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Daich Varela M, Georgiou M, Alswaiti Y, Kabbani J, Fujinami K, Fujinami-Yokokawa Y, Khoda S, Mahroo OA, Robson AG, Webster AR, AlTalbishi A, Michaelides M. CRB1-Associated Retinal Dystrophies: Genetics, Clinical Characteristics, and Natural History. Am J Ophthalmol 2023; 246:107-121. [PMID: 36099972 PMCID: PMC10555856 DOI: 10.1016/j.ajo.2022.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 01/24/2023]
Abstract
PURPOSE To analyze the clinical characteristics, natural history, and genetics of CRB1-associated retinal dystrophies. DESIGN Multicenter international retrospective cohort study. METHODS Review of clinical notes, ophthalmic images, and genetic testing results of 104 patients (91 probands) with disease-causing CRB1 variants. Macular optical coherence tomography (OCT) parameters, visual function, fundus characteristics, and associations between variables were the main outcome measures. RESULTS The mean age of the cohort at the first visit was 19.8 ± 16.1 (median 15) years, with a mean follow-up of 9.6 ± 10 years. Based on history, imaging, and clinical examination, 26 individuals were diagnosed with retinitis pigmentosa (RP; 25%), 54 with early-onset severe retinal dystrophy / Leber congenital amaurosis (EOSRD/LCA; 52%), and 24 with macular dystrophy (MD; 23%). Severe visual impairment was most frequent after 40 years of age for patients with RP and after 20 years of age for EOSRD/LCA. Longitudinal analysis revealed a significant difference between baseline and follow-up best-corrected visual acuity in the 3 subcohorts. Macular thickness decreased in most patients with EOSRD/LCA and MD, whereas the majority of patients with RP had increased perifoveal thickness. CONCLUSIONS A subset of individuals with CRB1 variants present with mild, adult-onset RP. EOSRD/LCA phenotype was significantly associated with null variants, and 167_169 deletion was exclusively present in the MD cohort. The poor OCT lamination may have a degenerative component, as well as being congenital. Disease symmetry and reasonable window for intervention highlight CRB1 retinal dystrophies as a promising target for trials of novel therapeutics.
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Affiliation(s)
- Malena Daich Varela
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom
| | - Michalis Georgiou
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; Jones Eye Institute (M.G.), University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Yahya Alswaiti
- St John of Jerusalem Eye Hospital group, Jerusalem, Palestine (Y.A., A.A.)
| | - Jamil Kabbani
- Imperial College London (J.K.), London, United Kingdom
| | - Kaoru Fujinami
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center (Y.F.-Y.), Tokyo, Japan
| | - Yu Fujinami-Yokokawa
- UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center (Y.F.-Y.), Tokyo, Japan; Department of Health Policy and Management, School of Medicine, Keio University(Y.F.-Y.), Tokyo, Japan
| | - Shaheeni Khoda
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom
| | - Omar A Mahroo
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom
| | - Anthony G Robson
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom
| | - Andrew R Webster
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom
| | - Alaa AlTalbishi
- St John of Jerusalem Eye Hospital group, Jerusalem, Palestine (Y.A., A.A.)
| | - Michel Michaelides
- Moorfields Eye Hospital (M.D.V., M.G., K.F., S.K., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom; UCL Institute of Ophthalmology, University College London (M.D.V., M.G., K.F., Y.F.-Y., O.A.M., A.G.R., A.R.W., M.M.), London, United Kingdom.
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CRB1-Related Retinal Dystrophies in a Cohort of 50 Patients: A Reappraisal in the Light of Specific Müller Cell and Photoreceptor CRB1 Isoforms. Int J Mol Sci 2021; 22:ijms222312642. [PMID: 34884448 PMCID: PMC8657784 DOI: 10.3390/ijms222312642] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 01/29/2023] Open
Abstract
Pathogenic variants in CRB1 lead to diverse recessive retinal disorders from severe Leber congenital amaurosis to isolated macular dystrophy. Until recently, no clear phenotype-genotype correlation and no appropriate mouse models existed. Herein, we reappraise the phenotype-genotype correlation of 50 patients with regards to the recently identified CRB1 isoforms: a canonical long isoform A localized in Müller cells (12 exons) and a short isoform B predominant in photoreceptors (7 exons). Twenty-eight patients with early onset retinal dystrophy (EORD) consistently had a severe Müller impairment, with variable impact on the photoreceptors, regardless of isoform B expression. Among them, two patients expressing wild type isoform B carried one variant in exon 12, which specifically damaged intracellular protein interactions in Müller cells. Thirteen retinitis pigmentosa patients had mainly missense variants in laminin G-like domains and expressed at least 50% of isoform A. Eight patients with the c.498_506del variant had macular dystrophy. In one family homozygous for the c.1562C>T variant, the brother had EORD and the sister macular dystrophy. In contrast with the mouse model, these data highlight the key role of Müller cells in the severity of CRB1-related dystrophies in humans, which should be taken into consideration for future clinical trials.
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Cheng Z, Hagan R, Yeo DCM. Identification of a novel CRB1 variant in a compound heterozygous state in a patient with CRB1-associated maculopathy and foveal retinoschisis. Ophthalmic Genet 2021; 43:253-257. [PMID: 34783605 DOI: 10.1080/13816810.2021.1998551] [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
PURPOSE To report a novel CRB1 variant responsible for autosomal recessive foveal retinoschisis and its associated clinical and electrophysiological data. METHODS A case report. RESULTS A 15-year-old boy has foveal retinoschisis similar to those seen in X-linked retinoschisis (XLRS). During follow-up, we observed the co-existence of foveoschitic changes and parafoveal macular atrophy. Molecular genetic testing identified compound heterozygous variants in the CRB1 gene, including a novel variant, c.3878 G > A, predicted to disrupt the normal translation of CRB1 and a previously reported likely pathogenic mutation, c.498_506del. Full-field electroretinograms (ERG) were normal but multifocal ERG showed focal reduced waveform amplitude corresponding to the area of atrophy. CONCLUSIONS A novel missense variant existing in a compound heterozygous state was identified. Biallelic CRB1 mutations can cause anatomical fovea disruption similar to XLRS but have very different electroretinogram findings. This case report enhances our understanding of the spectrum of biallelic CRB1 mutations.
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Affiliation(s)
- Zhihang Cheng
- Alder Hey Children's Nhs Foundation Trust, Department of Ophthalmology, Alder Hey Children's Hospital, Liverpool, United Kingdom of Great Britain and Northern Ireland
| | - Richard Hagan
- Alder Hey Children's Nhs Foundation Trust, Department of Ophthalmology, Alder Hey Children's Hospital, Liverpool, United Kingdom of Great Britain and Northern Ireland.,Clinical Engineering Department, Royal Liverpool University Hospital, Liverpool, United Kingdom of Great Britain and Northern Ireland
| | - Damien C M Yeo
- Alder Hey Children's Nhs Foundation Trust, Department of Ophthalmology, Alder Hey Children's Hospital, Liverpool, United Kingdom of Great Britain and Northern Ireland
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Roshandel D, Thompson JA, Heath Jeffery RC, Sampson DM, Chelva E, McLaren TL, Lamey TM, De Roach JN, Durkin SR, Chen FK. Multimodal Retinal Imaging and Microperimetry Reveal a Novel Phenotype and Potential Trial End Points in CRB1-Associated Retinopathies. Transl Vis Sci Technol 2021; 10:38. [PMID: 34003923 PMCID: PMC7910635 DOI: 10.1167/tvst.10.2.38] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Purpose Biallelic crumbs cell polarity complex component 1 (CRB1) mutations can present as Leber congenital amaurosis (LCA), retinitis pigmentosa (RP), or cystic maculopathy. This study reports a novel phenotype of asymptomatic fenestrated slit maculopathy (AFSM) and examines macular volume profile and microperimetry as clinical trial end points in CRB1-associated retinopathies. Methods Twelve patients from nine families with CRB1 mutation were recruited. Ultra-widefield (UWF) color fundus photography and autofluorescence (AF), spectral-domain optical coherence tomography (SD-OCT), microperimetry, and adaptive optics (AO) imaging were performed. Macular volume profiles were compared with age-matched healthy controls. Genotyping was performed using APEX genotyping microarrays, targeted next-generation sequencing, and Sanger sequencing. Results We identified one patient with LCA, five patients with RP, and four patients with macular dystrophy (MD) with biallelic CRB1 mutations. Two siblings with compound heterozygote genotype (c.[2843G>A]; [498_506del]) had AFSM characterized by localized outer retinal disruption on SD-OCT and parafoveal cone loss on AO imaging despite normal fundus appearance, visual acuity, and foveal sensitivity. UWF AF demonstrated preserved para-arteriolar retinal pigment epithelium (PPRPE) in all patients with RP. Microperimetry documented preserved central retinal function in six patients. The ratio of perifoveal-to-foveal retinal volume was greater than controls in 89% (8/9) of patients with RP or MD, whereas central subfield and total macular volume were outside normal limits in 67% (6/9). Conclusions AO imaging was helpful in detecting parafoveal cone loss in asymptomatic patients. Macular volume profile and microperimetry parameters may have utility as CRB1 trials end points. Translational Relevance Macular volume and sensitivity can be used as structural and functional end points for trials on CRB1-associated RP and MD.
