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Viakhireva I, Bychkov I, Markova T, Shatokhina O, Karandasheva K, Udalova V, Bekhtereva Y, Ryzhkova O, Skoblov M. The molecular complexity of COL2A1 splicing variants and their significance in phenotype severity. Bone 2024; 181:117013. [PMID: 38246255 DOI: 10.1016/j.bone.2024.117013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/25/2023] [Accepted: 01/05/2024] [Indexed: 01/23/2024]
Abstract
Pathogenic single nucleotide variants (SNVs) found in the COL2A1 gene are associated with a broad range of skeletal dysplasias due to their impact on the structure and function of the Col2a1 protein. However, the molecular mechanisms of some nucleotide variants detected during diagnostic testing remain unclear. The interpretation of missense and splicing variants caused by SNVs poses a significant challenge for clinicians. In this work, we analyzed 22 splicing variants in the COL2A1 gene which have been found in patients with COL2A1-associated skeletal dysplasias. Using a minigene system, we investigated the impact of these SNVs on splicing and gained insights into their molecular mechanisms and genotype-phenotype correlations for each patient. The results of our study are very useful for improving the accuracy of diagnosis and the management of patients with skeletal dysplasias caused by SNVs in the COL2A1 gene.
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Affiliation(s)
- I Viakhireva
- Research Centre for Medical Genetics, Moscow, Russian Federation.
| | - I Bychkov
- Research Centre for Medical Genetics, Moscow, Russian Federation
| | - T Markova
- Research Centre for Medical Genetics, Moscow, Russian Federation
| | - O Shatokhina
- Research Centre for Medical Genetics, Moscow, Russian Federation
| | - K Karandasheva
- Research Centre for Medical Genetics, Moscow, Russian Federation
| | - V Udalova
- LLC Genomed, Moscow, Russian Federation
| | | | - O Ryzhkova
- Research Centre for Medical Genetics, Moscow, Russian Federation
| | - M Skoblov
- Research Centre for Medical Genetics, Moscow, Russian Federation
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2
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Cormier MJ, Pedersen BS, Bayrak-Toydemir P, Quinlan AR. Combining genetic constraint with predictions of alternative splicing to prioritize deleterious splicing in rare disease studies. BMC Bioinformatics 2022; 23:482. [PMCID: PMC9664736 DOI: 10.1186/s12859-022-05041-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 11/07/2022] [Indexed: 11/16/2022] Open
Abstract
Abstract
Background
Despite numerous molecular and computational advances, roughly half of patients with a rare disease remain undiagnosed after exome or genome sequencing. A particularly challenging barrier to diagnosis is identifying variants that cause deleterious alternative splicing at intronic or exonic loci outside of canonical donor or acceptor splice sites.
Results
Several existing tools predict the likelihood that a genetic variant causes alternative splicing. We sought to extend such methods by developing a new metric that aids in discerning whether a genetic variant leads to deleterious alternative splicing. Our metric combines genetic variation in the Genome Aggregate Database with alternative splicing predictions from SpliceAI to compare observed and expected levels of splice-altering genetic variation. We infer genic regions with significantly less splice-altering variation than expected to be constrained. The resulting model of regional splicing constraint captures differential splicing constraint across gene and exon categories, and the most constrained genic regions are enriched for pathogenic splice-altering variants. Building from this model, we developed ConSpliceML. This ensemble machine learning approach combines regional splicing constraint with multiple per-nucleotide alternative splicing scores to guide the prediction of deleterious splicing variants in protein-coding genes. ConSpliceML more accurately distinguishes deleterious and benign splicing variants than state-of-the-art splicing prediction methods, especially in “cryptic” splicing regions beyond canonical donor or acceptor splice sites.
Conclusion
Integrating a model of genetic constraint with annotations from existing alternative splicing tools allows ConSpliceML to prioritize potentially deleterious splice-altering variants in studies of rare human diseases.
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Molecular Basis of Pathogenic Variants in the Fibrillar Collagens. Genes (Basel) 2022; 13:genes13071199. [PMID: 35885981 PMCID: PMC9320522 DOI: 10.3390/genes13071199] [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: 05/24/2022] [Revised: 06/26/2022] [Accepted: 06/28/2022] [Indexed: 12/04/2022] Open
Abstract
The fibrillar collagen family is comprised of the quantitatively major types I, II and III collagens and the quantitatively minor types V and XI. These form heterotypic collagen fibrils (composed of more than a single collagen type) where the minor collagens have a regulatory role in controlling fibril formation and diameter. The structural pre-requisites for normal collagen biosynthesis and fibrillogenesis result in many places where this process can be disrupted, and consequently a wide variety of phenotypes result when pathogenic changes occur in these fibrillar collagen genes. Another contributing factor is alternative splicing, both naturally occurring and as the result of pathogenic DNA alterations. This article will discuss how these factors should be taken into account when assessing DNA sequencing results from a patient.
