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Chen Y, Coorey NJ, Zhang M, Zeng S, Madigan MC, Zhang X, Gillies MC, Zhu L, Zhang T. Metabolism Dysregulation in Retinal Diseases and Related Therapies. Antioxidants (Basel) 2022; 11:antiox11050942. [PMID: 35624805 PMCID: PMC9137684 DOI: 10.3390/antiox11050942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 02/08/2023] Open
Abstract
The human retina, which is part of the central nervous system, has exceptionally high energy demands that requires an efficient metabolism of glucose, lipids, and amino acids. Dysregulation of retinal metabolism disrupts local energy supply and redox balance, contributing to the pathogenesis of diverse retinal diseases, including age-related macular degeneration, diabetic retinopathy, inherited retinal degenerations, and Macular Telangiectasia. A better understanding of the contribution of dysregulated metabolism to retinal diseases may provide better therapeutic targets than we currently have.
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Affiliation(s)
- Yingying Chen
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610017, China;
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
| | | | - Meixia Zhang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610017, China;
- Macular Disease Research Laboratory, Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610017, China
- Correspondence: (M.Z.); (T.Z.)
| | - Shaoxue Zeng
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
| | - Michele C. Madigan
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
- School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
| | - Xinyuan Zhang
- Department of Ocular Fundus Diseases, Beijing Tongren Eye Centre, Tongren Hospital, Capital Medical University, Beijing 100073, China;
- Beijing Retinal and Choroidal Vascular Study Group, Beijing 100073, China
| | - Mark C. Gillies
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
| | - Ling Zhu
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
| | - Ting Zhang
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; (S.Z.); (M.C.M.); (M.C.G.); (L.Z.)
- Correspondence: (M.Z.); (T.Z.)
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2
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Kayazawa T, Kuniyoshi K, Hatsukawa Y, Fujinami K, Yoshitake K, Tsunoda K, Shimojo H, Iwata T, Kusaka S. Clinical course of a Japanese girl with Leber congenital amaurosis associated with a novel nonsense pathogenic variant in NMNAT1: a case report and mini review. Ophthalmic Genet 2022; 43:400-408. [PMID: 35026968 DOI: 10.1080/13816810.2021.2023195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Leber congenital amaurosis (LCA), although rare, is one of the most severe forms of early-onset inherited retinal dystrophy (IRD). Here, we review the molecular genetics and phenotypic characteristics of patients with NMNAT1-associated IRD. The longitudinal clinical and molecular findings of a Japanese girl diagnosed with LCA associated with pathogenic variants in NMNAT1 c.648delG, (p.Trp216Ter*) and c.709C>T (p.Arg237Cys) have been described to highlight the salient clinical features of NMNAT1-associated IRD.
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Affiliation(s)
- Tomoyasu Kayazawa
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka, Japan
| | - Kazuki Kuniyoshi
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka, Japan
| | - Yoshikazu Hatsukawa
- Department of Ophthalmology, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Genetics, UCL Institute of Ophthalmology Associated with Moorfields Eye Hospital, London, UK.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Kazutoshi Yoshitake
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Graduate School of Agricultural and Life Science, Faculty of Agriculture, The University of Tokyo, Tokyo, Japan
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Hiroshi Shimojo
- Department of Ophthalmology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Shunji Kusaka
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka, Japan
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3
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NMNAT1-ASSOCIATED CONE-ROD DYSTROPHY: EVIDENCE FOR A SPECTRUM OF FOVEAL MALDEVELOPMENT. Retin Cases Brief Rep 2020; 16:385-392. [PMID: 32150116 DOI: 10.1097/icb.0000000000000992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To describe in detail the phenotype of two siblings with biallelic NMNAT1 mutations. METHODS A 4-year-old male patient (P1) and his 7-year-old sister (P2), product of a nonconsanguineous union of Egyptian ancestry, underwent a comprehensive ophthalmic examination, retinal imaging with spectral domain optical coherence tomography and near infrared (NIR) fundus autofluorescence (FAF), and full-field electroretinograms (ERG). RESULTS Patients had blurred vision and nystagmus at ∼3 years of age. P2 was hyperopic (+6D). Visual acuity in P1 was 20/100 at age 3 and remained at ∼20/125 at age 4; P2 visual acuity was 20/70 at age 4 and declined to ∼20/200 at age 7. ERGs recorded in P1 showed relatively large rod-mediated responses but nearly undetectable cone signals. There was foveal/parafoveal depigmentation. Spectral domain optical coherence tomography showed hypoplastic foveas, a thin outer nuclear layer centrally but normal thickness beyond the vascular arcades. At the foveal center, cone outer segments were absent and the outer nuclear layer was further hyporreflective. The inner retina was mostly within normal limits. There was central depigmentation on near infrared fundus autofluorescence. Biallelic mutations were identified in NMNAT1: One was previously reported (c.769 G>A; pGlu257Lys), and the other one (c.245T>C; pVal82Ala) was novel. CONCLUSION NMNAT1 mutations cause a consistent phenotype characterized by early-onset, progressive, cone>rod retinawide dysfunction and predominantly central abnormalities ranging from a hypoplastic to an atrophic fovea, supporting a critical role for NMNAT1 in central retinal development and maintenance. Relatively preserved inner retina and detectable photoreceptors may become therapeutic targets.
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NMNAT1 E257K variant, associated with Leber Congenital Amaurosis (LCA9), causes a mild retinal degeneration phenotype. Exp Eye Res 2018; 173:32-43. [PMID: 29674119 DOI: 10.1016/j.exer.2018.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 03/18/2018] [Accepted: 04/13/2018] [Indexed: 01/25/2023]
Abstract
NMNAT1 (nicotinamide mononucleotide adenylyltransferase 1) encodes a rate-limiting enzyme that catalyzes the biosynthesis of NAD+ and plays a role in neuroprotection. Mutations in NMNAT1 have been identified to cause a recessive, non-syndromic early form of blindness genetically defined as Leber Congenital Amaurosis 9 (LCA9). One of the most common alleles reported so far in NMNAT1 is the c.769G > A (E257K) missense mutation, which occurs in 70% of all LCA9 cases. However, given its relatively high population frequency and the observation of individuals with homozygous E257K variant without phenotype, the pathogenicity of this allele has been questioned. To address this issue, we have studied the pathogenic effects of this allele by generating a knock-in mouse model. Interestingly, no obvious morphological or functional defects are observed in Nmnat1 E257K homozygous mice up to one year old, even after light-damage. Together with the previous clinical reports, we propose that the E257K allele is a weak hypomorphic allele that has significantly reduced penetrance in the homozygous state. In contrast, compound heterozygous Nmnat1E257K/- mice exhibit photoreceptor defects which are exacerbated upon exposure to light. Furthermore, retina tissue- specific Nmnat1 conditional knockout mice exhibit photoreceptor degeneration before the retina has terminally differentiated. These findings suggest that NMNAT1 plays an important role in photoreceptors and is likely involved in both retinal development and maintenance of photoreceptor integrity.
