1
|
Zheng Y, Chen S. Transcriptional precision in photoreceptor development and diseases - Lessons from 25 years of CRX research. Front Cell Neurosci 2024; 18:1347436. [PMID: 38414750 PMCID: PMC10896975 DOI: 10.3389/fncel.2024.1347436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/19/2024] [Indexed: 02/29/2024] Open
Abstract
The vertebrate retina is made up of six specialized neuronal cell types and one glia that are generated from a common retinal progenitor. The development of these distinct cell types is programmed by transcription factors that regulate the expression of specific genes essential for cell fate specification and differentiation. Because of the complex nature of transcriptional regulation, understanding transcription factor functions in development and disease is challenging. Research on the Cone-rod homeobox transcription factor CRX provides an excellent model to address these challenges. In this review, we reflect on 25 years of mammalian CRX research and discuss recent progress in elucidating the distinct pathogenic mechanisms of four CRX coding variant classes. We highlight how in vitro biochemical studies of CRX protein functions facilitate understanding CRX regulatory principles in animal models. We conclude with a brief discussion of the emerging systems biology approaches that could accelerate precision medicine for CRX-linked diseases and beyond.
Collapse
Affiliation(s)
- Yiqiao Zheng
- Molecular Genetics and Genomics Graduate Program, Division of Biological and Biomedical Sciences, Saint Louis, MO, United States
- Department of Ophthalmology and Visual Sciences, Saint Louis, MO, United States
| | - Shiming Chen
- Molecular Genetics and Genomics Graduate Program, Division of Biological and Biomedical Sciences, Saint Louis, MO, United States
- Department of Ophthalmology and Visual Sciences, Saint Louis, MO, United States
- Department of Developmental Biology, Washington University in St. Louis, Saint Louis, MO, United States
| |
Collapse
|
2
|
Rodriguez-Martinez AC, Higgins BE, Tailor-Hamblin V, Malka S, Cheloni R, Collins AM, Bladen J, Henderson R, Moosajee M. Foveal Hypoplasia in CRB1-Related Retinopathies. Int J Mol Sci 2023; 24:13932. [PMID: 37762234 PMCID: PMC10531165 DOI: 10.3390/ijms241813932] [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: 07/25/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023] Open
Abstract
The CRB1 gene plays a role in retinal development and its maintenance. When disrupted, it gives a range of phenotypes such as early-onset severe retinal dystrophy/Leber congenital amaurosis (EOSRD/LCA), retinitis pigmentosa (RP), cone-rod dystrophy (CORD) and macular dystrophy (MD). Studies in CRB1 retinopathies have shown thickening and coarse lamination of retinal layers resembling an immature retina. Its role in foveal development has not yet been described; however, this retrospective study is the first to report foveal hypoplasia (FH) presence in a CRB1-related retinopathy cohort. Patients with pathogenic biallelic CRB1 variants from Moorfields Eye Hospital, London, UK, were collected. Demographic, clinical data and SD-OCT analyses with FH structural grading were performed. A total of 15 (48%) patients had EOSRD/LCA, 11 (35%) MD, 3 (9%) CORD and 2 (6%) RP. FH was observed in 20 (65%; CI: 0.47-0.79) patients, all of whom were grade 1. A significant difference in BCVA between patients with FH and without was found (p = 0.014). BCVA continued to worsen over time in both groups (p < 0.001), irrespective of FH. This study reports FH in a CRB1 cohort, supporting the role of CRB1 in foveal development. FH was associated with poorer BCVA and abnormal retinal morphology. Nonetheless, its presence did not alter the disease progression.
Collapse
Affiliation(s)
- Ana Catalina Rodriguez-Martinez
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 1LE, UK
| | - Bethany Elora Higgins
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - Vijay Tailor-Hamblin
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- UCL Experimental Psychology, London WC1H 0AP, UK
| | - Samantha Malka
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - Riccardo Cheloni
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - Alexander Mark Collins
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
| | - John Bladen
- King’s College Hospital NHS Foundation Trust, Strand, London WC2R 2LS, UK;
| | - Robert Henderson
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 1LE, UK
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (A.C.R.-M.); (B.E.H.); (V.T.-H.); (S.M.); (R.C.); (A.M.C.); (R.H.)