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Soh Z, Richards AJ, McNinch A, Alexander P, Martin H, Snead MP. Dominant Stickler Syndrome. Genes (Basel) 2022; 13:genes13061089. [PMID: 35741851 PMCID: PMC9222743 DOI: 10.3390/genes13061089] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 02/04/2023] Open
Abstract
The Stickler syndromes are a group of genetic connective tissue disorders associated with an increased risk of rhegmatogenous retinal detachment, deafness, cleft palate, and premature arthritis. This review article focuses on the molecular genetics of the autosomal dominant forms of the disease. Pathogenic variants in COL2A1 causing Stickler syndrome usually result in haploinsufficiency of the protein, whereas pathogenic variants of type XI collagen more usually exert dominant negative effects. The severity of the disease phenotype is thus dependent on the location and nature of the mutation, as well as the normal developmental role of the respective protein.
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Affiliation(s)
- Zack Soh
- John van Geest Centre for Brain Repair, Vitreoretinal Research Group, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK; (Z.S.); (A.J.R.); (A.M.); (H.M.)
| | - Allan J. Richards
- John van Geest Centre for Brain Repair, Vitreoretinal Research Group, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK; (Z.S.); (A.J.R.); (A.M.); (H.M.)
- NHS England Highly Specialised Stickler Syndrome Diagnostic Service, Cambridge University, NHS Foundation Trust, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
| | - Annie McNinch
- John van Geest Centre for Brain Repair, Vitreoretinal Research Group, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK; (Z.S.); (A.J.R.); (A.M.); (H.M.)
- NHS England Highly Specialised Stickler Syndrome Diagnostic Service, Cambridge University, NHS Foundation Trust, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
| | - Philip Alexander
- NHS England Highly Specialised Stickler Syndrome Diagnostic Service, Cambridge University, NHS Foundation Trust, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
| | - Howard Martin
- John van Geest Centre for Brain Repair, Vitreoretinal Research Group, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK; (Z.S.); (A.J.R.); (A.M.); (H.M.)
- NHS England Highly Specialised Stickler Syndrome Diagnostic Service, Cambridge University, NHS Foundation Trust, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
| | - Martin P. Snead
- John van Geest Centre for Brain Repair, Vitreoretinal Research Group, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK; (Z.S.); (A.J.R.); (A.M.); (H.M.)
- NHS England Highly Specialised Stickler Syndrome Diagnostic Service, Cambridge University, NHS Foundation Trust, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
- Correspondence:
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Clinical and Genetic Characteristics of COL2A1-Associated Skeletal Dysplasias in 60 Russian Patients: Part I. Genes (Basel) 2022; 13:genes13010137. [PMID: 35052477 PMCID: PMC8775336 DOI: 10.3390/genes13010137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/09/2022] [Accepted: 01/11/2022] [Indexed: 02/04/2023] Open
Abstract
The significant variability in the clinical manifestations of COL2A1-associated skeletal dysplasias makes it necessary to conduct a clinical and genetic analysis of individual nosological variants, which will contribute to improving our understanding of the pathogenetic mechanisms and prognosis. We presented the clinical and genetic characteristics of 60 Russian pediatric patients with type II collagenopathies caused by previously described and newly identified variants in the COL2A1 gene. Diagnosis confirmation was carried out by new generation sequencing of the target panel with subsequent validation of the identified variants using automated Sanger sequencing. It has been shown that clinical forms of spondyloepiphyseal dysplasias predominate in childhood, both with more severe clinical manifestations (58%) and with unusual phenotypes of mild forms with normal growth (25%). However, Stickler syndrome, type I was less common (17%). In the COL2A1 gene, 28 novel variants were identified, and a total of 63% of the variants were found in the triple helix region resulted in glycine substitution in Gly-XY repeats, which were identified in patients with clinical manifestations of congenital spondyloepiphyseal dysplasia with varying severity, and were not found in Stickler syndrome, type I and Kniest dysplasia. In the C-propeptide region, five novel variants leading to the development of unusual phenotypes of spondyloepiphyseal dysplasia have been identified.