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Li S, Xi Q, Zhang X, Yu D, Li L, Jiang Z, Chen Q, Wang QK, Traboulsi EI. Identification of a mutation in CNNM4 by whole exome sequencing in an Amish family and functional link between CNNM4 and IQCB1. Mol Genet Genomics 2018; 293:699-710. [PMID: 29322253 DOI: 10.1007/s00438-018-1417-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 01/06/2018] [Indexed: 12/15/2022]
Abstract
We investigated an Amish family in which three siblings presented with an early-onset childhood retinal dystrophy inherited in an autosomal recessive fashion. Genome-wide linkage analysis identified significant linkage to marker D2S2216 on 2q11 with a two-point LOD score of 1.95 and a multi-point LOD score of 3.76. Whole exome sequencing was then performed for the three affected individuals and identified a homozygous nonsense mutation (c.C1813T, p.R605X) in the cyclin and CBS domain divalent metal cation transport mediator 4 (CNNM4) gene located within the 2p14-2q14 Jalili syndrome locus. The initial assessment and collection of the family were performed before the clinical delineation of Jalili syndrome. Another assessment was made after the discovery of the responsible gene and the dental abnormalities characteristic of Jalili syndrome were retrospectively identified. The p.R605X mutation represents the first probable founder mutation of Jalili syndrome identified in the Amish community. The molecular mechanism underlying Jalili syndrome is unknown. Here we show that CNNM4 interacts with IQCB1, which causes Leber congenital amaurosis (LCA) when mutated. A truncated CNNM4 protein starting at R605 significantly increased the rate of apoptosis, and significantly increased the interaction between CNNM4 and IQCB1. Mutation p.R605X may cause Jalili syndrome by a nonsense-mediated decay mechanism, affecting the function of IQCB1 and apoptosis, or both. Our data, for the first time, functionally link Jalili syndrome gene CNNM4 to LCA gene IQCB1, providing important insights into the molecular pathogenic mechanism of retinal dystrophy in Jalili syndrome.
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Affiliation(s)
- Sisi Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research and Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Quansheng Xi
- Department of Molecular Cardiology, Center for Cardiovascular Genetics, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA
| | - Xiaoyu Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research and Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Dong Yu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research and Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Lin Li
- Department of Molecular Cardiology, Center for Cardiovascular Genetics, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA
| | - Zhenyang Jiang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research and Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Qiuyun Chen
- Department of Molecular Cardiology, Center for Cardiovascular Genetics, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, USA
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44195, USA
| | - Qing K Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research and Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, China.
- Department of Molecular Cardiology, Center for Cardiovascular Genetics, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA.
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, USA.
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44195, USA.
| | - Elias I Traboulsi
- Center for Genetic Eye Diseases, Cleveland Clinic Cole Eye Institute, Cleveland, OH, 44195, USA.
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Coussa RG, Lopez Solache I, Koenekoop RK. Leber congenital amaurosis, from darkness to light: An ode to Irene Maumenee. Ophthalmic Genet 2017; 38:7-15. [PMID: 28095138 DOI: 10.1080/13816810.2016.1275021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This article is dedicated to Irene Hussels Maumenee, Professor of Human Genetics and Ophthalmology, Johns Hopkins' Wilmer Eye Institute, Ocular Genetics Fellowship director in 1994-1995. Leber congenital amaurosis (LCA) has almost come full circle, from a profound and molecularly uncharacterized form of congenital retinal blindness to one in which a large number of causative genes and disease pathways are known, and the world's first human retinal disease to be treated by gene therapy. Dr. Maumenee's insights, efforts, and leadership have contributed significantly to this remarkable scientific journey. In this manuscript, we present a short summary of the known LCA genes, LCA disease subtypes, and emerging treatment options. Our manuscript consolidates previous knowledge with current findings in an attempt to provide a more comprehensive understanding of LCA.
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Affiliation(s)
- Razek Georges Coussa
- a Department of Paediatric Surgery, Montreal Children's Hospital , McGill University Health Centre , Montreal , Quebec , Canada.,b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
| | - Irma Lopez Solache
- b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
| | - Robert K Koenekoop
- a Department of Paediatric Surgery, Montreal Children's Hospital , McGill University Health Centre , Montreal , Quebec , Canada.,b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
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Coppieters F, Todeschini AL, Fujimaki T, Baert A, De Bruyne M, Van Cauwenbergh C, Verdin H, Bauwens M, Ongenaert M, Kondo M, Meire F, Murakami A, Veitia RA, Leroy BP, De Baere E. Hidden Genetic Variation in LCA9-Associated Congenital Blindness Explained by 5'UTR Mutations and Copy-Number Variations of NMNAT1. Hum Mutat 2015; 36:1188-96. [PMID: 26316326 PMCID: PMC5054839 DOI: 10.1002/humu.22899] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/19/2015] [Indexed: 11/28/2022]
Abstract
Leber congenital amaurosis (LCA) is a severe autosomal‐recessive retinal dystrophy leading to congenital blindness. A recently identified LCA gene is NMNAT1, located in the LCA9 locus. Although most mutations in blindness genes are coding variations, there is accumulating evidence for hidden noncoding defects or structural variations (SVs). The starting point of this study was an LCA9‐associated consanguineous family in which no coding mutations were found in the LCA9 region. Exploring the untranslated regions of NMNAT1 revealed a novel homozygous 5′UTR variant, c.‐70A>T. Moreover, an adjacent 5′UTR variant, c.‐69C>T, was identified in a second consanguineous family displaying a similar phenotype. Both 5′UTR variants resulted in decreased NMNAT1 mRNA abundance in patients’ lymphocytes, and caused decreased luciferase activity in human retinal pigment epithelial RPE‐1 cells. Second, we unraveled pseudohomozygosity of a coding NMNAT1 mutation in two unrelated LCA patients by the identification of two distinct heterozygous partial NMNAT1 deletions. Molecular characterization of the breakpoint junctions revealed a complex Alu‐rich genomic architecture. Our study uncovered hidden genetic variation in NMNAT1‐associated LCA and emphasized a shift from coding to noncoding regulatory mutations and repeat‐mediated SVs in the molecular pathogenesis of heterogeneous recessive disorders such as hereditary blindness.
