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Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation. Int J Mol Sci 2022; 23:ijms23137432. [PMID: 35806438 PMCID: PMC9266689 DOI: 10.3390/ijms23137432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/01/2022] [Indexed: 01/25/2023] Open
Abstract
Best Vitelliform Macular dystrophy (BVMD) is the most prevalent of the distinctive retinal dystrophies caused by mutations in the BEST1 gene. This gene, which encodes for a homopentameric calcium-activated ion channel, is crucial for the homeostasis and function of the retinal pigment epithelia (RPE), the cell type responsible for recycling the visual pigments generated by photoreceptor cells. In BVMD patients, mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight. In this work, we employ iPSC-RPE cells derived from a patient with the p.Pro77Ser dominant mutation to determine the correlation between this variant and the ocular phenotype. To this purpose, gene and protein expression and localization are evaluated in iPSC-RPE cells along with functional assays like phagocytosis and anion channel activity. Our cell model shows no differences in gene expression, protein expression/localization, or phagocytosis capacity, but presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation. We hypothesize that this variant disturbs the neck region of the BEST1 channel, affecting channel function but maintaining cell homeostasis in the short term. This data shed new light on the different phenotypes of dominant mutations in BEST1, and emphasize the importance of understanding its molecular mechanisms. Furthermore, the data widen the knowledge of this pathology and open the door for a better diagnosis and prognosis of the disease.
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2
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Peeters MHCA, Khan M, Rooijakkers AAMB, Mulders T, Haer-Wigman L, Boon CJF, Klaver CCW, van den Born LI, Hoyng CB, Cremers FPM, den Hollander AI, Dhaenens CM, Collin RWJ. PRPH2 mutation update: In silico assessment of 245 reported and 7 novel variants in patients with retinal disease. Hum Mutat 2021; 42:1521-1547. [PMID: 34411390 PMCID: PMC9290825 DOI: 10.1002/humu.24275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/22/2021] [Accepted: 08/16/2021] [Indexed: 01/31/2023]
Abstract
Mutations in PRPH2, encoding peripherin-2, are associated with the development of a wide variety of inherited retinal diseases (IRDs). To determine the causality of the many PRPH2 variants that have been discovered over the last decades, we surveyed all published PRPH2 variants up to July 2020, describing 720 index patients that in total carried 245 unique variants. In addition, we identified seven novel PRPH2 variants in eight additional index patients. The pathogenicity of all variants was determined using the ACMG guidelines. With this, 107 variants were classified as pathogenic, 92 as likely pathogenic, one as benign, and two as likely benign. The remaining 50 variants were classified as variants of uncertain significance. Interestingly, of the total 252 PRPH2 variants, more than half (n = 137) were missense variants. All variants were uploaded into the Leiden Open source Variation and ClinVar databases. Our study underscores the need for experimental assays for variants of unknown significance to improve pathogenicity classification, which would allow us to better understand genotype-phenotype correlations, and in the long-term, hopefully also support the development of therapeutic strategies for patients with PRPH2-associated IRD.
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Affiliation(s)
- Manon H C A Peeters
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Mubeen Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | | | - Timo Mulders
- Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Ophthalmology, Amsterdam UMC, Academic Medical Center, Amsterdam, The Netherlands
| | - Caroline C W Klaver
- Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Ophthalmology, Erasmus University Medical Centre, Rotterdam, The Netherlands.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - L Ingeborgh van den Born
- The Rotterdam Eye Hospital, Rotterdam, The Netherlands.,Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands
| | - Carel B Hoyng
- Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Claire-Marie Dhaenens
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Biochemistry and Molecular Biology, Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, Lille, France
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics and Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
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3
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Maggi J, Koller S, Bähr L, Feil S, Kivrak Pfiffner F, Hanson JVM, Maspoli A, Gerth-Kahlert C, Berger W. Long-Range PCR-Based NGS Applications to Diagnose Mendelian Retinal Diseases. Int J Mol Sci 2021; 22:ijms22041508. [PMID: 33546218 PMCID: PMC7913364 DOI: 10.3390/ijms22041508] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/27/2022] Open
Abstract
The purpose of this study was to develop a flexible, cost-efficient, next-generation sequencing (NGS) protocol for genetic testing. Long-range polymerase chain reaction (PCR) amplicons of up to 20 kb in size were designed to amplify entire genomic regions for a panel (n = 35) of inherited retinal disease (IRD)-associated loci. Amplicons were pooled and sequenced by NGS. The analysis was applied to 227 probands diagnosed with IRD: (A) 108 previously molecularly diagnosed, (B) 94 without previous genetic testing, and (C) 25 undiagnosed after whole-exome sequencing (WES). The method was validated with 100% sensitivity on cohort A. Long-range PCR-based sequencing revealed likely causative variant(s) in 51% and 24% of proband from cohorts B and C, respectively. Breakpoints of 3 copy number variants (CNVs) could be characterized. Long-range PCR libraries spike-in extended coverage of WES. Read phasing confirmed compound heterozygosity in 5 probands. The proposed sequencing protocol provided deep coverage of the entire gene, including intronic and promoter regions. Our method can be used (i) as a first-tier assay to reduce genetic testing costs, (ii) to elucidate missing heritability cases, (iii) to characterize breakpoints of CNVs at nucleotide resolution, (iv) to extend WES data to non-coding regions by spiking-in long-range PCR libraries, and (v) to help with phasing of candidate variants.
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Affiliation(s)
- Jordi Maggi
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - Samuel Koller
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - Luzy Bähr
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - Silke Feil
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - Fatma Kivrak Pfiffner
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - James V. M. Hanson
- Department of Ophthalmology, University Hospital Zurich and University of Zurich, 8091 Zurich, Switzerland; (J.V.M.H.); (C.G.-K.)
| | - Alessandro Maspoli
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
| | - Christina Gerth-Kahlert
- Department of Ophthalmology, University Hospital Zurich and University of Zurich, 8091 Zurich, Switzerland; (J.V.M.H.); (C.G.-K.)
| | - Wolfgang Berger
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (J.M.); (S.K.); (L.B.); (S.F.); (F.K.P.); (A.M.)