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Čopíková J, Paděrová J, Románková V, Havlovicová M, Balaščáková M, Zelinová M, Vejvalková Š, Simandlová M, Štěpánková J, Hořínová V, Kantorová E, Křečková G, Pospíšilová J, Boday A, Meszarosová AU, Turnovec M, Votýpka P, Lišková P, Kremlíková Pourová R. Expanding the phenotype spectrum associated with pathogenic variants in the COL2A1 and COL11A1 genes. Ann Hum Genet 2020; 84:380-392. [PMID: 32427345 DOI: 10.1111/ahg.12386] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 01/15/2023]
Abstract
We report the clinical findings of 26 individuals from 16 unrelated families carrying variants in the COL2A1 or COL11A1 genes. Using Sanger and next-generation sequencing, 11 different COL2A1 variants (seven novel), were identified in 13 families (19 affected individuals), all diagnosed with Stickler syndrome (STL) type 1. In nine families, the COL2A1 disease-causing variant arose de novo. Phenotypically, we observed myopia (95%) and retinal detachment (47%), joint hyperflexibility (92%), midface retrusion (84%), cleft palate (53%), and various degrees of hearing impairment (50%). One patient had a splenic artery aneurysm. One affected individual carrying pathogenic variant in COL2A1 showed no ocular signs including no evidence of membranous vitreous anomaly. In three families (seven affected individuals), three novel COL11A1 variants were found. The propositus with a de novo variant showed an ultrarare Marshall/STL overlap. In the second family, the only common clinical sign was postlingual progressive sensorineural hearing impairment (DFNA37). Affected individuals from the third family had typical STL2 signs. The spectrum of disease phenotypes associated with COL2A1 or COL11A1 variants continues to expand and includes typical STL and various bone dysplasias, but also nonsyndromic hearing impairment, isolated myopia with or without retinal detachment, and STL phenotype without clinically detectable ocular pathology.
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Affiliation(s)
- Jana Čopíková
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Jana Paděrová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Věra Románková
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Markéta Havlovicová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Miroslava Balaščáková
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Michaela Zelinová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Šárka Vejvalková
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Martina Simandlová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Jana Štěpánková
- Department of Ophthalmology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | | | - Eva Kantorová
- Department of Medical Genetics, Nemocnice České Budějovice, České Budějovice, Czech Republic
| | | | - Jana Pospíšilová
- Molecular Biology, AGEL Laboratories, Nový Jičín, Czech Republic
| | - Arpád Boday
- Molecular Biology, AGEL Laboratories, Nový Jičín, Czech Republic
| | - Anna Uhrová Meszarosová
- DNA Laboratory, Department of Child Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Marek Turnovec
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Pavel Votýpka
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Petra Lišková
- Research Unit for Rare Diseases, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic.,Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Radka Kremlíková Pourová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
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Abstract
The morphogenesis of the mammalian secondary plate is a series of highly dynamic developmental process, including the palate shelves vertical outgrowth, elevation to the horizontal plane and complete fusion in the midline. Extracellular matrix (ECM) proteins not only form the basic infrastructure for palatal mesenchymal cells to adhere via integrins but also interact with cells to regulate their functions such as proliferation and differentiation. ECM remodeling is essential for palatal outgrowth, expansion, elevation, and fusion. Multiple signaling pathways important for palatogenesis such as FGF, TGF β, BMP, and SHH remodels ECM dynamics. Dysregulation of ECM such as HA synthesis or ECM breakdown enzymes MMPs or ADAMTS causes cleft palate in mouse models. A better understanding of ECM remodeling will contribute to revealing the pathogenesis of cleft palate.