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Affiliation(s)
| | | | - Takuro Fujimaki
- Department of Ophthalmology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Annelot Baert
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | | | | | - Hannah Verdin
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - Miriam Bauwens
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - Maté Ongenaert
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Mie, Japan
| | - Françoise Meire
- Department of Ophthalmology, Queen Fabiola Children's University Hospital, Brussels, Belgium
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Reiner A Veitia
- Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
| | - Bart P Leroy
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium.,Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
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Sasaki Y, Margolin Z, Borgo B, Havranek JJ, Milbrandt J. Characterization of Leber Congenital Amaurosis-associated NMNAT1 Mutants. J Biol Chem 2015; 290:17228-38. [PMID: 26018082 DOI: 10.1074/jbc.m115.637850] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Indexed: 01/27/2023] Open
Abstract
Leber congenital amaurosis 9 (LCA9) is an autosomal recessive retinal degeneration condition caused by mutations in the NAD(+) biosynthetic enzyme NMNAT1. This condition leads to early blindness but no other consistent deficits have been reported in patients with NMNAT1 mutations despite its central role in metabolism and ubiquitous expression. To study how these mutations affect NMNAT1 function and ultimately lead to the retinal degeneration phenotype, we performed detailed analysis of LCA-associated NMNAT1 mutants, including the expression, nuclear localization, enzymatic activity, secondary structure, oligomerization, and promotion of axonal and cellular integrity in response to injury. In many assays, most mutants produced results similar to wild type NMNAT1. Indeed, NAD(+) synthetic activity is unlikely to be a primary mechanism underlying retinal degeneration as most LCA-associated NMNAT1 mutants had normal enzymatic activity. In contrast, the secondary structure of many NMNAT1 mutants was relatively less stable as they lost enzymatic activity after heat shock, whereas wild type NMNAT1 retains significant activity after this stress. These results suggest that LCA-associated NMNAT1 mutants are more vulnerable to stressful conditions that lead to protein unfolding, a potential contributor to the retinal degeneration observed in this syndrome.
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Affiliation(s)
- Yo Sasaki
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Zachary Margolin
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Benjamin Borgo
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - James J Havranek
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jeffrey Milbrandt
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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A novel missense NMNAT1 mutation identified in a consanguineous family with Leber congenital amaurosis by targeted next generation sequencing. Gene 2015; 569:104-8. [PMID: 25988908 DOI: 10.1016/j.gene.2015.05.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 05/09/2015] [Accepted: 05/15/2015] [Indexed: 11/20/2022]
Abstract
Leber congenital amaurosis is the earliest onset and most severe inherited retinal dystrophy. Mutations in 21 genes have been identified to be responsible for LCA. To detect the causative variants, we performed targeted next generation sequencing in two affected siblings of a consanguineous Chinese family with suspected LCA. A novel homozygous missense mutation (c.721C>T, p. Pro241Ser) of NMNAT1 has been identified. The mutation was inherited from their consanguineous parents who were heterozygous and was absent in 300 unrelated healthy individuals. NMNAT1, which encodes the nicotinamide mononucleotide adenylyltransferase 1, has been recently identified to be one of the LCA-causing genes. Our results expanded the spectrum of mutations in NMNAT1. In this study, targeted next generation sequencing provides an accurate and efficient method for identifying mutations in hereditary diseases with highly genetic and clinical heterogeneity.
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Lustremant C, Habeler W, Plancheron A, Goureau O, Grenot L, de la Grange P, Audo I, Nandrot EF, Monville C. Human induced pluripotent stem cells as a tool to model a form of Leber congenital amaurosis. Cell Reprogram 2013; 15:233-46. [PMID: 23663011 DOI: 10.1089/cell.2012.0076] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Our purpose was to investigate genes and molecular mechanisms involved in patients with Leber congenital amaurosis (LCA) and to model this type of LCA for drug screening. Fibroblasts from two unrelated clinically identified patients with a yet undetermined gene mutation were reprogrammed to pluripotency by retroviral transduction. These human induced pluripotent stem cells (hiPSCs) were differentiated into neural stem cells (NSCs) that mimicked the neural tube stage and retinal pigmented epithelial (RPE) cells that could be targeted by the disease. A genome-wide transcriptome analysis was performed with Affymetrix Exon Array GeneChip(®), comparing LCA-hiPSCs derivatives to controls. A genomic search for alteration in all genes known to be involved in LCA revealed a common polymorphism on the GUCY2D gene, referenced as the LCA type I (OMIM *600179 and #204000), but the causative gene remained unknown. The hiPSCs expressed the key pluripotency factors and formed embryoid bodies in vitro containing cells originating from all three germ layers. They were successfully differentiated into NSC and RPE cells. One gene, NNAT, was upregulated in LCA cell populations, and three genes were downregulated, GSTT1, TRIM61 and ZNF558, with potential correlates for molecular mechanisms of this type of LCA, in particular for protein degradation and oxidative stress. The two LCA patient-specific iPSC lines will contribute to modeling LCA phenotypes and screening candidate drugs.
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11
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Perrault I, Estrada-Cuzcano A, Lopez I, Kohl S, Li S, Testa F, Zekveld-Vroon R, Wang X, Pomares E, Andorf J, Aboussair N, Banfi S, Delphin N, den Hollander AI, Edelson C, Florijn R, Jean-Pierre M, Leowski C, Megarbane A, Villanueva C, Flores B, Munnich A, Ren H, Zobor D, Bergen A, Chen R, Cremers FPM, Gonzalez-Duarte R, Koenekoop RK, Simonelli F, Stone E, Wissinger B, Zhang Q, Kaplan J, Rozet JM. Union makes strength: a worldwide collaborative genetic and clinical study to provide a comprehensive survey of RD3 mutations and delineate the associated phenotype. PLoS One 2013; 8:e51622. [PMID: 23308101 PMCID: PMC3538699 DOI: 10.1371/journal.pone.0051622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/02/2012] [Indexed: 12/02/2022] Open
Abstract
Leber congenital amaurosis (LCA) is the earliest and most severe retinal degeneration (RD), and the most common cause of incurable blindness diagnosed in children. It is occasionally the presenting symptom of multisystemic ciliopathies which diagnosis will require a specific care of patients. Nineteen LCA genes are currently identified and three of them account for both non-syndromic and syndromic forms of the disease. RD3 (LCA12) was implicated as a LCA gene based on the identification of homozygous truncating mutations in two LCA families despite the screening of large cohorts of patients. Here we provide a comprehensive survey of RD3 mutations and of their clinical expression through the screening of a cohort of 852 patients originating worldwide affected with LCA or early-onset and severe RD. We identified three RD3 mutations in seven unrelated consanguineous LCA families - i.e., a 2 bp deletion and two nonsense mutations – predicted to cause complete loss of function. Five families originating from the Southern Shores of the Mediterranean segregated a similar mutation (c.112C>T, p.R38*) suggesting that this change may have resulted from an ancient founder effect. Considering the low frequency of RD3 carriers, the recurrence risk for LCA in non-consanguineous unions is negligible for both heterozygote and homozygote RD3 individuals. The LCA12 phenotype in our patients is highly similar to those of patients with mutant photoreceptor-specific guanylate cyclase (GUCY2D/LCA1). This observation is consistent with the report of the role of RD3 in trafficking of GUCYs and gives further support to a common mechanism of photoreceptor degeneration in LCA12 and LCA1, i.e., inability to increase cytoplasmic cGMP concentration in outer segments and thus to recover the dark-state. Similar to LCA1, LCA12 patients have no extraocular symptoms despite complete inactivation of both RD3 alleles, supporting the view that extraocular investigations in LCA infants with RD3 mutations should be avoided.