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 1LE, UK
- The Francis Crick Institute, London NW1 1AT, UK
| |
Collapse
|
3
|
Albakri A, Pisuchpen P, Capasso JE, Schneider A, Kopinsky S, Glaser T, Chiang JPW, Yomai AA, McNear D, Levin AV. Novel CRB1 pathogenic variant in Chuuk families with Leber congenital amaurosis. Am J Med Genet A 2023; 191:1007-1012. [PMID: 36595661 PMCID: PMC10262898 DOI: 10.1002/ajmg.a.63108] [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: 09/14/2022] [Revised: 11/13/2022] [Accepted: 11/15/2022] [Indexed: 01/05/2023]
Abstract
The purpose of this article is to determine the cause of Leber congenital amaurosis (LCA) in Chuuk state, Federated States of Micronesia (FSM). In this prospective observational case series, five patients with early-onset vision loss were examined in Chuuk state, FSM, during an ocular genetics visit to study the elevated incidence of microphthalmia. Because of their low vision these patients were incorrectly assumed to have microphthalmia. A complete ophthalmological exam established a clinical diagnosis of LCA. Candidate gene exons were sequenced with a targeted retinal dystrophy panel. Five subjects in three related families were diagnosed with LCA. All five were from Tonoas Island, within the Chuuk Lagoon, with ages ranging from 6 months to 16 years. DNA sequencing of affected individuals revealed a homozygous CRB1 NM_201253.3:c.3134del pathogenic variant, which was heterozygous in their parents. CRB1 genotypes were confirmed by a PCR restriction assay. We report identification of a founder pathogenic variant in CRB1 responsible for autosomal recessive LCA in this isolated community. This discovery will lead to appropriate recurrence risk counseling.
Collapse
Affiliation(s)
- Amani Albakri
- Pediatric and Ocular Genetics, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
- Division of Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Phattrawan Pisuchpen
- Pediatric and Ocular Genetics, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand
| | - Jenina E. Capasso
- Pediatric and Ocular Genetics, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
| | - Adele Schneider
- Pediatric and Ocular Genetics, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
- Division of Genetics, Einstein Healthcare Network, Philadelphia, Pennsylvania, USA
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Sarina Kopinsky
- Division of Genetics, Einstein Healthcare Network, Philadelphia, Pennsylvania, USA
| | - Tom Glaser
- Department of Cell Biology & Human Anatomy, University of California, Davis, California, USA
| | | | | | - Donna McNear
- Independent Educational Consultant, Cambridge, Minnesota, USA
| | - Alex V. Levin
- Pediatric and Ocular Genetics, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| |
Collapse
|
4
|
Lejoyeux R, Alonso AS, Lafolie J, Michaud V, Lasseaux E, Vasseur V, Derrien S, Robert MP, Le Mer Y, Tadayoni R, Arveiler B, Mauget-Faÿsse M. Foveal hypoplasia in parents of patients with albinism. Ophthalmic Genet 2022; 43:817-823. [PMID: 36098180 DOI: 10.1080/13816810.2022.2121841] [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: 01/27/2023]
Abstract
BACKGROUND Albinism is a group of genetic disorders characterized by general skin and retinal hypopigmentation. It is in most cases an autosomal recessive condition. Foveal hypoplasia (FH) is one of the main criteria for the diagnosis of albinism. The aim of this study was to analyze the macular profile of the parents of patients with albinism. METHODS This study included a case series of 27 patients with albinism seen in Rothschild Foundation between April 2017 and February 2020. Spectral-domain optical coherence tomography (SD-OCT) and OCT angiography (OCT-A) were performed in every patient when possible and in every available parents. FH was graded according to Thomas' classification based on OCT. Next generation sequencing-based gene panel testing was performed in parents and children when a FH was detected on OCT in a parent. RESULTS Twenty-seven patients with albinism were examined. Nine parents had FH based on the OCT B-scan (33%). In parents without FH based on the SD-OCT B-scan (67%), OCT-A showed a reduced avascular zone in the deep vascular plexus in 4 parents. Six parents carried variants that could explain their phenotype, including TYR R402Q hypomorphic alleles. CONCLUSION This study showed the presence of FH in parents of patients with albinism, and aimed to genetically explain this phenotype.
