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Jiao K, Cheng N, Huan X, Zhang J, Ding Y, Luan X, Liu L, Wang X, Zhu B, Du K, Fan J, Gao M, Xia X, Wang N, Wang T, Xi J, Luo S, Lu J, Zhao C, Yue D, Zhu W. Pseudoexon activation by deep intronic variation in GNE myopathy with thrombocytopenia. Muscle Nerve 2024; 69:708-718. [PMID: 38558464 DOI: 10.1002/mus.28092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 03/07/2024] [Accepted: 03/16/2024] [Indexed: 04/04/2024]
Abstract
INTRODUCTION/AIMS GNE myopathy is a rare autosomal recessive disorder caused by pathogenic variants in the GNE gene, which is essential for the sialic acid biosynthesis pathway. Although over 300 GNE variants have been reported, some patients remain undiagnosed with monoallelic pathogenic variants. This study aims to analyze the entire GNE genomic region to identify novel pathogenic variants. METHODS Patients with clinically compatible GNE myopathy and monoallelic pathogenic variants in the GNE gene were enrolled. The other GNE pathogenic variant was verified using comprehensive methods including exon 2 quantitative polymerase chain reaction and nanopore long-read single-molecule sequencing (LRS). RESULTS A deep intronic GNE variant, c.862+870C>T, was identified in nine patients from eight unrelated families. This variant generates a cryptic splice site, resulting in the activation of a novel pseudoexon between exons 5 and 6. It results in the insertion of an extra 146 nucleotides into the messengerRNA (mRNA), which is predicted to result in a truncated humanGNE1(hGNE1) protein. Peanut agglutinin(PNA) lectin staining of muscle tissues showed reduced sialylation of mucin O-glycans on sarcolemmal glycoproteins. Notably, a third of patients with the c.862+870C>T variant exhibited thrombocytopenia. A common core haplotype harboring the deep intronic GNE variant was found in all these patients. DISCUSSION The transcript with pseudoexon activation potentially affects sialic acid biosynthesis via nonsense-mediated mRNA decay, or resulting in a truncated hGNE1 protein, which interferes with normal enzyme function. LRS is expected to be more frequently incorporated in genetic analysis given its efficacy in detecting hard-to-find pathogenic variants.
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Affiliation(s)
- Kexin Jiao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Nachuan Cheng
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Xiao Huan
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Jialong Zhang
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Yu Ding
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Xinghua Luan
- Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - LingChun Liu
- The First People's Hospital of Yunnan Province, Kunming, China
| | - Xilu Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Bochen Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Kunzhao Du
- Jinshan Hospital Center for Neurosurgery, Jinshan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Jiale Fan
- The State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, The Institutes of Brain Science, Shanghai, China
| | - Mingshi Gao
- Department of Pathology, Huashan Hospital, Fudan University, Shanghai, China
| | - Xingyu Xia
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Ningning Wang
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Tao Wang
- Department of Anesthesiology, Zhongshan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Jianying Xi
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Sushan Luo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Jiahong Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Chongbo Zhao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Dongyue Yue
- Department of Neurology, Jing'an District Center Hospital of Shanghai, Shanghai, China
| | - Wenhua Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
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Suárez-Herrera N, Li CHZ, Leijsten N, Karjosukarso DW, Corradi Z, Bukkems F, Duijkers L, Cremers FPM, Hoyng CB, Garanto A, Collin RWJ. Preclinical Development of Antisense Oligonucleotides to Rescue Aberrant Splicing Caused by an Ultrarare ABCA4 Variant in a Child with Early-Onset Stargardt Disease. Cells 2024; 13:601. [PMID: 38607040 PMCID: PMC11011354 DOI: 10.3390/cells13070601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/19/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024] Open
Abstract
Precision medicine is rapidly gaining recognition in the field of (ultra)rare conditions, where only a few individuals in the world are affected. Clinical trial design for a small number of patients is extremely challenging, and for this reason, the development of N-of-1 strategies is explored to accelerate customized therapy design for rare cases. A strong candidate for this approach is Stargardt disease (STGD1), an autosomal recessive macular degeneration characterized by high genetic and phenotypic heterogeneity. STGD1 is caused by pathogenic variants in ABCA4, and amongst them, several deep-intronic variants alter the pre-mRNA splicing process, generally resulting in the insertion of pseudoexons (PEs) into the final transcript. In this study, we describe a 10-year-old girl harboring the unique deep-intronic ABCA4 variant c.6817-713A>G. Clinically, she presents with typical early-onset STGD1 with a high disease symmetry between her two eyes. Molecularly, we designed antisense oligonucleotides (AONs) to block the produced PE insertion. Splicing rescue was assessed in three different in vitro models: HEK293T cells, fibroblasts, and photoreceptor precursor cells, the last two being derived from the patient. Overall, our research is intended to serve as the basis for a personalized N-of-1 AON-based treatment to stop early vision loss in this patient.