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Affiliation(s)
- Danial Roshandel
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia
| | - Jennifer A Thompson
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Rachael C Heath Jeffery
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia
| | - Danuta M Sampson
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Surrey Biophotonics, Centre for Vision, Speech and Signal Processing and School of Biosciences and Medicine, The University of Surrey, Guildford, UK
| | - Enid Chelva
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Terri L McLaren
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Tina M Lamey
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - John N De Roach
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Shane R Durkin
- Discipline of Ophthalmology and Visual Science, The University of Adelaide, South Australia, Australia.,Department of Ophthalmology, The Royal Adelaide and Queen Elizabeth Hospital, Adelaide, South Australia, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia.,Department of Ophthalmology, Perth Children's Hospital, Nedlands, Western Australia, Australia
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5
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Talib M, Schooneveld MJ, Wijnholds J, Genderen MM, Schalij‐Delfos NE, Talsma HE, Florijn RJ, Brink JB, Cremers FP, Thiadens AA, Born LI, Hoyng CB, Meester‐Smoor MA, Bergen AA, Boon CJ. Defining inclusion criteria and endpoints for clinical trials: a prospective cross-sectional study in CRB1-associated retinal dystrophies. Acta Ophthalmol 2021; 99:e402-e414. [PMID: 33528094 PMCID: PMC8248330 DOI: 10.1111/aos.14597] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 11/29/2022]
Abstract
Purpose To investigate the retinal structure and function in patients with CRB1‐associated retinal dystrophies (RD) and to explore potential clinical endpoints. Methods In this prospective cross‐sectional study, 22 patients with genetically confirmed CRB1‐RD (aged 6–74 years), and who had a decimal best‐corrected visual acuity (BCVA) ≥ 0.05 at the last visit, were studied clinically with ETDRS BCVA, corneal topography, spectral‐domain optical coherence tomography (SD‐OCT), fundus autofluorescence, Goldmann visual field (VF), microperimetry, full‐field electroretinography (ERG) and full‐field stimulus testing (FST). Ten patients were from a genetic isolate (GI). Results Patients had retinitis pigmentosa (n = 19; GI and non‐GI), cone‐rod dystrophy (n = 2; GI) or macular dystrophy (n = 1; non‐GI). Median age at first symptom onset was 3 years (range 0.8–49). Median decimal BCVA in the better and worse‐seeing eye was 0.18 (range 0.05–0.83) and 0.08 (range light perception‐0.72), respectively. Spectral‐domain optical coherence tomography (SD‐OCT) showed cystoid maculopathy in 8 subjects; inner retinal thickening (n = 20), a well‐preserved (para)foveal outer retina (n = 7) or severe (para)foveal outer retinal atrophy (n = 14). All retinal layers were discernible in 13/21 patients (62%), with mild to moderate laminar disorganization in the others. Nanophthalmos was observed in 8 patients (36%). Full‐field stimulus testing (FST) provided a subjective outcome measure for retinal sensitivity in eyes with (nearly) extinguished ERG amplitudes. Conclusions Despite the generally severe course of CRB1‐RDs, symptom onset and central visual function are variable, even at advanced ages. Phenotypes may vary within the same family. Imaging and functional studies in a prospective longitudinal setting should clarify which endpoints may be most appropriate in a clinical trial.
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Affiliation(s)
- Mays Talib
- Department of Ophthalmology Leiden University Medical Center Leiden The Netherlands
| | - Mary J. Schooneveld
- Department of Ophthalmology Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
- Bartiméus Diagnostic Centre for complex visual disorders Zeist The Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology Leiden University Medical Center Leiden The Netherlands
| | - Maria M. Genderen
- Bartiméus Diagnostic Centre for complex visual disorders Zeist The Netherlands
| | | | - Herman E. Talsma
- Department of Ophthalmology Leiden University Medical Center Leiden The Netherlands
- Bartiméus Diagnostic Centre for complex visual disorders Zeist The Netherlands
| | - Ralph J. Florijn
- Department of Clinical Genetics Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
| | - Jacoline B. Brink
- Department of Clinical Genetics Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
| | - Frans P.M. Cremers
- Department of Human Genetics and Donders Institute for Brain Cognition and Behaviour Radboud University Medical Center Nijmegen The Netherlands
| | | | | | - Carel B. Hoyng
- Department of Ophthalmology Radboud University Medical Center Nijmegen The Netherlands
| | | | - Arthur A. Bergen
- Department of Clinical Genetics Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
- The Netherlands Institute for Neuroscience (NIN‐KNAW) Amsterdam The Netherlands
| | - Camiel J.F. Boon
- Department of Ophthalmology Leiden University Medical Center Leiden The Netherlands
- Department of Ophthalmology Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
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Wang Y, Sun W, Xiao X, Li S, Jia X, Wang P, Zhang Q. Clinical and Genetic Analysis of 63 Families Demonstrating Early and Advanced Characteristic Fundus as the Signature of CRB1 Mutations. Am J Ophthalmol 2021; 223:160-168. [PMID: 33342761 DOI: 10.1016/j.ajo.2020.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/17/2020] [Accepted: 10/12/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE To reveal the characteristics of ocular changes in patients with biallelic CRB1 mutations. DESIGN Comparative exome sequencing and retrospective case series on clinical data. METHODS Seventy-four patients from 63 families with biallelic potential pathogenic variants in CRB1 were selected from our in-house exome sequencing. The clinical data were reviewed and evaluated in detail, including best-corrected visual acuity, fundus photography, optical coherence tomography (OCT), and electroretinogram (ERG). RESULTS Biallelic CRB1 variants, involving 45 variants including 23 novel, were identified in 40 novel families based on exome sequencing. Analyzing clinical data of the 74 individuals from 63 families revealed the following CRB1-associated phenotypes: (1) early-onset reduced visual acuity with congenital nystagmus; (2) 2 types of characteristic retinal changes including yellowish geographic macular degeneration (YMD) or nummular pigment deposits (NPD) at posterior retina with bone-spicule pigmentation at midperipheral retina; (3) undetectable rod and cone responses on ERG; (4) cystoid macular edema or macular atrophy on OCT. YMD and NPD are unique and CRB1-associated. Long-term follow-up examination as well as age- and variant-dependent phenotypic analysis suggested YMD is the early fundus change that would gradually progress to NPD. CONCLUSIONS YMD and NPD are 2 major characteristic CRB1-associated fundus changes and the former one will advance to the latter with age. Recognizing such characteristic signs associated with biallelic CRB1 variants may be of value in areas without widespread access to genetic testing where a more targeted approach is needed and might be biomarkers for evaluation of effects for future intervention.
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Affiliation(s)
- Yingwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
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Talib M, Boon CJF. Retinal Dystrophies and the Road to Treatment: Clinical Requirements and Considerations. Asia Pac J Ophthalmol (Phila) 2020; 9:159-179. [PMID: 32511120 PMCID: PMC7299224 DOI: 10.1097/apo.0000000000000290] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/01/2020] [Indexed: 12/15/2022] Open
Abstract
: Retinal dystrophies (RDs) comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in the same gene may lead to different diagnoses, for example, retinitis pigmentosa or cone dystrophy. Conversely, mutations in different genes may lead to the same phenotype. The age at symptom onset, and the rate and characteristics of peripheral and central vision decline, may vary widely per disease group and even within families. For most RD cases, no effective treatment is currently available. However, preclinical studies and phase I/II/III gene therapy trials are ongoing for several RD subtypes, and recently the first retinal gene therapy has been approved by the US Food and Drug Administration for RPE65-associated RDs: voretigene neparvovec-rzyl (Luxturna). With the rapid advances in gene therapy studies, insight into the phenotypic spectrum and long-term disease course is crucial information for several RD types. The vast clinical heterogeneity presents another important challenge in the evaluation of potential efficacy in future treatment trials, and in establishing treatment candidacy criteria. This perspective describes these challenges, providing detailed clinical descriptions of several forms of RD that are caused by genes of interest for ongoing and future gene or cell-based therapy trials. Several ongoing and future treatment options will be described.
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Affiliation(s)
- Mays Talib
- Department of Ophthalmology, Leiden, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden, The Netherlands
- Department of Ophthalmology, Amsterdam UMC, Academic Medical Center, University of Amsterdam. Amsterdam, The Netherlands
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8
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Ghiam BK, Wood EH, Thanos A, Randhawa S. CRB1 related retinal degeneration with novel mutation. Am J Ophthalmol Case Rep 2020; 18:100699. [PMID: 32322752 PMCID: PMC7160514 DOI: 10.1016/j.ajoc.2020.100699] [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: 01/18/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 11/30/2022] Open
Abstract
Purpose To describe novel and previously unreported genetic mutations in the CRB1 gene in a patient with retinal dystrophy. To increase the genotype-phenotype understanding of CRB1-related retinal degenerative diseases and describe patients’ response to therapy. Observations Patient was evaluated for progressive loss of central and peripheral vision. Fundus photography, fundus autofluorescence (FAF), fluorescein angiography (FA), and ocular-coherence tomography (OCT) were used in the evaluation. Genetic screening was performed to explore underlying mutations. Genetics revealed a previously reported, pathogenic variant in the CRB1 gene (c.2842+5G > A), and a novel mutation (c.4014T > A) whose clinical significance is uncertain due to the absence of conclusive evidence. This case is phenotypically unique in that CME was refractory to therapy, while CME in CRB1 related maculopathy typically responds well to treatment. Conclusions and importance This study adds a breadth of phenotypic understanding to genetic analysis in CRB1 related retinal degenerative conditions. The newly described CRB1 variant mutation c.4014T > A may portend a poor prognosis for CME responsiveness to therapy. Genetic testing in an otherwise unexplained CME event may be useful to identify underlying CRB1 variants and reveal genotype-phenotype correlations, which may alter the treatment plan and prognosis.