Collapse
Affiliation(s)
- R Lejoyeux
- Departement of Retina, Rothschild Foundation hospital, Paris, France
| | - A-S Alonso
- Departement of Retina, Centre d'investigation clinique, Paris, France
| | - J Lafolie
- Departement of Retina, Centre d'investigation clinique, Paris, France
| | - V Michaud
- CHU de Bordeaux, Hôpital Pellegrin, Bordeaux, France
| | - E Lasseaux
- CHU de Bordeaux, Hôpital Pellegrin, Bordeaux, France
| | - V Vasseur
- Departement of Retina, Centre d'investigation clinique, Paris, France
| | - S Derrien
- Departement of Retina, Rothschild Foundation hospital, Paris, France.,Departement of Retina, Centre d'investigation clinique, Paris, France
| | - M P Robert
- Department of ophthalmology, Hôpital Necker, APHP, Paris, France
| | - Y Le Mer
- Departement of Retina, Rothschild Foundation hospital, Paris, France
| | - R Tadayoni
- Departement of Retina, Rothschild Foundation hospital, Paris, France
| | - B Arveiler
- CHU de Bordeaux, Hôpital Pellegrin, Bordeaux, France
| | - M Mauget-Faÿsse
- Departement of Retina, Rothschild Foundation hospital, Paris, France.,Departement of Retina, Centre d'investigation clinique, Paris, France
| |
Collapse
|
5
|
Clinical exome sequencing facilitates the understanding of genetic heterogeneity in Leber congenital amaurosis patients with variable phenotype in southern India. EYE AND VISION 2021; 8:20. [PMID: 33957996 PMCID: PMC8101128 DOI: 10.1186/s40662-021-00243-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/14/2021] [Indexed: 11/30/2022]
Abstract
Background Leber congenital amaurosis (LCA), primarily characterized by retinal degeneration is the most severe form of inherited retinal dystrophy (IRD) responsible for congenital blindness. The presence of phenotypic heterogeneity makes the diagnosis of LCA challenging, especially in the absence of pronounced disease pathognomonic, yet it can be well comprehended by employing molecular diagnosis. Therefore, the present study aimed to reveal the causative mutations in ten LCA patients with variable phenotypes using clinical exome sequencing (CES). Methods CES was performed in ten unrelated LCA patients. Ophthalmic information and family history of all patients were obtained to make a meaningful interpretation. The clinical exome data was analyzed and prioritized using a bioinformatics pipeline to identify mutations, which was further validated by Sanger sequencing. Segregation analysis was also performed on available family members. Results CES led to the identification of causative mutations in nine LCA patients. Seven patients harbored a mutation in six LCA candidate genes, including RPE65, LCA5 (n = 2), CRX, PRPH2, CEP290, and ALMS1, while two patients possess a mutation in IFT80 and RP1, known to cause other diseases. Three novel mutations in LCA5 (c.1823del), CRX (c.848del) and CEP290 (c.2483G > T) were identified. The current study reports for the first time, a mutation in PRPH2, CEP290, and ALMS1 from the Indian population. Additionally, we observed a novel association of LCA phenotype with IFT80 known to cause Jeune syndrome. Based on the genetic finding, the patient AS09, who harbored a mutation in the RP1 gene, was re-diagnosed with early-onset retinitis pigmentosa. Conclusion In conclusion, the results underline the importance of CES in clinically diagnosed LCA patients with variable phenotypes. The correlation between mutations in candidate genes and clinical phenotypes, helps to refine the clinical diagnosis. However, molecular evaluation with a larger cohort of LCA patients is needed for better understanding of the mutational spectrum in southern India. Supplementary Information The online version contains supplementary material available at 10.1186/s40662-021-00243-5.