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Affiliation(s)
- Nuria Suárez-Herrera
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Catherina H. Z. Li
- Department of Ophthalmology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (C.H.Z.L.); (C.B.H.)
| | - Nico Leijsten
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Dyah W. Karjosukarso
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Femke Bukkems
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Lonneke Duijkers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Frans P. M. Cremers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (C.H.Z.L.); (C.B.H.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Rob W. J. Collin
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
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Bolduc V, Guirguis F, Lubben B, Trank L, Silverstein S, Brull A, Nalls M, Cheng J, Garrett L, Bönnemann CG. A humanized knock-in Col6a1 mouse recapitulates a deep-intronic splice-activating variant. bioRxiv 2024:2024.03.21.581572. [PMID: 38585878 PMCID: PMC10996637 DOI: 10.1101/2024.03.21.581572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Antisense therapeutics such as splice-modulating antisense oligonucleotides (ASOs) are promising tools to treat diseases caused by splice-altering intronic variants. However, their testing in animal models is hampered by the generally poor sequence conservation of the intervening sequences between human and other species. Here we aimed to model in the mouse a recurrent, deep-intronic, splice-activating, COL6A1 variant, associated with a severe form of Collagen VI-related muscular dystrophies (COL6-RDs), for the purpose of testing human-ready antisense therapeutics in vivo. The variant, c.930+189C>T, creates a donor splice site and inserts a 72-nt-long pseudoexon, which, when translated, acts in a dominant-negative manner, but which can be skipped with ASOs. We created a unique humanized mouse allele (designated as "h"), in which a 1.9 kb of the mouse genomic region encoding the amino-terminus (N-) of the triple helical (TH) domain of collagen a1(VI) was swapped for the human orthologous sequence. In addition, we also created an allele that carries the c.930+189C>T variant on the same humanized knock-in sequence (designated as "h+189T"). We show that in both models, the human exons are spliced seamlessly with the mouse exons to generate a chimeric mouse-human collagen a1(VI) protein. In homozygous Col6a1 h+189T/h+189T mice, the pseudoexon is expressed at levels comparable to those observed in heterozygous patients' muscle biopsies. While Col6a1h/h mice do not show any phenotype compared to wildtype animals, Col6a1 h/h+189T and Col6a1 h+189T/h+189T mice have smaller muscle masses and display grip strength deficits detectable as early as 4 weeks of age. The pathogenic h+189T humanized knock-in mouse allele thus recapitulates the pathogenic splicing defects seen in patients' biopsies and allows testing of human-ready precision antisense therapeutics aimed at skipping the pseudoexon. Given that the COL6A1 N-TH region is a hot-spot for COL6-RD variants, the humanized knock-in mouse model can be utilized as a template to introduce other COL6A1 pathogenic variants. This unique humanized mouse model thus represents a valuable tool for the development of antisense therapeutics for COL6-RDs.