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Affiliation(s)
- Isabelle Perrault
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement (INSERM U781)- Université Paris Descartes- Fondation IMAGINE, Paris, France
| | | | - Irma Lopez
- McGill Ocular Genetics Laboratory, Montreal Children's Hospital, McGill University Health Centre, Montreal, Canada
| | - Susanne Kohl
- University Eye Hospital, Institute for Ophthalmic Research, Tübingen University, Tübingen, Germany
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yatsen University, Guangzhou, China
| | - Francesco Testa
- Department of Ophthalmology, Second University of Naples, Naples, Italy
| | - Renate Zekveld-Vroon
- The Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | - Xia Wang
- Department of Molecular and Human Genetics, Baylor College of Medecine, Houston, Texas, United States of America
| | - Esther Pomares
- Faculty of Biology, Department of Genetics, University of Barcelona, Barcelona, Spain
| | - Jean Andorf
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medecine, Iowa City, Iowa, United States of America
| | - Nisrine Aboussair
- Service de Génétique CHU Mohammed VI, Faculté de Médecine et de Pharmacie, Université Caddi Ayyed, Marrakech, Morocco
| | - Sandro Banfi
- Telethon Institute of Genetics and Medecine (TIGEM), Naples, Italy
- Medical Genetics, Department of General Pathology, Second University of Naples, Naples, Italy
| | - Nathalie Delphin
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement (INSERM U781)- Université Paris Descartes- Fondation IMAGINE, Paris, France
| | - Anneke I. den Hollander
- Department of Human genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | - Ralph Florijn
- The Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | | | | | - Andre Megarbane
- Service de Génétique Médicale, Université Saint Joseph, Beyrouth, Lebanon
| | - Cristina Villanueva
- Servicio de Génética, Asociacion Para Evitar La Ceguera en Mexico, Mexico City, Mexico
| | - Blanca Flores
- Servicio de Génética, Asociacion Para Evitar La Ceguera en Mexico, Mexico City, Mexico
| | - Arnold Munnich
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement (INSERM U781)- Université Paris Descartes- Fondation IMAGINE, Paris, France
| | - Huanan Ren
- McGill Ocular Genetics Laboratory, Montreal Children's Hospital, McGill University Health Centre, Montreal, Canada
| | - Ditta Zobor
- University Eye Hospital, Institute for Ophthalmic Research, Tübingen University, Tübingen, Germany
| | - Arthur Bergen
- The Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medecine, Houston, Texas, United States of America
| | - Frans P. M. Cremers
- Department of Human genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Roser Gonzalez-Duarte
- Faculty of Biology, Department of Genetics, University of Barcelona, Barcelona, Spain
| | - Robert K. Koenekoop
- McGill Ocular Genetics Laboratory, Montreal Children's Hospital, McGill University Health Centre, Montreal, Canada
| | | | - Edwin Stone
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medecine, Iowa City, Iowa, United States of America
| | - Bernd Wissinger
- University Eye Hospital, Institute for Ophthalmic Research, Tübingen University, Tübingen, Germany
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yatsen University, Guangzhou, China
| | - Josseline Kaplan
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement (INSERM U781)- Université Paris Descartes- Fondation IMAGINE, Paris, France
| | - Jean-Michel Rozet
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement (INSERM U781)- Université Paris Descartes- Fondation IMAGINE, Paris, France
- * E-mail:
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Mutations in NMNAT1 cause Leber congenital amaurosis and identify a new disease pathway for retinal degeneration. Nat Genet 2012; 44:1035-9. [PMID: 22842230 DOI: 10.1038/ng.2356] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 06/25/2012] [Indexed: 12/26/2022]
Abstract
Leber congenital amaurosis (LCA) is a blinding retinal disease that presents within the first year after birth. Using exome sequencing, we identified mutations in the nicotinamide adenine dinucleotide (NAD) synthase gene NMNAT1 encoding nicotinamide mononucleotide adenylyltransferase 1 in eight families with LCA, including the family in which LCA was originally linked to the LCA9 locus. Notably, all individuals with NMNAT1 mutations also have macular colobomas, which are severe degenerative entities of the central retina (fovea) devoid of tissue and photoreceptors. Functional assays of the proteins encoded by the mutant alleles identified in our study showed that the mutations reduce the enzymatic activity of NMNAT1 in NAD biosynthesis and affect protein folding. Of note, recent characterization of the slow Wallerian degeneration (Wld(s)) mouse model, in which prolonged axonal survival after injury is observed, identified NMNAT1 as a neuroprotective protein when ectopically expressed. Our findings identify a new disease mechanism underlying LCA and provide the first link between endogenous NMNAT1 dysfunction and a human nervous system disorder.
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Chiang PW, Wang J, Chen Y, Fu Q, Zhong J, Chen Y, Yi X, Wu R, Gan H, Shi Y, Chen Y, Barnett C, Wheaton D, Day M, Sutherland J, Heon E, Weleber RG, Gabriel LAR, Cong P, Chuang K, Ye S, Sallum JMF, Qi M. Exome sequencing identifies NMNAT1 mutations as a cause of Leber congenital amaurosis. Nat Genet 2012; 44:972-4. [DOI: 10.1038/ng.2370] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 07/09/2012] [Indexed: 01/01/2023]
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Abstract
Leber congenital amaurosis (LCA) is an infantile-onset form of inherited retinal degeneration characterized by severe vision loss1, 2. Two-thirds of LCA cases are caused by mutations in 17 known disease genes3 (RetNet Retinal Information Network). Using exome sequencing, we identified a homozygous missense mutation (c.25G>A, p.Val9Met) in NMNAT1 as likely disease-causing in two siblings of a consanguineous Pakistani kindred affected by LCA. This mutation segregated with disease in their kindred, including in three other children with LCA. NMNAT1 resides in the previously identified LCA9 locus and encodes the nuclear isoform of nicotinamide mononucleotide adenylyltransferase, a rate-limiting enzyme in nicotinamide adenine dinucleotide (NAD+) biosynthesis4, 5. Functional studies showed the p.Val9Met mutation decreased NMNAT1 enzyme activity. Sequencing NMNAT1 in 284 unrelated LCA families identified 14 rare mutations in 13 additional affected individuals. These results are the first to link an NMNAT isoform to disease and indicate that NMNAT1 mutations cause LCA.