Collapse
|
6
|
da Cruz AS, Silva DC, Minasi LB, de Farias Teixeira LK, Rodrigues FM, da Silva CC, do Carmo AS, da Silva MVGB, Utsunomiya YT, Garcia JF, da Cruz AD. Single-Nucleotide Polymorphism Variations Associated With Specific Genes Putatively Identified Enhanced Genetic Predisposition for 305-Day Milk Yield in the Girolando Crossbreed. Front Genet 2021; 11:573344. [PMID: 33584786 PMCID: PMC7876550 DOI: 10.3389/fgene.2020.573344] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 12/07/2020] [Indexed: 01/18/2023] Open
Abstract
Milk production phenotypes are the main focus of genetic selection in dairy herds, and although there are many genes identified as related to the biology of these traits in pure breeds, little is known about crossbreed animals. This study aimed to identify potential genes associated with the 305-day milk yield in 337 crossbreed Gir × Holstein (Girolando) animals. Milk production records were genotyped for 45,613 single-nucleotide polymorphisms (SNPs). This dataset was used for a genome-wide association study (GWAS) using the 305-day milk yield adjusted for the fixed effects of herd and year and linear and quadratic effects of age at calving (in days) and calving factor averaged per animal. Genes within the significant SNPs were retrieved from the Bos taurus ARS-UCD1.2 assembly (bosTau9) for gene ontology analysis. In summary, the GWAS identified 52 SNPs associated [p ≤ 10–4, false discovery rate (FDR) = 8.77%] with milk production, including NUB1 and SLC24A2, which were previously described as related to milk production traits in cattle. The results suggest that SNPs associated mainly with NUB1 and SLC24A2 could be useful to understand milk production in Girolando and used as predictive markers for selecting genetic predisposition for milk yield in Girolando.
Collapse
Affiliation(s)
- Alex Silva da Cruz
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| | - Danilo Conrado Silva
- Curso de Graduação em Medicina Veterinária, Instituto Acadêmico de Ciências Agrárias e Sustentabilidade, Universidade Estadual de Goiás, São Luís de Montes Belos, Brazil
| | - Lysa Bernardes Minasi
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| | - Larissa Kamídia de Farias Teixeira
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| | - Flávia Melo Rodrigues
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| | - Claudio Carlos da Silva
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| | - Adriana Santana do Carmo
- Escola de Veterinária e Zootecnia, Departamento de Zootecnia, Universidade Federal de Goiás, Goiânia, Brazil
| | | | - Yuri Tani Utsunomiya
- Departamento de Apoio a Produção e Saúde Animal, Faculdade de Medicina Veterinária, Universidade Estadual Paulista Júlio de Mesquita Filho, Araçatuba, Brazil
| | - José Fernando Garcia
- Departamento de Apoio a Produção e Saúde Animal, Faculdade de Medicina Veterinária, Universidade Estadual Paulista Júlio de Mesquita Filho, Araçatuba, Brazil
| | - Aparecido Divino da Cruz
- Mestrado em Genética, Núcleo de Pesquisas Replicon, Escola de Ciências Agrárias e Biológicas, Pontifícia Universidade Católica de Goiás, Goiânia, Brazil
| |
Collapse
|
7
|
Wu Y, Qiu J, Chen S, Chen X, Zhang J, Zhuang J, Liu S, Yang M, Zhou P, Chen H, Ge J, Yu K, Zhuang J. Crx Is Posttranscriptionally Regulated by Light Stimulation in Postnatal Rat Retina. Front Cell Dev Biol 2020; 8:174. [PMID: 32318566 PMCID: PMC7154164 DOI: 10.3389/fcell.2020.00174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 03/02/2020] [Indexed: 11/13/2022] Open
Abstract
Cone rod homeobox (Crx) plays a key role at the center of a regulatory network that coordinates many pathways in the retina. Its abnormal expression induces retinal disorders. However, the underlying regulatory mechanism of Crx expression is not well defined. Here, we present data that show that the levels of Crx mRNA were inconsistent with that of Crx protein in primary retinal neurocytes cultured in light conditions. Crx protein levels were significantly higher (2.56-fold) in cells cultured in the dark than in cells cultured in light, whereas Crx mRNA was not changed in either type of cell. Moreover, the expression of Crx protein showed a significant light intensity-dependent decrease. Consistently, Crx downstream genes rhodopsin and arrestin also decreased in retinal neurocytes upon light exposure. Furthermore, Crx promoter activity assay performed in primary retinal neurocytes further indicated that light exposure and darkness did not affect its inducibility. In addition, the inconsistency between Crx mRNA and protein expression after light exposure was not observed in 661w cells transfected with plasmid pcDNA3.1-Crx, suggesting that the inconsistency between Crx mRNA and protein induced by light was specific to the endogenous Crx. More importantly, this observation was confirmed in vivo in postnatal day 15 (P15) retinas but not in adult retinas, further implicating that the posttranscriptional regulation mechanism may be involved in Crx expression in the developing retina. Therefore, our study sheds light on the mechanism of Crx expression in postnatal rat retina.
