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Milibari D, Nowilaty SR, Ba-Abbad R. The Clinical and Mutational Spectrum of Bardet-Biedl Syndrome in Saudi Arabia. Genes (Basel) 2024; 15:762. [PMID: 38927698 PMCID: PMC11202873 DOI: 10.3390/genes15060762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/02/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
The retinal features of Bardet-Biedl syndrome (BBS) are insufficiently characterized in Arab populations. This retrospective study investigated the retinal features and genotypes of BBS in Saudi patients managed at a single tertiary eye care center. Data analysis of the identified 46 individuals from 31 families included visual acuity (VA), systemic manifestations, multimodal retinal imaging, electroretinography (ERG), family pedigrees, and genotypes. Patients were classified to have cone-rod, rod-cone, or generalized photoreceptor dystrophy based on the pattern of macular involvement on the retinal imaging. Results showed that nyctalopia and subnormal VA were the most common symptoms with 76% having VA ≤ 20/200 at the last visit (age: 5-35). Systemic features included obesity 91%, polydactyly 56.5%, and severe cognitive impairment 33%. The predominant retinal phenotype was cone-rod dystrophy 75%, 10% had rod-cone dystrophy and 15% had generalized photoreceptor dystrophy. ERGs were undetectable in 95% of patients. Among the 31 probands, 61% had biallelic variants in BBSome complex genes, 32% in chaperonin complex genes, and 6% had biallelic variants in ARL6; including six previously unreported variants. Interfamilial and intrafamilial variabilities were noted, without a clear genotype-phenotype correlation. Most BBS patients had advanced retinopathy and were legally blind by early adulthood, indicating a narrow therapeutic window for rescue strategies.
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Affiliation(s)
- Doaa Milibari
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh 12211, Saudi Arabia; (D.M.); (S.R.N.)
- Department of Ophthalmology, King Abdullah Medical City, Makkah 24211, Saudi Arabia
| | - Sawsan R. Nowilaty
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh 12211, Saudi Arabia; (D.M.); (S.R.N.)
| | - Rola Ba-Abbad
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh 12211, Saudi Arabia; (D.M.); (S.R.N.)
- Ocular Genetics Services, King Khaled Eye Specialist Hospital, Riyadh 12211, Saudi Arabia
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2
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Deitch I, Itskov S, Panneman D, Abu Shtaya A, Saban T, Goldberg Y, Ehrenberg M, Cremers FPM, Roosing S, Ben-Yosef T. Autosomal Recessive Rod-Cone Dystrophy with Mild Extra-Ocular Manifestations Due to a Splice-Affecting Variant in BBS9. Curr Issues Mol Biol 2024; 46:2566-2575. [PMID: 38534779 DOI: 10.3390/cimb46030163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/14/2024] [Accepted: 03/14/2024] [Indexed: 03/28/2024] Open
Abstract
Bardet-Biedl syndrome (BBS), one of the most common forms of syndromic inherited retinal diseases (IRDs), is characterized by the combination of retinal degeneration with additional extra-ocular manifestations, including obesity, intellectual disability, kidney disease, polydactyly and other skeletal abnormalities. We observed an Israeli patient with autosomal recessive apparently non-syndromic rod-cone dystrophy (RCD). Extra-ocular findings were limited to epilepsy and dental problems. Genetic analysis with a single molecule molecular inversion probes-based panel that targets the exons and splice sites of 113 genes associated with retinitis pigmentosa and Leber congenital amaurosis revealed a homozygous rare missense variant in the BBS9 gene (c.263C>T;p.(Ser88Leu)). This variant, which affects a highly conserved amino acid, is also located in the last base of Exon 3, and predicted to be splice-altering. An in vitro minigene splice assay demonstrated that this variant leads to the partial aberrant splicing of Exon 3. Therefore, we suggest that this variant is likely hypomorphic. This is in agreement with the relatively mild phenotype observed in the patient. Hence, the findings in our study expand the phenotypic spectrum associated with BBS9 variants and indicate that variants in this gene should be considered not only in BBS patients but also in individuals with non-syndromic IRD or IRD with very mild extra-ocular manifestations.
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Affiliation(s)
- Iris Deitch
- Rabin Medical Center, Department of Ophthalmology, Petach Tikva 4941492, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sofia Itskov
- Ruth & Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Daan Panneman
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Aasem Abu Shtaya
- Raphael Recanati Genetic Institute, Rabin Medical Center, Beilinson Hospital, Petach Tikva 4941492, Israel
- Unit of Gastroenterology, Carmel Medical Center, Haifa 3436212, Israel
| | - Tal Saban
- Rabin Medical Center, Department of Ophthalmology, Petach Tikva 4941492, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yael Goldberg
- Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Raphael Recanati Genetic Institute, Rabin Medical Center, Beilinson Hospital, Petach Tikva 4941492, Israel
| | - Miriam Ehrenberg
- Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Schneider Children's Medical Center of Israel, Department of Ophthalmology, Petach Tikva 4920235, Israel
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Tamar Ben-Yosef
- Ruth & Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 3109601, Israel
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3
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Dueñas Rey A, Del Pozo Valero M, Bouckaert M, Wood KA, Van den Broeck F, Daich Varela M, Thomas HB, Van Heetvelde M, De Bruyne M, Van de Sompele S, Bauwens M, Lenaerts H, Mahieu Q, Josifova D, Rivolta C, O'Keefe RT, Ellingford J, Webster AR, Arno G, Ayuso C, De Zaeytijd J, Leroy BP, De Baere E, Coppieters F. Combining a prioritization strategy and functional studies nominates 5'UTR variants underlying inherited retinal disease. Genome Med 2024; 16:7. [PMID: 38184646 PMCID: PMC10771650 DOI: 10.1186/s13073-023-01277-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 12/15/2023] [Indexed: 01/08/2024] Open
Abstract
BACKGROUND 5' untranslated regions (5'UTRs) are essential modulators of protein translation. Predicting the impact of 5'UTR variants is challenging and rarely performed in routine diagnostics. Here, we present a combined approach of a comprehensive prioritization strategy and functional assays to evaluate 5'UTR variation in two large cohorts of patients with inherited retinal diseases (IRDs). METHODS We performed an isoform-level re-analysis of retinal RNA-seq data to identify the protein-coding transcripts of 378 IRD genes with highest expression in retina. We evaluated the coverage of their 5'UTRs by different whole exome sequencing (WES) kits. The selected 5'UTRs were analyzed in whole genome sequencing (WGS) and WES data from IRD sub-cohorts from the 100,000 Genomes Project (n = 2397 WGS) and an in-house database (n = 1682 WES), respectively. Identified variants were annotated for 5'UTR-relevant features and classified into seven categories based on their predicted functional consequence. We developed a variant prioritization strategy by integrating population frequency, specific criteria for each category, and family and phenotypic data. A selection of candidate variants underwent functional validation using diverse approaches. RESULTS Isoform-level re-quantification of retinal gene expression revealed 76 IRD genes with a non-canonical retina-enriched isoform, of which 20 display a fully distinct 5'UTR compared to that of their canonical isoform. Depending on the probe design, 3-20% of IRD genes have 5'UTRs fully captured by WES. After analyzing these regions in both cohorts, we prioritized 11 (likely) pathogenic variants in 10 genes (ARL3, MERTK, NDP, NMNAT1, NPHP4, PAX6, PRPF31, PRPF4, RDH12, RD3), of which 7 were novel. Functional analyses further supported the pathogenicity of three variants. Mis-splicing was demonstrated for the PRPF31:c.-9+1G>T variant. The MERTK:c.-125G>A variant, overlapping a transcriptional start site, was shown to significantly reduce both luciferase mRNA levels and activity. The RDH12:c.-123C>T variant was found in cis with the hypomorphic RDH12:c.701G>A (p.Arg234His) variant in 11 patients. This 5'UTR variant, predicted to introduce an upstream open reading frame, was shown to result in reduced RDH12 protein but unaltered mRNA levels. CONCLUSIONS This study demonstrates the importance of 5'UTR variants implicated in IRDs and provides a systematic approach for 5'UTR annotation and validation that is applicable to other inherited diseases.
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Affiliation(s)
- Alfredo Dueñas Rey
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Marta Del Pozo Valero
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz, University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - Manon Bouckaert
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Katherine A Wood
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Filip Van den Broeck
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
| | - Malena Daich Varela
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Huw B Thomas
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Mattias Van Heetvelde
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Marieke De Bruyne
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Stijn Van de Sompele
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Miriam Bauwens
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Hanne Lenaerts
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Quinten Mahieu
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | | | - Carlo Rivolta
- Department of Ophthalmology, University of Basel, Basel, Switzerland
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Raymond T O'Keefe
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Jamie Ellingford
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
- Genomics England, London, UK
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Carmen Ayuso
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz, University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Julie De Zaeytijd
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
| | - Bart P Leroy
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
- Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elfride De Baere
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Frauke Coppieters
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium.
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium.
- Department of Pharmaceutics, Ghent University, Ghent, Belgium.
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4
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Zhong J, Xie Y, Ye H, Chen C, Sun T, Xu K, Zhang X, Li Y. Phenotypic diversity observed in a Chinese patient cohort with biallelic variants in Bardet-Biedl syndrome genes. Eye (Lond) 2023; 37:3398-3405. [PMID: 37031301 PMCID: PMC10630479 DOI: 10.1038/s41433-023-02516-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 02/19/2023] [Accepted: 03/27/2023] [Indexed: 04/10/2023] Open
Abstract
PURPOSE Bardet-Biedl syndrome (BBS) is a rare multisystem ciliopathy. The aim of this study was to describe the clinical and genetic features of a cohort of Chinese patients carrying biallelic BBS gene variants. METHODS We recruited 34 patients from 31 unrelated pedigrees who carried biallelic pathogenic variants in BBS genes. All patients underwent ophthalmic and systematic evaluations, as well as comprehensive molecular genetic analyses. Ultimately, 14 patients were followed up over time. RESULTS We identified 47 diseasing-causing variants in 10 BBS genes; 33 were novel. Diagnosis of BBS and non-syndromic retinitis pigmentosa (RP) were established in 28 patients from 27 pedigrees and 6 patients, respectively. The two most prevalent genes in patients with BBS were BBS2 and BBS4, accounting for 51.8% of the probands. The patients exhibited clinical heterogeneity, from patients with all six primary clinical components to patients suffering from non-syndromic RP. The common components were retinal dystrophy, polydactyly, and obesity, with frequencies of 78.6% to 100%, while renal anomaly frequencies were only 7.1%. Patients exhibited early and severe visual defects and retinal degeneration. Patients with biallelic missense variants in BBS2 suffered fewer clinical symptoms and mild visual impairment. Patients with BBS10 variants tended to have cone dystrophy. CONCLUSIONS Our study defined the mutated gene profiles and established the configuration of the variation frequencies for each BBS gene in Chinese patients. Overall, our patients showed early and severe visual defects and retinal degeneration. Genetic analysis is therefore crucial for diagnosis, genetic counseling, and future gene therapy in these patients.
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Affiliation(s)
- Junwei Zhong
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Yue Xie
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | | | - Chunjie Chen
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Tengyang Sun
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Ke Xu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Xiaohui Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Yang Li
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China.
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5
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Ruiz-Ceja KA, Capasso D, Pinelli M, Del Prete E, Carrella D, di Bernardo D, Banfi S. Definition of the transcriptional units of inherited retinal disease genes by meta-analysis of human retinal transcriptome data. BMC Genomics 2023; 24:206. [PMID: 37072692 PMCID: PMC10111803 DOI: 10.1186/s12864-023-09300-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 04/07/2023] [Indexed: 04/20/2023] Open
Abstract
BACKGROUND Inherited retinal diseases (IRD) are genetically heterogeneous disorders that cause the dysfunction or loss of photoreceptor cells and ultimately lead to blindness. To date, next-generation sequencing procedures fail to detect pathogenic sequence variants in coding regions of known IRD disease genes in about 30-40% of patients. One of the possible explanations for this missing heritability is the presence of yet unidentified transcripts of known IRD genes. Here, we aimed to define the transcript composition of IRD genes in the human retina by a meta-analysis of publicly available RNA-seq datasets using an ad-hoc designed pipeline. RESULTS We analysed 218 IRD genes and identified 5,054 transcripts, 3,367 of which were not previously reported. We assessed their putative expression levels and focused our attention on 435 transcripts predicted to account for at least 5% of the expression of the corresponding gene. We looked at the possible impact of the newly identified transcripts at the protein level and experimentally validated a subset of them. CONCLUSIONS This study provides an unprecedented, detailed overview of the complexity of the human retinal transcriptome that can be instrumental in contributing to the resolution of some cases of missing heritability in IRD patients.