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Affiliation(s)
- Benjamin K Ghiam
- Oakland University, William Beaumont School of Medicine, 586 Pioneer Dr, Rochester, MI, 48309, USA
| | - Edward H Wood
- William Beaumont Hospital, 3555 W. 13 Mile Road, Suite LL-20, Royal Oak, MI, 48073, USA
| | - Aristomenis Thanos
- Legacy Health, Legacy Emanuel Medical Center, 300 N. Graham St., Suite 300 Medical Office Building 3, Portland, OR, 97227, USA
| | - Sandeep Randhawa
- William Beaumont Hospital, 3555 W. 13 Mile Road, Suite LL-20, Royal Oak, MI, 48073, USA
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Quinn PM, Mulder AA, Henrique Alves C, Desrosiers M, de Vries SI, Klooster J, Dalkara D, Koster AJ, Jost CR, Wijnholds J. Loss of CRB2 in Müller glial cells modifies a CRB1-associated retinitis pigmentosa phenotype into a Leber congenital amaurosis phenotype. Hum Mol Genet 2019; 28:105-123. [PMID: 30239717 DOI: 10.1093/hmg/ddy337] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/17/2018] [Indexed: 11/14/2022] Open
Abstract
Variations in the human Crumbs homolog-1 (CRB1) gene lead to an array of retinal dystrophies including early onset of retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) in children. To investigate the physiological roles of CRB1 and CRB2 in retinal Müller glial cells (MGCs), we analysed mouse retinas lacking both proteins in MGC. The peripheral retina showed a faster progression of dystrophy than the central retina. The central retina showed retinal folds, disruptions at the outer limiting membrane, protrusion of photoreceptor nuclei into the inner and outer segment layers and ingression of photoreceptor nuclei into the photoreceptor synaptic layer. The peripheral retina showed a complete loss of the photoreceptor synapse layer, intermingling of photoreceptor nuclei within the inner nuclear layer and ectopic photoreceptor cells in the ganglion cell layer. Electroretinography showed severe attenuation of the scotopic a-wave at 1 month of age with responses below detection levels at 3 months of age. The double knockout mouse retinas mimicked a phenotype equivalent to a clinical LCA phenotype due to loss of CRB1. Localization of CRB1 and CRB2 in non-human primate (NHP) retinas was analyzed at the ultrastructural level. We found that NHP CRB1 and CRB2 proteins localized to the subapical region adjacent to adherens junctions at the outer limiting membrane in MGC and photoreceptors. Our data suggest that loss of CRB2 in MGC aggravates the CRB1-associated RP-like phenotype towards an LCA-like phenotype.
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Affiliation(s)
- Peter M Quinn
- Department of Ophthalmology, Leiden University Medical Center, RC Leiden, The Netherlands
| | - Aat A Mulder
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), RC Leiden, The Netherlands
| | - C Henrique Alves
- Department of Ophthalmology, Leiden University Medical Center, RC Leiden, The Netherlands
| | - Mélissa Desrosiers
- Department of Therapeutics, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris, UMR_S INSERM, CNRS, UMR, Paris, France
| | - Sharon I de Vries
- Department of Axonal Signaling, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), BA Amsterdam, The Netherlands
| | - Jan Klooster
- Department of Retina Signal Processing, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), BA Amsterdam, The Netherlands
| | - Deniz Dalkara
- Department of Therapeutics, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris, UMR_S INSERM, CNRS, UMR, Paris, France
| | - Abraham J Koster
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), RC Leiden, The Netherlands
| | - Carolina R Jost
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), RC Leiden, The Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, RC Leiden, The Netherlands.,The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, BA Amsterdam, The Netherlands
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10
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Quinn PM, Alves CH, Klooster J, Wijnholds J. CRB2 in immature photoreceptors determines the superior-inferior symmetry of the developing retina to maintain retinal structure and function. Hum Mol Genet 2019; 27:3137-3153. [PMID: 29893966 DOI: 10.1093/hmg/ddy194] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/11/2018] [Indexed: 11/13/2022] Open
Abstract
The mammalian apical-basal determinant Crumbs homolog-1 (CRB1) plays a crucial role in retinal structure and function by the maintenance of adherens junctions between photoreceptors and Müller glial cells. Patients with mutations in the CRB1 gene develop retinal dystrophies, including early-onset retinitis pigmentosa and Leber congenital amaurosis. Previously, we showed that Crb1 knockout mice developed a slow-progressing retinal phenotype at foci in the inferior retina, although specific ablation of Crb2 in immature photoreceptors leads to an early-onset phenotype throughout the retina. Here, we conditionally disrupted one or both alleles of Crb2 in immature photoreceptors, on a genetic background lacking Crb1, and studied the retinal dystrophies thereof. Our data showed that disruption of one allele of Crb2 in immature photoreceptors caused a substantial aggravation of the Crb1 phenotype in the entire inferior retina. The photoreceptor layer showed early-onset progressive thinning limited to the inferior retina, although the superior retina maintained intact. Surprisingly, disruption of both alleles of Crb2 in immature photoreceptors further aggravated the phenotype. Throughout the retina, photoreceptor synapses were disrupted and photoreceptor nuclei intermingled with nuclei of the inner nuclear layer. In the superior retina, the ganglion cell layer appeared thicker because of ectopic nuclei of photoreceptors. In conclusion, the data suggest that CRB2 is required to maintain retinal progenitor and photoreceptor cell adhesion and prevent photoreceptor ingression into the immature inner retina. We hypothesize, from these animal models, that decreased levels of CRB2 in immature photoreceptors adjust retinitis pigmentosa because of the loss of CRB1 into Leber congenital amaurosis phenotype.
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Affiliation(s)
- Peter M Quinn
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - C Henrique Alves
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan Klooster
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.,Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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11
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Chen X, Jiang C, Yang D, Sun R, Wang M, Sun H, Xu M, Zhou L, Chen M, Xie P, Yan B, Liu Q, Zhao C. CRB2 mutation causes autosomal recessive retinitis pigmentosa. Exp Eye Res 2018; 180:164-173. [PMID: 30593785 DOI: 10.1016/j.exer.2018.12.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 01/29/2023]
Abstract
Retinitis pigmentosa (RP), the most common form of inherited retinal dystrophies, exhibits significant genetic heterogeneity. The crumbs homolog 2 (CRB2) protein, together with CRB1 and CRB3, belongs to the Crumbs family. Given that CRB1 mutations account for 4% of RP cases, the role of CRB2 mutations in RP etiology has long been hypothesized but never confirmed. Herein, we report the identification of CRB2 as a novel RP causative gene in a Chinese consanguineous family and have analyzed its pathogenic effects. Comprehensive ophthalmic and systemic evaluations confirmed the clinical diagnosis of the two patients in this family as RP. WES revealed a homozygous missense mutation, CRB2 p.R1249G, to segregate the RP phenotype, which was highly conserved among multiple species. In vitro cellular study revealed that this mutation not only interrupted the stability of the transcribed CRB2 mRNA and the encoded CRB2 protein, but also interfered with the wild type CRB2 mRNA/protein and decreased their expression. This mutation was also shown to trigger epithelial-mesenchymal transition (EMT) in retinal pigment epithelium (RPE) cells, thus impairing regular RPE phagocytosis and induce RPE degeneration and apoptosis. Thus, we conclude that CRB2 p.R1249G mutation causes RP via accelerating EMT, dysfunction and loss of RPE cells, and establish CRB2 as a novel Crumbs family member associated with non-syndromic RP. We provide important hints for understanding of CRB2 defects and retinopathy, and for the involvement of EMT of RPE cells in RP pathogenesis.
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Affiliation(s)
- Xue Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China; Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Chao Jiang
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Daidi Yang
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Ruxu Sun
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Min Wang
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Hong Sun
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Min Xu
- Department of Ophthalmology, Northern Jiangsu People's Hospital, Yangzhou, 211406, China
| | - Luyin Zhou
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Mingkang Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Ping Xie
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Biao Yan
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Qinghuai Liu
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
| | - Chen Zhao
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China; Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China.
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12
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Dolón JF, Paniagua AE, Valle V, Segurado A, Arévalo R, Velasco A, Lillo C. Expression and localization of the polarity protein CRB2 in adult mouse brain: a comparison with the CRB1 rd8 mutant mouse model. Sci Rep 2018; 8:11652. [PMID: 30076417 PMCID: PMC6076319 DOI: 10.1038/s41598-018-30210-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 07/24/2018] [Indexed: 11/09/2022] Open
Abstract
Acquisition of cell polarization is essential for the performance of crucial functions, like a successful secretion and appropriate cell signaling in many tissues, and it depends on the correct functioning of polarity proteins, including the Crumbs complex. The CRB proteins, CRB1, CRB2 and CRB3, identified in mammals, are expressed in epithelial-derived tissues like brain, kidney and retina. CRB2 has a ubiquitous expression and has been detected in embryonic brain tissue; but currently there is no data regarding its localization in the adult brain. In our study, we characterized the presence of CRB2 in adult mice brain, where it is particularly enriched in cortex, hippocampus, hypothalamus and cerebellum. Double immunofluorescence analysis confirmed that CRB2 is a neuron-specific protein, present in both soma and projections where colocalizes with certain populations of exocytic and endocytic vesicles and with other members of the Crumbs complex. Finally, in the cortex of CRB1rd8 mutant mice that contain a mutation in the Crb1 gene generating a truncated CRB1 protein, there is an abnormal increase in the expression levels of the CRB2 protein which suggests a possible compensatory mechanism for the malfunction of CRB1 in this mutant background.