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
- Neuroscience Center Zurich (ZNZ), University and ETH Zurich, 8057 Zurich, Switzerland
- Correspondence: ; Tel.: +41-44-556-33-50
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Wang J, Liu H, Bertrand RE, Sarrion-Perdigones A, Gonzalez Y, Venken KJT, Chen R. A novel statistical method for interpreting the pathogenicity of rare variants. Genet Med 2020; 23:59-68. [PMID: 32884132 PMCID: PMC7796914 DOI: 10.1038/s41436-020-00948-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023] Open
Abstract
Purpose: To achieve the ultimate goal of personalized treatment of patients, accurate molecular diagnosis and precise interpretation of the impact of genetic variants on gene function is essential. With the sequencing cost becoming increasingly affordable, accurate distinguishing benign from pathogenic variants upon sequencing becomes the major bottleneck. Although large normal population sequence databases have become a key resource in filtering benign variants, they are not effective at filtering extremely rare variants. Methods: To address this challenge, we developed a novel statistical test by combining sequencing data from a patient cohort with a normal control population database. By comparing the expected and observed allele frequency in the patient cohort, variants that are likely benign can be identified. Results: The performance of this new method is evaluated on both simulated and real datasets coupled with experimental validation. As a result, we demonstrate this new test is well-powered to identify benign variants, particularly effective for variants with low frequency in the normal population. Conclusion: Overall, as a general test that can be applied to any type of variants in the context of all Mendelian diseases, our work provides a general framework for filtering benign variants with very low population allele frequency.
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Affiliation(s)
- Jun Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Hehe Liu
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Renae Elaine Bertrand
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Alejandro Sarrion-Perdigones
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Yezabel Gonzalez
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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Xuan Y, Zhang Y, Zong Y, Wang M, Li L, Ye X, Liu W, Chen J, Sun X, Zhang Y, Chen Y. The Clinical Features and Genetic Spectrum of a Large Cohort of Chinese Patients With Vitelliform Macular Dystrophies. Am J Ophthalmol 2020; 216:69-79. [PMID: 32278767 DOI: 10.1016/j.ajo.2020.03.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 11/18/2022]
Abstract
PURPOSE To provide the clinical and genetic characteristics of a large cohort of Chinese patients with vitelliform macular dystrophies. DESIGN Cross-sectional study. METHODS One hundred and thirty-four unrelated Chinese patients diagnosed with Best vitelliform macular dystrophy (BVMD), autosomal recessive bestrophinopathy (ARB), or adult vitelliform macular dystrophy (AVMD) were enrolled. Detailed ophthalmic examinations and genetic testing on vitelliform macular dystrophy-related genes were performed. Genotype and phenotype association were analyzed among different diagnostic groups. RESULTS In total, 87 BVMD, 30 AVMD, and 17 ARB patients were enrolled in this study. Genetic analysis identified 37 BEST1 mutations in 53 patients with BVMD and ARB. Of these, 5 variants (c.254A>C, c.291C>G, c.722C>G, c.848_850del, c.1740-2A>C) were novel. The variant c.898G>A was a hotspot mutation, which was identified in 13 patients with BVMD and 1 patient with ARB. There were significant differences of ocular biometric parameters among patients with homozygous or compound heterozygous mutations, heterozygous mutations, and those without mutations of BEST1. Homozygous or compound heterozygous patients had shortest axial length (AL), shallowest anterior chamber depth (ACD), and highest intraocular pressure (IOP); patients without mutations had longest AL, deepest ACD, and lowest IOP; and heterozygous patients were in between. Moreover, 7 patients harboring heterozygous mutations in BEST1 and 3 patients without BEST1 mutations showed similar clinical appearance to ARB in our cohort. CONCLUSIONS This is the largest sample size study of Chinese vitelliform macular dystrophy patients. Our results indicated that assessment of angle-closure risk is a necessary consideration for all types of BEST1-related vitelliform macular dystrophies. The study expanded both the clinical and genetic findings of 3 common types of vitelliform macular dystrophies in a Chinese population.
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Affiliation(s)
- Yi Xuan
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Youjia Zhang
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Yuan Zong
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia, Fudan University, Chinese Academy of Medical Sciences, Shanghai, China
| | - Min Wang
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Lei Li
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Xiaofeng Ye
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Wei Liu
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Junyi Chen
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia, Fudan University, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia, Fudan University, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yongjin Zhang
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Yuhong Chen
- Department of Ophthalmology & Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia, Fudan University, Chinese Academy of Medical Sciences, Shanghai, China.
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6
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Gao FJ, Qi YH, Hu FY, Wang DD, Xu P, Guo JL, Li JK, Zhang YJ, Li W, Chen F, Xu GZ, Liu W, Chang Q, Wu JH. Mutation spectrum of the bestrophin-1 gene in a large Chinese cohort with bestrophinopathy. Br J Ophthalmol 2019; 104:846-851. [DOI: 10.1136/bjophthalmol-2019-314679] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/02/2019] [Accepted: 09/06/2019] [Indexed: 11/04/2022]
Abstract
BackgroundBestrophin-1 (BEST1) gene is associated with a wide range of ocular phenotypes, collectively termed as bestrophinopathy. The aim of the current study was to identify the mutation spectrum of BEST1 in a large cohort of Chinese patients with bestrophinopathy.MethodsPatients clinically suspected of bestrophinopathy were screened using multigene panel testing. All BEST1 variants were confirmed by Sanger sequencing, and validated in the families.FindingsA total of 92 patients (Best vitelliform macular dystrophy (BVMD)=77; autosomal recessive bestrophinopathy (ARB)=15) from 58 unrelated families of Chinese origin and their available family members (n=65) were recruited. Overall, 39 distinct disease-causing BEST1 variants were identified, including 13 novel variants, and two reported variants but novel for ARB. Of them, 14 were associated with ARB, 23 with BVMD and two (c.604C>T and c.898G>A) with both BVMD and ARB. Most mutations associated with BVMD were missense (97.78%), while ARB was associated with more complex mutations, including missense (88.46%), splicing effect (3.85%), and frameshifts (15.38%). BEST1 hotspots were c.898G>A and c.584C>T among BVMD and ARB patients, respectively. Hot regions were located in exons 8, 2 and 6 in BVMD patients, and in exons 5 and 7 in ARB patients. The overall penetrance of BEST1 in our cohort was 71.30%, no de novo mutations were identified.ConclusionThis is the largest study to date that provides major population-based data of the BEST1 mutation spectrum in China. Our results can serve as a well-founded reference for genetic counselling for patients with bestrophinopathy of Chinese origin.