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Affiliation(s)
- Xia Wang
- Health Science Center, Shenzhen University , Shenzhen, China
| | - Chunman Li
- Health Science Center, Shenzhen University , Shenzhen, China
| | - Zeyao Zhu
- Health Science Center, Shenzhen University , Shenzhen, China
| | - Li Yuan
- Department of Stomatology, Shenzhen People's Hospital, 2nd Clinical Medical College of Jinan University , Shenzhen, China
| | - Wood Yee Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong , Hong Kong, China
| | - Ou Sha
- Health Science Center, Shenzhen University , Shenzhen, China
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8
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Rolvien T, Yorgan TA, Kornak U, Hermans-Borgmeyer I, Mundlos S, Schmidt T, Niemeier A, Schinke T, Amling M, Oheim R. Skeletal deterioration in COL2A1-related spondyloepiphyseal dysplasia occurs prior to osteoarthritis. Osteoarthritis Cartilage 2020; 28:334-343. [PMID: 31958497 DOI: 10.1016/j.joca.2019.12.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 11/05/2019] [Accepted: 12/31/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Spondyloepiphyseal dysplasia, a combination of progressive arthropathy with variable signs of skeletal dysplasia, can be a result of mutations in the collagen, type II, alpha 1 (COL2A1) gene. However, the bone involvement (e.g., density, microstructure) in this disorder has hitherto not been studied. DESIGN A 50-year-old female patient and her 8-year-old son with flattening of vertebral bodies and early-onset osteoarthritis were genetically tested using a custom designed gene bone panel including 386 genes. Bone microstructure and turnover were assessed using high-resolution peripheral quantitative computed tomography (HR-pQCT) and serum bone turnover markers, respectively. Furthermore, the bone and cartilage phenotype of male mice heterozygous for the loss-of-function mutation of Col2a1 (Col2a1+/d) was analyzed compared to wildtype littermates using μ-CT and histomorphometry. RESULTS We identified a dominant COL2A1 mutation (c.620G > A p.(Gly207Glu)) indicating spondyloepiphyseal dysplasia in the female patient and her son, both being severely affected by skeletal deterioration. Although there was no osteoarthritis detectable at first visit, the son was affected by trabecular osteopenia, which progressed over time. In an iliac crest biopsy obtained from the mother, osteoclast indices were remarkably increased. Col2a1+/d mice developed a moderate skeletal phenotype expressed by reduced cortical and trabecular parameters at 4 weeks. Importantly, no articular defects could be observed in the knee joints at 4 weeks, while osteoarthritis was only detectable in 12-week-old mice. CONCLUSIONS Our results indicate that collagen type II deficiency in spondyloepiphyseal dysplasia leads to skeletal deterioration with early-onset in humans and mice that occurs prior to the development of osteoarthritis.
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Affiliation(s)
- T Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - T A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - U Kornak
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany; Max Planck Institute for Molecular Genetics, FG Development and Disease, Berlin, Germany
| | - I Hermans-Borgmeyer
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - S Mundlos
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany; Max Planck Institute for Molecular Genetics, FG Development and Disease, Berlin, Germany
| | - T Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - A Niemeier
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - T Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - M Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - R Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
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9
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Snead M, Martin H, Bale P, Shenker N, Baguley D, Alexander P, McNinch A, Poulson A. Therapeutic and diagnostic advances in Stickler syndrome. THERAPEUTIC ADVANCES IN RARE DISEASE 2020; 1:2633004020978661. [PMID: 37180493 PMCID: PMC10032448 DOI: 10.1177/2633004020978661] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/16/2020] [Indexed: 05/16/2023]
Abstract
The Stickler syndromes are the leading cause of inherited retinal detachment and the most common cause of rhegmatogenous retinal detachment in childhood. The clinical and molecular genetic spectrum of this connective tissue disorder is discussed in this article, emphasising the key role the ophthalmologist has to play in the identification, diagnosis and prevention of blindness in the increasingly widely recognised sub-groups with ocular-only (or minimal systemic) involvement. Without diagnosis and prophylaxis in such high-risk subgroups, these patients are at high risk of Giant Retinal Tear detachment and blindness, especially in the paediatric population, where late or second eye involvement is common. Initially considered a monogenic disorder, there are now known to be at least 11 distinct phenotypic subgroups in addition to allied connective tissue disorders that can present to the clinician as part of the differential diagnosis. Plain language summary Treatment and diagnostic advances in Stickler syndrome The Stickler syndromes are a group of related connective tissue disorders that are associated with short-sight and a very high risk of blindness from detachment of the retina - the light sensitive film at the back of the eye. Other features include cleft palate, deafness and premature arthritis. It is the most common cause of retinal detachment in children and the most common cause of familial or inherited retinal detachment. In contrast to most other forms of blinding genetic eye disease, blindness from retinal detachment in Stickler syndrome is largely avoidable with accurate diagnosis and prophylactic (preventive) surgery. Recent advances in the understanding of the genetic causes of Stickler syndrome mean that the diagnosis can now be confirmed in over 95% of cases and, most importantly, the patient's individual risk of retinal detachment can be graded. Preventative surgery is hugely effective in reducing the incidence of retinal detachment in those patients shown to be at high risk. NHS England have led the way in the multidisciplinary care for patients with Stickler syndrome by launching a highly specialist service that has been free at point of care to all NHS patients in England since 2011 (https://www.england.nhs.uk/commissioning/spec-services/highly-spec-services, www.vitreoretinalservice.org).