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Affiliation(s)
- Jorge F Dolón
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Antonio E Paniagua
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain.,Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Vicente Valle
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Alicia Segurado
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Rosario Arévalo
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Almudena Velasco
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Concepción Lillo
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain.
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13
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Zhang X, Zhang D, Chen SC, Lamey T, Thompson JA, McLaren T, De Roach JN, Chen FK, McLenachan S. Establishment of an induced pluripotent stem cell line from a retinitis pigmentosa patient with compound heterozygous CRB1 mutation. Stem Cell Res 2018; 31:147-151. [PMID: 30092450 DOI: 10.1016/j.scr.2018.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 07/19/2018] [Accepted: 08/01/2018] [Indexed: 11/25/2022] Open
Abstract
The human iPSC line LEIi006-A was generated from dermal fibroblasts from a patient with retinitis pigmentosa using episomal plasmids containing OCT4, SOX2, KLF4, L-MYC, LIN28, mir302/367 microRNA and shRNA for p53. The iPSC cells carry compound heterozygous mutations (c.1892A > G and c.2548G > A) in the CRB1 gene. LEIi006-A expressed pluripotent stem cell markers, had a normal karyotype and could be differentiated into endoderm, mesoderm and ectodermal lineages, as well as retinal organoids.
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Affiliation(s)
- Xiao Zhang
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia; Lions Eye Institute, Nedlands, Western Australia, Australia
| | - Dan Zhang
- Lions Eye Institute, Nedlands, Western Australia, Australia
| | | | - Tina Lamey
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia; Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Jennifer A Thompson
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Terri McLaren
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - John N De Roach
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia; Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia; Lions Eye Institute, Nedlands, Western Australia, Australia; Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia; Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia.
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia; Lions Eye Institute, Nedlands, Western Australia, Australia
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14
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Khan KN, Robson A, Mahroo OAR, Arno G, Inglehearn CF, Armengol M, Waseem N, Holder GE, Carss KJ, Raymond LF, Webster AR, Moore AT, McKibbin M, van Genderen MM, Poulter JA, Michaelides M. A clinical and molecular characterisation of CRB1-associated maculopathy. Eur J Hum Genet 2018; 26:687-694. [PMID: 29391521 PMCID: PMC5945653 DOI: 10.1038/s41431-017-0082-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/14/2017] [Accepted: 12/05/2017] [Indexed: 12/22/2022] Open
Abstract
To date, over 150 disease-associated variants in CRB1 have been described, resulting in a range of retinal disease phenotypes including Leber congenital amaurosis and retinitis pigmentosa. Despite this, no genotype–phenotype correlations are currently recognised. We performed a retrospective review of electronic patient records to identify patients with macular dystrophy due to bi-allelic variants in CRB1. In total, seven unrelated individuals were identified. The median age at presentation was 21 years, with a median acuity of 0.55 decimalised Snellen units (IQR = 0.43). The follow-up period ranged from 0 to 19 years (median = 2.0 years), with a median final decimalised Snellen acuity of 0.65 (IQR = 0.70). Fundoscopy revealed only a subtly altered foveal reflex, which evolved into a bull’s-eye pattern of outer retinal atrophy. Optical coherence tomography identified structural changes—intraretinal cysts in the early stages of disease, and later outer retinal atrophy. Genetic testing revealed that one rare allele (c.498_506del, p.(Ile167_Gly169del)) was present in all patients, with one patient being homozygous for the variant and six being heterozygous. In trans with this, one variant recurred twice (p.(Cys896Ter)), while the four remaining alleles were each observed once (p.(Pro1381Thr), p.(Ser478ProfsTer24), p.(Cys195Phe) and p.(Arg764Cys)). These findings show that the rare CRB1 variant, c.498_506del, is strongly associated with localised retinal dysfunction. The clinical findings are much milder than those observed with bi-allelic, loss-of-function variants in CRB1, suggesting this in-frame deletion acts as a hypomorphic allele. This is the most prevalent disease-causing CRB1 variant identified in the non-Asian population to date.
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Affiliation(s)
- Kamron N Khan
- University College London Institute of Ophthalmology, University College London, London, UK. .,Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK. .,Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK. .,Department of Ophthalmology, St. James's University Teaching Hospital, Leeds, UK.
| | - Anthony Robson
- Department of Electrophysiology, Moorfields Eye Hospital, London, UK
| | - Omar A R Mahroo
- University College London Institute of Ophthalmology, University College London, London, UK.,Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK
| | - Gavin Arno
- University College London Institute of Ophthalmology, University College London, London, UK
| | - Chris F Inglehearn
- Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK
| | - Monica Armengol
- Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK
| | - Naushin Waseem
- Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK
| | - Graham E Holder
- Department of Electrophysiology, Moorfields Eye Hospital, London, UK
| | - Keren J Carss
- NIHR BioResource - Rare Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UK.,Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge, CB2 0PT, UK.,Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Lucy F Raymond
- NIHR BioResource - Rare Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UK.,Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge, CB2 0PT, UK.,Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Andrew R Webster
- University College London Institute of Ophthalmology, University College London, London, UK.,Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK
| | - Anthony T Moore
- University College London Institute of Ophthalmology, University College London, London, UK.,Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK.,Ophthalmology Department, University of California San Francisco Medical School, San Francisco, CA, USA
| | - Martin McKibbin
- Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK.,Department of Ophthalmology, St. James's University Teaching Hospital, Leeds, UK
| | - Maria M van Genderen
- Bartiméus Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands.,Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - James A Poulter
- Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK
| | - Michel Michaelides
- University College London Institute of Ophthalmology, University College London, London, UK.,Inherited Eye Disease Service, Moorfields Eye Hospital, London, UK
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15
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Quinn PM, Pellissier LP, Wijnholds J. The CRB1 Complex: Following the Trail of Crumbs to a Feasible Gene Therapy Strategy. Front Neurosci 2017; 11:175. [PMID: 28424578 PMCID: PMC5380682 DOI: 10.3389/fnins.2017.00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/16/2017] [Indexed: 12/24/2022] Open
Abstract
Once considered science fiction, gene therapy is rapidly becoming scientific reality, targeting a growing number of the approximately 250 genes linked to hereditary retinal disorders such as retinitis pigmentosa and Leber's congenital amaurosis. Powerful new technologies have emerged, leading to the development of humanized models for testing and screening these therapies, bringing us closer to the goal of personalized medicine. These tools include the ability to differentiate human induced pluripotent stem cells (iPSCs) to create a “retina-in-a-dish” model and the self-formed ectodermal autonomous multi-zone, which can mimic whole eye development. In addition, highly specific gene-editing tools are now available, including the CRISPR/Cas9 system and the recently developed homology-independent targeted integration approach, which allows gene editing in non-dividing cells. Variants in the CRB1 gene have long been associated with retinopathies, and more recently the CRB2 gene has also been shown to have possible clinical relevance with respect to retinopathies. In this review, we discuss the role of the CRB protein complex in patients with retinopathy. In addition, we discuss new opportunities provided by stem cells and gene-editing tools, and we provide insight into how the retinal therapeutic pipeline can be improved. Finally, we discuss the current state of adeno-associated virus-mediated gene therapy and how it can be applied to treat retinopathies associated with mutations in CRB1.
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Affiliation(s)
- Peter M Quinn
- Department of Ophthalmology, Leiden University Medical CenterLeiden, Netherlands
| | - Lucie P Pellissier
- Unité Physiologie de la Reproduction et des Comportements, INRA UMR85, Centre National de la Recherche Scientifique UMR-7247, Institut Français du Cheval et de l'Équitation, Université François RabelaisNouzilly, France
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical CenterLeiden, Netherlands.,Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and SciencesAmsterdam, Netherlands
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16
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Talib M, van Schooneveld MJ, van Genderen MM, Wijnholds J, Florijn RJ, Ten Brink JB, Schalij-Delfos NE, Dagnelie G, Cremers FPM, Wolterbeek R, Fiocco M, Thiadens AA, Hoyng CB, Klaver CC, Bergen AA, Boon CJF. Genotypic and Phenotypic Characteristics of CRB1-Associated Retinal Dystrophies: A Long-Term Follow-up Study. Ophthalmology 2017; 124:884-895. [PMID: 28341475 DOI: 10.1016/j.ophtha.2017.01.047] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/27/2017] [Accepted: 01/27/2017] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To describe the phenotype, long-term clinical course, clinical variability, and genotype of patients with CRB1-associated retinal dystrophies. DESIGN Retrospective cohort study. PARTICIPANTS Fifty-five patients with CRB1-associated retinal dystrophies from 16 families. METHODS A medical record review of 55 patients for age at onset, medical history, initial symptoms, best-corrected visual acuity, ophthalmoscopy, fundus photography, full-field electroretinography (ffERG), Goldmann visual fields (VFs), and spectral-domain optical coherence tomography. MAIN OUTCOME MEASURES Age at onset, visual acuity survival time, visual acuity decline rate, and electroretinography and imaging findings. RESULTS A retinitis pigmentosa (RP) phenotype was present in 50 patients, 34 of whom were from a Dutch genetic isolate (GI), and 5 patients had a Leber congenital amaurosis phenotype. The mean follow-up time was 15.4 years (range, 0-55.5 years). For the RP patients, the median age at symptom onset was 4.0 years. In the RP group, median ages for reaching low vision, severe visual impairment, and blindness were 18, 32, and 44 years, respectively, with a visual acuity decline rate of 0.03 logarithm of the minimum angle of resolution per year. The presence of a truncating mutation did not alter the annual decline rate significantly (P = 0.75). Asymmetry in visual acuity was found in 31% of patients. The annual VF decline rate was 5% in patients from the genetic isolate, which was significantly faster than in non-GI patients (P < 0.05). Full-field electroretinography responses were extinguished in 50% of patients, were pathologically attenuated without a documented rod or cone predominance in 30% of patients, and showed a rod-cone dysfunction pattern in 20% of RP patients. Cystoid fluid collections in the macula were found in 50% of RP patients. CONCLUSIONS Mutations in the CRB1 gene are associated with a spectrum of progressive retinal degeneration. Visual acuity survival analyses indicate that the optimal intervention window for subretinal gene therapy is within the first 2 to 3 decades of life.