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Hollingsworth TJ, Gross AK. Defective trafficking of rhodopsin and its role in retinal degenerations. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 293:1-44. [PMID: 22251557 DOI: 10.1016/b978-0-12-394304-0.00006-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Retinitis pigmentosa is a retinal degeneration transmitted by varied modes of inheritance and affects approximately 1 in 4000 individuals. The photoreceptors of the outer retina, as well as the retinal pigmented epithelium which supports the outer retina metabolically and structurally, are the retinal regions most affected by the disorder. In several forms of retinitis pigmentosa, the mislocalization of the rod photoreceptor protein rhodopsin is thought to be a contributing factor underlying the pathophysiology seen in patients. The mutations causing this mislocalization often occur in genes coding proteins involved in ciliary formation, vesicular transport, rod outer segment disc formation, and stability, as well as the rhodopsin protein itself. Often, these mutations result in the most early-onset cases of both recessive and dominant retinitis pigmentosa, and the following presents a discussion of the proteins, their degenerative phenotypes, and possible treatments of the disease.
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Affiliation(s)
- T J Hollingsworth
- Department of Vision Sciences, University of Alabama, Birmingham, Alabama, USA
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Coppieters F, Casteels I, Meire F, De Jaegere S, Hooghe S, van Regemorter N, Van Esch H, Matuleviciene A, Nunes L, Meersschaut V, Walraedt S, Standaert L, Coucke P, Hoeben H, Kroes HY, Vande Walle J, de Ravel T, Leroy BP, De Baere E. Genetic screening of LCA in Belgium: predominance of CEP290 and identification of potential modifier alleles in AHI1 of CEP290-related phenotypes. Hum Mutat 2011; 31:E1709-66. [PMID: 20683928 PMCID: PMC3048164 DOI: 10.1002/humu.21336] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Leber Congenital Amaurosis (LCA), the most severe inherited retinal dystrophy, is genetically heterogeneous, with 14 genes accounting for 70% of patients. Here, 91 LCA probands underwent LCA chip analysis and subsequent sequencing of 6 genes (CEP290, CRB1, RPE65, GUCY2D, AIPL1and CRX), revealing mutations in 69% of the cohort, with major involvement of CEP290 (30%). In addition, 11 patients with early-onset retinal dystrophy (EORD) and 13 patients with Senior-Loken syndrome (SLS), LCA-Joubert syndrome (LCA-JS) or cerebello-oculo-renal syndrome (CORS) were included. Exhaustive re-inspection of the overall phenotypes in our LCA cohort revealed novel insights mainly regarding the CEP290-related phenotype. The AHI1 gene was screened as a candidate modifier gene in three patients with the same CEP290 genotype but different neurological involvement. Interestingly, a heterozygous novel AHI1 mutation, p.Asn811Lys, was found in the most severely affected patient. Moreover, AHI1 screening in five other patients with CEP290-related disease and neurological involvement revealed a second novel missense variant, p.His758Pro, in one LCA patient with mild mental retardation and autism. These two AHI1 mutations might thus represent neurological modifiers of CEP290-related disease. © 2010 Wiley-Liss, Inc.
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Affiliation(s)
- Frauke Coppieters
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
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Kahle JJ, Gulbahce N, Shaw CA, Lim J, Hill DE, Barabási AL, Zoghbi HY. Comparison of an expanded ataxia interactome with patient medical records reveals a relationship between macular degeneration and ataxia. Hum Mol Genet 2010; 20:510-27. [PMID: 21078624 PMCID: PMC3016911 DOI: 10.1093/hmg/ddq496] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Spinocerebellar ataxias 6 and 7 (SCA6 and SCA7) are neurodegenerative disorders caused by expansion of CAG repeats encoding polyglutamine (polyQ) tracts in CACNA1A, the alpha1A subunit of the P/Q-type calcium channel, and ataxin-7 (ATXN7), a component of a chromatin-remodeling complex, respectively. We hypothesized that finding new protein partners for ATXN7 and CACNA1A would provide insight into the biology of their respective diseases and their relationship to other ataxia-causing proteins. We identified 118 protein interactions for CACNA1A and ATXN7 linking them to other ataxia-causing proteins and the ataxia network. To begin to understand the biological relevance of these protein interactions within the ataxia network, we used OMIM to identify diseases associated with the expanded ataxia network. We then used Medicare patient records to determine if any of these diseases co-occur with hereditary ataxia. We found that patients with ataxia are at 3.03-fold greater risk of these diseases than Medicare patients overall. One of the diseases comorbid with ataxia is macular degeneration (MD). The ataxia network is significantly (P= 7.37 × 10−5) enriched for proteins that interact with known MD-causing proteins, forming a MD subnetwork. We found that at least two of the proteins in the MD subnetwork have altered expression in the retina of Ataxin-7266Q/+ mice suggesting an in vivo functional relationship with ATXN7. Together these data reveal novel protein interactions and suggest potential pathways that can contribute to the pathophysiology of ataxia, MD, and diseases comorbid with ataxia.
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Affiliation(s)
- Juliette J Kahle
- Department of Cellular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Manoli I, Golas G, Westbroek W, Vilboux T, Markello TC, Introne W, Maynard D, Pederson B, Tsilou E, Jordan MB, Hart PS, White JG, Gahl WA, Huizing M. Chediak-Higashi syndrome with early developmental delay resulting from paternal heterodisomy of chromosome 1. Am J Med Genet A 2010; 152A:1474-83. [PMID: 20503323 DOI: 10.1002/ajmg.a.33389] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disease characterized by variable oculocutaneous albinism, immunodeficiency, mild bleeding diathesis, and an accelerated lymphoproliferative state. Abnormal lysosome-related organelle membrane function leads to the accumulation of large intracellular vesicles in several cell types, including granulocytes, melanocytes, and platelets. This report describes a severe case of CHS resulting from paternal heterodisomy of chromosome 1, causing homozygosity for the most distal nonsense mutation (p.E3668X, exon 50) reported to date in the LYST/CHS1 gene. The mutation is located in the WD40 region of the CHS1 protein. The patient's fibroblasts expressed no detectable CHS1. Besides manifesting the classical CHS findings, the patient exhibited hypotonia and global developmental delays, raising concerns about other effects of heterodisomy. An interstitial 747 kb duplication on 6q14.2-6q14.3 was identified in the propositus and paternal samples by comparative genomic hybridization. SNP genotyping revealed no additional whole chromosome or segmental isodisomic regions or other dosage variations near the crossover breakpoints on chromosome 1. Unmasking of a separate autosomal recessive cause of developmental delay, or an additive effect of the paternal heterodisomy, could underlie the severity of the phenotype in this patient.