Collapse
Affiliation(s)
- Yihui Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jin Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shuilian Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xi Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jiejie Zhuang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Sian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Meng Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Pan Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Haoting Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jian Ge
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Keming Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhuang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| |
Collapse
|
8
|
Magliyah M, Saifaldein AA, Schatz P. Late presentation of RPE65 retinopathy in three siblings. Doc Ophthalmol 2020; 140:289-297. [PMID: 31925606 PMCID: PMC7205780 DOI: 10.1007/s10633-019-09745-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/30/2019] [Indexed: 11/23/2022]
Abstract
Purpose Gene therapy for RPE65 retinopathy has been recently approved. The purpose of this study was to assess retinal structure and function in 3 siblings presenting with late-stage RPE65 retinopathy and to assess the unmet need for such therapy in Saudi Arabia. Methods Search of the retinal dystrophy registry at King Khaled Eye Specialist Hospital and clinical examination including multimodal retinal imaging, full-field electroretinography (ERG), dark adapted full-field stimulus sensitivity thresholds, and molecular genetic testing in 3 patients. Results Nine (9) patients were identified with biallelic RPE65 mutations, corresponding to a prevalence rate of 9/187 = 5% among early onset retinal dystrophies. Of these, 3 siblings (2 male and 1 female) with RPE65 retinopathy were assessed in detail, because of an unusual, late presentation. They were all over 30 years old at the time of their most recent visits and had non-recordable ERGs. The 2 male siblings presented with poor vision and paracentral loss of the inner segment ellipsoid (ISe) and focal attenuation of the outer nuclear layer (ONL) in the macula. On the other hand, the female sibling presented with 20/100 vision with preserved foveal ISe and intact ONL throughout the macula and significantly lower light sensitivity thresholds compared to her male siblings. A homozygous missense p.Arg91Trp mutation in RPE65 was identified in all. All patients were eligible for gene therapy, demonstrating a central retinal thickness of more than 100 microns on repeated examinations. Conclusions RPE65 retinopathy seems to be relatively common on the Arabian peninsula, and in addition it may be underdiagnosed. To the best of our knowledge, this is the first detailed presentation, including multimodal retinal imaging and electrophysiological assessment, of such patients from this region. Patients with late presentation of RPE65 retinopathy may be eligible for gene therapy, in terms of remaining retinal function and structural preservation. The therapeutic window of such therapy remains to be determined. Electronic supplementary material The online version of this article (10.1007/s10633-019-09745-z) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Moustafa Magliyah
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia.,Ophthalmology Department, Prince Mohammed Medical City, Aljouf, Saudi Arabia
| | | | - Patrik Schatz
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. .,Department of Ophthalmology, Clinical Sciences, Skane University Hospital, Lund University, Lund, Sweden.
| |
Collapse
|
9
|
Yi Z, Xiao X, Li S, Sun W, Zhang Q. Pathogenicity discrimination and genetic test reference for CRX variants based on genotype-phenotype analysis. Exp Eye Res 2019; 189:107846. [PMID: 31626798 DOI: 10.1016/j.exer.2019.107846] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/27/2019] [Accepted: 10/14/2019] [Indexed: 12/22/2022]
Abstract
The cone-rod homeobox (CRX) gene is specifically expressed in developing and mature photoreceptors and is relatively conserved, with limited polymorphisms in coding regions. Rare variants in CRX are usually considered causative for different forms of retinal degeneration, but this might be problematic based on recent data. This study aimed to classify CRX variants based on a genotype-phenotype analysis of our data and the literature. Twenty-four CRX variants, including 14 novel variants, were detected in 37 Chinese families based on exome sequencing data obtained from 4971 Chinese probands with different forms of eye diseases. After detailed phenotypic analysis and cosegregation analysis in families with CRX variants, the 24 variants could be classified into three groups: benign (six), likely benign (six), and pathogenic (12). Somatic mosaicism was identified in a family with unaffected parents (the father had a mutant allele that was detected in approximately 17% of his leukocyte DNA) and two affected sons. Furthermore, a thorough reassessment was systematically performed for all 113 heterozygous variants as well as for their associated phenotypes from our cohort and patients previously reported. Two critical findings on the pathogenicity of CRX variants were obtained based on the genotype-phenotype correlation, family segregation and ensemble predicting methods: 1) approximately half of heterozygous missense variants are likely benign, and 2) heterozygous truncating variants affecting the homeodomain are likely benign. Truncating mutations after the homeodomain are likely associated with a more severe phenotype. Although most heterozygous pathogenic variants in CRX are associated with autosomal dominant retinal degeneration, a homozygous c.268C> T (p.Arg90Trp) substitution and homozygous complete deletion of CRX have been reported to cause Leber congenital amaurosis. In conclusion, many rare missense variants and some truncating variants in CRX are likely benign, although previously, they might have been predicted to be damaging by some online tools. Evaluation of the pathogenicity of a CRX variant should consider both its nature and location. The information obtained in this study is critical in the era of routine clinical genetic test, not only for CRX but also for many other genes with many more variants. Functional studies and additional genotype-phenotype analyses are expected to confirm these associations.