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Affiliation(s)
- Mays Talib
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Maria M van Genderen
- Bartiméus, Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ralph J Florijn
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
| | - Jacoline B Ten Brink
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Gislin Dagnelie
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland
| | - Frans P M Cremers
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ron Wolterbeek
- Department of Medical Statistics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marta Fiocco
- Department of Medical Statistics, Leiden University Medical Center, Leiden, The Netherlands; Mathematical Institute, Leiden University, Leiden, The Netherlands
| | - Alberta A Thiadens
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caroline C Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Arthur A Bergen
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands; The Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands; Department of Ophthalmology, Academic Medical Center, Amsterdam, The Netherlands.
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17
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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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18
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LONG-TERM FOLLOW-UP OF PATIENTS WITH RETINITIS PIGMENTOSA TYPE 12 CAUSED BY CRB1 MUTATIONS. Retina 2017; 37:161-172. [PMID: 27380427 DOI: 10.1097/iae.0000000000001127] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Shah N, Damani MR, Zhu XS, Bedoukian EC, Bennett J, Maguire AM, Leroy BP. Isolated maculopathy associated with biallelic CRB1 mutations. Ophthalmic Genet 2016; 38:190-193. [PMID: 27096895 DOI: 10.3109/13816810.2016.1155225] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Neepa Shah
- a Division of Ophthalmology , Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA.,b Scheie Eye Institute, University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Mausam R Damani
- a Division of Ophthalmology , Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA.,b Scheie Eye Institute, University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Xiaosong Sonia Zhu
- a Division of Ophthalmology , Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA
| | - Emma C Bedoukian
- c Individualized Medical Genetics Center, Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA
| | - Jean Bennett
- b Scheie Eye Institute, University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Albert M Maguire
- a Division of Ophthalmology , Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA.,b Scheie Eye Institute, University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Bart P Leroy
- a Division of Ophthalmology , Children's Hospital of Philadelphia , Philadelphia , Pennsylvania , USA.,d Department of Ophthalmology & Center for Medical Genetics , Ghent University Hospital & Ghent University , Ghent , Belgium
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20
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Tsang SH, Burke T, Oll M, Yzer S, Lee W, Xie YA, Allikmets R. Whole exome sequencing identifies CRB1 defect in an unusual maculopathy phenotype. Ophthalmology 2014; 121:1773-82. [PMID: 24811962 DOI: 10.1016/j.ophtha.2014.03.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 03/07/2014] [Accepted: 03/07/2014] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVE To report a new phenotype caused by mutations in the CRB1 gene in a family with 2 affected siblings. DESIGN Molecular genetics and observational case studies. PARTICIPANTS Two affected siblings and 3 unaffected family members. METHODS Each subject received a complete ophthalmic examination together with color fundus photography, fundus autofluorescence (FAF), and spectral-domain optical coherence tomography (SD-OCT). Microperimetry 1 (MP-1) mapping and electroretinogram (ERG) analysis were performed on the proband. Screening for disease-causing mutations was performed by whole exome sequencing in 3 family members followed by segregation analyses in the entire family. MAIN OUTCOME MEASURES Appearance of the macula as examined by clinical examination, fundus photography, FAF imaging, SD-OCT, and visual function by MP-1 and ERG. RESULTS The proband and her affected brother exhibited unusual, previously unreported, findings of a macular dystrophy with relative sparing of the retinal periphery beyond the vascular arcades. The FAF imaging showed severely affected areas of hypoautofluorescence that extended nasally beyond the optic disc in both eyes. A central macular patch of retinal pigment epithelium (RPE) sparing was evident in both eyes on FAF, whereas photoreceptor sparing was documented in the right eye only using SD-OCT. The affected brother presented with irregular patterns of autofluorescence in both eyes characterized by concentric rings of alternating hyper- and hypoautofluorescence, and foveal sparing of photoreceptors and RPE, as seen on SD-OCT, bilaterally. After negative results in screening for mutations in candidate genes including ABCA4 and PRPH2, DNA from 3 members of the family, including both affected siblings and their mother, was screened by whole exome sequencing resulting in identification of 2 CRB1 missense mutations, c.C3991T:p.R1331C and c.C4142T:p.P1381L, which segregated with the disease in the family. Of the 2, the p.R1331C CRB1 mutation has not been described before and the p.P1381L variant has been described in 1 patient with Leber congenital amaurosis. CONCLUSIONS This report illustrates a novel presentation of a macular dystrophy caused by CRB1 mutations. Both affected siblings exhibited a relatively well-developed retinal structure and preservation of generalized retinal function. An unusual 5-year progression of macular atrophy alone was observed that has not been described in any other CRB1-associated phenotypes.
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Affiliation(s)
- Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology & Cell Biology, Columbia University, New York, New York
| | - Tomas Burke
- Department of Ophthalmology, Columbia University, New York, New York; Department of Ophthalmology, Stoke Mandeville Hospital, Aylesbury, Buckinghamshire, United Kingdom
| | - Maris Oll
- Department of Ophthalmology, Columbia University, New York, New York; University Eye Clinic, Tartu University, Tartu, Estonia
| | - Suzanne Yzer
- Department of Ophthalmology, Columbia University, New York, New York; Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York
| | - Yajing Angela Xie
- Department of Ophthalmology, Columbia University, New York, New York
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology & Cell Biology, Columbia University, New York, New York.
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21
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Khan MI, Azam M, Ajmal M, Collin RWJ, den Hollander AI, Cremers FPM, Qamar R. The molecular basis of retinal dystrophies in pakistan. Genes (Basel) 2014; 5:176-95. [PMID: 24705292 PMCID: PMC3978518 DOI: 10.3390/genes5010176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/14/2014] [Accepted: 02/14/2014] [Indexed: 12/23/2022] Open
Abstract
The customary consanguineous nuptials in Pakistan underlie the frequent occurrence of autosomal recessive inherited disorders, including retinal dystrophy (RD). In many studies, homozygosity mapping has been shown to be successful in mapping susceptibility loci for autosomal recessive inherited disease. RDs are the most frequent cause of inherited blindness worldwide. To date there is no comprehensive genetic overview of different RDs in Pakistan. In this review, genetic data of syndromic and non-syndromic RD families from Pakistan has been collected. Out of the 132 genes known to be involved in non-syndromic RD, 35 different genes have been reported to be mutated in families of Pakistani origin. In the Pakistani RD families 90% of the mutations causing non-syndromic RD and all mutations causing syndromic forms of the disease have not been reported in other populations. Based on the current inventory of all Pakistani RD-associated gene defects, a cost-efficient allele-specific analysis of 11 RD-associated variants is proposed, which may capture up to 35% of the genetic causes of retinal dystrophy in Pakistan.
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Affiliation(s)
- Muhammad Imran Khan
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Maleeha Azam
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Muhammad Ajmal
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands.
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands.
| | - Frans P M Cremers
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Raheel Qamar
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
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22
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Li S, Shen T, Xiao X, Guo X, Zhang Q. Detection of CRB1 mutations in families with retinal dystrophy through phenotype-oriented mutational screening. Int J Mol Med 2014; 33:913-8. [PMID: 24535598 DOI: 10.3892/ijmm.2014.1655] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/28/2014] [Indexed: 11/06/2022] Open
Abstract
Mutations in the crumbs homolog (CRB)1 gene are among the common causes of severe early onset retinal dystrophy. Some characteristic clinical phenotypes are frequently associated with mutations in CRB1. The aim of this study was to examine whether characteristic phenotype-directed mutational screening facilitated the detection of CRB1 mutations. The study included 22 probands with at least one of the potential CRB1-associated phenotypes for retinal dystrophy. Variants were detected using Sanger sequencing. The complete sequences of the coding and adjacent intronic regions of CRB1 were analyzed, revealing homozygous or compound heterozygous mutations in CRB1 in seven of 22 probands, involving six novel (c.136delA, c.1841G>T, c.3017C>A, c.3488G>T, c.3991C>T and c.4089dupTGTTGCTT) and four known (c.2222T>C, c.2671T>G, c.3676G>T and c.4005+2T>G) mutations. The mutations were present in three of four probands with macular nummular pigmentation and in four of seven probands with early onset retinitis pigmentosa with macular involvement. The results suggested that macular nummular pigmentation is a gene-specific indication for CRB1‑associated retinal dystrophy and confirm that CRB1 mutations are also common causes of early onset retinitis pigmentosa. Identification of gene-specific phenotypes is uselful in identifying genetic defects underlying heterogeneous retinal dystrophy.