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Affiliation(s)
- Martin Snead
- Vitreoretinal Research Group, NHS England
Stickler Syndrome Diagnostic Service, Cambridge University NHS Foundation
Trust, University of Cambridge, Addenbrooke’s Hospital, Hill Road, Cambridge
CB2 0QQ, UK
| | - Howard Martin
- Vitreoretinal Research Group, University of
Cambridge and NHS England Stickler Syndrome Diagnostic Service, Cambridge
University NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
| | - Peter Bale
- Department of Rheumatology Cambridge University
NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
| | - Nick Shenker
- Department of Rheumatology Cambridge University
NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
| | - David Baguley
- Division of Clinical Neurosciences, School of
Medicine, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre,
Ropewalk House, Nottingham, UK
- Nottingham Audiology Services, Nottingham
University Hospitals, Nottingham, UK
| | - Philip Alexander
- Vitreoretinal Research Group, University of
Cambridge and NHS England Stickler Syndrome Diagnostic Service, Cambridge
University NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
| | - Annie McNinch
- Vitreoretinal Research Group, University of
Cambridge and NHS England Stickler Syndrome Diagnostic Service, Cambridge
University NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
| | - Arabella Poulson
- Vitreoretinal Research Group, University of
Cambridge and NHS England Stickler Syndrome Diagnostic Service, Cambridge
University NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK
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10
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Zhang B, Zhang Y, Wu N, Li J, Liu H, Wang J. Integrated analysis of COL2A1 variant data and classification of type II collagenopathies. Clin Genet 2019; 97:383-395. [PMID: 31758797 DOI: 10.1111/cge.13680] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 11/29/2022]
Abstract
The COL2A1 gene encodes the alpha-1 chain of type II procollagen. Type II collagen, comprised of three identical alpha-1 chains, is the major component of cartilage. COL2A1 gene variants are the etiologies of genetic diseases, termed type II collagenopathies, with a wide spectrum of clinical presentations. To date, at least 460 distinct COL2A1 mutations, identified in 663 independent probands, and 21 definite disorders have been reported. Nevertheless, a well-defined genotype-phenotype correlation has not been established, and few hot spots of mutation have been reported. In this study, we analyzed data of COL2A1 variants and clinical information of patients obtained from the Leiden Open Variation Database 3.0, as well as the currently available relevant literature. We determined the characteristics of the COL2A1 variants and distributions of the clinical manifestations in patients, and identified four likely genotype-phenotype correlations. Moreover, we classified 21 COL2A1-related disorders into five categories, which may assist clinicians in understanding the essence of these complex phenotypes and prompt genetic screening in clinical practice.
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Affiliation(s)
- Boyan Zhang
- Orthopedic Medical Center, The Second Hospital of Jilin University, Changchun, China
| | - Yue Zhang
- Department of Radiation Oncology, First Bethune Hospital of Jilin University, Changchun, China
| | - Naichao Wu
- Orthopedic Medical Center, The Second Hospital of Jilin University, Changchun, China
| | - Jianing Li
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun, China
| | - He Liu
- Orthopedic Medical Center, The Second Hospital of Jilin University, Changchun, China
| | - Jincheng Wang
- Orthopedic Medical Center, The Second Hospital of Jilin University, Changchun, China
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11
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Huang X, Lin Y, Chen C, Zhu Y, Gao H, Li T, Liu B, Lyu C, Huang Y, Wu Q, Li H, Jin C, Liang X, Lu L. Targeted next‑generation sequencing identifies two novel COL2A1 gene mutations in Stickler syndrome with bilateral retinal detachment. Int J Mol Med 2018; 42:1819-1826. [PMID: 30015854 PMCID: PMC6108863 DOI: 10.3892/ijmm.2018.3752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/19/2018] [Indexed: 01/12/2023] Open
Abstract
Stickler syndrome is a group of inherited connective tissue disorders characterized by distinctive facial and ocular abnormalities, hearing loss and early‑onset arthritis. The aim of the present study was to investigate the genetic changes in two Chinese patients with Stickler syndrome, manifested as bilateral retinal detachment and peripheral retinal degeneration. Complete ophthalmic examinations, including best‑corrected visual acuity, slit‑lamp examination and fundus examination, were performed. Genomic DNA was extracted from leukocytes of the peripheral blood collected from the patients, their unaffected family members and 200 unrelated control subjects from the same population. Next‑generation sequencing of established genes associated with ocular disease was performed. A heterozygous collagen type II α1 chain (COL2A1) mutation c.1310G>C (p.R437P) in exon 21 was identified in Family 1 and a heterozygous COL2A1 mutation c.2302‑1G>A in intron 34 was identified in Family 2. The functional effects of the mutations were assessed by polymorphism phenotyping (PolyPhen) and sorting intolerant from tolerant (SIFT) analysis. The c.1310G>C mutation was predicted to damage protein structure and function, and the c.2302‑1G>A mutation was predicted to result in a splicing defect. The findings of the current study expand the established mutation spectrum of COL2A1, and may facilitate genetic counseling and development of therapeutic strategies for patients with Stickler syndrome.