Collapse
Affiliation(s)
- Zhen Yi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road, Guangzhou, 510060, China.
| |
Collapse
|
10
|
Qu Z, Yimer TA, Xie S, Wong F, Yu S, Liu X, Han S, Ma J, Lu Z, Hu X, Qin Y, Huang Y, Lv Y, Li J, Tang Z, Liu F, Liu M. Knocking out lca5 in zebrafish causes cone-rod dystrophy due to impaired outer segment protein trafficking. Biochim Biophys Acta Mol Basis Dis 2019; 1865:2694-2705. [PMID: 31348989 DOI: 10.1016/j.bbadis.2019.07.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/06/2019] [Accepted: 07/22/2019] [Indexed: 01/19/2023]
Abstract
Leber congenital amaurosis (LCA) is the most serious form of inherited retinal dystrophy that leads to blindness or severe visual impairment within a few months after birth. Approximately 1-2% of the reported cases are caused by mutations in the LCA5 gene. This gene encodes a ciliary protein called LCA5 that is localized to the connecting cilium of photoreceptors. The retinal phenotypes caused by LCA5 mutations and the underlying pathological mechanisms are still not well understood. In this study, we knocked out the lca5 gene in zebrafish using CRISPR/Cas9 technology. An early onset visual defect is detected by the ERG in 7 dpf lca5-/- zebrafish. Histological analysis by HE staining and immunofluorescence reveal progressive degeneration of rod and cone photoreceptors, with a pattern that cones are more severely affected than rods. In addition, ultrastructural analysis by transmission electron microscopy shows disordered and broken membrane discs in rods' and cones' outer segments, respectively. In our lca5-/- zebrafish, the red-cone opsin and cone α-transducin are selectively mislocalized to the inner segment and synaptic terminal. Moreover, we found that Ift88, a key component of the intraflagellar transport complex, is retained in the outer segments. These data suggest that the intraflagellar transport complex-mediated outer segment protein trafficking might be impaired due to lca5 deletion, which finally leads to a type of retinal degeneration mimicking the phenotype of cone-rod dystrophy in human. Our work provides a novel animal model to study the physiological function of LCA5 and develop potential treatments of LCA.
Collapse
Affiliation(s)
- Zhen Qu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Tinsae Assefa Yimer
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Shanglun Xie
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Fulton Wong
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Shanshan Yu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Xiliang Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Shanshan Han
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Juanjuan Ma
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Zhaojing Lu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Xuebin Hu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Yayun Qin
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Yuwen Huang
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Yuexia Lv
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Jingzhen Li
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Zhaohui Tang
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Fei Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China.
| | - Mugen Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China.
| |
Collapse
|
11
|
Abstract
Retinal blindness is an important cause of pediatric visual loss. Leber's congenital amaurosis (LCA) is one of these causes, often wrongly included in the spectrum of retinitis pigmentosa. The disease has become the center of research after initial reports of success in management with gene therapy. This review discusses in brief the clinical presentation and investigative modalities used in LCA. Further, the road to gene discovery and details of currently applied gene therapy are presented. LCA is one of the first successfully managed human diseases and offers an entirely new dimension in ocular therapeutics.
Collapse
|