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Affiliation(s)
- Karla Alejandra Ruiz-Ceja
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Program in Molecular Life Science, University of Campania "Luigi Vanvitelli", Via Vivaldi, 43, 81100, Caserta, Italy
| | - Dalila Capasso
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Scuola Superiore Meridionale (SSM, School of Advanced Studies), Genomic and Experimental Medicine Program, University of Naples "Federico II", Largo S. Marcellino, 10, 80138, Napoli, Italy
| | - Michele Pinelli
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Eugenio Del Prete
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Diego Carrella
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Diego di Bernardo
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Chemical Engineering, University of Naples "Federico II", Piazzale Tecchio, 80, 80125, Napoli, Italy
| | - Sandro Banfi
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy.
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", Via de Crecchio, 7, 80138, Napoli, Italy.
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Sangermano R, Galdikaité-Braziené E, Bujakowska KM. Non-syndromic Retinal Degeneration Caused by Pathogenic Variants in Joubert Syndrome Genes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:173-182. [PMID: 37440031 DOI: 10.1007/978-3-031-27681-1_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Inherited retinal degenerations (IRDs) are a group of genetic disorders characterized by progressive dysfunction and loss of photoreceptors. IRDs are classified as non-syndromic or syndromic, depending on whether retinal degeneration manifests alone or in combination with other associated symptoms. Joubert syndrome (JBTS) is a genetically and clinically heterogeneous disorder affecting the central nervous system and other organs and tissues, including the neuroretina. To date, 39 genes have been associated with JBTS, a majority of which encode structural or functional components of the primary cilium, a specialized sensory organelle present in most post-mitotic cells, including photoreceptors. The use of whole exome and IRD panel next-generation sequencing in routine diagnostics of non-syndromic IRD cases led to the discovery of pathogenic variants in JBTS genes that cause photoreceptor loss without other syndromic features. Here, we recapitulate these findings, describing the JBTS gene defects leading to non-syndromic IRDs.
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Affiliation(s)
- Riccardo Sangermano
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Egle Galdikaité-Braziené
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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Mizumoto K, Kato K, Fujinami K, Sugita T, Sugita I, Hattori A, Saitoh S, Ueno S, Tsunoda K, Iwata T, Kondo M. A Japanese boy with Bardet-Biedl syndrome caused by a novel homozygous variant in the ARL6 gene who was initially diagnosed with retinitis punctata albescens: A case report. Medicine (Baltimore) 2022; 101:e32161. [PMID: 36550847 PMCID: PMC9771268 DOI: 10.1097/md.0000000000032161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Bardet-Biedl Syndrome (BBS) is an autosomal recessive systemic disorder characterized by retinitis pigmentosa, polydactyly, obesity, intellectual disability, renal impairments, and hypogonadism. The purpose of this study was to determine the ocular characteristics of a boy with BBS caused by a novel homozygous variant in the ARL6 (alternative named BBS3) gene who had been originally diagnosed with retinitis punctata albescens. METHODS This was an observational case study. The patient underwent ophthalmological examinations, electroretinography, and genetic analyses using whole-exome sequencing. RESULTS A 7-year-old boy was examined in our hospital with complaints of a progressive reduction of his visual acuity and night blindness in both eyes. There was no family history of eye diseases and no consanguineous marriage. Fundus examinations showed numerous white spots in the deep retina and retinal pigment epithelium. Fundus autofluorescence showed hypofluorescence consistent with these spots. Both the scotopic and photopic components of the full-field electroretinographies were non-detectable. Based on these clinical findings, this boy was suspected to have retinitis punctata albescens. Subsequent genetic testing using whole-exome sequencing revealed a novel homozygous variants in the ARL6/BBS3 gene (NM_001278293.3:c.528G>A, (p.Trp176Ter)). A systemic examination by the pediatric department revealed that this boy had a history of a surgical excision of polydactyly on his left foot when he was born, and that he was mildly obese. There were no prominent intellectual or gonadal dysfunctions, no craniofacial or dental abnormalities, no congenital heart disease, and no hearing impairment. He was then clinically and genetically diagnosed with BBS. CONCLUSION AND IMPORTANCE In children with night blindness and progressive visual dysfunction, it is important for ophthalmologists to consult clinical geneticists and pediatricians to rule out the possibility of systemic diseases such as BBS.
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Affiliation(s)
- Keitaro Mizumoto
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Kumiko Kato
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan
- *Correspondence: Kumiko Kato, Department of Ophthalmology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan (e-mail: )
| | - Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Tadasu Sugita
- Department of Ophthalmology, Sugita Eye Hospital, Nagoya, Japan
| | - Iichiro Sugita
- Department of Ophthalmology, Sugita Eye Hospital, Nagoya, Japan
| | - Ayako Hattori
- Department of Pediatrics and Neonatology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Shinji Ueno
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Kazushige Tsunoda
- Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan
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8
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Goyal S, Vanita V. A missense mutation in TTC8/BBS8 affecting mRNA splicing in patients with non-syndromic retinitis pigmentosa. Mol Genet Genomics 2022; 297:1439-1449. [PMID: 35939099 DOI: 10.1007/s00438-022-01933-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 07/19/2022] [Indexed: 11/27/2022]
Abstract
Splicing disruption is one type of mutation mechanism for disease-predisposing alleles. To date, less than 30 mutations in TTC8/BBS8 have been reported; however, mutations affecting the splice site are rare. Generally missense mutations are assumed to alter protein function; however, reports have shown that mutations in protein coding exons can disrupt splicing by altering exonic splicing silencer or enhancer motifs. Hence, a missense mutation c.1347G > C (p.Q449H) involving final base of the exon 13 in the TTC8, previously identified by us to be linked with non-syndromic autosomal recessive retinitis pigmentosa (arRP), in an Indian family, that might deleteriously affect splicing has been functionally characterized. RNA was isolated, cDNA prepared and amplified using region-specific primers. PCR products were purified and sequenced bi-directionally by Sanger sequencing. Effect of mutation (c.1347G > C) on mRNA splicing has been predicted using bioinformatics tools. We reported that missense mutation (c.1347G > C) at the last base of exon 13 of TTC8 disrupted the canonical donor splice-site resulting in aberrant RNA splicing. A cryptic donor splice-site got activated 77 bases downstream of the authentic splice donor site in intron 13, resulting in the retention of 77 bases of intron 13, and a frameshift leading to pre-mature termination codon in exon 14 at codon 486. Further, duplication of exon 15 and fusion of its duplicated copy occurred with exon 13. The binding site for SC35 protein, normally involved in splicing, also got disrupted (as predicted by SpliceAid2 software), hence, leading to alternative splicing. Our findings strongly suggest that a missense mutation c.1347G > C in TTC8 disrupted the splice donor site causing retention of 77 bases of intron 13, resulting in a frameshift and subsequently introduced a pre-mature termination codon into exon 14, hence creating an altered mRNA transcript. These findings emphasize the significance of examining missense mutations especially in TTC8, to determine their pathogenic role through alternative splicing. Present findings also reiterate the notion that mutations in the TTC8/BBS8 cause phenotypic heterogeneity and does not always follow Mendelian genetics in this ciliopathy.
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Affiliation(s)
- Shiwali Goyal
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Vanita Vanita
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
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9
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Nasser F, Kohl S, Kurtenbach A, Kempf M, Biskup S, Zuleger T, Haack TB, Weisschuh N, Stingl K, Zrenner E. Ophthalmic and Genetic Features of Bardet Biedl Syndrome in a German Cohort. Genes (Basel) 2022; 13:genes13071218. [PMID: 35886001 PMCID: PMC9322102 DOI: 10.3390/genes13071218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 06/29/2022] [Accepted: 07/02/2022] [Indexed: 12/04/2022] Open
Abstract
The aim of this study was to characterize the ophthalmic and genetic features of Bardet Biedl (BBS) syndrome in a cohort of patients from a German specialized ophthalmic care center. Sixty-one patients, aged 5−56 years, underwent a detailed ophthalmic examination including visual acuity and color vision testing, electroretinography (ERG), visually evoked potential recording (VEP), fundus examination, and spectral domain optical coherence tomography (SD-OCT). Adaptive optics flood illumination ophthalmoscopy was performed in five patients. All patients had received diagnostic genetic testing and were selected upon the presence of apparent biallelic variants in known BBS-associated genes. All patients had retinal dystrophy with morphologic changes of the retina. Visual acuity decreased from ~0.2 (decimal) at age 5 to blindness 0 at 50 years. Visual field examination could be performed in only half of the patients and showed a concentric constriction with remaining islands of function in the periphery. ERG recordings were mostly extinguished whereas VEP recordings were reduced in about half of the patients. The cohort of patients showed 51 different likely biallelic mutations—of which 11 are novel—in 12 different BBS-associated genes. The most common associated genes were BBS10 (32.8%) and BBS1 (24.6%), and by far the most commonly observed variants were BBS10 c.271dup;p.C91Lfs*5 (21 alleles) and BBS1 c.1169T>G;p.M390R (18 alleles). The phenotype associated with the different BBS-associated genes and genotypes in our cohort is heterogeneous, with diverse features without genotype−phenotype correlation. The results confirm and expand our knowledge of this rare disease.
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Affiliation(s)
- Fadi Nasser
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
- Department of Ophthalmology, University of Leipzig, 04103 Leipzig, Germany
- Correspondence:
| | - Susanne Kohl
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
| | - Anne Kurtenbach
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
| | - Melanie Kempf
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
- Center for Rare Eye Diseases, University of Tübingen, 72076 Tuebingen, Germany
| | | | - Theresia Zuleger
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tuebingen, Germany; (T.Z.); (T.B.H.)
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tuebingen, Germany; (T.Z.); (T.B.H.)
| | - Nicole Weisschuh
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
| | - Katarina Stingl
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
- Center for Rare Eye Diseases, University of Tübingen, 72076 Tuebingen, Germany
| | - Eberhart Zrenner
- Centre for Ophthalmology, University of Tübingen, 72076 Tuebingen, Germany; (S.K.); (A.K.); (M.K.); (N.W.); (K.S.); (E.Z.)
- Werner Reichardt Centre for Integrative Neuroscience (CIN), University of Tübingen, 72076 Tuebingen, Germany
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10
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Singh J, Sharma M, Jain N, Aftab I, Vikram N, Singh TP, Sharma P, Sharma S. Lactoferrin and its nano-formulations in rare eye diseases. Indian J Ophthalmol 2022; 70:2328-2334. [PMID: 35791114 PMCID: PMC9426081 DOI: 10.4103/ijo.ijo_303_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/22/2022] [Accepted: 06/03/2022] [Indexed: 11/05/2022] Open
Abstract
Lactoferrin (LF) is an iron-binding glycoprotein released from mucous secreting cells and neutrophils. LF can be used in a broad range of eye diseases related to the retina, cornea, and optic nerve. The retina is particularly affected by oxidative stress inside the photoreceptor being constantly exposed to light which induces accumulation of reactive oxygen species (ROS) in the retinal pigmented epithelium (RPE) causing damage to photoreceptor recycling. Retinitis pigmentosa (RP) and macular degeneration are inherited retinopathies that consist of different disease-causing genes, that cause mutations with highly varied clinical consequences. Age-related macular degeneration is a chronic disease of the retina and one of the major causes of sight loss. This review provides an application of lactoferrin and LF-based nano-formulations or nanoparticles in the field of retinal diseases or corneal diseases such as retinitis pigmentosa, retinoblastoma, age-related macular degeneration (AMD), keratoconus and uveitis. Several studies have found that lactoferrin's antibacterial activity is not limited to its iron sequestration, but also its ability as a nanoparticle that acts as a carrier to deliver drugs by crossing the blood-retina barrier (BRB) and its involvement in cell cycle control, which is not possible by many transferrin proteins.
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Affiliation(s)
- Jiya Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Mohita Sharma
- Tirupati Eye Centre and Research Institute, Noida, Uttar Pradesh, India
| | - Neha Jain
- The Cornea Institute, KAR Campus, L V Prasad Eye Institute, Hyderabad, Telangana, India
| | - Insha Aftab
- Tirupati Eye Centre and Research Institute, Noida, Uttar Pradesh, India
| | - Naval Vikram
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
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11
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Aurora A and AKT Kinase Signaling Associated with Primary Cilia. Cells 2021; 10:cells10123602. [PMID: 34944109 PMCID: PMC8699881 DOI: 10.3390/cells10123602] [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: 09/06/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 02/07/2023] Open
Abstract
Dysregulation of kinase signaling is associated with various pathological conditions, including cancer, inflammation, and autoimmunity; consequently, the kinases involved have become major therapeutic targets. While kinase signaling pathways play crucial roles in multiple cellular processes, the precise manner in which their dysregulation contributes to disease is dependent on the context; for example, the cell/tissue type or subcellular localization of the kinase or substrate. Thus, context-selective targeting of dysregulated kinases may serve to increase the therapeutic specificity while reducing off-target adverse effects. Primary cilia are antenna-like structures that extend from the plasma membrane and function by detecting extracellular cues and transducing signals into the cell. Cilia formation and signaling are dynamically regulated through context-dependent mechanisms; as such, dysregulation of primary cilia contributes to disease in a variety of ways. Here, we review the involvement of primary cilia-associated signaling through aurora A and AKT kinases with respect to cancer, obesity, and other ciliopathies.