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Affiliation(s)
- Xinhua Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Ying Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Chuan Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Yi Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Hongbin Gao
- Department of Toxicology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Tao Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Bingqian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Cancan Lyu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Ying Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Qingxiu Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Haichun Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Chenjin Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xiaoling Liang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Lin Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
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12
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Barat-Houari M, Sarrabay G, Gatinois V, Fabre A, Dumont B, Genevieve D, Touitou I. Mutation Update for COL2A1 Gene Variants Associated with Type II Collagenopathies. Hum Mutat 2015; 37:7-15. [PMID: 26443184 DOI: 10.1002/humu.22915] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 09/23/2015] [Indexed: 12/19/2022]
Abstract
Mutations in the COL2A1 gene cause a spectrum of rare autosomal-dominant conditions characterized by skeletal dysplasia, short stature, and sensorial defects. An early diagnosis is critical to providing relevant patient care and follow-up, and genetic counseling to affected families. There are no recent exhaustive descriptions of the causal mutations in the literature. Here, we provide a review of COL2A1 mutations extracted from the Leiden Open Variation Database (LOVD) that we updated with data from PubMed and our own patients. Over 700 patients were recorded, harboring 415 different mutations. One-third of the mutations are dominant-negative mutations that affect the glycine residue in the G-X-Y repeats of the alpha 1 chain. These mutations disrupt the collagen triple helix and are common in achondrogenesis type II and hypochondrogenesis. The mutations resulting in a premature stop codon are found in less severe phenotypes such as Stickler syndrome. The p.(Arg275Cys) substitution is found in all patients with COL2A1-associated Czech dysplasia. LOVD-COL2A1 provides support and potential collaborative material for scientific and clinical projects aimed at elucidating phenotype-genotype correlation and differential diagnosis in patients with type II collagenopathies.
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Affiliation(s)
- Mouna Barat-Houari
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France.,Genetics & Immunopathology of Inflammatory Osteoarticular Diseases, INSERM UMR1183, Montpellier, France
| | - Guillaume Sarrabay
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France.,Genetics & Immunopathology of Inflammatory Osteoarticular Diseases, INSERM UMR1183, Montpellier, France
| | - Vincent Gatinois
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France.,University of Montpellier, Montpellier, France
| | - Aurélie Fabre
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France
| | - Bruno Dumont
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France
| | - David Genevieve
- Genetics & Immunopathology of Inflammatory Osteoarticular Diseases, INSERM UMR1183, Montpellier, France.,University of Montpellier, Montpellier, France.,Department of Medical Genetics, Reference Center for Developmental Abnormalities and Constitutional Bone Diseases, CHRU, Montpellier, France
| | - Isabelle Touitou
- Laboratory of Rare and Autoinflammatory Diseases, CHRU, Montpellier, France.,Genetics & Immunopathology of Inflammatory Osteoarticular Diseases, INSERM UMR1183, Montpellier, France.,University of Montpellier, Montpellier, France
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13
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Savasta S, Salpietro V, Spartà MV, Foiadelli T, Laino D, Lobefalo L, Marseglia GL, Verrotti A. Stickler syndrome associated with epilepsy: report of three cases. Eur J Pediatr 2015; 174:697-701. [PMID: 25809783 DOI: 10.1007/s00431-015-2514-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/20/2015] [Accepted: 03/03/2015] [Indexed: 11/25/2022]
Abstract
UNLABELLED Stickler syndrome is a genetically heterogeneous collagenopathy characterized by auditory, ocular, musculoskeletal, and orofacial abnormalities. Stickler syndrome type 1 typically presents ophthalmologic involvement and is due to heterozygous defects of the COL2A1 gene, that have been also identified as the molecular cause of a continuous spectrum of different disorders mainly affecting the cartilage and bone (i.e., Kniest dysplasia, achondrogenesis type II, Legg-Calvè-Perthes disease). We report three Caucasian children with: (a) ocular, oral, facial, auditory, and musculoskeletal manifestations of Stickler syndrome type 1; (b) history of generalized and/or partial seizures coupled with abnormal electroencephalographic records; and (c) pathogenic heterozygous mutations of the COL2A1 gene. Epilepsy has been never reported so far in literature as a possible feature of Stickler syndrome, although neurological presentations, including epilepsy and brain abnormalities, have been occasionally described in other COL2A1-related phenotypes (e.g., Legg-Calvè-Perthes disease). CONCLUSIONS This report raises the possibility of a potential occurrence of seizures among the clinical manifestations of Stickler syndrome type 1, suggesting the presence of a continuous neurological spectrum in some individuals harboring heterozygous mutations in COL2A1. WHAT IS KNOWN • Stickler syndrome is a genetically heterogeneous collagenopathy characterized by auditory, ocular, musculoskeletal, and orofacial anomalies. What is New: • Involvement of the nervous central system is not a typical feature of Stickler syndrome and the association with epilepsy has not been reported so far. • This report raises the possibility of a potential occurrence of seizures among the clinical manifestations of Stickler syndrome type 1, suggesting a continuous neurological spectrum in some individuals affected by heterozygous mutations of COL2A1.