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Affiliation(s)
- Irini Manoli
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland, USA.
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Aboussair N, Berahou A, Perrault I, Elalaoui SC, Megzari A, Rozet JM, Kaplan J, Sefiani A. [First North African observation of Leber congenital amaurosis secondary to CEP290 gene mutation]. J Fr Ophtalmol 2010; 33:117.e1-5. [PMID: 20056295 DOI: 10.1016/j.jfo.2009.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 04/13/2009] [Indexed: 01/24/2023]
Abstract
Leber congenital amaurosis (LCA) is a the earliest and most severe form of retinal dystrophy responsible for congenital blindness. LCA has genetic heterogeneity and the study of this disease is elucidating the genetics and molecular interactions involved in the development of the retina. To date, 11 LCA genes have been mapped, ten of which have been identified. The CEP290 gene has been shown to account for Joubert and Senior-Loken syndromes and to be a frequent cause of nonsyndromic LCA. We report here the first Arab patient, born to consanguineous parents, with Leber congenital amaurosis attributable to mutation of the CEP290 gene.
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Affiliation(s)
- N Aboussair
- Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Maroc.
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Chung DC, Traboulsi EI. Leber congenital amaurosis: clinical correlations with genotypes, gene therapy trials update, and future directions. J AAPOS 2009; 13:587-92. [PMID: 20006823 DOI: 10.1016/j.jaapos.2009.10.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 02/06/2023]
Abstract
Leber congenital amaurosis comprises a group of early onset childhood retinal dystrophies, characterized by vision loss, nystagmus, and severe retinal dysfunction. To date, 15 causative genes have been identified that account for the heterogeneous presentation and clinical course. Knowledge of key aspects of phenotype and clinical course can contribute to the determination of a precise genetic etiology using genetic testing. Gene-based therapies are emerging, and knowledge of a patient's genotype is essential. A review of clinical presentation and disease course, their correlation to specific genotypes, and underlying physiological mechanisms, coupled with the latest results of human gene therapy trials, will assist the clinician in patient diagnosis and counseling.
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Affiliation(s)
- Daniel C Chung
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
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Wang H, den Hollander AI, Moayedi Y, Abulimiti A, Li Y, Collin RW, Hoyng CB, Lopez I, Bray M, Lewis RA, Lupski JR, Mardon G, Koenekoop RK, Chen R, Koenekoop RK, Chen R. Mutations in SPATA7 cause Leber congenital amaurosis and juvenile retinitis pigmentosa. Am J Hum Genet 2009; 84:380-7. [PMID: 19268277 DOI: 10.1016/j.ajhg.2009.02.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/04/2009] [Accepted: 02/06/2009] [Indexed: 11/25/2022] Open
Abstract
Leber congenital amaurosis (LCA) and juvenile retinitis pigmentosa (RP) are the most common hereditary causes of visual impairment in infants and children. Using homozygosity mapping, we narrowed down the critical region of the LCA3 locus to 3.8 Mb between markers D14S1022 and D14S1005. By direct Sanger sequencing of all genes within this region, we found a homozygous nonsense mutation in the SPATA7 gene in Saudi Arabian family KKESH-060. Three other loss-of-function mutations were subsequently discovered in patients with LCA or juvenile RP from distinct populations. Furthermore, we determined that Spata7 is expressed in the mature mouse retina. Our findings reveal another human visual-disease gene that causes LCA and juvenile RP.
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den Hollander AI, Roepman R, Koenekoop RK, Cremers FPM. Leber congenital amaurosis: genes, proteins and disease mechanisms. Prog Retin Eye Res 2008; 27:391-419. [PMID: 18632300 DOI: 10.1016/j.preteyeres.2008.05.003] [Citation(s) in RCA: 556] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Leber congenital amaurosis (LCA) is the most severe retinal dystrophy causing blindness or severe visual impairment before the age of 1 year. Linkage analysis, homozygosity mapping and candidate gene analysis facilitated the identification of 14 genes mutated in patients with LCA and juvenile retinal degeneration, which together explain approximately 70% of the cases. Several of these genes have also been implicated in other non-syndromic or syndromic retinal diseases, such as retinitis pigmentosa and Joubert syndrome, respectively. CEP290 (15%), GUCY2D (12%), and CRB1 (10%) are the most frequently mutated LCA genes; one intronic CEP290 mutation (p.Cys998X) is found in approximately 20% of all LCA patients from north-western Europe, although this frequency is lower in other populations. Despite the large degree of genetic and allelic heterogeneity, it is possible to identify the causative mutations in approximately 55% of LCA patients by employing a microarray-based, allele-specific primer extension analysis of all known DNA variants. The LCA genes encode proteins with a wide variety of retinal functions, such as photoreceptor morphogenesis (CRB1, CRX), phototransduction (AIPL1, GUCY2D), vitamin A cycling (LRAT, RDH12, RPE65), guanine synthesis (IMPDH1), and outer segment phagocytosis (MERTK). Recently, several defects were identified that are likely to affect intra-photoreceptor ciliary transport processes (CEP290, LCA5, RPGRIP1, TULP1). As the eye represents an accessible and immune-privileged organ, it appears to be uniquely suitable for human gene replacement therapy. Rodent (Crb1, Lrat, Mertk, Rpe65, Rpgrip1), avian (Gucy2D) and canine (Rpe65) models for LCA and profound visual impairment have been successfully corrected employing adeno-associated virus or lentivirus-based gene therapy. Moreover, phase 1 clinical trials have been carried out in humans with RPE65 deficiencies. Apart from ethical considerations inherently linked to treating children, major obstacles for the treatment of LCA could be the putative developmental deficiencies in the visual cortex in persons blind from birth (amblyopia), the absence of sufficient numbers of viable photoreceptor or RPE cells in LCA patients, and the unknown and possibly toxic effects of overexpression of transduced genes. Future LCA research will focus on the identification of the remaining causal genes, the elucidation of the molecular mechanisms of disease in the retina, and the development of gene therapy approaches for different genetic subtypes of LCA.
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Affiliation(s)
- Anneke I den Hollander
- Department of Human Genetics & Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Abstract
Over the last decade there have been major advances in our understanding of the molecular pathology of inherited retinal dystrophies. This paper reviews recent advances in the identification of genetic mutations underlying infantile-onset inherited retinal disorders and considers how this knowledge may lead to novel therapeutic approaches.
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Affiliation(s)
- P Moradi
- Institute of Ophthalmology UCL, London, UK
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Abstract
Leber congenital amaurosis (LCA) is a congenital retinal dystrophy that was first described almost 150 years ago. LCA still remains an important cause of blindness with about 20% of children in schools for the blind being affected by it. LCA has genetic heterogeneity and the study of this disease is elucidating the genetics and molecular interactions involved in the development of the retina. This paper reviews the clinical history of the disease since it was first described. We further discuss the differential diagnosis of the disease and the difficulties encountered in making the diagnosis. We also review the genetics of the disease and the role of future therapies.