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7
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Khan M, Cornelis SS, Khan MI, Elmelik D, Manders E, Bakker S, Derks R, Neveling K, van de Vorst M, Gilissen C, Meunier I, Defoort S, Puech B, Devos A, Schulz HL, Stöhr H, Grassmann F, Weber BHF, Dhaenens CM, Cremers FPM. Cost-effective molecular inversion probe-based ABCA4 sequencing reveals deep-intronic variants in Stargardt disease. Hum Mutat 2019; 40:1749-1759. [PMID: 31212395 DOI: 10.1002/humu.23787] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/18/2019] [Accepted: 04/29/2019] [Indexed: 12/17/2022]
Abstract
PURPOSE Stargardt disease (STGD1) is caused by biallelic mutations in ABCA4, but many patients are genetically unsolved due to insensitive mutation-scanning methods. We aimed to develop a cost-effective sequencing method for ABCA4 exons and regions carrying known causal deep-intronic variants. METHODS Fifty exons and 12 regions containing 14 deep-intronic variants of ABCA4 were sequenced using double-tiled single molecule Molecular Inversion Probe (smMIP)-based next-generation sequencing. DNAs of 16 STGD1 cases carrying 29 ABCA4 alleles and of four healthy persons were sequenced using 483 smMIPs. Thereafter, DNAs of 411 STGD1 cases with one or no ABCA4 variant were sequenced. The effect of novel noncoding variants on splicing was analyzed using in vitro splice assays. RESULTS Thirty-four ABCA4 variants previously identified in 16 STGD1 cases were reliably identified. In 155/411 probands (38%), two causal variants were identified. We identified 11 deep-intronic variants present in 62 alleles. Two known and two new noncanonical splice site variants showed splice defects, and one novel deep-intronic variant (c.4539+2065C>G) resulted in a 170-nt mRNA pseudoexon insertion (p.[Arg1514Lysfs*35,=]). CONCLUSIONS smMIPs-based sequence analysis of coding and selected noncoding regions of ABCA4 enabled cost-effective mutation detection in STGD1 cases in previously unsolved cases.
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Affiliation(s)
- Mubeen Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stéphanie S Cornelis
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Muhammad Imran Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Duaa Elmelik
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eline Manders
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sem Bakker
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronny Derks
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maartje van de Vorst
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Isabelle Meunier
- Institut des Neurosciences de Montpellier, INSERM, Université de Montpellier, Montpellier, France
| | - Sabine Defoort
- Service d'exploration de la vision et neuro-ophtalmologie, CHRU de Lille, Lille, France
| | - Bernard Puech
- Service d'exploration de la vision et neuro-ophtalmologie, CHRU de Lille, Lille, France
| | - Aurore Devos
- University of Lille, INSERM UMR-S1172, CHU Lille, Biochemistry and Molecular Biology Department, UF Genopathies, Lille, France
| | - Heidi L Schulz
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Heidi Stöhr
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Felix Grassmann
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany.,Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Bernhard H F Weber
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Claire-Marie Dhaenens
- University of Lille, INSERM UMR-S1172, CHU Lille, Biochemistry and Molecular Biology Department, UF Genopathies, Lille, France
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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Jonsson F, Westin IM, Österman L, Sandgren O, Burstedt M, Holmberg M, Golovleva I. ATP-binding cassette subfamily A, member 4 intronic variants c.4773+3A>G and c.5461-10T>C cause Stargardt disease due to defective splicing. Acta Ophthalmol 2018; 96:737-743. [PMID: 29461686 DOI: 10.1111/aos.13676] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/21/2017] [Indexed: 12/13/2022]
Abstract
PURPOSE Inherited retinal dystrophies (IRDs) represent a group of progressive conditions affecting the retina. There is a great genetic heterogeneity causing IRDs, and to date, more than 260 genes are associated with IRDs. Stargardt disease, type 1 (STGD1) or macular degeneration with flecks, STGD1 represents a disease with early onset, central visual impairment, frequent appearance of yellowish flecks and mutations in the ATP-binding cassette subfamily A, member 4 (ABCA4) gene. A large number of intronic sequence variants in ABCA4 have been considered pathogenic although their functional effect was seldom demonstrated. In this study, we aimed to reveal how intronic variants present in patients with Stargardt from the same Swedish family affect splicing. METHODS The splicing of the ABCA4 gene was studied in human embryonic kidney cells, HEK293T, and in human retinal pigment epithelium cells, ARPE-19, using a minigene system containing variants c.4773+3A>G and c.5461-10T>C. RESULTS We showed that both ABCA4 variants, c.4773+3A>G and c.5461-10T>C, cause aberrant splicing of the ABCA4 minigene resulting in exon skipping. We also demonstrated that splicing of ABCA4 has different outcomes depending on transfected cell type. CONCLUSION Two intronic variants c.4773+3A>G and c.5461-10T>C, both predicted to affect splicing, are indeed disease-causing mutations due to skipping of exons 33, 34, 39 and 40 of ABCA4 gene. The experimental proof that ABCA4 mutations in STGD patients affect protein function is crucial for their inclusion to future clinical trials; therefore, functional testing of all ABCA4 intronic variants associated with Stargardt disease by minigene technology is desirable.