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Affiliation(s)
- Véronique Bolduc
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Fady Guirguis
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Berit Lubben
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Lindsey Trank
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Sarah Silverstein
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Astrid Brull
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Matthew Nalls
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Jun Cheng
- NHGRI Transgenic and Gene Editing Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
| | - Lisa Garrett
- NHGRI Transgenic and Gene Editing Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
| | - Carsten G. Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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4
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Spangsberg Petersen US, Dembic M, Martínez-Pizarro A, Richard E, Holm LL, Havelund JF, Doktor TK, Larsen MR, Færgeman NJ, Desviat LR, Andresen BS. Regulating PCCA gene expression by modulation of pseudoexon splicing patterns to rescue enzyme activity in propionic acidemia. Mol Ther Nucleic Acids 2024; 35:102101. [PMID: 38204914 PMCID: PMC10776996 DOI: 10.1016/j.omtn.2023.102101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 12/08/2023] [Indexed: 01/12/2024]
Abstract
Pseudoexons are nonfunctional intronic sequences that can be activated by deep-intronic sequence variation. Activation increases pseudoexon inclusion in mRNA and interferes with normal gene expression. The PCCA c.1285-1416A>G variation activates a pseudoexon and causes the severe metabolic disorder propionic acidemia by deficiency of the propionyl-CoA carboxylase enzyme encoded by PCCA and PCCB. We characterized this pathogenic pseudoexon activation event in detail and identified hnRNP A1 to be important for normal repression. The PCCA c.1285-1416A>G variation disrupts an hnRNP A1-binding splicing silencer and simultaneously creates a splicing enhancer. We demonstrate that blocking this region of regulation with splice-switching antisense oligonucleotides restores normal splicing and rescues enzyme activity in patient fibroblasts and in a cellular model created by CRISPR gene editing. Interestingly, the PCCA pseudoexon offers an unexploited potential to upregulate gene expression because healthy tissues show relatively high inclusion levels. By blocking inclusion of the nonactivated wild-type pseudoexon, we can increase both PCCA and PCCB protein levels, which increases the activity of the heterododecameric enzyme. Surprisingly, we can increase enzyme activity from residual levels in not only patient fibroblasts harboring PCCA missense variants but also those harboring PCCB missense variants. This is a potential treatment strategy for propionic acidemia.
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Affiliation(s)
- Ulrika Simone Spangsberg Petersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
- Department of Clinical Genetics, Odense University Hospital, 5000 Odense C, Denmark
- Department of Mathematics and Computer Science, University of Southern Denmark, 5230 Odense M, Denmark
| | - Ainhoa Martínez-Pizarro
- Centro de Biología Molecular Severo Ochoa, UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Eva Richard
- Centro de Biología Molecular Severo Ochoa, UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Lise Lolle Holm
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Jesper Foged Havelund
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Thomas Koed Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Martin Røssel Larsen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Nils J. Færgeman
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Lourdes Ruiz Desviat
- Centro de Biología Molecular Severo Ochoa, UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Brage Storstein Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
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5
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Levy AM, Ganapathi M, Chung WK, Tümer Z. A deep intronic DLG4 variant resulting in DLG4-related synaptopathy. Clin Genet 2024; 105:77-80. [PMID: 37525972 DOI: 10.1111/cge.14411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/02/2023]
Abstract
The rare autosomal dominant brain disorder DLG4-related synaptopathy is caused by de novo variants in DLG4 (encoding PSD-95), the majority of which are predicted to be protein-truncating. In addition to splice site variants, a number of synonymous and missense DLG4 variants are predicted to exert their effect through altered RNA splicing, although the pathogenicity of these variants is uncertain without functional RNA studies. Here, we describe a young boy with a deep intronic DLG4 variant (c.2105+235C>T) identified using whole genome sequencing. By using reverse-transcription PCR on RNA derived from peripheral blood, we demonstrate that DLG4 mRNA expression is detectable in blood and the deep intronic variant gives rise to two alternative DLG4 transcripts, one of which includes a pseudoexon. Both alternative transcripts are out-of-frame and predicted to result in protein-truncation, thereby establishing the genetic diagnosis for the proband. This adds to the evidence concerning the pathogenic potential of deep intronic variants and underlines the importance of functional studies, even in cases where reported tissue-specific gene expression might suggest otherwise.