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Affiliation(s)
- Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Tao Shen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xiangming Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
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23
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Corton M, Tatu SD, Avila-Fernandez A, Vallespín E, Tapias I, Cantalapiedra D, Blanco-Kelly F, Riveiro-Alvarez R, Bernal S, García-Sandoval B, Baiget M, Ayuso C. High frequency of CRB1 mutations as cause of Early-Onset Retinal Dystrophies in the Spanish population. Orphanet J Rare Dis 2013; 8:20. [PMID: 23379534 PMCID: PMC3637806 DOI: 10.1186/1750-1172-8-20] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Accepted: 01/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND CRB1 mutations are reported as cause of severe congenital and early-onset retinal dystrophies (EORD) with different phenotypic manifestations, including Leber congenital amaurosis (LCA), retinitis pigmentosa (RP) and cone-rod dystrophies. Comprehensive mutational scanning of the whole gene has been only performed in few cohorts, mainly in LCA patients. Here, we aimed investigating the real prevalence of CRB1 mutations in the Spanish population by extensive screening of CRB1 mutations in a large cohort of LCA and EORP cases. METHODS This report integrates data from previous studies on CRB1 defects in our Spanish cohort of LCA and early-onset RP (EORP) with new findings from a comprehensive mutational screening of the whole gene. The molecular tools used include mutation genotyping arrays, whole-genome homozygosity mapping, an optimized high-resolution melting (HRM) analysis and Sanger sequencing. RESULTS A large clinically well-characterized cohort of 404 Spanish cases was studied, 114 of which suffered from LCA and 290 from EORP. This study reveals that 11% of Spanish patients carried mutations in CRB1, ranging from 9% of EORP to 14% of LCA cases. More than three quarters of the mutations identified herein have been first described in this Spanish cohort, 13 of them are unreported new variants and 13 had been previously reported in our previous studies. CONCLUSIONS This work provides a wide spectrum of CRB1 mutations in the Spanish EORD patients and evidences the major role of CRB1 as causal gene in the Spanish EORP patients. It is noteworthy that a high rate of private mutations only described in our cohort has been found so far. To our knowledge, this study represents the most complete mutational screening of CRB1 in a Spanish LCA and EORP cohort, allowing us to establish gene-specific frequencies and to provide a wide spectrum of CRB1 mutations in the Spanish population.
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Affiliation(s)
- Marta Corton
- Department of Genetics, IIS - Fundación Jiménez Díaz, Madrid, Spain
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24
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Mishra M, Rentsch M, Knust E. Crumbs regulates polarity and prevents light-induced degeneration of the simple eyes of Drosophila, the ocelli. Eur J Cell Biol 2012; 91:706-16. [PMID: 22608020 DOI: 10.1016/j.ejcb.2012.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Revised: 03/27/2012] [Accepted: 03/27/2012] [Indexed: 11/27/2022] Open
Abstract
The evolutionary conserved transmembrane protein Crumbs (Crb) regulates morphogenesis of photoreceptor cells in the compound eye of Drosophila and prevents light-dependent retinal degeneration. Here we examine the role of Crb in the ocelli, the simple eyes of Drosophila. We show that Crb is expressed in ocellar photoreceptor cells, where it defines a stalk membrane apical to the adherens junctions, similar as in photoreceptor cells of the compound eyes. Loss of function of crb disrupts polarity of ocellar photoreceptor cells, and results in mislocalisation of adherens junction proteins. This phenotype is more severe than that observed in mutant photoreceptor cells of the compound eye, and resembles more that of embryonic epithelia lacking crb. Similar as in compound eyes, crb protects ocellar photoreceptors from light induced degeneration, a function that depends on the extracellular portion of the Crb protein. Our data demonstrate that the function of crb in photoreceptor development and homeostasis is conserved in compound eyes and ocelli and underscores the evolutionarily relationship between these visual sense organs of Drosophila. The data will be discussed with respect to the difference in apico-basal organisation of these two cell types.
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Affiliation(s)
- Monalisa Mishra
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, D-01307 Dresden, Germany
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25
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Bujakowska K, Audo I, Mohand-Saïd S, Lancelot ME, Antonio A, Germain A, Léveillard T, Letexier M, Saraiva JP, Lonjou C, Carpentier W, Sahel JA, Bhattacharya SS, Zeitz C. CRB1 mutations in inherited retinal dystrophies. Hum Mutat 2011; 33:306-15. [PMID: 22065545 DOI: 10.1002/humu.21653] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/26/2011] [Indexed: 02/06/2023]
Abstract
Mutations in the CRB1 gene are associated with variable phenotypes of severe retinal dystrophies, ranging from leber congenital amaurosis (LCA) to rod-cone dystrophy, also called retinitis pigmentosa (RP). Moreover, retinal dystrophies resulting from CRB1 mutations may be accompanied by specific fundus features: preservation of the para-arteriolar retinal pigment epithelium (PPRPE) and retinal telangiectasia with exudation (also referred to as Coats-like vasculopathy). In this publication, we report seven novel mutations and classify over 150 reported CRB1 sequence variants that were found in more that 240 patients. The data from previous reports were used to analyze a potential correlation between CRB1 variants and the clinical features of respective patients. This meta-analysis suggests that the differential phenotype of patients with CRB1 mutations is due to additional modifying factors rather than particular mutant allele combination.
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26
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González-del Pozo M, Borrego S, Barragán I, Pieras JI, Santoyo J, Matamala N, Naranjo B, Dopazo J, Antiñolo G. Mutation screening of multiple genes in Spanish patients with autosomal recessive retinitis pigmentosa by targeted resequencing. PLoS One 2011; 6:e27894. [PMID: 22164218 PMCID: PMC3229495 DOI: 10.1371/journal.pone.0027894] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 10/27/2011] [Indexed: 01/22/2023] Open
Abstract
Retinitis Pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterised ultimately by the loss of photoreceptor cells. RP is the leading cause of visual loss in individuals younger than 60 years, with a prevalence of about 1 in 4000. The molecular genetic diagnosis of autosomal recessive RP (arRP) is challenging due to the large genetic and clinical heterogeneity. Traditional methods for sequencing arRP genes are often laborious and not easily available and a screening technique that enables the rapid detection of the genetic cause would be very helpful in the clinical practice. The goal of this study was to develop and apply microarray-based resequencing technology capable of detecting both known and novel mutations on a single high-throughput platform. Hence, the coding regions and exon/intron boundaries of 16 arRP genes were resequenced using microarrays in 102 Spanish patients with clinical diagnosis of arRP. All the detected variations were confirmed by direct sequencing and potential pathogenicity was assessed by functional predictions and frequency in controls. For validation purposes 4 positive controls for variants consisting of previously identified changes were hybridized on the array. As a result of the screening, we detected 44 variants, of which 15 are very likely pathogenic detected in 14 arRP families (14%). Finally, the design of this array can easily be transformed in an equivalent diagnostic system based on targeted enrichment followed by next generation sequencing.
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Affiliation(s)
- María González-del Pozo
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
| | - Salud Borrego
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
| | - Isabel Barragán
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
| | - Juan I. Pieras
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
| | - Javier Santoyo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
- Medical Genome Project, Andalusian Center for Human Genomic Sequencing, Sevilla, Spain
- Departamento de Bioinformática y Genómica, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Nerea Matamala
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Medical Genome Project, Andalusian Center for Human Genomic Sequencing, Sevilla, Spain
| | - Belén Naranjo
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Joaquín Dopazo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
- Medical Genome Project, Andalusian Center for Human Genomic Sequencing, Sevilla, Spain
- Departamento de Bioinformática y Genómica, Centro de Investigación Príncipe Felipe, Valencia, Spain
- Functional Genomics Node (INB), Valencia, Spain
- * E-mail: (JD); (GA)
| | - Guillermo Antiñolo
- Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Sevilla, Spain
- Medical Genome Project, Andalusian Center for Human Genomic Sequencing, Sevilla, Spain
- * E-mail: (JD); (GA)
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Zenteno JC, Buentello-Volante B, Ayala-Ramirez R, Villanueva-Mendoza C. Homozygosity mapping identifies the Crumbs homologue 1 (Crb1) gene as responsible for a recessive syndrome of retinitis pigmentosa and nanophthalmos. Am J Med Genet A 2011; 155A:1001-6. [PMID: 21484995 DOI: 10.1002/ajmg.a.33862] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 11/22/2010] [Indexed: 11/07/2022]
Abstract
The association of retinitis pigmentosa (RP) and microphthalmia has been reported in a number of familial and isolated cases. Here, the results of genetic analysis in a familial case of early RP associated with nanophthalmos are described. Two affected sibs were ascertained from an endogamous population in Mexico. A genome-wide linkage analysis was performed by means of an Affymetrix 250K microarray. Five large regions of homozygosity were demonstrated. The largest interval comprised 15.08 Mb at chromosome 1q31-32.1 and contained the Crumbs homologue-1, CRB1, a gene responsible for a number of recessive retinal dystrophies. Nucleotide sequence analysis demonstrated a c.1125C>G transversion in CRB1 exon 5, predicting a novel p.Tyr375X variant. To our knowledge this is the first instance in which a CRB1 mutation has been associated with early RP and nanophthalmos. Our results suggest a role for CRB1 in promoting axial growth of the eye. Clinical analysis of additional subjects with retinal dystrophies due to CRB1 mutations will help to identify if the high hyperopia, a frequently observed trait in these subjects, could be related to decreased eye axial length (nanophthalmos).