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Affiliation(s)
- Frida Jonsson
- Medical Biosciences/Medical and Clinical Genetics; University of Umeå; Umeå Sweden
| | - Ida Maria Westin
- Medical Biosciences/Medical and Clinical Genetics; University of Umeå; Umeå Sweden
| | - Lennart Österman
- Medical Biosciences/Medical and Clinical Genetics; University of Umeå; Umeå Sweden
| | - Ola Sandgren
- Clinical Sciences/Ophthalmology; University of Umeå; Umeå Sweden
| | - Marie Burstedt
- Clinical Sciences/Ophthalmology; University of Umeå; Umeå Sweden
| | - Monica Holmberg
- Medical Biosciences/Medical and Clinical Genetics; University of Umeå; Umeå Sweden
| | - Irina Golovleva
- Medical Biosciences/Medical and Clinical Genetics; University of Umeå; Umeå Sweden
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Mutation screening in genes known to be responsible for Retinitis Pigmentosa in 98 Small Han Chinese Families. Sci Rep 2017; 7:1948. [PMID: 28512305 PMCID: PMC5434011 DOI: 10.1038/s41598-017-00963-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 03/03/2017] [Indexed: 01/10/2023] Open
Abstract
Retinitis pigmentosa (RP) is highly heterogeneous in both clinical and genetic fields. Accurate mutation screening is very beneficial in improving clinical diagnosis and gene-specific treatment of RP patients. The reason for the difficulties in genetic diagnosis of RP is that the ethnic-specific mutation databases that contain both clinical and genetic information are largely insufficient. In this study, we recruited 98 small Han Chinese families clinically diagnosed as RP, including of 22 dominant, 19 recessive, 52 sporadic, and five X-linked. We then used whole exome sequencing (WES) analysis to detect mutations in the genes known for RP in 101 samples from these 98 families. In total, we identified 57 potential pathogenic mutations in 40 of the 98 (41%) families in 22 known RP genes, including 45 novel mutations. We detected mutations in 13 of the 22 (59%) typical autosomal dominant families, 8 of the 19 (42%) typical autosomal recessive families, 16 of the 52 (31%) sporadic small families, and four of the five (80%) X-linked families. Our results extended the mutation spectrum of known RP genes in Han Chinese, thus making a contribution to RP gene diagnosis and the pathogenetic study of RP genes.
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Ramkumar HL, Gudiseva HV, Kishaba KT, Suk JJ, Verma R, Tadimeti K, Thorson JA, Ayyagari R. A Report on Molecular Diagnostic Testing for Inherited Retinal Dystrophies by Targeted Genetic Analyses. Genet Test Mol Biomarkers 2016; 21:66-73. [PMID: 28005406 DOI: 10.1089/gtmb.2016.0251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIM To test the utility of targeted sequencing as a method of clinical molecular testing in patients diagnosed with inherited retinal degeneration (IRD). METHODS After genetic counseling, peripheral blood was drawn from 188 probands and 36 carriers of IRD. Single gene testing was performed on each patient in a Clinical Laboratory Improvement Amendment (CLIA) certified laboratory. DNA was isolated, and all exons in the gene of interest were analyzed along with 20 base pairs of flanking intronic sequence. Genetic testing was most often performed on ABCA4, CTRP5, ELOV4, BEST1, CRB1, and PRPH2. Pathogenicity of novel sequence changes was predicted by PolyPhen2 and sorting intolerant from tolerant (SIFT). RESULTS Of the 225 genetic tests performed, 150 were for recessive IRD, and 75 were for dominant IRD. A positive molecular diagnosis was made in 70 (59%) of probands with recessive IRD and 19 (26%) probands with dominant IRD. Analysis confirmed 12 (34%) of individuals as carriers of familial mutations associated with IRD. Thirty-two novel variants were identified; among these, 17 sequence changes in four genes were predicted to be possibly or probably damaging including: ABCA4 (14), BEST1 (2), PRPH2 (1), and TIMP3 (1). CONCLUSIONS Targeted analysis of clinically suspected genes in 225 subjects resulted in a positive molecular diagnosis in 26% of patients with dominant IRD and 59% of patients with recessive IRD. Novel damaging mutations were identified in four genes. Single gene screening is not an ideal method for diagnostic testing given the phenotypic and genetic heterogeneity among IRD cases. High-throughput sequencing of all genes associated with retinal degeneration may be more efficient for molecular diagnosis.
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Affiliation(s)
- Hema L Ramkumar
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - Harini V Gudiseva
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - Kameron T Kishaba
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - John J Suk
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - Rohan Verma
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - Keerti Tadimeti
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
| | - John A Thorson
- 2 Department of Pathology, University of California , San Diego, La Jolla, California
| | - Radha Ayyagari
- 1 Shiley Eye Institute, Jacobs Retina Center, University of California , San Diego, La Jolla, California
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Ahmed K, Ahmed M, Potrata B, Willis TA, Grant HL, Allsop MJ, Hewison J, Downey L, Gale R, McKibbin M. Patient attitudes towards prenatal diagnostic testing for inherited retinal disease. Prenat Diagn 2015; 35:913-8. [PMID: 26126503 DOI: 10.1002/pd.4644] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 06/23/2015] [Accepted: 06/25/2015] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To explore factors that influence decision-making in relation to prenatal diagnostic testing (PDT) for inherited retinal disease (IRD). METHOD Semi-structured interviews were conducted with 50 adults with IRD, selected from a larger sample to provide a diversity of backgrounds and opinions on genetic testing. Interviews were transcribed verbatim and analysed using thematic analysis. RESULTS Mostly participants supported PDT, believing that it would provide information to help them prepare for and plan the future care of the child and the potential for early access to emerging therapies. Opposition to PDT stemmed from its use to justify termination of pregnancy, with participants feeling that it was not justified as they retained a good quality of life despite their visual impairment. Participants raised concerns about the risk of PDT and the accuracy of the results. However, most suggested that it should be available as an option for others, but for specific reasons and not as a part of routine care. CONCLUSION The variation in attitudes towards PDT and uncertainty about the risk and accuracy of results suggest that individuals at risk of having a child with IRD should have access to genetic counselling to support decision making.