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Affiliation(s)
- Amanda M Levy
- Department of Clinical Genetics, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Mythily Ganapathi
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York City, New York, USA
| | - Wendy K Chung
- Department of Pediatrics, Columbia University Irving Medical Center, New York City, New York, USA
| | - Zeynep Tümer
- Department of Clinical Genetics, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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6
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Loginova M, Druzhinina S, Paramonov I, Zarubin M. Discovery of the novel HLA-DQB1*06:02:01:32 allele, a variant of HLA-DQB1*06:02:01:01, in a Russian individual. HLA 2023. [PMID: 36961290 DOI: 10.1111/tan.15032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 03/11/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023]
Abstract
One nucleotide substitution in pseudoexon 5 of HLA-DQB1*06:02:01:01 results in a novel allele, HLA-DQB1*06:02:01:32.
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Affiliation(s)
- Maria Loginova
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute under the Federal Medicine and Biology Agency, 72, Krasnoarmeyskaya Street, Kirov, 610027, Russia
- Federal State Budget Educational Institution of Higher Professional Education: Vyatka State University, 36, Moskovskaya Street, Kirov, 610000, Russia
| | - Svetlana Druzhinina
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute under the Federal Medicine and Biology Agency, 72, Krasnoarmeyskaya Street, Kirov, 610027, Russia
| | - Igor Paramonov
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute under the Federal Medicine and Biology Agency, 72, Krasnoarmeyskaya Street, Kirov, 610027, Russia
| | - Maksim Zarubin
- State Budgetary Health Institution: Irkutsk Regional Blood Transfusion Station, 122, Baikalskaya Street, Irkutsk, 664046, Russia
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7
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Guo DC, Duan X, Mimnagh K, Cecchi AC, Marin IC, Yu Y, Velasco WV, Lee K, Zhu X, Murdock DR, Leal SM, Wheeler MM, Smith J, Bamshad MJ, Milewicz DM. An FBN1 deep intronic variant is associated with pseudoexon formation and a variable Marfan phenotype in a five generation family. Clin Genet 2023; 103:704-708. [PMID: 36861389 PMCID: PMC10159920 DOI: 10.1111/cge.14322] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/09/2023] [Accepted: 02/12/2023] [Indexed: 03/03/2023]
Abstract
Exome sequencing of genes associated with heritable thoracic aortic disease (HTAD) failed to identify a pathogenic variant in a large family with Marfan syndrome (MFS). A genome-wide linkage analysis for thoracic aortic disease identified a peak at 15q21.1, and genome sequencing identified a novel deep intronic FBN1 variant that segregated with thoracic aortic disease in the family (LOD score 2.7) and was predicted to alter splicing. RT-PCR and bulk RNA sequencing of RNA harvested from fibroblasts explanted from the affected proband revealed an insertion of a pseudoexon between exons 13 and 14 of the FBN1 transcript, predicted to lead to nonsense mediated decay (NMD). Treating the fibroblasts with an NMD inhibitor, cycloheximide, greatly improved the detection of the pseudoexon-containing transcript. Family members with the FBN1 variant had later onset aortic events and fewer MFS systemic features than typical for individuals with haploinsufficiency of FBN1. Variable penetrance of the phenotype and negative genetic testing in MFS families should raise the possibility of deep intronic FBN1 variants and the need for additional molecular studies.