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12
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Baiyasi A, Barbosa J, Parendo A, Lin X. Pleiotropy of a Stickler syndrome genotype. Eur J Ophthalmol 2021; 32:NP10-NP12. [PMID: 34313156 DOI: 10.1177/11206721211035611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE To report a case of pleiotropy in the COL2A1 gene typically associated with Stickler Syndrome Type 1. OBSERVATIONS A patient with a confirmed mutation of the COL2A1 gene presented with an isolated retinitis pigmentosa phenotype. CONCLUSIONS The mutated COL2A1 gene in Stickler Syndrome Type 1 represents a site of pleiotropy, highlighting a change in phenotype across the same genotype potentially due to tissue alternative splicing.
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Affiliation(s)
- Ahmad Baiyasi
- Wayne State University School of Medicine, Detroit, MI, USA
| | - Joshua Barbosa
- Ophthalmology, Kresge Eye Institute & Wayne State University, Detroit, MI, USA
| | - Anthony Parendo
- Ophthalmology, Kresge Eye Institute & Wayne State University, Detroit, MI, USA
| | - Xihui Lin
- Ophthalmology, Kresge Eye Institute & Wayne State University, Detroit, MI, USA
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13
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Liang Q, Wu N, Zaneveld S, Liu H, Fu S, Wang K, Bertrand R, Wang J, Li Y, Chen R. Transcript isoforms of Reep6 have distinct functions in the retina. Hum Mol Genet 2021; 30:1907-1918. [PMID: 34104971 DOI: 10.1093/hmg/ddab157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/30/2021] [Accepted: 05/31/2021] [Indexed: 12/21/2022] Open
Abstract
Much of the complexity of the eukaryotic cell transcriptome is due to the alternative splicing of mRNA. However, knowledge on how transcriptome complexity is translated into functional complexity remains limited. For example, although different isoforms of a gene may show distinct temporal and spatial expression patterns, it is largely unknown whether these isoforms encode proteins with distinct functions matching their expression pattern. In this report, we investigated the function and relationship of the two isoforms of Reep6, namely Reep6.1 and Reep6.2, in rod photoreceptor cells. These two isoforms result from the alternative splicing of exon 5 and show mutually exclusive expression patterns. Reep6.2 is the canonical isoform that is expressed in non-retinal tissues while Reep6.1 is the only expressed isoform in the adult retina. The Reep6.1 isoform-specific knockout mouse, Reep6E5/E5, is generated by deleting exon 5 and a homozygous deletion phenotypically displayed a rod degeneration phenotype comparable to a Reep6 full knockout mouse, indicating that the Reep6.1 isoform is essential for the rod photoreceptor cell survival. Consistent with the results obtained from a loss-of-function experiment, overexpression of Reep6.2 failed to rescue the rod degeneration phenotype of Reep6 knockout mice while overexpression of Reep6.1 does lead to rescue. These results demonstrate that, consistent with the expression pattern of the isoform, Reep6.1 has rod-specific functions that cannot be substituted by its canonical isoform. Our findings suggested that a strict regulation of splicing is required for the maintenance of photoreceptor cells.
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Affiliation(s)
- Qingnan Liang
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Nathaniel Wu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Smriti Zaneveld
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Hehe Liu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Shangyi Fu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Keqing Wang
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Renae Bertrand
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Jun Wang
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Yumei Li
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Rui Chen
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
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14
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Fadaie Z, Whelan L, Dockery A, Li CHZ, van den Born LI, Hoyng CB, Gilissen C, Corominas J, Rowlands C, Megaw R, Lampe AK, Cremers FPM, Farrar GJ, Ellingford JM, Kenna PF, Roosing S. BBS1 branchpoint variant is associated with non-syndromic retinitis pigmentosa. J Med Genet 2021; 59:438-444. [PMID: 33910932 DOI: 10.1136/jmedgenet-2020-107626] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/11/2021] [Accepted: 02/26/2021] [Indexed: 11/03/2022]
Abstract
BACKGROUND Inherited retinal diseases (IRDs) can be caused by variants in >270 genes. The Bardet-Biedl syndrome 1 (BBS1) gene is one of these genes and may be associated with syndromic and non-syndromic autosomal recessive retinitis pigmentosa (RP). Here, we identified a branchpoint variant in BBS1 and assessed its pathogenicity by in vitro functional analysis. METHODS Whole genome sequencing was performed for three unrelated monoallelic BBS1 cases with non-syndromic RP. A fourth case received MGCM 105 gene panel analysis. Functional analysis using a midigene splice assay was performed for the putative pathogenic branchpoint variant in BBS1. After confirmation of its pathogenicity, patients were clinically re-evaluated, including assessment of non-ocular features of Bardet-Biedl syndrome. RESULTS Clinical assessments of probands showed that all individuals displayed non-syndromic RP with macular involvement. Through detailed variant analysis and prioritisation, two pathogenic variants in BBS1, the most common missense variant, c.1169T>G (p.(Met390Arg)), and a branchpoint variant, c.592-21A>T, were identified. Segregation analysis confirmed that in all families, probands were compound heterozygous for c.1169T>G and c.592-21A>T. Functional analysis of the branchpoint variant revealed a complex splicing defect including exon 8 and exon 7/8 skipping, and partial in-frame deletion of exon 8. CONCLUSION A putative severe branchpoint variant in BBS1, together with a mild missense variant, underlies non-syndromic RP in four unrelated individuals. To our knowledge, this is the first report of a pathogenic branchpoint variant in IRDs that results in a complex splice defect. In addition, this research highlights the importance of the analysis of non-coding regions in order to provide a conclusive molecular diagnosis.
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Affiliation(s)
- Zeinab Fadaie
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain Cognition and Behaviour, RadboudUMC, Nijmegen, The Netherlands
| | - Laura Whelan
- School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Adrian Dockery
- School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Catherina H Z Li
- Donders Institute for Brain Cognition and Behaviour, RadboudUMC, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands
| | | | - Carel B Hoyng
- Donders Institute for Brain Cognition and Behaviour, RadboudUMC, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
- Radboud Institute of Molecular Life Sciences, RadboudUMC, Nijmegen, The Netherlands
| | - Jordi Corominas
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
- Radboud Institute of Molecular Life Sciences, RadboudUMC, Nijmegen, The Netherlands
| | - Charlie Rowlands
- North West Genomic Laboratory Hub, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, St Mary's Hospital, Manchester, UK
- Division of Evolution and Genomic Sciences, Neuroscience and Mental Health Domain, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UK
| | - Roly Megaw
- MRC Human Genetics Unit, University of Edinburgh Western General Hospital, Edinburgh, UK
- Princess Alexandra Eye Pavilion, Department of Ophthalmology, University of Edinburgh Western General Hospital, Edinburgh, UK
| | - Anne K Lampe
- South East of Scotland Clinical Genetics Service, Western General Hospital, Edinburgh, UK
| | - Frans P M Cremers
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain Cognition and Behaviour, RadboudUMC, Nijmegen, The Netherlands
| | - Gwyneth Jane Farrar
- School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Jamie M Ellingford
- North West Genomic Laboratory Hub, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, St Mary's Hospital, Manchester, UK
- Division of Evolution and Genomic Sciences, Neuroscience and Mental Health Domain, The University of Manchester Faculty of Biology Medicine and Health, Manchester, UK
| | - Paul F Kenna
- School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Susanne Roosing
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain Cognition and Behaviour, RadboudUMC, Nijmegen, The Netherlands
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15
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Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Ciliopathies are a group of heterogeneous inherited disorders associated with dysfunction of the cilium, a ubiquitous microtubule-based organelle involved in a broad range of cellular functions. Most ciliopathies are syndromic, since several organs whose cells produce a cilium, such as the retina, cochlea or kidney, are affected by mutations in ciliary-related genes. In the retina, photoreceptor cells present a highly specialized neurosensory cilium, the outer segment, stacked with membranous disks where photoreception and phototransduction occurs. The daily renewal of the more distal disks is a unique characteristic of photoreceptor outer segments, resulting in an elevated protein demand. All components necessary for outer segment formation, maintenance and function have to be transported from the photoreceptor inner segment, where synthesis occurs, to the cilium. Therefore, efficient transport of selected proteins is critical for photoreceptor ciliogenesis and function, and any alteration in either cargo delivery to the cilium or intraciliary trafficking compromises photoreceptor survival and leads to retinal degeneration. To date, mutations in more than 100 ciliary genes have been associated with retinal dystrophies, accounting for almost 25% of these inherited rare diseases. Interestingly, not all mutations in ciliary genes that cause retinal degeneration are also involved in pleiotropic pathologies in other ciliated organs. Depending on the mutation, the same gene can cause syndromic or non-syndromic retinopathies, thus emphasizing the highly refined specialization of the photoreceptor neurosensory cilia, and raising the possibility of photoreceptor-specific molecular mechanisms underlying common ciliary functions such as ciliary transport. In this review, we will focus on ciliary transport in photoreceptor cells and discuss the molecular complexity underpinning retinal ciliopathies, with a special emphasis on ciliary genes that, when mutated, cause either syndromic or non-syndromic retinal ciliopathies.
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Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
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16
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The Alter Retina: Alternative Splicing of Retinal Genes in Health and Disease. Int J Mol Sci 2021; 22:ijms22041855. [PMID: 33673358 PMCID: PMC7917623 DOI: 10.3390/ijms22041855] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/14/2022] Open
Abstract
Alternative splicing of mRNA is an essential mechanism to regulate and increase the diversity of the transcriptome and proteome. Alternative splicing frequently occurs in a tissue- or time-specific manner, contributing to differential gene expression between cell types during development. Neural tissues present extremely complex splicing programs and display the highest number of alternative splicing events. As an extension of the central nervous system, the retina constitutes an excellent system to illustrate the high diversity of neural transcripts. The retina expresses retinal specific splicing factors and produces a large number of alternative transcripts, including exclusive tissue-specific exons, which require an exquisite regulation. In fact, a current challenge in the genetic diagnosis of inherited retinal diseases stems from the lack of information regarding alternative splicing of retinal genes, as a considerable percentage of mutations alter splicing or the relative production of alternative transcripts. Modulation of alternative splicing in the retina is also instrumental in the design of novel therapeutic approaches for retinal dystrophies, since it enables precision medicine for specific mutations.
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17
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Hsu Y, Seo S, Sheffield VC. Photoreceptor cilia, in contrast to primary cilia, grant entry to a partially assembled BBSome. Hum Mol Genet 2021; 30:87-102. [PMID: 33517424 DOI: 10.1093/hmg/ddaa284] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 11/16/2020] [Accepted: 01/27/2021] [Indexed: 12/26/2022] Open
Abstract
The BBSome is a protein complex consisting of BBS1, BBS2, BBS4, BBS5, BBS7, BBS8, BBS9 and BBS18 that associates with intraflagellar transport complexes and specializes in ciliary trafficking. In primary cilia, ciliary entry requires the fully assembled BBSome as well as the small GTPase, ARL6 (BBS3). Retinal photoreceptors possess specialized cilia. In light of key structural and functional differences between primary and specialized cilia, we examined the principles of BBSome recruitment to photoreceptor cilia. We performed sucrose gradient fractionation using retinal lysates of Bbs2-/-, Bbs7-/-, Bbs8-/- and Bbs3-/- mice to determine the status of BBSome assembly, then determined localization of BBSome components using immunohistochemistry. Surprisingly, we found that a subcomplex of the BBSome containing at least BBS1, BBS5, BBS8 and BBS9 is recruited to cilia in the absence of BBS2 or BBS7. In contrast, a BBSome subcomplex consisting of BBS1, BBS2, BBS5, BBS7 and BBS9 is found in Bbs8-/- retinas and is denied ciliary entry in photoreceptor cells. In addition, the BBSome remains fully assembled in Bbs3-/- retinas and can be recruited to photoreceptor cilia in the absence of BBS3. We compared phenotypic severity of their retinal degeneration phenotypes. These findings demonstrate that unlike primary cilia, photoreceptor cilia admit a partially assembled BBSome meeting specific requirements. In addition, the recruitment of the BBSome to photoreceptor cilia does not require BBS3. These findings indicate that the ciliary entry of the BBSome is subjected to cell-specific regulation, particularly in cells with highly adapted forms of cilia such as photoreceptors.
