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Chen JM, Lin JH, Masson E, Liao Z, Férec C, Cooper DN, Hayden M. The Experimentally Obtained Functional Impact Assessments of 5' Splice Site GT'GC Variants Differ Markedly from Those Predicted. Curr Genomics 2020; 21:56-66. [PMID: 32655299 PMCID: PMC7324893 DOI: 10.2174/1389202921666200210141701] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 01/26/2023] Open
Abstract
Introduction: 5' splice site GT>GC or +2T>C variants have been frequently reported to cause human genetic disease and are routinely scored as pathogenic splicing mutations. However, we have recently demonstrated that such variants in human disease genes may not invariably be pathogenic. Moreover, we found that no splicing prediction tools appear to be capable of reliably distinguishing those +2T>C variants that generate wild-type transcripts from those that do not. Methodology Herein, we evaluated the performance of a novel deep learning-based tool, SpliceAI, in the context of three datasets of +2T>C variants, all of which had been characterized functionally in terms of their impact on pre-mRNA splicing. The first two datasets refer to our recently described “in vivo” dataset of 45 known disease-causing +2T>C variants and the “in vitro” dataset of 103 +2T>C substitutions subjected to full-length gene splicing assay. The third dataset comprised 12 BRCA1 +2T>C variants that were recently analyzed by saturation genome editing. Results Comparison of the SpliceAI-predicted and experimentally obtained functional impact assessments of these variants (and smaller datasets of +2T>A and +2T>G variants) revealed that although SpliceAI performed rather better than other prediction tools, it was still far from perfect. A key issue was that the impact of those +2T>C (and +2T>A) variants that generated wild-type transcripts represents a quantitative change that can vary from barely detectable to an almost full expression of wild-type transcripts, with wild-type transcripts often co-existing with aberrantly spliced transcripts. Conclusion Our findings highlight the challenges that we still face in attempting to accurately identify splice-altering variants.
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Affiliation(s)
- Jian-Min Chen
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Jin-Huan Lin
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Emmanuelle Masson
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Zhuan Liao
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Claude Férec
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - David N Cooper
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Matthew Hayden
- 1EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200Brest, France; 2Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China; 3Shanghai Institute of Pancreatic Diseases, Shanghai, China; 4CHRU Brest, Service de Génétique Médicale et de Biologie de la Reproduction, Brest, France; 5Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
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Lin JH, Tang XY, Boulling A, Zou WB, Masson E, Fichou Y, Raud L, Le Tertre M, Deng SJ, Berlivet I, Ka C, Mort M, Hayden M, Leman R, Houdayer C, Le Gac G, Cooper DN, Li ZS, Férec C, Liao Z, Chen JM. First estimate of the scale of canonical 5' splice site GT>GC variants capable of generating wild-type transcripts. Hum Mutat 2019; 40:1856-1873. [PMID: 31131953 DOI: 10.1002/humu.23821] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/10/2019] [Accepted: 05/24/2019] [Indexed: 12/13/2022]
Abstract
It has long been known that canonical 5' splice site (5'SS) GT>GC variants may be compatible with normal splicing. However, to date, the actual scale of canonical 5'SSs capable of generating wild-type transcripts in the case of GT>GC substitutions remains unknown. Herein, combining data derived from a meta-analysis of 45 human disease-causing 5'SS GT>GC variants and a cell culture-based full-length gene splicing assay of 103 5'SS GT>GC substitutions, we estimate that ~15-18% of canonical GT 5'SSs retain their capacity to generate between 1% and 84% normal transcripts when GT is substituted by GC. We further demonstrate that the canonical 5'SSs in which substitution of GT by GC-generated normal transcripts exhibit stronger complementarity to the 5' end of U1 snRNA than those sites whose substitutions of GT by GC did not lead to the generation of normal transcripts. We also observed a correlation between the generation of wild-type transcripts and a milder than expected clinical phenotype but found that none of the available splicing prediction tools were capable of reliably distinguishing 5'SS GT>GC variants that generated wild-type transcripts from those that did not. Our findings imply that 5'SS GT>GC variants in human disease genes may not invariably be pathogenic.