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Affiliation(s)
- Dong-Chuan Guo
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Xueyan Duan
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Kathleen Mimnagh
- Department of Internal Medicine, WVU School of Medicine-Charleston Division (Retired), Morgantown, West Virginia, USA
| | - Alana C Cecchi
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Isabella C Marin
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Yang Yu
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Walter V Velasco
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Kwanghyuk Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Xue Zhu
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - David R Murdock
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Suzanne M Leal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Marsha M Wheeler
- Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Josh Smith
- Genome Sciences, University of Washington, Seattle, Washington, USA
| | | | - Dianna M Milewicz
- Department of Internal Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
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8
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Reurink J, Weisschuh N, Garanto A, Dockery A, van den Born LI, Fajardy I, Haer-Wigman L, Kohl S, Wissinger B, Farrar GJ, Ben-Yosef T, Pfiffner FK, Berger W, Weener ME, Dudakova L, Liskova P, Sharon D, Salameh M, Offenheim A, Heon E, Girotto G, Gasparini P, Morgan A, Bergen AA, Ten Brink JB, Klaver CCW, Tranebjærg L, Rendtorff ND, Vermeer S, Smits JJ, Pennings RJE, Aben M, Oostrik J, Astuti GDN, Corominas Galbany J, Kroes HY, Phan M, van Zelst-Stams WAG, Thiadens AAHJ, Verheij JBGM, van Schooneveld MJ, de Bruijn SE, Li CHZ, Hoyng CB, Gilissen C, Vissers LELM, Cremers FPM, Kremer H, van Wijk E, Roosing S. Whole genome sequencing for USH2A-associated disease reveals several pathogenic deep-intronic variants that are amenable to splice correction. HGG Adv 2023; 4:100181. [PMID: 36785559 DOI: 10.1016/j.xhgg.2023.100181] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 01/12/2023] [Indexed: 01/19/2023] Open
Abstract
A significant number of individuals with a rare disorder such as Usher syndrome (USH) and (non-)syndromic autosomal recessive retinitis pigmentosa (arRP) remain genetically unexplained. Therefore, we assessed subjects suspected of USH2A-associated disease and no or mono-allelic USH2A variants using whole genome sequencing (WGS) followed by an improved pipeline for variant interpretation to provide a conclusive diagnosis. One hundred subjects were screened using WGS to identify causative variants in USH2A or other USH/arRP-associated genes. In addition to the existing variant interpretation pipeline, a particular focus was put on assessing splice-affecting properties of variants, both in silico and in vitro. Also structural variants were extensively addressed. For variants resulting in pseudoexon inclusion, we designed and evaluated antisense oligonucleotides (AONs) using minigene splice assays and patient-derived photoreceptor precursor cells. Biallelic variants were identified in 49 of 100 subjects, including novel splice-affecting variants and structural variants, in USH2A or arRP/USH-associated genes. Thirteen variants were shown to affect USH2A pre-mRNA splicing, including four deep-intronic USH2A variants resulting in pseudoexon inclusion, which could be corrected upon AON treatment. We have shown that WGS, combined with a thorough variant interpretation pipeline focused on assessing pre-mRNA splicing defects and structural variants, is a powerful method to provide subjects with a rare genetic condition, a (likely) conclusive genetic diagnosis. This is essential for the development of future personalized treatments and for patients to be eligible for such treatments.
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9
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Loginova M, Druzhinina S, Paramonov I, Zarubin M. Recognition of the novel HLA-DQB1*05:02:01:15 allele in a Russian bone marrow donor. HLA 2023; 101:708-709. [PMID: 36617701 DOI: 10.1111/tan.14968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/10/2023]
Abstract
One nucleotide substitution in pseudoexon 5 of HLA-DQB1*05:02:01:01 results in a novel allele, HLA-DQB1*05:02:01:15.
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Affiliation(s)
- Maria Loginova
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute Under the Federal Medicine and Biology Agency, Kirov, Russia.,Federal State Budget Educational Institution of Higher Professional Education: Vyatka State University, Kirov, Russia
| | - Svetlana Druzhinina
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute Under the Federal Medicine and Biology Agency, Kirov, Russia
| | - Igor Paramonov
- Federal State Budget Research Institution: Kirov Hematology and Blood Transfusion Research Institute Under the Federal Medicine and Biology Agency, Kirov, Russia
| | - Maksim Zarubin
- State Budgetary Health Institution: Irkutsk Regional Blood Transfusion Station, Irkutsk, Russia
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10
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Waldrop MA, Moore SA, Mathews KD, Darbro BW, Medne L, Finkel R, Connolly AM, Crawford TO, Drachman D, Wein N, Habib AA, Krzesniak-Swinarska MA, Zaidman CM, Collins JJ, Jokela M, Udd B, Day JW, Ortiz-Guerrero G, Statland J, Butterfield RJ, Dunn DM, Weiss RB, Flanigan KM. Intron mutations and early transcription termination in Duchenne and Becker muscular dystrophy. Hum Mutat 2022; 43:511-528. [PMID: 35165973 PMCID: PMC9901284 DOI: 10.1002/humu.24343] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 11/11/2022]
Abstract
DMD pathogenic variants for Duchenne and Becker muscular dystrophy are detectable with high sensitivity by standard clinical exome analyses of genomic DNA. However, up to 7% of DMD mutations are deep intronic and analysis of muscle-derived RNA is an important diagnostic step for patients who have negative genomic testing but abnormal dystrophin expression in muscle. In this study, muscle biopsies were evaluated from 19 patients with clinical features of a dystrophinopathy, but negative clinical DMD mutation analysis. Reverse transcription-polymerase chain reaction or high-throughput RNA sequencing methods identified 19 mutations with one of three pathogenic pseudoexon types: deep intronic point mutations, deletions or insertions, and translocations. In association with point mutations creating intronic splice acceptor sites, we observed the first examples of DMD pseudo 3'-terminal exon mutations causing high efficiency transcription termination within introns. This connection between splicing and premature transcription termination is reminiscent of U1 snRNP-mediating telescripting in sustaining RNA polymerase II elongation across large genes, such as DMD. We propose a novel classification of three distinct types of mutations identifiable by muscle RNA analysis, each of which differ in potential treatment approaches. Recognition and appropriate characterization may lead to therapies directed toward full-length dystrophin expression for some patients.