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Affiliation(s)
- Khuram Ahmed
- Eye Clinic, St. James's University Hospital, Leeds, UK
| | - Mushtaq Ahmed
- Yorkshire Regional Genetics, Chapel Allerton Hospital, Leeds, UK
| | - Barbara Potrata
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK
| | - Thomas A Willis
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK
| | - Hilary L Grant
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK
| | - Matthew J Allsop
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK
| | - Jenny Hewison
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK
| | | | - Richard Gale
- York Teaching Hospital NHS Foundation Trust, York, UK
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12
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Manes G, Guillaumie T, Vos WL, Devos A, Audo I, Zeitz C, Marquette V, Zanlonghi X, Defoort-Dhellemmes S, Puech B, Said SM, Sahel JA, Odent S, Dollfus H, Kaplan J, Dufier JL, Le Meur G, Weber M, Faivre L, Cohen FB, Béroud C, Picot MC, Verdier C, Sénéchal A, Baudoin C, Bocquet B, Findlay JB, Meunier I, Dhaenens CM, Hamel CP. High prevalence of PRPH2 in autosomal dominant retinitis pigmentosa in france and characterization of biochemical and clinical features. Am J Ophthalmol 2015; 159:302-14. [PMID: 25447119 DOI: 10.1016/j.ajo.2014.10.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE To assess the prevalence of PRPH2 in autosomal dominant retinitis pigmentosa (adRP), to report 6 novel mutations, to characterize the biochemical features of a recurrent novel mutation, and to study the clinical features of adRP patients. DESIGN Retrospective clinical and molecular genetic study. METHODS Clinical investigations included visual field testing, fundus examination, high-resolution spectral-domain optical coherence tomography (OCT), fundus autofluorescence imaging, and electroretinogram (ERG) recording. PRPH2 was screened by Sanger sequencing in a cohort of 310 French families with adRP. Peripherin-2 protein was produced in yeast and analyzed by Western blot. RESULTS We identified 15 mutations, including 6 novel and 9 previously reported changes in 32 families, accounting for a prevalence of 10.3% in this adRP population. We showed that a new recurrent p.Leu254Gln mutation leads to protein aggregation, suggesting abnormal folding. The clinical severity of the disease in examined patients was moderate with 78% of the eyes having 1-0.5 of visual acuity and 52% of the eyes retaining more than 50% of the visual field. Some patients characteristically showed vitelliform deposits or macular involvement. In some families, pericentral RP or macular dystrophy were found in family members while widespread RP was present in other members of the same families. CONCLUSIONS The mutations in PRPH2 account for 10.3% of adRP in the French population, which is higher than previously reported (0%-8%) This makes PRPH2 the second most frequent adRP gene after RHO in our series. PRPH2 mutations cause highly variable phenotypes and moderate forms of adRP, including mild cases, which could be underdiagnosed.
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13
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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: 15] [Impact Index Per Article: 1.5] [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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15
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Current understanding of genetics and genetic testing and information needs and preferences of adults with inherited retinal disease. Eur J Hum Genet 2014; 22:1058-62. [PMID: 24398793 DOI: 10.1038/ejhg.2013.296] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 11/07/2013] [Accepted: 11/22/2013] [Indexed: 11/08/2022] Open
Abstract
Advances in sequencing technology and the movement of genetic testing into all areas of medicine will increase opportunities for molecular confirmation of a clinical diagnosis. For health-care professionals without formal genetics training, there is a need to know what patients understand about genetics and genetic testing and their information needs and preferences for the disclosure of genetic testing results. These topics were explored during face-to-face interviews with 50 adults with inherited retinal disease, selected in order to provide a diversity of opinions. Participants had variable understanding of genetics and genetic testing, including basic concepts such as inheritance patterns and the risk to dependents, and many did not understand the term 'genetic counselling'. Most were keen for extra information on the risk to others, the process for genetic testing and how to share the information with other family members. Participants were divided as to whether genetic testing should be offered at the time of the initial diagnosis or later. Many would prefer the results to be given by face-to-face consultation, supplemented by further information in a format accessible to those with visual impairment. Health-care professionals and either leaflets or websites of trusted agencies were the preferred sources of information. Permission should be sought for disclosure of genetic information to other family members. The information needs of many patients with inherited retinal disease appear to be unmet. An understanding of their information needs and preferences is required to help health-care professionals provide optimal services that meet patient expectations.