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Affiliation(s)
- Jin-Huan Lin
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France.,Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Xin-Ying Tang
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Arnaud Boulling
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France
| | - Wen-Bin Zou
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Emmanuelle Masson
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France.,CHU Brest, Service de Génétique, Brest, France
| | - Yann Fichou
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Loann Raud
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France
| | | | - Shun-Jiang Deng
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | | | - Chandran Ka
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France.,CHU Brest, Service de Génétique, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Matthew Mort
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Matthew Hayden
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Raphaël Leman
- Laboratoire de Biologie et Génétique du Cancer, Centre François Baclesse, Caen, France.,Department of Genetics, F76000 and Normandy University, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen University Hospital, Rouen, France
| | - Claude Houdayer
- Department of Genetics, F76000 and Normandy University, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen University Hospital, Rouen, France
| | - Gerald Le Gac
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France.,CHU Brest, Service de Génétique, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Zhao-Shen Li
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Claude Férec
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France
| | - Zhuan Liao
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Jian-Min Chen
- EFS, Univ Brest, Inserm, UMR 1078, GGB, F-29200, Brest, France
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Ota M, Takeshima Y, Nishida A, Awano H, Lee T, Yagi M, Matsuo M. A G-to-T transversion at the splice acceptor site of dystrophin exon 14 shows multiple splicing outcomes that are not exemplified by transition mutations. Genet Test Mol Biomarkers 2011; 16:3-8. [PMID: 21854195 DOI: 10.1089/gtmb.2010.0276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mutations at splicing consensus sequences have been shown to induce splicing errors such as exon skipping or cryptic splice site activation. Here, we identified eight splicing products caused by a G-to-T transversion mutation at the splice acceptor site of exon 14 of the dystrophin gene (c.1603-1G>T). Unexpectedly, the most abundant product showed skipping of the two consecutive exons 14 and 15, and exon 14 skipping was observed as the second most abundant product. To examine the cause of this splicing multiplicity, minigenes containing dystrophin exons 14 and 15 with their flanking introns were constructed and subjected to in vitro splicing. Minigenes with the wild-type sequence or a G>A transition at position c.1603-1 produced only the mature mRNA. On the other hand, the minigenes with a G>T or G>C transversion mutation produced multiple splicing products. A time-course analysis of the in vitro splicing revealed that splicing of the middle intron, intron 14, was the first step in transcript maturation for all four minigene constructs. The identity of the mutant nucleotide, but not its position, is a factor leading to multiple splicing outcomes. Our results suggest that exon skipping therapy for Duchenne's muscular dystrophy should be carefully monitored for their splicing outcomes.
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Affiliation(s)
- Mitsunori Ota
- Department of Pediatrics, Graduate School of Medicine, Kobe University, Kobe, Japan
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Tuffery-Giraud S, Saquet C, Thorel D, Disset A, Rivier F, Malcolm S, Claustres M. Mutation spectrum leading to an attenuated phenotype in dystrophinopathies. Eur J Hum Genet 2005; 13:1254-60. [PMID: 16077730 DOI: 10.1038/sj.ejhg.5201478] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Although Becker muscular dystrophy (BMD; MIM 300376) is mainly caused by gross deletions of the dystrophin gene, the nature of the mutations involved in the remaining cases is of importance because of the milder clinical course of Becker. We have extensively characterized the mRNA changes associated with five novel point mutations giving rise to a Becker phenotype, which confirm that Becker arises largely due to alterations in splicing. In two cases the milder phenotype arises because of exon skipping, leading to an in-frame deletion (c.1603-2A>C and c.4250T>A). In further two cases intronic mutations (c.4519-5C>G and c.961-5925A>C) result in complex splicing changes, but with some residual normal transcripts. The last case, c.10412T>A (p.Leu3471X), results in a truncated transcript missing only part of the COOH terminal of the protein, suggesting that this region is not crucial for dystrophin function. The detection of a low amount of dystrophin in this patient could be attributable to a reduced efficiency of nonsense-mediated decay. The results emphasize that mRNA analysis is important in defining Becker mutations and will be of value in assessing various gene therapy strategies.
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Affiliation(s)
- Sylvie Tuffery-Giraud
- Laboratoire de Génétique Moleculaire et Chromosomique, CHU de Montpellier, Montpellier, France.
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5
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Abstract
Duchenne (DMD) and Becker (BMD) type muscular dystrophies are allelic X-linked recessive disorders caused by mutations in the gene encoding dystrophin. About 65% of the cases are caused by deletions, while 5-10% are duplications. The remaining 30% of affected individuals may have smaller mutations (point mutations or small deletions/insertions) which cannot be identified by current diagnostic screening strategies. In order to look for pathogenic small mutations in the dystrophin gene, we have screened the 18 exons located in the hot spot region of this gene through two different single strand conformation polymorphism (SSCP) conditions. Five different pathogenic mutations were identified in 6 out of 192 DMD/BMD patients without detectable deletions: 2 nonsense, 1 bp insertion, 1 bp deletion and 1 intronic. Except for the intronic change, which alters a splice site, all the others cause a premature stop codon. In addition, 8 apparently neutral changes were identified. However, interestingly, one of them was not identified in 195 normal chromosomes, although it was previously described in a DMD patient from a different population. The possibility that this mutation may be pathogenic is discussed. Except for two neutral changes, all the others are apparently here described for the first time.
