1136/jmg.2005.040188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To describe the clinical features of and genetic locus associated with autosomal-dominant macular dystrophy (MCDR5) in a large Greek family. METHODS 26 members of a single family underwent clinical examinations and venepuncture. A genomewide linkage scan using 400 microsatellite markers distributed with an average spacing of 10 cM throughout the human genome. RESULTS 14 members of the study family exhibited clinical features of the disease including decreased central vision and macular abnormalities in the posterior pole of the retina. Analysis of loci known to be associated with macular dystrophy did not show positive linkage. A genomewide linkage scan showed linkage to chromosome 19q, with a two-point maximum LOD score of 5.809 at theta = 0 between the disease and marker locus D19S412. On the basis of recombination events, the disease interval was localised between markers D19S420 and D19S540 on chromosome 19q, at a span of about 3.8 cM, in an area known to contain 120 known genes/transcripts. Eleven of these genes/transcripts were sequenced, and no disease-causing mutation was identified. CONCLUSIONS This study describes a new locus on 19q associated with autosomal-dominant macular dystrophy, designated as MCDR5. Additional study of other family members will be necessary to further narrow the interval and identify the responsible gene. The study of MCDR5 will aid in elucidation of the underlying pathogenic mechanisms for this and other macular diseases, including age-related macular degeneration.
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Weleber RG, Gregory-Evans K. Retinitis Pigmentosa and Allied Disorders. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50023-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Deutman AF, Hoyng CB, van Lith-Verhoeven JJ. Macular Dystrophies. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50070-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Rozet JM, Gerber S, Ducroq D, Hamel C, Dufier JL, Kaplan J. Les dystrophies maculaires héréditaires. J Fr Ophtalmol 2005; 28:113-24. [PMID: 15767907 DOI: 10.1016/s0181-5512(05)81033-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Hereditary macular dystrophies are degenerative diseases of the central area of the retina associating primary anomalies of the retinal pigment epithelium and sensory retina. These conditions, whose hallmark is a loss of visual acuity, are a major cause of blindness and affect patients at all ages. Macular dystrophies group diseases that are heterogenous at the genetic level, as well as at the clinical, histological and physiopathological levels. Monogenic macular dystrophies are rare autosomal dominant conditions, with the exception of Stargardt disease in its typical form, which is not only relatively frequent but is also inherited as an autosomal recessive trait. During the last few years, the molecular bases of these conditions have begun to be elucidated with the identification of several responsible genes. For some macular dystrophies, this new information has confirmed pre-existing hypotheses on their pathophysiology, but for others, the discovery of the disease gene has added further complexity to the disease process. Two contradictory concepts were particularly highlighted by these genetic studies. Several phenotypes previously described as different clinical entities were brought together by the identification of mutations in the same gene, and converselyome conditions that were clinically assigned the same name, often heterogeneous at the clinical level, appeared genetically and physiopathologically heterogeneous. In addition, it is worth noting that the monogenic macular dystrophy genes were often regarded as potential factors for susceptibility to age-related macular degenerations. However, to date, only ABCA4 mutations have been associated with a minority of this frequent multifactorial condition. The aim of this article is to give a progress report on the monogenic macular dystrophy genes and to review current knowledge concerning the pathophysiology of these conditions.
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Affiliation(s)
- J-M Rozet
- Unité de Recherche sur les Handicaps Génétiques de l'Enfant, INSERM UR 393, Hôpital Necker-Enfants Malades, 149 rue de Sèvres, 75743 Paris cedex 15, France
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Yang Z, Alvarez BV, Chakarova C, Jiang L, Karan G, Frederick JM, Zhao Y, Sauvé Y, Li X, Zrenner E, Wissinger B, Hollander AID, Katz B, Baehr W, Cremers FP, Casey JR, Bhattacharya SS, Zhang K. Mutant carbonic anhydrase 4 impairs pH regulation and causes retinal photoreceptor degeneration. Hum Mol Genet 2004; 14:255-65. [PMID: 15563508 DOI: 10.1093/hmg/ddi023] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retina and retinal pigment epithelium (RPE) belong to the metabolically most active tissues in the human body. Efficient removal of acid load from retina and RPE is a critical function mediated by the choriocapillaris. However, the mechanism by which pH homeostasis is maintained is largely unknown. Here, we show that a functional complex of carbonic anhydrase 4 (CA4) and Na+/bicarbonate co-transporter 1 (NBC1) is specifically expressed in the choriocapillaris and that missense mutations in CA4 linked to autosomal dominant rod-cone dystrophy disrupt NBC1-mediated HCO3- transport. Our results identify a novel pathogenic pathway in which a defect in a functional complex involved in maintaining pH balances, but not expressed in retina or RPE, leads to photoreceptor degeneration. The importance of a functional CA4 for survival of photoreceptors implies that CA inhibitors, which are widely used as medications, particularly in the treatment of glaucoma, may have long-term adverse effects on vision.
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Affiliation(s)
- Zhenglin Yang
- Department of Ophthalmology and Visual Science, University of Utah Health Science Center, Salt Lake City 84112, USA
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Ambasudhan R, Wang X, Jablonski MM, Thompson DA, Lagali PS, Wong PW, Sieving PA, Ayyagari R. Atrophic macular degeneration mutations in ELOVL4 result in the intracellular misrouting of the protein. Genomics 2004; 83:615-25. [PMID: 15028284 DOI: 10.1016/j.ygeno.2003.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Accepted: 10/07/2003] [Indexed: 11/20/2022]
Abstract
Elongation of very long chain fatty acids 4 (ELOVL4) is a novel member of the ELO family of genes that are involved in fatty acid metabolism. ELOVL4 encodes a putative transmembrane protein of 314 amino acids that carries a possible endoplasmic reticulum (ER) retention/retrieval signal (KXKXX) at the C-terminus. Two distinct mutations, a 5-bp deletion and a complex mutation from the same region in exon 6 of this gene, have been reported so far and are associated with autosomal dominant atrophic macular degeneration (adMD/STGD3). Both of these deletions could result in C-terminal truncation and loss of the ER retention signal in the mutant protein. We expressed the wild-type and mutant proteins in COS-7 and CHO cells to study the intracellular distribution of ELOVL4 and to identify possible implications of the above mutations in its localization. Immunofluorescence analysis of these proteins along with organelle marker antibodies revealed predominant ER localization for wild-type ELOVL4. Targeted deletion of the dilysine motif at the C-terminus of the protein resulted in the loss of ER localization. Immunoelectron microscopy and immunofluorescence analysis revealed a similar ER localization pattern for the protein in human photoreceptors. These data indicate that ELOVL4 is an ER-resident protein, which supports its suggested function in fatty acid elongation. We also demonstrate that the localization of both mutant proteins was dramatically changed from an ER to a Golgi distribution. Our observations suggest that the consequences of defective protein trafficking could underlie the molecular mechanism associated with degeneration of the macula in the patients with adMD/STGD3.
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Affiliation(s)
- Rajesh Ambasudhan
- Kellogg Eye Center, Ophthalmology, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA
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