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Affiliation(s)
- Ying Hsu
- Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Val C Sheffield
- Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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18
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Sundar J, Matalkah F, Jeong B, Stoilov P, Ramamurthy V. The Musashi proteins MSI1 and MSI2 are required for photoreceptor morphogenesis and vision in mice. J Biol Chem 2021; 296:100048. [PMID: 33168629 PMCID: PMC7948980 DOI: 10.1074/jbc.ra120.015714] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 12/11/2022] Open
Abstract
The Musashi family of RNA-binding proteins is known for its role in stem-cell renewal and is a negative regulator of cell differentiation. Interestingly, in the retina, the Musashi proteins MSI1 and MSI2 are differentially expressed throughout the cycle of retinal development, with MSI2 protein displaying robust expression in the adult retinal tissue. In this study, we investigated the importance of Musashi proteins in the development and function of photoreceptor neurons in the retina. We generated a pan-retinal and rod photoreceptor neuron-specific conditional KO mouse lacking MSI1 and MSI2. Independent of the sex, photoreceptor neurons with simultaneous deletion of Msi1 and Msi2 were unable to respond to light and displayed severely disrupted photoreceptor outer segment morphology and ciliary defects. Mice lacking MSI1 and MSI2 in the retina exhibited neuronal degeneration, with complete loss of photoreceptors within 6 months. In concordance with our earlier studies that proposed a role for Musashi proteins in regulating alternative splicing, the loss of MSI1 and MSI2 prevented the use of photoreceptor-specific exons in transcripts critical for outer segment morphogenesis, ciliogenesis, and synaptic transmission. Overall, we demonstrate a critical role for Musashi proteins in the morphogenesis of terminally differentiated photoreceptor neurons. This role is in stark contrast with the canonical function of these two proteins in the maintenance and renewal of stem cells.
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Affiliation(s)
- Jesse Sundar
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA
| | - Fatimah Matalkah
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA
| | - Bohye Jeong
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA
| | - Peter Stoilov
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA.
| | - Visvanathan Ramamurthy
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA; Department of Ophthalmology and Visual Sciences, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA; Department of Neuroscience, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA.
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19
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Vig A, Poulter JA, Ottaviani D, Tavares E, Toropova K, Tracewska AM, Mollica A, Kang J, Kehelwathugoda O, Paton T, Maynes JT, Wheway G, Arno G, Khan KN, McKibbin M, Toomes C, Ali M, Di Scipio M, Li S, Ellingford J, Black G, Webster A, Rydzanicz M, Stawiński P, Płoski R, Vincent A, Cheetham ME, Inglehearn CF, Roberts A, Heon E. DYNC2H1 hypomorphic or retina-predominant variants cause nonsyndromic retinal degeneration. Genet Med 2020; 22:2041-2051. [PMID: 32753734 PMCID: PMC7708302 DOI: 10.1038/s41436-020-0915-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 01/02/2023] Open
Abstract
PURPOSE Determining the role of DYNC2H1 variants in nonsyndromic inherited retinal disease (IRD). METHODS Genome and exome sequencing were performed for five unrelated cases of IRD with no identified variant. In vitro assays were developed to validate the variants identified (fibroblast assay, induced pluripotent stem cell [iPSC] derived retinal organoids, and a dynein motility assay). RESULTS Four novel DYNC2H1 variants (V1, g.103327020_103327021dup; V2, g.103055779A>T; V3, g.103112272C>G; V4, g.103070104A>C) and one previously reported variant (V5, g.103339363T>G) were identified. In proband 1 (V1/V2), V1 was predicted to introduce a premature termination codon (PTC), whereas V2 disrupted the exon 41 splice donor site causing incomplete skipping of exon 41. V1 and V2 impaired dynein-2 motility in vitro and perturbed IFT88 distribution within cilia. V3, homozygous in probands 2-4, is predicted to cause a PTC in a retina-predominant transcript. Analysis of retinal organoids showed that this new transcript expression increased with organoid differentiation. V4, a novel missense variant, was in trans with V5, previously associated with Jeune asphyxiating thoracic dystrophy (JATD). CONCLUSION The DYNC2H1 variants discussed herein were either hypomorphic or affecting a retina-predominant transcript and caused nonsyndromic IRD. Dynein variants, specifically DYNC2H1 variants are reported as a cause of non syndromic IRD.
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Affiliation(s)
- Anjali Vig
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Institute of Medical Science, The University of Toronto, Toronto, Canada
| | - James A Poulter
- Department of Ophthalmology, St James' University Hospital, Leeds, UK
| | | | - Erika Tavares
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Katerina Toropova
- Department of Biological Sciences, Birbeck, University of London, London, UK
| | - Anna Maria Tracewska
- DNA Analysis Unit, ŁUKASIEWICZ Research Network-PORT Polish Center for Technology Development, Wrocław, Poland
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Antonio Mollica
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Jasmine Kang
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | | | - Tara Paton
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Canada
| | - Jason T Maynes
- Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, Toronto, Canada
| | | | - Gavin Arno
- UCL Institute of Ophthalmology, London, UK
- Moorfields Eye Hospital, London, UK
| | - Kamron N Khan
- Department of Ophthalmology, St James' University Hospital, Leeds, UK
| | - Martin McKibbin
- Department of Ophthalmology, St James' University Hospital, Leeds, UK
| | - Carmel Toomes
- Department of Ophthalmology, St James' University Hospital, Leeds, UK
| | - Manir Ali
- Department of Ophthalmology, St James' University Hospital, Leeds, UK
| | - Matteo Di Scipio
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Shuning Li
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Jamie Ellingford
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicines and health, The University of Manchester, Manchester, UK
- Manchester Academic Health Science Centre (MAHSC), University of Manchester, Manchester, UK
| | - Graeme Black
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicines and health, The University of Manchester, Manchester, UK
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Andrew Webster
- UCL Institute of Ophthalmology, London, UK
- Moorfields Eye Hospital, London, UK
| | | | - Piotr Stawiński
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Ajoy Vincent
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Institute of Medical Science, The University of Toronto, Toronto, Canada
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada
| | | | | | - Anthony Roberts
- Department of Biological Sciences, Birbeck, University of London, London, UK.
| | - Elise Heon
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada.
- Institute of Medical Science, The University of Toronto, Toronto, Canada.
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.
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20
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Ran J, Zhou J. Targeting the photoreceptor cilium for the treatment of retinal diseases. Acta Pharmacol Sin 2020; 41:1410-1415. [PMID: 32753732 DOI: 10.1038/s41401-020-0486-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/28/2020] [Indexed: 02/08/2023] Open
Abstract
Photoreceptors, as polarised sensory neurons, are essential for light sensation and phototransduction, which are highly dependent on the photoreceptor cilium. Structural defects and/or dysfunction of the photoreceptor cilium caused by mutations in photoreceptor-specific genes or common ciliary genes can lead to retinal diseases, including syndromic and nonsyndromic diseases. In this review, we describe the structure and function of the photoreceptor cilium. We also discuss recent findings that underscore the dysregulation of the photoreceptor cilium in various retinal diseases and the therapeutic potential of targeting ciliary genes in these diseases.
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21
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Tatour Y, Ben-Yosef T. Syndromic Inherited Retinal Diseases: Genetic, Clinical and Diagnostic Aspects. Diagnostics (Basel) 2020; 10:diagnostics10100779. [PMID: 33023209 PMCID: PMC7600643 DOI: 10.3390/diagnostics10100779] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023] Open
Abstract
Inherited retinal diseases (IRDs), which are among the most common genetic diseases in humans, define a clinically and genetically heterogeneous group of disorders. Over 80 forms of syndromic IRDs have been described. Approximately 200 genes are associated with these syndromes. The majority of syndromic IRDs are recessively inherited and rare. Many, although not all, syndromic IRDs can be classified into one of two major disease groups: inborn errors of metabolism and ciliopathies. Besides the retina, the systems and organs most commonly involved in syndromic IRDs are the central nervous system, ophthalmic extra-retinal tissues, ear, skeleton, kidney and the cardiovascular system. Due to the high degree of phenotypic variability and phenotypic overlap found in syndromic IRDs, correct diagnosis based on phenotypic features alone may be challenging and sometimes misleading. Therefore, genetic testing has become the benchmark for the diagnosis and management of patients with these conditions, as it complements the clinical findings and facilitates an accurate clinical diagnosis and treatment.
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22
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Deletion in the Bardet-Biedl Syndrome Gene TTC8 Results in a Syndromic Retinal Degeneration in Dogs. Genes (Basel) 2020; 11:genes11091090. [PMID: 32962042 PMCID: PMC7565673 DOI: 10.3390/genes11091090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/12/2020] [Accepted: 09/15/2020] [Indexed: 02/06/2023] Open
Abstract
In golden retriever dogs, a 1 bp deletion in the canine TTC8 gene has been shown to cause progressive retinal atrophy (PRA), the canine equivalent of retinitis pigmentosa. In humans, TTC8 is also implicated in Bardet–Biedl syndrome (BBS). To investigate if the affected dogs only exhibit a non-syndromic PRA or develop a syndromic ciliopathy similar to human BBS, we recruited 10 affected dogs to the study. The progression of PRA for two of the dogs was followed for 2 years, and a rigorous clinical characterization allowed a careful comparison with primary and secondary characteristics of human BBS. In addition to PRA, the dogs showed a spectrum of clinical and morphological signs similar to primary and secondary characteristics of human BBS patients, such as obesity, renal anomalies, sperm defects, and anosmia. We used Oxford Nanopore long-read cDNA sequencing to characterize retinal full-length TTC8 transcripts in affected and non-affected dogs, the results of which suggest that three isoforms are transcribed in the retina, and the 1 bp deletion is a loss-of-function mutation, resulting in a canine form of Bardet–Biedl syndrome with heterogeneous clinical signs.
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23
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Mary L, Chennen K, Stoetzel C, Antin M, Leuvrey A, Nourisson E, Alanio-Detton E, Antal MC, Attié-Bitach T, Bouvagnet P, Bouvier R, Buenerd A, Clémenson A, Devisme L, Gasser B, Gilbert-Dussardier B, Guimiot F, Khau Van Kien P, Leroy B, Loget P, Martinovic J, Pelluard F, Perez MJ, Petit F, Pinson L, Rooryck-Thambo C, Poch O, Dollfus H, Schaefer E, Muller J. Bardet-Biedl syndrome: Antenatal presentation of forty-five fetuses with biallelic pathogenic variants in known Bardet-Biedl syndrome genes. Clin Genet 2020; 95:384-397. [PMID: 30614526 DOI: 10.1111/cge.13500] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/20/2018] [Accepted: 12/29/2018] [Indexed: 02/06/2023]
Abstract
Bardet-Biedl syndrome (BBS) is an emblematic ciliopathy associated with retinal dystrophy, obesity, postaxial polydactyly, learning disabilities, hypogonadism and renal dysfunction. Before birth, enlarged/cystic kidneys as well as polydactyly are the hallmark signs of BBS to consider in absence of familial history. However, these findings are not specific to BBS, raising the problem of differential diagnoses and prognosis. Molecular diagnosis during pregnancies remains a timely challenge for this heterogeneous disease (22 known genes). We report here the largest cohort of BBS fetuses to better characterize the antenatal presentation. Prenatal ultrasound (US) and/or autopsy data from 74 fetuses with putative BBS diagnosis were collected out of which molecular diagnosis was established in 51 cases, mainly in BBS genes (45 cases) following the classical gene distribution, but also in other ciliopathy genes (6 cases). Based on this, an updated diagnostic decision tree is proposed. No genotype/phenotype correlation could be established but postaxial polydactyly (82%) and renal cysts (78%) were the most prevalent symptoms. However, autopsy revealed polydactyly that was missed by prenatal US in 55% of the cases. Polydactyly must be carefully looked for in pregnancies with apparently isolated renal anomalies in fetuses.