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Affiliation(s)
- Salvatore Savasta
- Department of Pediatrics, IRCSS Policlinico "San Matteo", University of Pavia, Pavia, Italy,
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14
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Lien HW, Yang CH, Cheng CH, Hung CC, Liao WH, Hwang PP, Han YS, Huang CJ. A novel zinc finger protein 219-like (ZNF219L) is involved in the regulation of collagen type 2 alpha 1a (col2a1a) gene expression in zebrafish notochord. Int J Biol Sci 2013; 9:872-86. [PMID: 24155663 PMCID: PMC3805895 DOI: 10.7150/ijbs.7126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/24/2013] [Indexed: 12/01/2022] Open
Abstract
The notochord is required for body plan patterning in vertebrates, and defects in notochord development during embryogenesis can lead to diseases affecting the adult. It is therefore important to elucidate the gene regulatory mechanism underlying notochord formation. In this study, we cloned the zebrafish zinc finger 219-like (ZNF219L) based on mammalian ZNF219, which contains nine C2H2-type zinc finger domains. Through whole-mount in situ hybridization, we found that znf219L mRNA is mainly expressed in the zebrafish midbrain-hindbrain boundary, hindbrain, and notochord during development. The znf219L morpholino knockdown caused partial abnormal notochord phenotype and reduced expression of endogenous col2a1a in the notochord specifically. In addition, ZNF219L could recognize binding sites with GGGGG motifs and trigger augmented activity of the col2a1a promoter in a luciferase assay. Furthermore, in vitro binding experiments revealed that ZNF219L recognizes the GGGGG motifs in the promoter region of the zebrafish col2a1a gene through its sixth and ninth zinc finger domains. Taken together, our results reveal that ZNF219L is involved in regulating the expression of col2a1a in zebrafish notochord specifically.
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Affiliation(s)
- Huang-Wei Lien
- 1. Institute of Fisheries Sciences, National Taiwan University, Taipei 106, Taiwan
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15
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Tan EH, Razak SA, Abdullah JM, Mohamed Yusoff AA. De-novo mutations and genetic variation in the SCN1A gene in Malaysian patients with generalized epilepsy with febrile seizures plus (GEFS+). Epilepsy Res 2012; 102:210-5. [PMID: 22944210 DOI: 10.1016/j.eplepsyres.2012.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 08/05/2012] [Accepted: 08/10/2012] [Indexed: 12/27/2022]
Abstract
Generalized epilepsy with febrile seizures plus (GEFS+) comprises a group of clinically and genetically heterogeneous epilepsy syndrome. Here, we provide the first report of clinical presentation and mutational analysis of SCN1A gene in 36 Malaysian GEFS+ patients. Mutational analysis of SCN1A gene revealed twenty seven sequence variants (missense mutation and silent polymorphism also intronic polymorphism), as well as 2 novel de-novo mutations were found in our patients at coding regions, c.5197A>G (N1733D) and c.4748A>G (H1583R). Our findings provide potential genetic insights into the pathogenesis of GEFS+ in Malaysian populations concerning the SCN1A gene mutations.
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Affiliation(s)
- Emmilia Husni Tan
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
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16
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Nagendran S, Richards AJ, McNinch A, Sandford RN, Snead MP. Somatic mosaicism and the phenotypic expression of COL2A1 mutations. Am J Med Genet A 2012; 158A:1204-7. [DOI: 10.1002/ajmg.a.35303] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 12/27/2011] [Indexed: 11/06/2022]
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17
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Herini ES, Gunadi, Harahap ISK, Yusoff S, Morikawa S, Patria SY, Nishimura N, Sunartini, Sutaryo, Takada S, Matsuo M, Nishio H. Generalized epilepsy with febrile seizures plus (GEFS+) spectrum: Clinical manifestations and SCN1A mutations in Indonesian patients. Epilepsy Res 2010; 90:132-9. [DOI: 10.1016/j.eplepsyres.2010.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/01/2010] [Accepted: 04/08/2010] [Indexed: 10/19/2022]
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Stickler syndrome caused by COL2A1 mutations: genotype-phenotype correlation in a series of 100 patients. Eur J Hum Genet 2010; 18:872-80. [PMID: 20179744 DOI: 10.1038/ejhg.2010.23] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome.