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Pasquay C, Wang LF, Lorenz B, Preising MN. Bestrophin 1 – Phenotypes and Functional Aspects in Bestrophinopathies. Ophthalmic Genet 2013; 36:193-212. [DOI: 10.3109/13816810.2013.863945] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Fujinami K, Zernant J, Chana RK, Wright GA, Tsunoda K, Ozawa Y, Tsubota K, Webster AR, Moore AT, Allikmets R, Michaelides M. ABCA4 gene screening by next-generation sequencing in a British cohort. Invest Ophthalmol Vis Sci 2013; 54:6662-74. [PMID: 23982839 DOI: 10.1167/iovs.13-12570] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We applied a recently reported next-generation sequencing (NGS) strategy for screening the ABCA4 gene in a British cohort with ABCA4-associated disease and report novel mutations. METHODS We identified 79 patients with a clinical diagnosis of ABCA4-associated disease who had a single variant identified by the ABCA4 microarray. Comprehensive phenotypic data were obtained, and the NGS strategy was applied to identify the second allele by means of sequencing the entire coding region and adjacent intronic sequences of the ABCA4 gene. Identified variants were confirmed by Sanger sequencing and assessed for pathogenicity by in silico analysis. RESULTS Of the 42 variants detected by prescreening with the microarray, in silico analysis suggested that 34, found in 66 subjects, were disease-causing and 8, found in 13 subjects, were benign variants. We detected 42 variants by NGS, of which 39 were classified as disease-causing. Of these 39 variants, 31 were novel, including 16 missense, 7 splice-site-altering, 4 nonsense, 1 in-frame deletion, and 3 frameshift variants. Two or more disease-causing variants were confirmed in 37 (47%) of 79 patients, one disease-causing variant in 36 (46%) subjects, and no disease-causing variant in 6 (7%) individuals. CONCLUSIONS Application of the NGS platform for ABCA4 screening enabled detection of the second disease-associated allele in approximately half of the patients in a British cohort where one mutation had been detected with the arrayed primer extension (APEX) array. The time- and cost-efficient NGS strategy is useful in screening large cohorts, which will be increasingly valuable with the advent of ABCA4-directed therapies.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
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Braun TA, Mullins RF, Wagner AH, Andorf JL, Johnston RM, Bakall BB, Deluca AP, Fishman GA, Lam BL, Weleber RG, Cideciyan AV, Jacobson SG, Sheffield VC, Tucker BA, Stone EM. Non-exomic and synonymous variants in ABCA4 are an important cause of Stargardt disease. Hum Mol Genet 2013; 22:5136-45. [PMID: 23918662 PMCID: PMC3842174 DOI: 10.1093/hmg/ddt367] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mutations in ABCA4 cause Stargardt disease and other blinding autosomal recessive retinal disorders. However, sequencing of the complete coding sequence in patients with clinical features of Stargardt disease sometimes fails to detect one or both mutations. For example, among 208 individuals with clear clinical evidence of ABCA4 disease ascertained at a single institution, 28 had only one disease-causing allele identified in the exons and splice junctions of the primary retinal transcript of the gene. Haplotype analysis of these 28 probands revealed 3 haplotypes shared among ten families, suggesting that 18 of the 28 missing alleles were rare enough to be present only once in the cohort. We hypothesized that mutations near rare alternate splice junctions in ABCA4 might cause disease by increasing the probability of mis-splicing at these sites. Next-generation sequencing of RNA extracted from human donor eyes revealed more than a dozen alternate exons that are occasionally incorporated into the ABCA4 transcript in normal human retina. We sequenced the genomic DNA containing 15 of these minor exons in the 28 one-allele subjects and observed five instances of two different variations in the splice signals of exon 36.1 that were not present in normal individuals (P < 10−6). Analysis of RNA obtained from the keratinocytes of patients with these mutations revealed the predicted alternate transcript. This study illustrates the utility of RNA sequence analysis of human donor tissue and patient-derived cell lines to identify mutations that would be undetectable by exome sequencing.
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A clinical molecular genetic service for United Kingdom families with choroideraemia. Eur J Med Genet 2013; 56:432-8. [DOI: 10.1016/j.ejmg.2013.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 06/17/2013] [Indexed: 11/20/2022]
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Dawn of ocular gene therapy: implications for molecular diagnosis in retinal disease. SCIENCE CHINA-LIFE SCIENCES 2013; 56:125-33. [PMID: 23393028 DOI: 10.1007/s11427-013-4443-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/28/2012] [Indexed: 12/26/2022]
Abstract
Personalized medicine aims to utilize genomic information about patients to tailor treatment. Gene replacement therapy for rare genetic disorders is perhaps the most extreme form of personalized medicine, in that the patients' genome wholly determines their treatment regimen. Gene therapy for retinal disorders is poised to become a clinical reality. The eye is an optimal site for gene therapy due to the relative ease of precise vector delivery, immune system isolation, and availability for monitoring of any potential damage or side effects. Due to these advantages, clinical trials for gene therapy of retinal diseases are currently underway. A necessary precursor to such gene therapies is accurate molecular diagnosis of the mutation(s) underlying disease. In this review, we discuss the application of Next Generation Sequencing (NGS) to obtain such a diagnosis and identify disease causing genes, using retinal disorders as a case study. After reviewing ocular gene therapy, we discuss the application of NGS to the identification of novel Mendelian disease genes. We then compare current, array based mutation detection methods against next NGS-based methods in three retinal diseases: Leber's Congenital Amaurosis, Retinitis Pigmentosa, and Stargardt's disease. We conclude that next-generation sequencing based diagnosis offers several advantages over array based methods, including a higher rate of successful diagnosis and the ability to more deeply and efficiently assay a broad spectrum of mutations. However, the relative difficulty of interpreting sequence results and the development of standardized, reliable bioinformatic tools remain outstanding concerns. In this review, recent advances NGS based molecular diagnoses are discussed, as well as their implications for the development of personalized medicine.
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A novel compound heterozygous mutation in the BEST1 gene causes autosomal recessive Best vitelliform macular dystrophy. Eye (Lond) 2012; 26:866-71. [PMID: 22422030 DOI: 10.1038/eye.2012.27] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE To determine the genetic basis of early onset autosomal recessive Best vitelliform macular dystrophy (arBVMD) in a family with three affected children. DESIGN Clinical and family-based genetic study. METHODS Seven subjects making up a family with three children affected by Best vitelliform macular dystrophy were studied. Standard ophthalmic exam with dilated ophthalmoscopy and imaging were performed in each individual. The eleven exons of BEST1 were directly sequenced. RESULTS All three affected children have the clinical characteristic features of Best vitelliform macular dystrophy: large macular vitelliform lesions, scattered vitelliform lesions along the arcades and in the peripheral retina, and an accumulation of serous retinal fluid. A novel compound heterozygous mutation in the BEST1 gene was found in the three affected individuals (L41P and I201T). The unaffected parents and children only harbor one heterozygous mutation. CONCLUSION arBVMD can be caused by the compound heterozygous mutation L41P and I201T in the BEST1 gene.