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Affiliation(s)
- Laura Mary
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France
| | - Kirsley Chennen
- Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France.,Complex Systems and Translational Bioinformatics, ICube, University of Strasbourg, CNRS, Illkirch, France
| | - Corinne Stoetzel
- Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France
| | - Manuela Antin
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Anne Leuvrey
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elsa Nourisson
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elisabeth Alanio-Detton
- Gynécologie-obstétrique, Centre de Dépistage Anténatal, Hôpital Maison-Blanche, Reims, France
| | - Maria C Antal
- Institut d'Histologie, Icube, Université de Strasbourg, Strasbourg, France.,Service de Pathologie, UF6349 Fœtopathologie, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Tania Attié-Bitach
- INSERM U1163, Institut IMAGINE, Université Paris Descartes, Paris, France.,Service d'Histologie-Embryologie-Cytogénétique, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Patrice Bouvagnet
- Laboratoire de Cardiogénétique, Malformations Cardiaques Congénitale, Hôpitaux Civils de Lyon, France
| | - Raymonde Bouvier
- Département de Pathologie, Centre Hospitalier Est, Hôpitaux Civils de Lyon, Lyon, France
| | - Annie Buenerd
- Département de Pathologie, Centre Hospitalier Est, Hôpitaux Civils de Lyon, Lyon, France
| | - Alix Clémenson
- Service d'Anatomie et Cytologie Pathologiques, CHU de Saint-Etienne, Saint-Étienne, France
| | - Louise Devisme
- Institut d'Anatomo-Pathologie, Centre de Biologie Pathologie, Centre Hospitalier Universitaire de Lille, Lille, France
| | - Bernard Gasser
- Laboratoire de Pathologie, GHR Mulhouse-Sud Alsace, Mulhouse, France
| | - Brigitte Gilbert-Dussardier
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Poitiers, Poitiers, France.,EA3808 - NEUVACOD, Université de Poitiers, Poitiers, France
| | - Fabien Guimiot
- Unité Fonctionnelle de Fœtopathologie, Département de Génétique, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Philippe Khau Van Kien
- Unité de Génétique Médicale et Cytogénétique, Centre Hospitalier Universitaire de Nîmes, Nîmes, France
| | - Brigitte Leroy
- Service d'Anatomie Pathologique, CHI Poissy Saint Germain-en-Laye, Poissy, France
| | - Philippe Loget
- Service d'Anatomie Pathologique, Hôpital Pontchaillou, Université Rennes 1, Rennes, France
| | - Jelena Martinovic
- Unité de Fœtopathologie, Hôpital Antoine Béclère, Assistance Publique-Hôpitaux de Paris, Clamart, France
| | - Fanny Pelluard
- Service d'Anatomie-Cytologie Pathologique, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France.,INSERM UMR1053, Bordeaux Research in Translational Oncology, BaRITOn, Université de Bordeaux, Bordeaux, France
| | - Marie-Josée Perez
- Unité de Fœtopathologie, Service de Génétique Médicale, Centre Hospitalier Universitaire, Montpellier, France
| | - Florence Petit
- Clinique de Génétique Guy Fontaine, Centre Hospitalier Universitaire de Lille, Lille, France
| | - Lucile Pinson
- Département de Génétique Médicale, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
| | - Caroline Rooryck-Thambo
- Université Bordeaux, MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Olivier Poch
- Complex Systems and Translational Bioinformatics, ICube, University of Strasbourg, CNRS, Illkirch, France
| | - Hélène Dollfus
- Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France.,Service de Génétique Médicale, IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,Centre des Affections Rares en Génétique Ophtalmologique, FSMR SENSGENE, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elise Schaefer
- Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France.,Service de Génétique Médicale, IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Jean Muller
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,Laboratoire de Génétique Médicale, UMR_S INSERM U1112, IGMA, Faculté de Médecine FMTS, Université de Strasbourg, Strasbourg, France
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24
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Collin GB, Won J, Krebs MP, Hicks WJ, Charette JR, Naggert JK, Nishina PM. Disruption in murine Eml1 perturbs retinal lamination during early development. Sci Rep 2020; 10:5647. [PMID: 32221352 PMCID: PMC7101416 DOI: 10.1038/s41598-020-62373-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/09/2020] [Indexed: 11/23/2022] Open
Abstract
During mammalian development, establishing functional neural networks in stratified tissues of the mammalian central nervous system depends upon the proper migration and positioning of neurons, a process known as lamination. In particular, the pseudostratified neuroepithelia of the retina and cerebrocortical ventricular zones provide a platform for progenitor cell proliferation and migration. Lamination defects in these tissues lead to mispositioned neurons, disrupted neuronal connections, and abnormal function. The molecular mechanisms necessary for proper lamination in these tissues are incompletely understood. Here, we identified a nonsense mutation in the Eml1 gene in a novel murine model, tvrm360, displaying subcortical heterotopia, hydrocephalus and disorganization of retinal architecture. In the retina, Eml1 disruption caused abnormal positioning of photoreceptor cell nuclei early in development. Upon maturation, these ectopic photoreceptors possessed cilia and formed synapses but failed to produce robust outer segments, implying a late defect in photoreceptor differentiation secondary to mislocalization. In addition, abnormal positioning of Müller cell bodies and bipolar cells was evident throughout the inner neuroblastic layer. Basal displacement of mitotic nuclei in the retinal neuroepithelium was observed in tvrm360 mice at postnatal day 0. The abnormal positioning of retinal progenitor cells at birth and ectopic presence of photoreceptors and secondary neurons upon maturation suggest that EML1 functions early in eye development and is crucial for proper retinal lamination during cellular proliferation and development.
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Affiliation(s)
- G B Collin
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - J Won
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - M P Krebs
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - W J Hicks
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - J R Charette
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - J K Naggert
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA
| | - P M Nishina
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine, 04609, USA.
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25
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Gonzàlez-Duarte R, de Castro-Miró M, Tuson M, Ramírez-Castañeda V, Gils RV, Marfany G. Scaling New Heights in the Genetic Diagnosis of Inherited Retinal Dystrophies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1185:215-219. [PMID: 31884614 DOI: 10.1007/978-3-030-27378-1_35] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During the last 20 years, our group has focused on identifying the genes and mutations causative of inherited retinal dystrophies (IRDs). By applying massive sequencing approaches (NGS) in more than 500 familial and sporadic cases, we attained high diagnostic efficiency (85%) with a custom target gene panel and over 75% using whole exome sequencing (WES). Close to 40% of pathogenic alleles are novel mutations, which demand specific in silico tests and in vitro assays. Notably, missense variants are by far the most common type of mutation identified (around 40%), with small in-frame indels being less frequent (2%). To fill the gap of unsolved cases, when no candidate gene or only a single pathogenic allele has been identified, additional scientific and technical issues remain to be addressed. Reliable detection of genomic rearrangements and copy number variants (partial or complete), deep intronic mutations, variants that cause aberrant splicing events in retina-specific transcripts, functional assessment of hypomorphic missense alleles, mutations in regulatory sequences, the contribution of modifier genes to the IRD phenotype, and detection of low heteroplasmy mtDNA mutations are among the new challenges to be met.
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Affiliation(s)
- Roser Gonzàlez-Duarte
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
| | | | | | | | | | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,DBGen Ocular Genomics SL, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Institut de Biomedicina (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
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26
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Klink BU, Gatsogiannis C, Hofnagel O, Wittinghofer A, Raunser S. Structure of the human BBSome core complex. eLife 2020; 9:53910. [PMID: 31951201 PMCID: PMC7018512 DOI: 10.7554/elife.53910] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/15/2020] [Indexed: 01/09/2023] Open
Abstract
The BBSome is a heterooctameric protein complex that plays a central role in primary cilia homeostasis. Its malfunction causes the severe ciliopathy Bardet-Biedl syndrome (BBS). The complex acts as a cargo adapter that recognizes signaling proteins such as GPCRs and links them to the intraflagellar transport machinery. The underlying mechanism is poorly understood. Here we present a high-resolution cryo-EM structure of a human heterohexameric core subcomplex of the BBSome. The structure reveals the architecture of the complex in atomic detail. It explains how the subunits interact with each other and how disease-causing mutations hamper this interaction. The complex adopts a conformation that is open for binding to membrane-associated GTPase Arl6 and a large positively charged patch likely strengthens the interaction with the membrane. A prominent negatively charged cleft at the center of the complex is likely involved in binding of positively charged signaling sequences of cargo proteins.
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Affiliation(s)
- Björn Udo Klink
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Alfred Wittinghofer
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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27
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ASCOT identifies key regulators of neuronal subtype-specific splicing. Nat Commun 2020; 11:137. [PMID: 31919425 PMCID: PMC6952364 DOI: 10.1038/s41467-019-14020-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 12/12/2019] [Indexed: 12/22/2022] Open
Abstract
Public archives of next-generation sequencing data are growing exponentially, but the difficulty of marshaling this data has led to its underutilization by scientists. Here, we present ASCOT, a resource that uses annotation-free methods to rapidly analyze and visualize splice variants across tens of thousands of bulk and single-cell data sets in the public archive. To demonstrate the utility of ASCOT, we identify novel cell type-specific alternative exons across the nervous system and leverage ENCODE and GTEx data sets to study the unique splicing of photoreceptors. We find that PTBP1 knockdown and MSI1 and PCBP2 overexpression are sufficient to activate many photoreceptor-specific exons in HepG2 liver cancer cells. This work demonstrates how large-scale analysis of public RNA-Seq data sets can yield key insights into cell type-specific control of RNA splicing and underscores the importance of considering both annotated and unannotated splicing events.
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28
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Wheway G, Lord J, Baralle D. Splicing in the pathogenesis, diagnosis and treatment of ciliopathies. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194433. [PMID: 31698098 DOI: 10.1016/j.bbagrm.2019.194433] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/12/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022]
Abstract
Primary cilia are essential signalling organelles found on the apical surface of epithelial cells, where they coordinate chemosensation, mechanosensation and light sensation. Motile cilia play a central role in establishing fluid flow in the respiratory tract, reproductive tract, brain ventricles and ear. Genetic defects affecting the structure or function of cilia can lead to a broad range of developmental and degenerative diseases known as ciliopathies. Splicing contributes to the pathogenesis, diagnosis and treatment of ciliopathies. Tissue-specific alternative splicing contributes to the tissue-specific manifestation of ciliopathy phenotypes, for example the retinal-specific effects of some genetic defects, due to specific transcript expression in the highly specialised ciliated cells of the retina, the photoreceptor cells. Ciliopathies can arise both as a result of genetic variants in spliceosomal proteins, or as a result of variants affecting splicing of specific cilia genes. Here we discuss the opportunities and challenges in diagnosing ciliopathies using RNA sequence analysis and the potential for treating ciliopathies in a relatively mutation-neutral way by targeting splicing. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Gabrielle Wheway
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland
| | - Jenny Lord
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland
| | - Diana Baralle
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland.
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Targeted sequencing of linkage region in Dominican families implicates PRIMA1 and the SPATA7-PTPN21-ZC3H14-EML5-TTC8 locus in carotid-intima media thickness and atherosclerotic events. Sci Rep 2019; 9:11621. [PMID: 31406157 PMCID: PMC6691113 DOI: 10.1038/s41598-019-48186-1] [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: 09/25/2018] [Accepted: 07/29/2019] [Indexed: 11/22/2022] Open
Abstract
Carotid intima-media thickness (cIMT) is a subclinical marker for atherosclerosis. Previously, we reported a quantitative trait locus (QTL) for total cIMT on chromosome 14q and identified PRiMA1, FOXN3 and CCDC88C as candidate genes using a common variants (CVs)-based approach. Herein, we further evaluated the genetic contribution of the QTL to cIMT by resequencing. We sequenced all exons within the QTL and genomic regions of PRiMA1, FOXN3 and CCDC88C in Dominican families with evidence for linkage to the QTL. Unrelated Dominicans from the Northern Manhattan Study (NOMAS) were used for validation. Single-variant-based and gene-based analyses were performed for CVs and rare variants (RVs). The strongest evidence for association with CVs was found in PRiMA1 (p = 8.2 × 10−5 in families, p = 0.01 in NOMAS at rs12587586), and in the five-gene cluster SPATA7-PTPN21-ZC3H14-EML5-TTC8 locus (p = 1.3 × 10−4 in families, p = 0.01 in NOMAS at rs2274736). No evidence for association with RVs was found in PRiMA1. The top marker from previous study in PRiMA1 (rs7152362) was associated with fewer atherosclerotic events (OR = 0.67; p = 0.02 in NOMAS) and smaller cIMT (β = −0.58, p = 2.8 × 10−4 in Family). Within the five-gene cluster, evidence for association was found for exonic RVs (p = 0.02 in families, p = 0.28 in NOMAS), which was enriched among RVs with higher functional potentials (p = 0.05 in NOMAS for RVs in the top functional tertile). In summary, targeted resequencing provided validation and novel insights into the genetic architecture of cIMT, suggesting stronger effects for RVs with higher functional potentials. Furthermore, our data support the clinical relevance of CVs associated with subclinical atherosclerosis.