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The influence of pre-mRNA splicing on phenotypic modification in Stickler's syndrome and other type II collagenopathies. Eye (Lond) 2008; 22:1243-50. [PMID: 18309338 DOI: 10.1038/eye.2008.34] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE This paper will illustrate how variation in the processing of mutant pre-mRNA can affect the phenotypic outcome of inherited disorders of type II collagen. METHODS Type 1 Stickler's syndrome is one of the different phenotypes resulting from mutations in COL2A1 (the type II collagenopathies). It is also the commonest, but often goes undiagnosed due to the variability of phenotypic features, which in some cases may consist of only abnormal vitreous development. Most cases of type 1 Stickler's syndrome are due to premature termination codons in the mRNA, resulting in haploinsufficiency. This leaves a conundrum as to why the disease is so variable. Using RT-PCR of illegitimate transcript and also minigenes, we have investigated how certain mutations can variably affect mRNA processing. RESULTS Here, we demonstrate and discuss how apparently similar mutations can have a dramatically different effect on splicing of the pre-mRNA, switching transcripts from ones which would be degraded by nonsense-mediated decay into messages that will be translated into mutant proteins that can exert a dominant-negative effect and ultimately modify the resulting phenotype. CONCLUSION Variability of Stickler's syndrome can, in part, be due to the variable effect that mutations have on the processing of the COL2A1 transcript.
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Clinical evaluation and COL2A1 gene analysis in 21 Brazilian families with Stickler syndrome: identification of novel mutations, further genotype/phenotype correlation, and its implications for the diagnosis. Eur J Med Genet 2008; 51:183-96. [PMID: 18276201 DOI: 10.1016/j.ejmg.2007.12.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 12/27/2007] [Indexed: 10/22/2022]
Abstract
We present clinical and molecular evaluation from a large cohort of patients with Stickler syndrome: 78 individuals from 21 unrelated Brazilian families. The patients were selected in a Hospital with a craniofacial dysmorphology assistance service and clinical diagnosis was based on the presence of cleft palate associated to facial and ocular anomalies of Stickler syndrome. Analysis of COL2A1 gene revealed 9 novel and 4 previously described pathogenic mutations. Except for the mutation c.556G>T (p.Gly186X), all the others were located in the triple helical domain. We did not find genotype/phenotype correlation in relation to type and position of the mutation in the triple helical domain. However, a significantly higher proportion of myopia in patients with mutations located in this domain was observed in relation to those with the mutation in the non-tripe helical domain (c.556G>T; P<0.04). A trend towards a higher prevalence of glaucoma, although not statistically significant, was observed in the presence of the mutation c.556G>T. It is possible that this mutation alters the splicing of the mRNA instead of only creating a premature stop codon and therefore it can lead to protein products of different ocular effects. One novel DNA variation (c.1266+7G>C) occurs near a splice site and it was observed to co-segregate with the phenotype in one of the two families with this DNA variation. As in silico analysis predicted that the c.1266+7G>C DNA variation can affect the efficiency of the splicing, we still cannot rule it out as non-pathogenic. Our study also showed that ascertainment through cleft palate associated to other craniofacial signs can be very efficient for identification of Stickler syndrome patients. Still, high frequency of familial cases and high frequency of underdevelopment of distal lateral tibial epiphyses observed in our patients suggested that the inclusion of this information can improve the clinical diagnosis of Stickler syndrome.
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21
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Ropers HH. New perspectives for the elucidation of genetic disorders. Am J Hum Genet 2007; 81:199-207. [PMID: 17668371 PMCID: PMC1950818 DOI: 10.1086/520679] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 06/06/2007] [Indexed: 12/29/2022] Open
Abstract
For almost 15 years, genome research has focused on the search for major risk factors in common diseases, with disappointing results. Only recently, whole-genome association studies have begun to deliver because of the introduction of high-density single-nucleotide-polymorphism arrays and massive enlargement of cohort sizes, but most of the risk factors detected account for only a small proportion of the total genetic risk, and their diagnostic value is negligible. There is reason to believe that the complexity of many "multifactorial" disorders is primarily due to genetic heterogeneity, with defects of different genes causing the same disease. Moreover, de novo copy-number variation has been identified as a major cause of mental retardation and other complex disorders, suggesting that new mutations are an important, previously overlooked factor in the etiology of complex diseases. These observations support the notion that research into the previously neglected monogenic disorders should become a priority of genome research. Because of the introduction of novel high-throughput, low-cost sequencing methods, sequencing and genotyping will soon converge, with far-reaching implications for the elucidation of genetic disease and health care.
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