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Affiliation(s)
- Ednan Ahmed
- Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
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Preising MN, Paunescu K, Friedburg C, Lorenz B. [Genetic and clinical heterogeneity in LCA patients. The end of uniformity]. Ophthalmologe 2007; 104:490-8. [PMID: 17525851 DOI: 10.1007/s00347-007-1533-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND Leber congenital amaurosis (LCA) usually describes patients with severely reduced vision due to a retinal dystrophy in early childhood. METHODS In 135 families in a case series with severely reduced vision due to a retinal dystrophy in early childhood a complete ophthalmologic examination was extended by two-color threshold perimetry, fundus autofluorescence (FAF), und optical coherence tomography (OCT). Mutation screening included AIPL1, CRB1, CRX, GUCY2D, LRAT, RPE65, RPGRIP, and TULP1. RESULTS GUCY2D mutations caused the most severe phenotype with severely reduced vision from birth but unremarkable fundus appearance. RPE65 mutations were correlated with an obvious lack of FAF. CRB1 mutations showed a significantly thickened retina on OCT. CRX mutations were associated with a progressive form of cone-rod dystrophy. CONCLUSION A genotype-phenotype correlation for selected genes allows an optimized strategy for the molecular genetic work-up.
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Affiliation(s)
- M N Preising
- Abt. für Kinderophthalmologie, Strabismologie und Ophthalmogenetik, Klinikum der Universität Regensburg, 93042, Regensburg
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Inoue T, Terada K, Furukawa A, Koike C, Tamaki Y, Araie M, Furukawa T. Cloning and characterization of mr-s, a novel SAM domain protein, predominantly expressed in retinal photoreceptor cells. BMC DEVELOPMENTAL BIOLOGY 2006; 6:15. [PMID: 16539743 PMCID: PMC1435744 DOI: 10.1186/1471-213x-6-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 03/16/2006] [Indexed: 11/17/2022]
Abstract
Background Sterile alpha motif (SAM) domains are ~70 residues long and have been reported as common protein-protein interaction modules. This domain is found in a large number of proteins, including Polycomb group (PcG) proteins and ETS family transcription factors. In this work, we report the cloning and functional characterization of a novel SAM domain-containing protein, which is predominantly expressed in retinal photoreceptors and the pineal gland and is designated mouse mr-s (major retinal SAM domain protein). Results mr-s is evolutionarily conserved from zebrafish through human, organisms through which the mechanism of photoreceptor development is also highly conserved. Phylogenetic analysis suggests that the SAM domain of mr-s is most closely related to a mouse polyhomeotic (ph) ortholog, Mph1/Rae28, which is known as an epigenetic molecule involved in chromatin modifications. These findings provide the possibility that mr-s may play a critical role by regulating gene expression in photoreceptor development. mr-s is preferentially expressed in the photoreceptors at postnatal day 3–6 (P3-6), when photoreceptors undergo terminal differentiation, and in the adult pineal gland. Transcription of mr-s is directly regulated by the cone-rod homeodomain protein Crx. Immunoprecipitation assay showed that the mr-s protein self-associates mainly through the SAM domain-containing region as well as ph. The mr-s protein localizes mainly in the nucleus, when mr-s is overexpressed in HEK293T cells. Moreover, in the luciferase assays, we found that mr-s protein fused to GAL4 DNA-binding domain functions as a transcriptional repressor. We revealed that the repression activity of mr-s is not due to a homophilic interaction through its SAM domain but to the C-terminal region. Conclusion We identified a novel gene, mr-s, which is predominantly expressed in retinal photoreceptors and pineal gland. Based on its expression pattern and biochemical analysis, we predict that mr-s may function as a transcriptional repressor in photoreceptor cells and in pinealocytes of the pineal gland.
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Affiliation(s)
- Tatsuya Inoue
- Osaka Bioscience Institute; 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
- PRESTO, Japan Science and Technology Agency; 4-1-8 Honcho, Kawaguchi, Saitama, Japan
- Department of Ophthalmology, Tokyo University School of Medicine; 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Koji Terada
- Osaka Bioscience Institute; 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
| | - Akiko Furukawa
- Osaka Bioscience Institute; 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
- Department of Ophthalmology, Osaka University Medical School; Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Chieko Koike
- Osaka Bioscience Institute; 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
| | - Yasuhiro Tamaki
- Department of Ophthalmology, Tokyo University School of Medicine; 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Makoto Araie
- Department of Ophthalmology, Tokyo University School of Medicine; 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takahisa Furukawa
- Osaka Bioscience Institute; 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
- PRESTO, Japan Science and Technology Agency; 4-1-8 Honcho, Kawaguchi, Saitama, Japan
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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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Hanein S, Perrault I, Gerber S, Tanguy G, Hamel C, Dufier JL, Rozet JM, Kaplan J. [Leber congenital amaurosis: comprehensive survey of genetic heterogeneity. A clinical definition update]. J Fr Ophtalmol 2005; 28:98-105. [PMID: 15767905 DOI: 10.1016/s0181-5512(05)81031-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium, but they are involved in strikingly different physiologic pathways, resulting in an unforeseeable pathophysiologic variety. This broad genetic and physiologic heterogeneity, which could greatly increase in the coming years, hinders molecular diagnosis in LCA patients. Genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here we report a comprehensive mutational analysis of all the known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% of patients. GUCY2D accounted for by far the largest part of the LCA cases in our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%) and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited in the search for phenotype variations. Genotype-phenotype correlations were found that made it possible to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rod-cone dystrophy. In addition, objective ophthalmologic data subdivided each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the onerous task of genotyping new patients, but only if the most precise clinical history since birth is available.