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Niederlova V, Modrak M, Tsyklauri O, Huranova M, Stepanek O. Meta-analysis of genotype-phenotype associations in Bardet-Biedl syndrome uncovers differences among causative genes. Hum Mutat 2019; 40:2068-2087. [PMID: 31283077 DOI: 10.1002/humu.23862] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 06/17/2019] [Accepted: 07/03/2019] [Indexed: 12/16/2022]
Abstract
Bardet-Biedl syndrome (BBS) is a recessive genetic disease causing multiple organ anomalies. Most patients carry mutations in genes encoding for the subunits of the BBSome, an octameric ciliary transport complex, or accessory proteins involved in the BBSome assembly or function. BBS proteins have been extensively studied using in vitro, cellular, and animal models. However, the molecular functions of particular BBS proteins and the etiology of the BBS symptoms are still largely elusive. In this study, we applied a meta-analysis approach to study the genotype-phenotype association in humans using our database of all reported BBS patients. The analysis revealed that the identity of the causative gene and the character of the mutation partially predict the clinical outcome of the disease. Besides their potential use for clinical prognosis, our analysis revealed functional differences of particular BBS genes in humans. Core BBSome subunits BBS2, BBS7, and BBS9 manifest as more critical for the function and development of kidneys than peripheral subunits BBS1, BBS4, and BBS8/TTC8, suggesting that incomplete BBSome retains residual function at least in the kidney.
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Affiliation(s)
- Veronika Niederlova
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Modrak
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Oksana Tsyklauri
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martina Huranova
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ondrej Stepanek
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
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31
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Dilan TL, Singh RK, Saravanan T, Moye A, Goldberg AFX, Stoilov P, Ramamurthy V. Bardet-Biedl syndrome-8 (BBS8) protein is crucial for the development of outer segments in photoreceptor neurons. Hum Mol Genet 2019; 27:283-294. [PMID: 29126234 DOI: 10.1093/hmg/ddx399] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/06/2017] [Indexed: 11/15/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is an autosomal recessive ciliopathy characterized by developmental abnormalities and vision loss. To date, mutations in 21 genes have been linked to BBS. The products of eight of these BBS genes form a stable octameric complex termed the BBSome. Mutations in BBS8, a component of the BBSome, cause early vision loss, but the role of BBS8 in supporting vision is not known. To understand the mechanisms by which BBS8 supports rod and cone photoreceptor function, we generated animal models lacking BBS8. The loss of BBS8 protein led to concomitant decrease in the levels of BBSome subunits, BBS2 and BBS5 and increase in the levels of the BBS1 and BBS4 subunits. BBS8 ablation was associated with severe reduction of rod and cone photoreceptor function and progressive degeneration of each photoreceptor subtype. We observed disorganized and shortened photoreceptor outer segments (OS) at post-natal day 10 as the OS elaborates. Interestingly, loss of BBS8 led to changes in the distribution of photoreceptor axonemal proteins and hyper-acetylation of ciliary microtubules. In contrast to properly localized phototransduction machinery, we observed OS accumulation of syntaxin3, a protein normally found in the cytoplasm and the synaptic termini. In conclusion, our studies demonstrate the requirement for BBS8 in early development and elaboration of ciliated photoreceptor OS, explaining the need for BBS8 in normal vision. The findings from our study also imply that early targeting of both rods and cones in BBS8 patients is crucial for successful restoration of vision.
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Affiliation(s)
- Tanya L Dilan
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | - Ratnesh K Singh
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | | | - Abigail Moye
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | | | - Peter Stoilov
- Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | - Visvanathan Ramamurthy
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA.,Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WA 26506, USA
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32
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Coon SL, Fu C, Hartley SW, Holtzclaw L, Mays JC, Kelly MC, Kelley MW, Mullikin JC, Rath MF, Savastano LE, Klein DC. Single Cell Sequencing of the Pineal Gland: The Next Chapter. Front Endocrinol (Lausanne) 2019; 10:590. [PMID: 31616371 PMCID: PMC6764290 DOI: 10.3389/fendo.2019.00590] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/12/2019] [Indexed: 11/25/2022] Open
Abstract
The analysis of pineal cell biology has undergone remarkable development as techniques have become available which allow for sequencing of entire transcriptomes and, most recently, the sequencing of the transcriptome of individual cells. Identification of at least nine distinct cell types in the rat pineal gland has been made possible, allowing identification of the precise cells of origin and expression of transcripts for the first time. Here the history and current state of knowledge generated by these transcriptomic efforts is reviewed, with emphasis on the insights suggested by the findings.
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Affiliation(s)
- Steven L. Coon
- Molecular Genomics Core, Office of the Scientific Director, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Cong Fu
- Key Laboratory of Organ Regeneration & Transplantation of the Ministry of Education, The First Hospital of Jilin University, Changchun, China
- National-Local Joint Engineering Laboratory of Animal Models for Human Diseases, Changchun, China
| | - Steven W. Hartley
- Comparative Genomics Analysis Unit, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States
| | - Lynne Holtzclaw
- Microscopy and Imaging Core, Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Joseph C. Mays
- Institute on Systems Genetics, New York University School of Medicine, New York, NY, United States
| | - Michael C. Kelly
- Single Cell Analysis Facility, Frederick National Lab for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Matthew W. Kelley
- Section on Developmental Neuroscience, Laboratory of Cochlear Development, Division of Intramural Research, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
| | - James C. Mullikin
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Rockville, MD, United States
| | - Martin F. Rath
- Department of Neuroscience, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Luis E. Savastano
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI, United States
| | - David C. Klein
- Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: David C. Klein
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33
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Verbakel SK, van Huet RAC, Boon CJF, den Hollander AI, Collin RWJ, Klaver CCW, Hoyng CB, Roepman R, Klevering BJ. Non-syndromic retinitis pigmentosa. Prog Retin Eye Res 2018; 66:157-186. [PMID: 29597005 DOI: 10.1016/j.preteyeres.2018.03.005] [Citation(s) in RCA: 500] [Impact Index Per Article: 83.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 03/20/2018] [Accepted: 03/22/2018] [Indexed: 12/23/2022]
Abstract
Retinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. RP is a leading cause of visual disability, with a worldwide prevalence of 1:4000. Although the majority of RP cases are non-syndromic, 20-30% of patients with RP also have an associated non-ocular condition. RP typically manifests with night blindness in adolescence, followed by concentric visual field loss, reflecting the principal dysfunction of rod photoreceptors; central vision loss occurs later in life due to cone dysfunction. Photoreceptor function measured with an electroretinogram is markedly reduced or even absent. Optical coherence tomography (OCT) and fundus autofluorescence (FAF) imaging show a progressive loss of outer retinal layers and altered lipofuscin distribution in a characteristic pattern. Over the past three decades, a vast number of disease-causing variants in more than 80 genes have been associated with non-syndromic RP. The wide heterogeneity of RP makes it challenging to describe the clinical findings and pathogenesis. In this review, we provide a comprehensive overview of the clinical characteristics of RP specific to genetically defined patient subsets. We supply a unique atlas with color fundus photographs of most RP subtypes, and we discuss the relevant considerations with respect to differential diagnoses. In addition, we discuss the genes involved in the pathogenesis of RP, as well as the retinal processes that are affected by pathogenic mutations in these genes. Finally, we review management strategies for patients with RP, including counseling, visual rehabilitation, and current and emerging therapeutic options.
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Affiliation(s)
- Sanne K Verbakel
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ramon A C van Huet
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands; Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W J Collin
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Carel B Hoyng
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - B Jeroen Klevering
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.
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34
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Bujakowska KM, Liu Q, Pierce EA. Photoreceptor Cilia and Retinal Ciliopathies. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028274. [PMID: 28289063 DOI: 10.1101/cshperspect.a028274] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
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Affiliation(s)
- Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Qin Liu
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
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35
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Weihbrecht K, Goar WA, Pak T, Garrison JE, DeLuca AP, Stone EM, Scheetz TE, Sheffield VC. Keeping an Eye on Bardet-Biedl Syndrome: A Comprehensive Review of the Role of Bardet-Biedl Syndrome Genes in the Eye. MEDICAL RESEARCH ARCHIVES 2017; 5. [PMID: 29457131 DOI: 10.18103/mra.v5i9.1526] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Upwards of 90% of individuals with Bardet-Biedl syndrome (BBS) display rod-cone dystrophy with early macular involvement. BBS is an autosomal recessive, genetically heterogeneous, pleiotropic ciliopathy for which 21 causative genes have been discovered to date. In addition to retinal degeneration, the cardinal features of BBS include obesity, cognitive impairment, renal anomalies, polydactyly, and hypogonadism. Here, we review the genes, proteins, and protein complexes involved in BBS and the BBS model organisms available for the study of retinal degeneration. We include comprehensive lists for all known BBS genes, their known phenotypes, and the model organisms available. We also review the molecular mechanisms believed to lead to retinal degeneration. We provide an overview of the mode of inheritance and describe the relationships between BBS genes and Joubert syndrome, Leber Congenital Amaurosis, Senior-Løken syndrome, and non-syndromic retinitis pigmentosa. Finally, we propose ways that new advances in technology will allow us to better understand the role of different BBS genes in retinal formation and function.
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Affiliation(s)
- Katie Weihbrecht
- Department of Pediatrics, University of Iowa; Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Wesley A Goar
- Department of Pediatrics, University of Iowa; Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Thomas Pak
- Department of Pediatrics, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Janelle E Garrison
- Department of Pediatrics, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Adam P DeLuca
- Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Todd E Scheetz
- Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
| | - Val C Sheffield
- Department of Pediatrics, University of Iowa; Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa; Iowa City, IA 52242, USA.,Stephen A. Wynn Institute for Vision Research, University of Iowa; Iowa City, IA 52242, USA
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36
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Huang D, Fletcher S, Wilton SD, Palmer N, McLenachan S, Mackey DA, Chen FK. Inherited Retinal Disease Therapies Targeting Precursor Messenger Ribonucleic Acid. Vision (Basel) 2017; 1:vision1030022. [PMID: 31740647 PMCID: PMC6836112 DOI: 10.3390/vision1030022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 07/24/2017] [Accepted: 08/24/2017] [Indexed: 02/07/2023] Open
Abstract
Inherited retinal diseases are an extremely diverse group of genetically and phenotypically heterogeneous conditions characterized by variable maturation of retinal development, impairment of photoreceptor cell function and gradual loss of photoreceptor cells and vision. Significant progress has been made over the last two decades in identifying the many genes implicated in inherited retinal diseases and developing novel therapies to address the underlying genetic defects. Approximately one-quarter of exonic mutations related to human inherited diseases are likely to induce aberrant splicing products, providing opportunities for the development of novel therapeutics that target splicing processes. The feasibility of antisense oligomer mediated splice intervention to treat inherited diseases has been demonstrated in vitro, in vivo and in clinical trials. In this review, we will discuss therapeutic approaches to treat inherited retinal disease, including strategies to correct splicing and modify exon selection at the level of pre-mRNA. The challenges of clinical translation of this class of emerging therapeutics will also be discussed.