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Duno M, Schwartz M, Larsen PL, Rosenberg T. Phenotypic and genetic spectrum of Danish patients with ABCA4-related retinopathy. Ophthalmic Genet 2012; 33:225-31. [PMID: 22229821 DOI: 10.3109/13816810.2011.643441] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Pathogenic variations in the ABCA4 gene were originally recognized as genetic background for the autosomal recessive disorders Stargardt disease and fundus flavimaculatus, but have expanded to embrace a diversity of retinal diseases, giving rise to the new diagnostic term, ABCA4-related retinopathy. Diagnostic genotyping of ABCA4 is complicated by the large size of the gene and the existence of approximately 600 known pathogenic variations, along with numerous rare polymorphisms. A commercial diagnostic array-based assay has been developed targeting known mutations, however a conclusive genetic diagnosis must rely on a comprehensive genetic screening as the mutation spectrum of ABCA4-related retinopathies continues to expand. MATERIAL AND METHODS Among 161 patients with a Stargardt-related phenotype previously assessed with the commercial ABCA4 mutation microarray, we analyzed the ABCA4 gene with High-resolution melting (HRM) in patients in whom the array analysis identified either a heterozygous mutation (n = 50) or no mutation (n = 30). RESULTS The HRM method detected each of the already known mutations and polymorphisms. We identified the second ABCA4 mutation in 31 of 50 heterozygous patients (62%). Several novel mutations were identified of which four were identified multiple times. The recurrent novel mutations were subsequently assessed among the 30 patients with possible ABCA4-related diseases, previously found to be negative for known ABCA4 mutations by array analysis. In total, 30 different mutations were identified of which 21 have not been described before. CONCLUSION Scandinavian patients with ABCA4-related retinopathy appear to have a distinct mutation spectrum, which can be identified in patients of diverse clinical phenotypes.
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Affiliation(s)
- Morten Duno
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Denmark.
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Song J, Smaoui N, Ayyagari R, Stiles D, Benhamed S, MacDonald IM, Daiger SP, Tumminia SJ, Hejtmancik F, Wang X. High-throughput retina-array for screening 93 genes involved in inherited retinal dystrophy. Invest Ophthalmol Vis Sci 2011; 52:9053-60. [PMID: 22025579 DOI: 10.1167/iovs.11-7978] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Retinal dystrophy (RD) is a broad group of hereditary disorders with heterogeneous genotypes and phenotypes. Current available genetic testing for these diseases is complicated, time consuming, and expensive. This study was conducted to develop and apply a microarray-based, high-throughput resequencing system to detect sequence alterations in genes related to inherited RD. METHODS A customized 300-kb resequencing chip, Retina-Array, was developed to detect sequence alterations of 267,550 bases of both sense and antisense sequence in 1470 exons spanning 93 genes involved in inherited RD. Retina-Array was evaluated in 19 patient samples with inherited RD provided by the eyeGENE repository and four Centre d'Etudes du Polymorphisme Humaine reference samples through a high-throughput experimental approach that included an automated PCR assay setup and quantification, efficient post-quantification data processing, optimized pooling and fragmentation, and standardized chip processing. RESULTS The performance of the chips demonstrated that the average base pair call rate and accuracy were 93.56% and 99.86%, respectively. In total, 304 candidate variations were identified using a series of customized screening filters. Among 174 selected variations, 123 (70.7%) were further confirmed by dideoxy sequencing. Analysis of patient samples using Retina-Array resulted in the identification of 10 known mutations and 12 novel variations with high probability of deleterious effects. CONCLUSIONS This study suggests that Retina-Array might be a valuable tool for the detection of disease-causing mutations and disease severity modifiers in a single experiment. Retinal-Array may provide a powerful and feasible approach through which to study genetic heterogeneity in retinal diseases.
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Affiliation(s)
- Jin Song
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda,MD 20892, USA
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MacDonald IM, Gudiseva HV, Villanueva A, Greve M, Caruso R, Ayyagari R. Phenotype and genotype of patients with autosomal recessive bestrophinopathy. Ophthalmic Genet 2011; 33:123-9. [PMID: 21809908 DOI: 10.3109/13816810.2011.592172] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To describe the phenotype and genotype of patients with autosomal recessive bestrophinopathy. METHODOLOGY The phenotype of the subjects was described after a complete ophthalmological examination, and in various cases, ancillary testing of the visual field, optical coherent tomography, full field electroretinography and electrophysiology. Genetic analysis was carried out by screening the Bestrophin-1 (BEST1) gene for mutations by dideoxy sequencing and segregation analysis. RESULTS We identified three previously described mutations (Ala195Val, Leu191Pro and Arg141His) and two potentially pathogenic changes (Trp93Pro and Trp287Ter) in the Best-1 gene. Two patients carried compound heterozygous mutations, Trp93Pro/Ala195Val, and Leu191Pro/Trp287Ter. Two sisters were homozygous for an Arg141His mutation. All individuals with Best1 gene mutations had signs of maculopathy. CONCLUSIONS Our observations expand the limited number of phenotypes associated with mutations in the Best1 gene. Patients with compound heteroyzygous Best1 mutations developed atypical forms of Best disease. Two siblings with homozygous Arg141His mutation developed symptoms of typical Best vitelliform dystrophy while their parents had clinical features of mild maculopathy.
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A novel missense mutation in the rds/peripherin gene associated with retinal pattern dystrophy. Retin Cases Brief Rep 2010; 4:84-5. [PMID: 25390130 DOI: 10.1097/icb.0b013e318198d8f7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To present a case of retinal pattern dystrophy and the genetic analysis identifying the molecular basis of the disease. METHODS A 46-year-old man with a 6-year history of vision loss of the right eye. A clinical exam revealed pattern dystrophy of the retina bilaterally, with more involvement of the right eye. RESULTS Molecular diagnostic analysis of the retinal degeneration slow (RDS)/peripherin gene showed a novel change at nucleotide position 665 (G665C) that alters the amino acid at position 222 from cysteine to serine (C222S). CONCLUSION This study describes an RDS/peripherin mutation in a case of retinal pattern dystrophy, which is the first identification of this mutation to our knowledge.