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Affiliation(s)
- S Hanein
- Unité de Recherche sur les Handicaps Génétiques de l'Enfant, INSERM U 393, Hôpital Necker-Enfants Malades, Paris, France
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Ozgül RK, Bozkurt B, Kiratli H, Oğüş A. Exclusion of LCA5 locus in a consanguineous Turkish family with macular coloboma-type LCA. Eye (Lond) 2005; 20:817-9. [PMID: 16082399 DOI: 10.1038/sj.eye.6702024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Leber's congenital amaurosis (LCA) is an inherited retinal dystrophy, which causes severe visual impairment in early childhood. Recent molecular genetic studies have linked 11 loci (AIPL1, CRB1, CRX, GUCY2D, RPE65, RDH12, RPGRIP1, TULP1, LCA3, LCA5, and LCA9) to LCA. LCA5 is a new locus, which maps to the 6q11-q16 chromosomal region and was found to be associated with macular coloboma-type LCA in a Pakistani family. Herein, we describe the molecular genetic features of a consanguineous Turkish family in which four children have macular coloboma-type LCA. METHODS Haplotype analysis was performed on the DNA of the family members using microsatellite markers against GUCY2D, RPE65, and LCA5. Genomic DNA was screened for mutations by means of single-strand conformational polymorphism (SSCP) analysis in exons of the RPE65 and CRX genes. RESULTS In haplotype analysis, no linkage to LCA5 or GUCY2D loci was detected. None of the tested markers showed homozygosity or segregation between affected siblings. PCR-SSCP mutation analysis revealed no mutations in the screened RPE65 and CRX genes. CONCLUSION We excluded LCA5 as the genetic cause of macular coloboma-type LCA in this Turkish family. Macular coloboma-type LCA shows genetic heterogeneity and it is not possible to establish a phenotype-genotype correlation with LCA5 and macular coloboma.
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Affiliation(s)
- R K Ozgül
- Department of Molecular Biology, Hacettepe University, Ankara, Turkey.
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Abstract
Leber congenital amaurosis (LCA; estimated prevalence 1 : 50,000-100,000) is an early-onset inherited cause of childhood blindness characterized by a severe retinal dystrophy immediately after birth. Variants in at least six genes, AIPL1, CRB1, CRX, GUCY2D, RPE65, and RPGRIP1, have been associated with a diagnosis consistent with LCA or early-onset retinitis pigmentosa and together account for less than 50% of all LCA cases. Genetically heterogeneous inheritance has complicated the molecular analysis of LCA cases, especially sporadic ones where conventional methods are of limited value. Until recently, the management of patients with LCA relied mainly on clinical examination, electrophysiology, and other ancillary tests. Genotyping, i.e., determining the exact genetic defect causing LCA in each specific case, was not routinely performed since the comprehensive screening of six genes by SSCP and/or direct sequencing is relatively inefficient and cost-prohibitive. Patients, therefore, were often left with no specific information on their disease status. Recent advances in genotyping technologies have allowed the introduction of comprehensive and affordable screening procedures to determine causal genetic variation, resulting in precise molecular diagnosis, more accurate visual prognosis, and suggestions towards treatment options.
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Affiliation(s)
- Rando Allikmets
- Department of Ophthalmology Columbia University Eye Institute Research, Rm. 715 630 West 168th Street New York, NY 10032 USA.
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Perrault I, Hanein S, Gerber S, Barbet F, Ducroq D, Dollfus H, Hamel C, Dufier JL, Munnich A, Kaplan J, Rozet JM. Retinal dehydrogenase 12 (RDH12) mutations in leber congenital amaurosis. Am J Hum Genet 2004; 75:639-46. [PMID: 15322982 PMCID: PMC1182050 DOI: 10.1086/424889] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 07/28/2004] [Indexed: 11/03/2022] Open
Abstract
Leber congenital amaurosis (LCA), the most early-onset and severe form of all inherited retinal dystrophies, is responsible for congenital blindness. Ten LCA genes have been mapped, and seven of these have been identified. Because some of these genes are involved in the visual cycle, we regarded the retinal pigment epithelium and photoreceptor-specific retinal dehydrogenase (RDH) genes as candidate genes in LCA. Studying a series of 110 unrelated patients with LCA, we found mutations in the photoreceptor-specific RDH12 gene in a significant subset of patients (4.1%). Interestingly, all patients harboring RDH12 mutations had a severe yet progressive rod-cone dystrophy with severe macular atrophy but no or mild hyperopia.
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Affiliation(s)
- Isabelle Perrault
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Sylvain Hanein
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Sylvie Gerber
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Fabienne Barbet
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Dominique Ducroq
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Helene Dollfus
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Christian Hamel
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Jean-Louis Dufier
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Arnold Munnich
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Josseline Kaplan
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Jean-Michel Rozet
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
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Koenekoop RK. An overview of Leber congenital amaurosis: a model to understand human retinal development. Surv Ophthalmol 2004; 49:379-98. [PMID: 15231395 DOI: 10.1016/j.survophthal.2004.04.003] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Leber congenital amaurosis is a congenital retinal dystrophy described almost 150 years ago. Today, Leber congenital amaurosis is proving instrumental in our understanding of the molecular events that determine normal and aberrant retinal development. Six genes have been shown to be mutated in Leber congenital amaurosis, and they participate in a wide variety of retinal pathways: retinoid metabolism (RPE65), phototransduction (GUCY2D), photoreceptor outer segment development (CRX), disk morphogenesis (RPGRIP1), zonula adherens formation (CRB1), and cell-cycle progression (AIPL1). Longitudinal studies of visual performance show that most Leber congenital amaurosis patients remain stable, some deteriorate, and rare cases exhibit improvements. Histopathological analyses reveal that most cases have extensive degenerative retinal changes, some have an entirely normal retinal architecture, whereas others have primitive, poorly developed retinas. Animal models of Leber congenital amaurosis have greatly added to understanding the impact of the genetic defects on retinal cell death, and response to rescue. Gene therapy for RPE65 deficient dogs partially restored sight, and provides the first real hope of treatment for this devastating blinding condition.
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Affiliation(s)
- Robert K Koenekoop
- McGill Ocular Genetics Laboratory, Montreal Children's Hospital, McGill University Health Center, Montreal, Quebec, Canada
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Hanein S, Perrault I, Gerber S, Tanguy G, Barbet F, Ducroq D, Calvas P, Dollfus H, Hamel C, Lopponen T, Munier F, Santos L, Shalev S, Zafeiriou D, Dufier JL, Munnich A, Rozet JM, Kaplan J. Leber congenital amaurosis: comprehensive survey of the genetic heterogeneity, refinement of the clinical definition, and genotype-phenotype correlations as a strategy for molecular diagnosis. Hum Mutat 2004; 23:306-17. [PMID: 15024725 DOI: 10.1002/humu.20010] [Citation(s) in RCA: 247] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium but they are involved in strikingly different physiologic pathways resulting in an unforeseeable physiopathologic variety. This wide genetic and physiologic heterogeneity that could largely increase in the coming years, hinders the molecular diagnosis in LCA patients. The genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here, we report a comprehensive mutational analysis of the all known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% patients. GUCY2D appeared to account for most LCA cases of our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%), and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited to search for phenotype variations. Sound genotype-phenotype correlations were found that allowed us to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rod-cone dystrophy. Besides, objective ophthalmologic data allowed us to subdivide each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the heavy task of genotyping new patients but only if one has access to the most precise clinical history since birth.
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Affiliation(s)
- Sylvain Hanein
- Unité de Recherches sur les Handicaps Génétiques de l'Enfant, Hôpital Necker-Enfants Malades, Paris, France
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