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Affiliation(s)
- Di Huang
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Sue Fletcher
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Steve D. Wilton
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Norman Palmer
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
| | - David A. Mackey
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
| | - Fred K. Chen
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth 6000, Australia
- Correspondence: ; Tel.: +61-8-9381-0817
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37
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Ku CA, Hull S, Arno G, Vincent A, Carss K, Kayton R, Weeks D, Anderson GW, Geraets R, Parker C, Pearce DA, Michaelides M, MacLaren RE, Robson AG, Holder GE, Heon E, Raymond FL, Moore AT, Webster AR, Pennesi ME. Detailed Clinical Phenotype and Molecular Genetic Findings in CLN3-Associated Isolated Retinal Degeneration. JAMA Ophthalmol 2017; 135:749-760. [PMID: 28542676 DOI: 10.1001/jamaophthalmol.2017.1401] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Mutations in genes traditionally associated with syndromic retinal disease are increasingly found to cause nonsyndromic inherited retinal degenerations. Mutations in CLN3 are classically associated with juvenile neuronal ceroid lipofuscinosis, a rare neurodegenerative disease with early retinal degeneration and progressive neurologic deterioration, but have recently also been identified in patients with nonsyndromic inherited retinal degenerations. To our knowledge, detailed clinical characterization of such cases has yet to be reported. Objective To provide detailed clinical, electrophysiologic, structural, and molecular genetic findings in nonsyndromic inherited retinal degenerations associated with CLN3 mutations. Design, Setting, and Participants A multi-institutional case series of 10 patients who presented with isolated nonsyndromic retinal disease and mutations in CLN3. Patient ages ranged from 16 to 70 years; duration of follow-up ranged from 3 to 29 years. Main Outcomes and Measures Longitudinal clinical evaluation, including full ophthalmic examination, multimodal retinal imaging, perimetry, and electrophysiology. Molecular analyses were performed using whole-genome sequencing or whole-exome sequencing. Electron microscopy studies of peripheral lymphocytes and CLN3 transcript analysis with polymerase chain reaction amplification were performed in a subset of patients. Results There were 7 females and 3 males in this case series, with a mean (range) age at last review of 37.1 (16-70) years. Of the 10 patients, 4 had a progressive late-onset rod-cone dystrophy, with a mean (range) age at onset of 29.7 (20-40) years, and 6 had an earlier onset rod-cone dystrophy, with a mean (range) age at onset of 12.1 (7-17) years. Ophthalmoscopic examination features included macular edema, mild intraretinal pigment migration, and widespread atrophy in advanced disease. Optical coherence tomography imaging demonstrated significant photoreceptor loss except in patients with late-onset disease who had a focal preservation of the ellipsoid zone and outer nuclear layer in the fovea. Electroretinography revealed a rod-cone pattern of dysfunction in 6 patients and were completely undetectable in 2 patients. Six novel CLN3 variants were identified in molecular analyses. Conclusions and Relevance This report describes detailed clinical, imaging, and genetic features of CLN3-associated nonsyndromic retinal degeneration. The age at onset and natural progression of retinal disease differs greatly between syndromic and nonsyndromic CLN3 disease, which may be associated with genotypic differences.
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Affiliation(s)
- Cristy A Ku
- Casey Eye Institute, Oregon Health & Science University, Portland
| | - Sarah Hull
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Gavin Arno
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Keren Carss
- National Health Service Blood and Transplant Centre, Department of Haematology, University of Cambridge, Cambridge, England6National Institute for Health Research BioResource: Rare Diseases, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, England
| | - Robert Kayton
- Pathology Department, Oregon Health & Science University, Portland
| | - Douglas Weeks
- Pathology Department, Oregon Health & Science University, Portland
| | - Glenn W Anderson
- Histopathology Department, Great Ormond Street Hospital for Children, London, England
| | - Ryan Geraets
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Camille Parker
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - David A Pearce
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota10Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls
| | - Michel Michaelides
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Robert E MacLaren
- Moorfields Eye Hospital, London, England11Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, England12Oxford University Hospitals National Health Service Foundation Trust, Oxford, England
| | - Anthony G Robson
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Graham E Holder
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - F Lucy Raymond
- National Health Service Blood and Transplant Centre, Department of Haematology, University of Cambridge, Cambridge, England6National Institute for Health Research BioResource: Rare Diseases, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, England13Cambridge Institute for Medical Research, Department of Medical Genetics, University of Cambridge, Cambridge, England
| | - Anthony T Moore
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England14Department of Ophthalmology, University of California, San Francisco Medical School, San Francisco
| | - Andrew R Webster
- University College London Institute of Ophthalmology, London, England3Moorfields Eye Hospital, London, England
| | - Mark E Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland
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Genetic characterization and disease mechanism of retinitis pigmentosa; current scenario. 3 Biotech 2017; 7:251. [PMID: 28721681 DOI: 10.1007/s13205-017-0878-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa is a group of genetically transmitted disorders affecting 1 in 3000-8000 individual people worldwide ultimately affecting the quality of life. Retinitis pigmentosa is characterized as a heterogeneous genetic disorder which leads by progressive devolution of the retina leading to a progressive visual loss. It can occur in syndromic (with Usher syndrome and Bardet-Biedl syndrome) as well as non-syndromic nature. The mode of inheritance can be X-linked, autosomal dominant or autosomal recessive manner. To date 58 genes have been reported to associate with retinitis pigmentosa most of them are either expressed in photoreceptors or the retinal pigment epithelium. This review focuses on the disease mechanisms and genetics of retinitis pigmentosa. As retinitis pigmentosa is tremendously heterogeneous disorder expressing a multiplicity of mutations; different variations in the same gene might induce different disorders. In recent years, latest technologies including whole-exome sequencing contributing effectively to uncover the hidden genesis of retinitis pigmentosa by reporting new genetic mutations. In future, these advancements will help in better understanding the genotype-phenotype correlations of disease and likely to develop new therapies.
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Ullah A, Umair M, Yousaf M, Khan SA, Nazim-ud-din M, Shah K, Ahmad F, Azeem Z, Ali G, Alhaddad B, Rafique A, Jan A, Haack TB, Strom TM, Meitinger T, Ghous T, Ahmad W. Sequence variants in four genes underlying Bardet-Biedl syndrome in consanguineous families. Mol Vis 2017; 23:482-494. [PMID: 28761321 PMCID: PMC5524433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 07/19/2017] [Indexed: 12/03/2022] Open
Abstract
PURPOSE To investigate the molecular basis of Bardet-Biedl syndrome (BBS) in five consanguineous families of Pakistani origin. METHODS Linkage in two families (A and B) was established to BBS7 on chromosome 4q27, in family C to BBS8 on chromosome 14q32.1, and in family D to BBS10 on chromosome 12q21.2. Family E was investigated directly with exome sequence analysis. RESULTS Sanger sequencing revealed two novel mutations and three previously reported mutations in the BBS genes. These mutations include two deletions (c.580_582delGCA, c.1592_1597delTTCCAG) in the BBS7 gene, a missense mutation (p.Gln449His) in the BBS8 gene, a frameshift mutation (c.271_272insT) in the BBS10 gene, and a nonsense mutation (p.Ser40*) in the MKKS (BBS6) gene. CONCLUSIONS Two novel mutations and three previously reported variants, identified in the present study, further extend the body of evidence implicating BBS6, BBS7, BBS8, and BBS10 in causing BBS.
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Affiliation(s)
- Asmat Ullah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muhammad Umair
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan,Institute of Human Genetics, Technische Universitat Munchen, Munchen, Germany,Institute of Human Genetics, Helmholtz Zentrum Munchen, Neuherberg, Germany
| | - Maryam Yousaf
- Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Sher Alam Khan
- Kohat University of Science and Technology (KUST), Khyber Pakhtunkhwa Province, Pakistan
| | - Muhammad Nazim-ud-din
- Department of Biotechnology, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Khadim Shah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Farooq Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Zahid Azeem
- Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Ghazanfar Ali
- Department of Biotechnology, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Bader Alhaddad
- Institute of Human Genetics, Technische Universitat Munchen, Munchen, Germany,Institute of Human Genetics, Helmholtz Zentrum Munchen, Neuherberg, Germany
| | - Afzal Rafique
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Abid Jan
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan,Kohat University of Science and Technology (KUST), Khyber Pakhtunkhwa Province, Pakistan
| | - Tobias B. Haack
- Institute of Human Genetics, Technische Universitat Munchen, Munchen, Germany,Institute of Human Genetics, Helmholtz Zentrum Munchen, Neuherberg, Germany
| | - Tim M. Strom
- Institute of Human Genetics, Technische Universitat Munchen, Munchen, Germany,Institute of Human Genetics, Helmholtz Zentrum Munchen, Neuherberg, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universitat Munchen, Munchen, Germany,Institute of Human Genetics, Helmholtz Zentrum Munchen, Neuherberg, Germany
| | - Tahseen Ghous
- Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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Li L, Chen Y, Jiao X, Jin C, Jiang D, Tanwar M, Ma Z, Huang L, Ma X, Sun W, Chen J, Ma Y, M'hamdi O, Govindarajan G, Cabrera PE, Li J, Gupta N, Naeem MA, Khan SN, Riazuddin S, Akram J, Ayyagari R, Sieving PA, Riazuddin SA, Hejtmancik JF. Homozygosity Mapping and Genetic Analysis of Autosomal Recessive Retinal Dystrophies in 144 Consanguineous Pakistani Families. Invest Ophthalmol Vis Sci 2017; 58:2218-2238. [PMID: 28418496 PMCID: PMC5397137 DOI: 10.1167/iovs.17-21424] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose The Pakistan Punjab population has been a rich source for identifying genes causing or contributing to autosomal recessive retinal degenerations (arRD). This study was carried out to delineate the genetic architecture of arRD in the Pakistani population. Methods The genetic origin of arRD in a total of 144 families selected only for having consanguineous marriages and multiple members affected with arRD was examined. Of these, causative mutations had been identified in 62 families while only the locus had been identified for an additional 15. The remaining 67 families were subjected to homozygosity exclusion mapping by screening of closely flanking microsatellite markers at 180 known candidate genes/loci followed by sequencing of the candidate gene for pathogenic changes. Results Of these 67 families subjected to homozygosity mapping, 38 showed homozygosity for at least one of the 180 regions, and sequencing of the corresponding genes showed homozygous cosegregating mutations in 27 families. Overall, mutations were detected in approximately 61.8 % (89/144) of arRD families tested, with another 10.4% (15/144) being mapped to a locus but without a gene identified. Conclusions These results suggest the involvement of unmapped novel genes in the remaining 27.8% (40/144) of families. In addition, this study demonstrates that homozygosity mapping remains a powerful tool for identifying the genetic defect underlying genetically heterogeneous arRD disorders in consanguineous marriages for both research and clinical applications.
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Affiliation(s)
- Lin Li
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Yabin Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Xiaodong Jiao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Chongfei Jin
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3Department of Medicine, Brookdale University Hospital and Medical Center, New York, New York, United States
| | - Dan Jiang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mukesh Tanwar
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 4Department of Genetics, Maharshi Dayanand University Rohtak, Haryana, India
| | - Zhiwei Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Li Huang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaoyin Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 6Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Wenmin Sun
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Jianjun Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 7Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Yan Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Oussama M'hamdi
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Gowthaman Govindarajan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Patricia E Cabrera
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jiali Li
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Nikhil Gupta
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan 9Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California-San Diego, La Jolla, California, United States
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States 14McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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Pierrache LHM, Kimchi A, Ratnapriya R, Roberts L, Astuti GDN, Obolensky A, Beryozkin A, Tjon-Fo-Sang MJH, Schuil J, Klaver CCW, Bongers EMHF, Haer-Wigman L, Schalij N, Breuning MH, Fischer GM, Banin E, Ramesar RS, Swaroop A, van den Born LI, Sharon D, Cremers FPM. Whole-Exome Sequencing Identifies Biallelic IDH3A Variants as a Cause of Retinitis Pigmentosa Accompanied by Pseudocoloboma. Ophthalmology 2017; 124:992-1003. [PMID: 28412069 DOI: 10.1016/j.ophtha.2017.03.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE To identify the genetic cause of and describe the phenotype in 4 families with autosomal recessive retinitis pigmentosa (arRP) that can be associated with pseudocoloboma. DESIGN Case series. PARTICIPANTS Seven patients from 4 unrelated families with arRP, among whom 3 patients had bilateral early-onset macular pseudocoloboma. METHODS We performed homozygosity mapping and whole-exome sequencing in 5 probands and 2 unaffected family members from 4 unrelated families. Subsequently, Sanger sequencing and segregation analysis were performed in additional family members. We reviewed the medical history of individuals carrying IDH3A variants and performed additional ophthalmic examinations, including full-field electroretinography, fundus photography, fundus autofluorescence imaging, and optical coherence tomography. MAIN OUTCOME MEASURES IDH3A variants, age at diagnosis, visual acuity, fundus appearance, visual field, and full-field electroretinography, fundus autofluorescence, and optical coherence tomography findings. RESULTS We identified 7 different variants in IDH3A in 4 unrelated families, that is, 5 missense, 1 nonsense, and 1 frameshift variant. All participants showed symptoms early in life, ranging from night blindness to decreased visual acuity, and were diagnosed between the ages of 1 and 11 years. Four participants with biallelic IDH3A variants displayed a typical arRP phenotype and 3 participants were diagnosed with arRP and pseudocoloboma of the macula. CONCLUSIONS IDH3A variants were identified as a novel cause of typical arRP in some individuals associated with macular pseudocoloboma. We observed both phenotypes in 2 siblings carrying the same compound heterozygous variants, which could be explained by variable disease expression and warrants caution when making assertions about genotype-phenotype correlations.