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Affiliation(s)
- Juan Carlos Zenteno
- Faculty of Medicine, Department of Biochemistry, National Autonomous University of Mexico, Mexico City, Mexico.
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28
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Pearson RA, Barber AC, West EL, MacLaren RE, Duran Y, Bainbridge JW, Sowden JC, Ali RR. Targeted disruption of outer limiting membrane junctional proteins (Crb1 and ZO-1) increases integration of transplanted photoreceptor precursors into the adult wild-type and degenerating retina. Cell Transplant 2010; 19:487-503. [PMID: 20089206 DOI: 10.3727/096368909x486057] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Diseases culminating in photoreceptor loss are a major cause of untreatable blindness. Transplantation of rod photoreceptors is feasible, provided donor cells are at an appropriate stage of development when transplanted. Nevertheless, the proportion of cells that integrate into the recipient outer nuclear layer (ONL) is low. The outer limiting membrane (OLM), formed by adherens junctions between Müller glia and photoreceptors, may impede transplanted cells from migrating into the recipient ONL. Adaptor proteins such as Crumbs homologue 1 (Crb1) and zona occludins (ZO-1) are essential for localization of the OLM adherens junctions. We investigated whether targeted disruption of these proteins enhances donor cell integration. Transplantation of rod precursors in wild-type mice achieved 949 +/- 141 integrated cells. By contrast, integration is significantly higher when rod precursors are transplanted into Crb1(rd8/rd8) mice, a model of retinitis pigmentosa and Lebers congenital amaurosis that lacks functional CRB1 protein and displays disruption of the OLM (7,819 +/- 1,297; maximum 15,721 cells). We next used small interfering (si)RNA to transiently reduce the expression of ZO-1 and generate a reversible disruption of the OLM. ZO-1 knockdown resulted in similar, significantly improved, integration of transplanted cells in wild-type mice (7,037 +/- 1,293; maximum 11,965 cells). Finally, as the OLM remains largely intact in many retinal disorders, we tested whether transient ZO-1 knockdown increased integration in a model of retinitis pigmentosa, the rho(-/-) mouse; donor cell integration was significantly increased from 313 +/- 58 cells without treatment to 919 +/- 198 cells after ZO-1 knockdown. This study shows that targeted disruption of OLM junctional proteins enhances integration in the wild-type and degenerating retina and may be a useful approach for developing photoreceptor transplantation strategies.
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Affiliation(s)
- R A Pearson
- Department of Genetics, University College London Institute of Ophthalmology, London, UK.
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29
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Gosens I, den Hollander AI, Cremers FPM, Roepman R. Composition and function of the Crumbs protein complex in the mammalian retina. Exp Eye Res 2008; 86:713-26. [PMID: 18407265 DOI: 10.1016/j.exer.2008.02.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2007] [Revised: 01/09/2008] [Accepted: 02/18/2008] [Indexed: 11/27/2022]
Abstract
The Crumbs proteins (CRBs) are transmembrane proteins, homologous to Drosophila Crumbs, with a key role in defining the apical membrane domain in photoreceptors as well as in embryonic epithelia. Crumbs proteins are conserved between species and their intracellular domains are involved in organizing a conserved macromolecular protein scaffold with important roles in cell polarity as well as morphogenesis and maintenance of the retina. Mutations in the gene encoding human CRB1, the first one identified out of the three human orthologs, have been associated with a number of retinal dystrophies including Leber amaurosis and retinitis pigmentosa type 12. Although no other mammalian Crumbs complex members as of yet have been associated with retinal degeneration, disruption of different zebrafish and fruitfly orthologs can lead to various retinal defects. The core Crumbs complex localizes apical to the outer limiting membrane, where photoreceptors and Müller glia contact each other. Correct functioning of Crumbs ensures adhesion between these cells by an unknown mechanism. This review summarizes the current view on the composition and function of the Crumbs prsotein complex in the mammalian retina. Recently, a number of new members of the Crumbs protein complex have been identified. These include most members of the membrane palmitoylated protein family (MPP), involved in assembly of macromolecular protein complexes. Some components of the complex are found to exert a function in the photoreceptor synapses and/or at the region of the connecting cilium. Studies using polarized cell cultures or model organisms, like Drosophila and zebrafish, suggest important links of the Crumbs protein complex to several biological processes in the mammalian eye, including retinal patterning, ciliogenesis and vesicular transport.
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Affiliation(s)
- Ilse Gosens
- Department of Human Genetics and Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 10, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Davis JA, Handford PA, Redfield C. The N1317H Substitution Associated with Leber Congenital Amaurosis Results in Impaired Interdomain Packing in Human CRB1 Epidermal Growth Factor-like (EGF) Domains. J Biol Chem 2007; 282:28807-28814. [PMID: 17660513 DOI: 10.1074/jbc.m704015200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcium-binding epidermal growth factor-like (cbEGF) domain is a widely occurring module in proteins of diverse function. Amino acid substitutions that disrupt its structure or calcium affinity have been associated with various disorders. The extracellular portion of CRB1, the human homologue of Drosophila Crumbs, exhibits a modular domain organization that includes EGF and cbEGF domains. The N1317H substitution in the 19th cbEGF domain of CRB1 is associated with the serious visual disorder Leber congenital amaurosis. We have investigated the structure and Ca(2+) binding of recombinant wild-type and N1317H CRB1 fragments (EGF18-cbEGF19) using NMR and find that Ca(2+) binding is altered, resulting in disruption of long range interactions between adjacent EGF domains in CRB1. From these observations, we propose that this substitution affects the structural integrity of CRB1 in the inter-photoreceptor matrix of the retina, where it is expressed. Furthermore, we identify disease-causing substitutions in other cbEGF-containing proteins that are likely to result in similar disruption of interdomain packing, supporting the hypothesis that the tandem cbEGF domain linkages are critical for the structure and function of proteins containing cbEGF domains.
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Affiliation(s)
- Jason A Davis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Penny A Handford
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Christina Redfield
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
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31
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Berger S, Bulgakova NA, Grawe F, Johnson K, Knust E. Unraveling the genetic complexity of Drosophila stardust during photoreceptor morphogenesis and prevention of light-induced degeneration. Genetics 2007; 176:2189-200. [PMID: 17603117 PMCID: PMC1950624 DOI: 10.1534/genetics.107.071449] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Drosophila Stardust, a membrane-associated guanylate kinase (MAGUK), recruits the transmembrane protein Crumbs and the cytoplasmic proteins DPATJ and DLin-7 into an apically localized protein scaffold. This evolutionarily conserved complex is required for epithelial cell polarity in Drosophila embryos and mammalian cells in culture. In addition, mutations in Drosophila crumbs and DPATJ impair morphogenesis of photoreceptor cells (PRCs) and result in light-dependent retinal degeneration. Here we show that stardust is a genetically complex locus. While all alleles tested perturb epithelial cell polarity in the embryo, only a subset of them affects morphogenesis of PRCs or induces light-dependent retinal degeneration. Alleles retaining particular postembryonic functions still express some Stardust protein in pupal and/or adult eyes. The phenotypic complexity is reflected by the expression of distinct splice variants at different developmental stages. All proteins expressed in the retina contain the PSD95, Discs Large, ZO-1 (PDZ), Src homology 3 (SH3), and guanylate kinase (GUK) domain, but lack a large region in the N terminus encoded by one exon. These results suggest that Stardust-based protein scaffolds are dynamic, which is not only mediated by multiple interaction partners, but in addition by various forms of the Stardust protein itself.
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Affiliation(s)
- Sandra Berger
- Max-Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-10307 Dresden, Germany
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Lotery AJ, Baas D, Ridley C, Jones RPO, Klaver CCW, Stone E, Nakamura T, Luff A, Griffiths H, Wang T, Bergen AAB, Trump D. Reduced secretion of fibulin 5 in age-related macular degeneration and cutis laxa. Hum Mutat 2006; 27:568-74. [PMID: 16652333 PMCID: PMC1828612 DOI: 10.1002/humu.20344] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Age-related macular degeneration (ARMD) is the leading cause of irreversible visual loss in the Western world, affecting approximately 25 million people worldwide. The pathogenesis is complex and missense mutations in FBLN5 have been reported in association with ARMD. We have investigated the role of fibulin 5 in ARMD by completing the first European study of the gene FBLN5 in ARMD (using 2 European cohorts of 805 ARMD patients and 279 controls) and by determining the functional effects of the missense mutations on fibulin 5 expression. We also correlated the FBLN5 genotype with the ARMD phenotype. We found two novel sequence changes in ARMD patients that were absent in controls and expressed these and the other nine reported FBLN5 mutations associated with ARMD and two associated with the autosomal recessive disease cutis laxa. Fibulin 5 secretion was significantly reduced (P<0.001) for four ARMD (p.G412E, p.G267S, p.I169 T, and p.Q124P) and two cutis laxa (p.S227P, p.C217R) mutations. These results suggest that some missense mutations associated with ARMD lead to decreased fibulin 5 secretion with a possible corresponding reduction in elastinogenesis. This study confirms the previous work identifying an association between FBLN5 mutations and ARMD and for the first time suggests a functional mechanism by which these mutations can lead to ARMD. It further demonstrates that FBLN5 mutations can be associated with different phenotypes of ARMD (not limited to the previously described cuticular drusen type). Such knowledge may ultimately lead to the development of novel therapies for this common disease.