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Affiliation(s)
- R Sitnik
- Departamento de Biologia, Instituto de Biociências, University of São Paulo, Brazil
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Mehler MF. Brain dystrophin, neurogenetics and mental retardation. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 32:277-307. [PMID: 10751678 DOI: 10.1016/s0165-0173(99)00090-9] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Duchenne muscular dystrophy (DMD) and the allelic disorder Becker muscular dystrophy (BMD) are common X-linked recessive neuromuscular disorders that are associated with a spectrum of genetically based developmental cognitive and behavioral disabilities. Seven promoters scattered throughout the huge DMD/BMD gene locus normally code for distinct isoforms of the gene product, dystrophin, that exhibit nervous system developmental, regional and cell-type specificity. Dystrophin is a complex plasmalemmal-cytoskeletal linker protein that possesses multiple functional domains, autosomal and X-linked homologs and associated binding proteins that form multiunit signaling complexes whose composition is unique to each cellular and developmental context. Through additional interactions with a variety of proteins of the extracellular matrix, plasma membrane, cytoskeleton and distinct intracellular compartments, brain dystrophin acquires the capability to participate in the modulatory actions of a large number of cellular signaling pathways. During neural development, dystrophin is expressed within the neural tube and selected areas of the embryonic and postnatal neuraxis, and may regulate distinct aspects of neurogenesis, neuronal migration and cellular differentiation. By contrast, in the mature brain, dystrophin is preferentially expressed by specific regional neuronal subpopulations within proximal somadendritic microdomains associated with synaptic terminal membranes. Increasing experimental evidence suggests that in adult life, dystrophin normally modulates synaptic terminal integrity, distinct forms of synaptic plasticity and regional cellular signal integration. At a systems level, dystrophin may regulate essential components of an integrated sensorimotor attentional network. Dystrophin deficiency in DMD/BMD patients and in the mdx mouse model appears to impair intracellular calcium homeostasis and to disrupt multiple protein-protein interactions that normally promote information transfer and signal integration from the extracellular environment to the nucleus within regulated microdomains. In DMD/BMD, the individual profiles of cognitive and behavioral deficits, mental retardation and other phenotypic variations appear to depend on complex profiles of transcriptional regulation associated with individual dystrophin mutations that result in the corresponding presence or absence of individual brain dystrophin isoforms that normally exhibit developmental, regional and cell-type-specific expression and functional regulation. This composite experimental model will allow fine-level mapping of cognitive-neurogenetic associations that encompass the interrelationships between molecular, cellular and systems levels of signal integration, and will further our understanding of complex gene-environmental interactions and the pathogenetic basis of developmental disorders associated with mental retardation.
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Affiliation(s)
- M F Mehler
- Departments of Neurology, Neuroscience and Psychiatry, the Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Ozawa E, Noguchi S, Mizuno Y, Hagiwara Y, Yoshida M. From dystrophinopathy to sarcoglycanopathy: evolution of a concept of muscular dystrophy. Muscle Nerve 1998; 21:421-38. [PMID: 9533777 DOI: 10.1002/(sici)1097-4598(199804)21:4<421::aid-mus1>3.0.co;2-b] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Duchenne and Becker muscular dystrophies are collectively termed dystrophinopathy. Dystrophinopathy and severe childhood autosomal recessive muscular dystrophy (SCARMD) are clinically very similar and had not been distinguished in the early 20th century. SCARMD was first classified separately from dystrophinopathy due to differences in the mode of inheritance. Studies performed several years ago clarified some immunohistochemical and genetic characteristics of SCARMD, but many remained to be clarified. In 1994, the sarcoglycan complex was discovered among dystrophin-associated proteins. Subsequently, on the basis of our immunohistochemical findings which indicated that all components of the sarcoglycan complex are absent in SCARMD muscles, and the previous genetic findings, we proposed that a mutation of any one of the sarcoglycan genes leads to SCARMD. This hypothesis explained and predicted various characteristics of SCARMD at the molecular level, most of which have been verified by subsequent discoveries in our own as well as various other laboratories. SCARMD is now called sarcoglycanopathy, which is caused by a defect of any one of four different sarcoglycan genes, and thus far mutations in sarcoglycan genes have been documented in the SCARMD patients. In this review, the evolution of the concept of sarcoglycanopathy separate from that of dystrophinopathy is explained by comparing studies on these diseases.
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Affiliation(s)
- E Ozawa
- National Institute of Neuroscience, NCNP, Kodaira, Tokyo, Japan
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Chen B, North PE, Parham DM. Implications of a common polymorphism in intron 12 of the dystrophin gene for deletion detection by multiplex PCR. Gene 1998; 209:211-7. [PMID: 9524268 DOI: 10.1016/s0378-1119(98)00051-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The multiplex polymerase chain reaction (PCR) is a reliable and efficient method for detecting dystrophin gene deletions in about 65% of patients with Duchenne or Becker muscular dystrophy (DMD or BMD). The 9-plex PCR assay, which simultaneously amplifies the muscle-specific promoter and exons 3, 6, 13, 43, 47, 50, 52 and 60, is one of the multiplex PCR assays used routinely to test for DMD and BMD deletions. In this study, we describe a previously unrecognized A to G base variation in intron 12 (nt -110 from exon 13) of the dystrophin gene. This variant, located within the annealing site of the exon 13 forward primer, prevented amplification of exon 13 in the 9-plex PCR assay. Present in 56% (25 of 45) of normal Caucasian alleles and 23% (3 of 13) of normal black American alleles, it is likely encountered frequently during dystrophin deletion analysis by multiplex PCR, and may complicate test result interpretation. Therefore, we suggest two modifications for the multiplex PCR detection of dystrophin gene deletion.
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Affiliation(s)
- B Chen
- Molecular Diagnosis Laboratory, Arkansas Children's Hospital, 800 Marshall Street, Little Rock, AR 72202, USA.
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