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Affiliation(s)
- Laurence H M Pierrache
- The Rotterdam Eye Hospital, Rotterdam, The Netherlands; Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adva Kimchi
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Rinki Ratnapriya
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Lisa Roberts
- UCT/MRC Human Genetics Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Galuh D N Astuti
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands; Division of Human Genetics, Center for Biomedical Research, Faculty of Medicine, Diponegoro University, Semarang, Indonesia
| | - Alexey Obolensky
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Avigail Beryozkin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Jose Schuil
- Bartiméus Institute for the Visually Impaired, Zeist, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ernie M H F Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Nicoline Schalij
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martijn H Breuning
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Gratia M Fischer
- Department of Ophthalmology, Dr. George Mukhari Academic Hospital, Sefako Makgatho Health Sciences University (SMU), Ga-Rankuwa, Pretoria, South Africa
| | - Eyal Banin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Raj S Ramesar
- UCT/MRC Human Genetics Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - L Ingeborgh van den Born
- The Rotterdam Eye Hospital, Rotterdam, The Netherlands; Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
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Simple and complex retinal dystrophies are associated with profoundly different disease networks. Sci Rep 2017; 7:41835. [PMID: 28139756 PMCID: PMC5282568 DOI: 10.1038/srep41835] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/28/2016] [Indexed: 12/20/2022] Open
Abstract
Retinopathies are a group of monogenetic or complex retinal diseases associated with high unmet medical need. Monogenic disorders are caused by rare genetic variation and usually arise early in life. Other diseases, such as age-related macular degeneration (AMD), develop late in life and are considered to be of complex origin as they develop from a combination of genetic, ageing, environmental and lifestyle risk factors. Here, we contrast the underlying disease networks and pathological mechanisms of monogenic as opposed to complex retinopathies, using AMD as an example of the latter. We show that, surprisingly, genes associated with the different forms of retinopathies in general do not overlap despite their overlapping retinal phenotypes. Further, AMD risk genes participate in multiple networks with interaction partners that link to different ubiquitous pathways affecting general tissue integrity and homeostasis. Thus AMD most likely represents an endophenotype with differing underlying pathogenesis in different subjects. Localising these pathomechanisms and processes within and across different retinal anatomical compartments provides a novel representation of AMD that may be extended to complex disease in general. This approach may generate improved treatment options that target multiple processes with the aim of restoring tissue homeostasis and maintaining vision.
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Collin RWJ. Unraveling the mysteries of pre-mRNA splicing in the retina via stem cell technology. Stem Cell Investig 2016; 3:72. [PMID: 27868054 DOI: 10.21037/sci.2016.10.05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 10/12/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Rob W J Collin
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
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Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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45
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Volta F, Gerdes JM. The role of primary cilia in obesity and diabetes. Ann N Y Acad Sci 2016; 1391:71-84. [DOI: 10.1111/nyas.13216] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/19/2016] [Accepted: 08/01/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Francesco Volta
- Institute for Diabetes and Regeneration Research; Helmholtz Zentrum München; Garching Germany
| | - Jantje M. Gerdes
- Institute for Diabetes and Regeneration Research; Helmholtz Zentrum München; Garching Germany
- German Center for Diabetes Research; DZD; Munich Germany
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Hartley SW, Mullikin JC, Klein DC, Park M, Coon SL. Alternative Isoform Analysis of Ttc8 Expression in the Rat Pineal Gland Using a Multi-Platform Sequencing Approach Reveals Neural Regulation. PLoS One 2016; 11:e0163590. [PMID: 27684375 PMCID: PMC5042479 DOI: 10.1371/journal.pone.0163590] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/12/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative isoform regulation (AIR) vastly increases transcriptome diversity and plays an important role in numerous biological processes and pathologies. However, the detection and analysis of isoform-level differential regulation is difficult, particularly in the face of complex and incompletely-annotated transcriptomes. Here we have used Illumina short-read/high-throughput RNA-Seq to identify 55 genes that exhibit neurally-regulated AIR in the pineal gland, and then used two other complementary experimental platforms to further study and characterize the Ttc8 gene, which is involved in Bardet-Biedl syndrome and non-syndromic retinitis pigmentosa. Use of the JunctionSeq analysis tool led to the detection of several novel exons and splice junctions in this gene, including two novel alternative transcription start sites which were found to display disproportionately strong neurally-regulated differential expression in several independent experiments. These high-throughput sequencing results were validated and augmented via targeted qPCR and long-read Pacific Biosciences SMRT sequencing. We confirmed the existence of numerous novel splice junctions and the selective upregulation of the two novel start sites. In addition, we identified more than 20 novel isoforms of the Ttc8 gene that are co-expressed in this tissue. By using information from multiple independent platforms we not only greatly reduce the risk of errors, biases, and artifacts influencing our results, we also are able to characterize the regulation and splicing of the Ttc8 gene more deeply and more precisely than would be possible via any single platform. The hybrid method outlined here represents a powerful strategy in the study of the transcriptome.
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Affiliation(s)
- Stephen W. Hartley
- Comparative Genomics Analysis Unit, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
- * E-mail:
| | - James C. Mullikin
- Comparative Genomics Analysis Unit, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - David C. Klein
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Morgan Park
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Rockville, Maryland, 20852, United States of America
| | - NISC Comparative Sequencing Program
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Rockville, Maryland, 20852, United States of America
| | - Steven L. Coon
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
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Spickett C, Hysi P, Hammond CJ, Prescott A, Fincham GS, Poulson AV, McNinch AM, Richards AJ, Snead MP. Deep Intronic Sequence Variants in COL2A1 Affect the Alternative Splicing Efficiency of Exon 2, and May Confer a Risk for Rhegmatogenous Retinal Detachment. Hum Mutat 2016; 37:1085-96. [PMID: 27406592 DOI: 10.1002/humu.23050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/29/2016] [Indexed: 11/10/2022]
Abstract
COL2A1 mutations causing haploinsufficiency of type II collagen cause type 1 Stickler syndrome that has a high risk of retinal detachment and failure of the vitreous to develop normally. Exon 2 of COL2A1 is alternatively spliced, expressed in the eye but not in mature cartilage and encodes a region that binds growth factors TGFβ1 and BMP-2. We investigated how both an apparently de novo variant and a polymorphism in intron 2 altered the efficiency of COL2A1 exon 2 splicing and how the latter may act as a predisposing risk factor for the occurrence of posterior vitreous detachment (PVD)-associated rhegmatogenous retinal detachment (RRD) in the general population. Using amplification of illegitimate transcripts and allele-specific minigenes expressed in cultured cells, we demonstrate variability in exon 2 inclusion not only between different control individuals, but also between different COL2A1 alleles. We identify transacting factors that bind to allele-specific RNA sequences, and investigate the effect of knockdown and overexpression of these factors on exon 2 splicing efficiency. Finally, using a specific cohort of patients with PVD-associated RRD and a control population, we demonstrate a significant difference in the frequency of the COL2A1 intronic variant rs1635532 between the two groups.
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Affiliation(s)
- Carl Spickett
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK.,Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Pirro Hysi
- Academic Unit Ophthalmology, King's College London, London, SE1 7EH, UK
| | | | - Alan Prescott
- College of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - Gregory S Fincham
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK
| | - Arabella V Poulson
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK
| | - Annie M McNinch
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK.,Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.,Regional Molecular Genetics Laboratory, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK
| | - Allan J Richards
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK. .,Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK. .,Regional Molecular Genetics Laboratory, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK.
| | - Martin P Snead
- Vitreoretinal Research Group, Cambridge University NHS Foundation Trust, Cambridge, CB2 0QQ, UK
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48
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Murphy D, Cieply B, Carstens R, Ramamurthy V, Stoilov P. The Musashi 1 Controls the Splicing of Photoreceptor-Specific Exons in the Vertebrate Retina. PLoS Genet 2016; 12:e1006256. [PMID: 27541351 PMCID: PMC4991804 DOI: 10.1371/journal.pgen.1006256] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/22/2016] [Indexed: 01/08/2023] Open
Abstract
Alternative pre-mRNA splicing expands the coding capacity of eukaryotic genomes, potentially enabling a limited number of genes to govern the development of complex anatomical structures. Alternative splicing is particularly prevalent in the vertebrate nervous system, where it is required for neuronal development and function. Here, we show that photoreceptor cells, a type of sensory neuron, express a characteristic splicing program that affects a broad set of transcripts and is initiated prior to the development of the light sensing outer segments. Surprisingly, photoreceptors lack prototypical neuronal splicing factors and their splicing profile is driven to a significant degree by the Musashi 1 (MSI1) protein. A striking feature of the photoreceptor splicing program are exons that display a "switch-like" pattern of high inclusion levels in photoreceptors and near complete exclusion outside of the retina. Several ubiquitously expressed genes that are involved in the biogenesis and function of primary cilia produce highly photoreceptor specific isoforms through use of such "switch-like" exons. Our results suggest a potential role for alternative splicing in the development of photoreceptors and the conversion of their primary cilia to the light sensing outer segments.
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Affiliation(s)
- Daniel Murphy
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America
| | - Benjamin Cieply
- Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Russ Carstens
- Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Visvanathan Ramamurthy
- Departments of Biochemistry, Ophthalmology and Center for Neuroscience, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America
| | - Peter Stoilov
- Department of Biochemistry and Cancer Institute, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America
- * E-mail:
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49
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Ullah I, Kabir F, Iqbal M, Gottsch CBS, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Pathogenic mutations in TULP1 responsible for retinitis pigmentosa identified in consanguineous familial cases. Mol Vis 2016; 22:797-815. [PMID: 27440997 PMCID: PMC4947966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 07/14/2016] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To identify pathogenic mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous familial cases. METHODS Seven large familial cases with multiple individuals diagnosed with retinitis pigmentosa were included in the study. Affected individuals in these families underwent ophthalmic examinations to document the symptoms and confirm the initial diagnosis. Blood samples were collected from all participating members, and genomic DNA was extracted. An exclusion analysis with microsatellite markers spanning the TULP1 locus on chromosome 6p was performed, and two-point logarithm of odds (LOD) scores were calculated. All coding exons along with the exon-intron boundaries of TULP1 were sequenced bidirectionally. We constructed a single nucleotide polymorphism (SNP) haplotype for the four familial cases harboring the K489R allele and estimated the likelihood of a founder effect. RESULTS The ophthalmic examinations of the affected individuals in these familial cases were suggestive of RP. Exclusion analyses confirmed linkage to chromosome 6p harboring TULP1 with positive two-point LOD scores. Subsequent Sanger sequencing identified the single base pair substitution in exon14, c.1466A>G (p.K489R), in four families. Additionally, we identified a two-base deletion in exon 4, c.286_287delGA (p.E96Gfs77*); a homozygous splice site variant in intron 14, c.1495+4A>C; and a novel missense variation in exon 15, c.1561C>T (p.P521S). All mutations segregated with the disease phenotype in the respective families and were absent in ethnically matched control chromosomes. Haplotype analysis suggested (p<10(-6)) that affected individuals inherited the causal mutation from a common ancestor. CONCLUSIONS Pathogenic mutations in TULP1 are responsible for the RP phenotype in seven familial cases with a common ancestral mutation responsible for the disease phenotype in four of the seven families.
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Affiliation(s)
- Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Muhammad Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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50
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Kabir F, Ullah I, Ali S, Gottsch AD, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Loss of function mutations in RP1 are responsible for retinitis pigmentosa in consanguineous familial cases. Mol Vis 2016; 22:610-25. [PMID: 27307693 PMCID: PMC4901054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/08/2016] [Indexed: 10/31/2022] Open
Abstract
PURPOSE This study was undertaken to identify causal mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous families. METHODS Large consanguineous families were ascertained from the Punjab province of Pakistan. An ophthalmic examination consisting of a fundus evaluation and electroretinography (ERG) was completed, and small aliquots of blood were collected from all participating individuals. Genomic DNA was extracted from white blood cells, and a genome-wide linkage or a locus-specific exclusion analysis was completed with polymorphic short tandem repeats (STRs). Two-point logarithm of odds (LOD) scores were calculated, and all coding exons and exon-intron boundaries of RP1 were sequenced to identify the causal mutation. RESULTS The ophthalmic examination showed that affected individuals in all families manifest cardinal symptoms of RP. Genome-wide scans localized the disease phenotype to chromosome 8q, a region harboring RP1, a gene previously implicated in the pathogenesis of RP. Sanger sequencing identified a homozygous single base deletion in exon 4: c.3697delT (p.S1233Pfs22*), a single base substitution in intron 3: c.787+1G>A (p.I263Nfs8*), a 2 bp duplication in exon 2: c.551_552dupTA (p.Q185Yfs4*) and an 11,117 bp deletion that removes all three coding exons of RP1. These variations segregated with the disease phenotype within the respective families and were not present in ethnically matched control samples. CONCLUSIONS These results strongly suggest that these mutations in RP1 are responsible for the retinal phenotype in affected individuals of all four consanguineous families.
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Affiliation(s)
- Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahbaz Ali
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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