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Tosi J, Tsui I, Lima LH, Wang NK, Tsang SH. Case report: autofluorescence imaging and phenotypic variance in a sibling pair with early-onset retinal dystrophy due to defective CRB1 function. Curr Eye Res 2009; 34:395-400. [PMID: 19401883 DOI: 10.1080/02713680902859639] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PURPOSE To phenotype two siblings with autosomal recessive early-onset retinal dystrophy due to CRB1 mutations. METHODS Autofluorescence (AF) imaging, high resolution optical coherence tomography (OCT), and full-field electroretinography (ERG) were performed. The results of DNA sequencing from polymerase chain reaction (PCR) products of the CRB1 gene were obtained from hospital records. RESULTS Two siblings, 14 years old and 17 years old, were compound heterozygotes for 749 del Ser and C948Y mutations in the gene encoding CRB1. AF imaging documented the preservation of retinal pigment epithelium (RPE) along the arterioles. High-resolution OCT showed abnormally thick retinae with increased lamination. CONCLUSION Leber congenital amaurosis caused by CRB1 is a unique form of early-onset retinal dystrophy because it spares the para-arteriolar RPE and causes abnormal retinal lamination with thickening. These findings, detectable with AF imaging and high-resolution OCT, can be combined with electrophysiology and genetic testing to molecularly classify retinal degenerations efficiently.
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Affiliation(s)
- Joaquin Tosi
- Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, New York, USA
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Bekaert M, Teeling EC. UniPrime: a workflow-based platform for improved universal primer design. Nucleic Acids Res 2008; 36:e56. [PMID: 18424794 PMCID: PMC2425486 DOI: 10.1093/nar/gkn191] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UniPrime is an open-source software (http://uniprime.batlab.eu), which automatically designs large sets of universal primers by simply inputting a gene ID reference. UniPrime automatically retrieves and aligns homologous sequences from GenBank, identifies regions of conservation within the alignment and generates suitable primers that can amplify variable genomic regions. UniPrime differs from previous automatic primer design programs in that all steps of primer design are automated, saved and are phylogenetically limited. We have experimentally verified the efficiency and success of this program by amplifying and sequencing four diverse genes (AOF2, EFEMP1, LRP6 and OAZ1) across multiple Orders of mammals. UniPrime is an experimentally validated, fully automated program that generates successful cross-species primers that take into account the biological aspects of the PCR.
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Affiliation(s)
- Michaël Bekaert
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
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28
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Roberts L, Rebello G, Ramesar R, Greenberg J. Management of a South African family with retinitis pigmentosa-should potential therapy influence translational research protocols? J Ocul Biol Dis Infor 2008; 1:55-8. [PMID: 20072635 PMCID: PMC2802413 DOI: 10.1007/s12177-008-9001-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 02/13/2008] [Indexed: 11/28/2022] Open
Abstract
Mutation analysis of retinal candidate genes is performed as part of an ongoing research to identify the causative genetic defect in South African families with retinal degenerative disorders (RDDs). A translational research protocol has been established whereby probands are counseled and given their molecular genetic results to take back to other family members, who can then request individual diagnostic testing. A Thr17Met mutation of the rhodopsin gene was identified in a Caucasian South African family with autosomal dominant retinitis pigmentosa. Patients with this mutation appear to benefit from treatment using oral vitamin A supplementation. This family has been informed that a molecular diagnosis is available; however, one individual has refused testing and none of the younger generation has shown interest in receiving molecular results or genetic counseling. Adapting the established protocol for the translation of RDD research results and contacting mutation positive individuals may be justifiable in light of the potential benefit of therapy.
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Burgess R, Millar ID, Leroy BP, Urquhart JE, Fearon IM, De Baere E, Brown PD, Robson AG, Wright GA, Kestelyn P, Holder GE, Webster AR, Manson FDC, Black GCM. Biallelic mutation of BEST1 causes a distinct retinopathy in humans. Am J Hum Genet 2008; 82:19-31. [PMID: 18179881 DOI: 10.1016/j.ajhg.2007.08.004] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 08/03/2007] [Accepted: 08/14/2007] [Indexed: 11/18/2022] Open
Abstract
We describe a distinct retinal disorder, autosomal-recessive bestrophinopathy (ARB), that is consequent upon biallelic mutation in BEST1 and is associated with central visual loss, a characteristic retinopathy, an absent electro-oculogram light rise, and a reduced electroretinogram. Heterozygous mutations in BEST1 have previously been found to cause the two dominantly inherited disorders, Best macular dystrophy and autosomal-dominant vitreoretinochoroidopathy. The transmembrane protein bestrophin-1, encoded by BEST1, is located at the basolateral membrane of the retinal pigment epithelium in which it probably functions as a Cl(-) channel. We sequenced BEST1 in five families, identifying DNA variants in each of ten alleles. These encoded six different missense variants and one nonsense variant. The alleles segregated appropriately for a recessive disorder in each family. No clinical or electrophysiological abnormalities were identified in any heterozygotes. We conducted whole-cell patch-clamping of HEK293 cells transfected with bestrophin-1 to measure the Cl(-) current. Two ARB missense isoforms severely reduced channel activity. However, unlike two other alleles previously associated with Best disease, cotransfection with wild-type bestrophin-1 did not impair the formation of active wild-type bestrophin-1 channels, consistent with the recessive nature of the condition. We propose that ARB is the null phenotype of bestrophin-1 in humans.
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Affiliation(s)
- Rosemary Burgess
- Academic Unit of Medical Genetics and Regional Genetics Service, St. Mary's Hospital, Hathersage Road, Manchester M13 0JH, UK
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