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Affiliation(s)
- Andrew J Lotery
- Human Genetics Division, University of Southampton, Southampton, Hampshire, United Kingdom.
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Kantardzhieva A, Alexeeva S, Versteeg I, Wijnholds J. MPP3 is recruited to the MPP5 protein scaffold at the retinal outer limiting membrane. FEBS J 2006; 273:1152-65. [PMID: 16519681 DOI: 10.1111/j.1742-4658.2006.05140.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mutations in the human Crumbs homologue 1 (CRB1) gene are a frequent cause of various forms of retinitis pigmentosa. The CRB1-membrane-associated palmitoylated protein (MPP)5 protein complex is thought to organize an intracellular protein scaffold in the retina that is involved in maintenance of photoreceptor-Müller glia cell adhesion. This study focused on the binding characteristics and subcellular localization of MPP3, a novel member of the MPP5 protein scaffold at the outer limiting membrane (OLM), and of the DLG1 protein scaffold at the outer plexiform layer of the retina. MPP3 localized at the photoreceptor synapse and at the subapical region adjacent to adherens junctions at the OLM. Localization studies in human retinae revealed that MPP3 colocalized with MPP5 and CRB1 at the subapical region. MPP3 and MPP4 colocalized with DLG1 at the outer plexiform layer. Mouse Dlg1 formed separate complexes with Mpp3 and Mpp4 in vivo. These data implicate a role for MPP3 in photoreceptor polarity and, by association with MPP5, pinpoint MPP3 as a functional candidate gene for inherited retinopathies. The separate Mpp3/Dlg1 and Mpp4/Dlg1 complexes at the outer plexiform layer point towards additional yet unrecognized functions of these membrane associated guanylate kinase proteins.
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Affiliation(s)
- Albena Kantardzhieva
- Department of Neuromedical Genetics, The Netherlands Institute for Neurosciences (NIN), KNAW, Amsterdam, The Netherlands
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Abouzeid H, Li Y, Maumenee IH, Dharmaraj S, Sundin O. A G1103R mutation in CRB1 is co-inherited with high hyperopia and Leber congenital amaurosis. Ophthalmic Genet 2006; 27:15-20. [PMID: 16543197 DOI: 10.1080/13816810500481840] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To identify the genetic basis of recessive inheritance of high hyperopia and Leber congenital amaurosis (LCA) in a family of Middle Eastern origin. MATERIALS AND METHODS The patients were examined using standard ophthalmic techniques. DNA samples were obtained and genetic linkage was carried out using polymorphic markers flanking the known genes and loci for LCA. Exons were amplified and sequenced. RESULTS All four members of this family affected by LCA showed high to extreme hyperopia, with average spherical refractive errors ranging from +5.00 to +10.00. Linkage was obtained to 1q31.3 with a maximal LOD score of 5.20 and a mutation found in exon 9 of the CRB1 gene, causing a G1103R substitution at a highly conserved site in the protein. CRB1 is a vertebrate homolog of the Drosophila crumbs gene, which is required for photoreceptor morphogenesis, and has been associated with either retinitis pigmentosa (RP) or LCA. This sequence variant has previously been reported as a compound heterozygote in one sporadic LCA patient. CONCLUSION Although hyperopia has been associated with LCA, it is typically moderate and variable between patients with the same mutation. In addition, some CRB1 mutations can be associated with either RP or LCA. We have shown that hyperopia and LCA are linked to the mutant CRB1 gene itself and are not dependent on unlinked modifiers.
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Affiliation(s)
- H Abouzeid
- The Johns Hopkins Center for Hereditary Eye Diseases, Wilmer Eye Institute, Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287-9237, USA.
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Richard M, Grawe F, Knust E. DPATJ plays a role in retinal morphogenesis and protects against light-dependent degeneration of photoreceptor cells in theDrosophila eye. Dev Dyn 2006; 235:895-907. [PMID: 16245332 DOI: 10.1002/dvdy.20595] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The establishment of apicobasal polarity in epithelial cells is a prerequisite for their function. Drosophila photoreceptor cells derive from epithelial cells, and their apical membranes undergo elaborate differentiation during pupal development, forming photosensitive rhabdomeres and associated stalk membranes. Crumbs (Crb), a transmembrane protein involved in the maintenance of epithelial polarity in the embryo, defines the stalk as a subdomain of the apical membrane. Crb organizes a complex composed of several PDZ domain-containing proteins, including DPATJ (formerly known as Discs lost). Taking advantage of a DPATJ mutant line in which only a truncated form of the protein is synthesized, we demonstrate that DPATJ is necessary for the stability of the Crb complex at the stalk membrane and is crucial for stalk membrane development and rhabdomere maintenance during late pupal stages. Moreover, DPATJ protects against light-induced photoreceptor degeneration.
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Affiliation(s)
- Mélisande Richard
- Institut für Genetik, Heinrich Heine Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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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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den Hollander AI, Davis J, van der Velde-Visser SD, Zonneveld MN, Pierrottet CO, Koenekoop RK, Kellner U, van den Born LI, Heckenlively JR, Hoyng CB, Handford PA, Roepman R, Cremers FPM. CRB1 mutation spectrum in inherited retinal dystrophies. Hum Mutat 2005; 24:355-69. [PMID: 15459956 DOI: 10.1002/humu.20093] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mutations in the Crumbs homologue 1 (CRB1) gene have been reported in patients with a variety of autosomal recessive retinal dystrophies, including retinitis pigmentosa (RP) with preserved paraarteriolar retinal pigment epithelium (PPRPE), RP with Coats-like exudative vasculopathy, early onset RP without PPRPE, and Leber congenital amaurosis (LCA). We extended our investigations of CRB1 in these retinal dystrophies, and identified nine novel CRB1 sequence variants. In addition, we screened patients with "classic" RP and classic Coats disease (without RP), but no pathologic sequence variants were found in the CRB1 gene. In total, 71 different sequence variants have been identified on 184 CRB1 alleles of patients with retinal dystrophies, including amino acid substitutions, frameshift, nonsense, and splice site mutations, in-frame deletions, and large insertions. Recent studies in two animal models, mouse and Drosophila, and in vivo high-resolution microscopy in patients with LCA, have shed light on the role of CRB1 in the pathogenesis of retinal dystrophies and its function in the photoreceptors. In this article, we provide an overview of the currently known CRB1 sequence variants, predict their effect, and propose a genotype-phenotype correlation model for CRB1 mutations.
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Affiliation(s)
- Anneke I den Hollander
- Department of Human Genetics, University Medical Center Nijmegen, Nijmegen, The Netherlands.
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Abstract
During embryonic development, polarized epithelial cells are either formed during cleavage or formed from mesenchymal cells. Because the formation of epithelia during embryogenesis has to occur with high fidelity to ensure proper development, embryos allow a functional approach to study epithelial cell polarization in vivo. In particular, genetic model organisms have greatly advanced our understanding of the generation and maintenance of epithelial cell polarity. Many novel and important polarity genes have been identified and characterized in invertebrate systems, like Drosophila melanogaster and Caenorhabditis elegans. With the rapid identification of mammalian homologues of these invertebrate polarity genes, it has become clear that many important protein domains, single proteins and even entire protein complexes are evolutionarily conserved. It is to be expected that the field of epithelial cell polarity is just experiencing the 'top of the iceberg' of a large protein network that is fundamental for the specific adhesive, cell signalling and transport functions of epithelial cells.
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Affiliation(s)
- H-Arno J Müller
- Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, Düsseldorf D-40225, Germany.
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Khaliq S, Abid A, Hameed A, Anwar K, Mohyuddin A, Azmat Z, Shami SA, Ismail M, Mehdi SQ. Mutation screening of Pakistani families with congenital eye disorders. Exp Eye Res 2003; 76:343-8. [PMID: 12573663 DOI: 10.1016/s0014-4835(02)00304-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To map the disease loci several Pakistani families suffering from autosomal recessive retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium and Leber congenital amaurosis (LCA) were analyzed. Analysis revealed close genetic linkage between the disease phenotype of some of the families (3330RP, 111RP and 010LCA) and the microsatellite markers on chromosome 1q31. Mutation screening of the candidate gene CRB1 revealed a G to A transversion in exon 7 in arRP family 330RP and a T to C substitution in another arRP family, 111RP. In exon 9 of the CRB1 gene a T to C transversion was found in the family suffering from LCA (010LCA). The LCA phenotype of another family (011LCA) in which the CRB1 locus was excluded, showed linkage with microsatellite markers D17S1294 and D17S796 on chromosome 17p13.1. The association of the candidate gene GUCY2D (17p13.1) with the disease phenotype was excluded as no disease-associated mutation was found in any of its exons. Mutation screening of another candidate gene, AIPL1 located in the same region, showed a novel homozygous C to A substitution in exon 2. These sequence changes are unique for the Pakistani families and some of these have not been reported previously.
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Affiliation(s)
- Shagufta Khaliq
- Dr A. Q. Khan Research Laboratories, Biomedical and Genetic Engineering Division, 24 Mauve area, P.O. Box 2891, Islamabad, Pakistan.
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Abstract
The cliché 'a picture is worth a thousand words' is a testament to the power of the visual system in helping us deal with our physical environment. Rarely do perturbations to the visual system, even minor ones, go unnoticed. Major defects in eye development may occur in the absence of systemic problems which threaten health. Ocular anomalies offer a window into many developmental events which would otherwise be difficult to study.
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Affiliation(s)
- R A Saleem
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
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