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Affiliation(s)
- Megan A. Waldrop
- The Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH 43205,Department of Neurology, The Ohio State University, Columbus, OH 43205,Department of Pediatrics, The Ohio State University, Columbus, OH 43205
| | - Steven A. Moore
- Department of Pathology, The University of Iowa, Iowa City, IA, 52242
| | | | | | - Livja Medne
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104
| | | | - Anne M. Connolly
- Department of Neurology, Washington University, Saint Louis, MO 63110
| | | | | | - Nicolas Wein
- The Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH 43205
| | | | | | - Craig M. Zaidman
- Department of Neurology, Washington University, Saint Louis, MO 63110
| | - James J. Collins
- Department of Pediatric Neurology, Mercy Hospitals, Springfield, MO 65804
| | - Manu Jokela
- Neuromuscular Research Center, Tampere University Hospital and University of Tampere, Tampere, Finland,Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Bjarne Udd
- Neuromuscular Research Center, Tampere University Hospital and University of Tampere, Tampere, Finland
| | - John W. Day
- Department of Neurology, University of Minnesota Medical Center, Minneapolis, MN 55454
| | | | - Jeff Statland
- Department of Neurology, University of Kansas, Kansas City, KS
| | - Russell J. Butterfield
- Department of Pediatrics, The University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Diane M. Dunn
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Robert B. Weiss
- Department of Pediatrics, The University of Utah School of Medicine, Salt Lake City, UT 84112,Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Kevin M. Flanigan
- The Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH 43205,Department of Neurology, The Ohio State University, Columbus, OH 43205,Department of Pediatrics, The Ohio State University, Columbus, OH 43205
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11
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Petersen USS, Doktor TK, Andresen BS. Pseudoexon activation in disease by non-splice site deep intronic sequence variation - wild type pseudoexons constitute high-risk sites in the human genome. Hum Mutat 2021; 43:103-127. [PMID: 34837434 DOI: 10.1002/humu.24306] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 11/06/2021] [Indexed: 12/27/2022]
Abstract
Accuracy of pre-messenger RNA (pre-mRNA) splicing is crucial for normal gene expression. Complex regulation supports the spliceosomal distinction between authentic exons and the many seemingly functional splice sites delimiting pseudoexons. Pseudoexons are nonfunctional intronic sequences that can be activated for aberrant inclusion in mRNA, which may cause disease. Pseudoexon activation is very challenging to predict, in particular when activation occurs by sequence variants that alter the splicing regulatory environment without directly affecting splice sites. As pseudoexon inclusion often evades detection due to activation of nonsense-mediated mRNA decay, and because conventional diagnostic procedures miss deep intronic sequence variation, pseudoexon activation is a heavily underreported disease mechanism. Pseudoexon characteristics have mainly been studied based on in silico predicted sequences. Moreover, because recognition of sequence variants that create or strengthen splice sites is possible by comparison with well-established consensus sequences, this type of pseudoexon activation is by far the most frequently reported. Here we review all known human disease-associated pseudoexons that carry functional splice sites and are activated by deep intronic sequence variants located outside splice site sequences. We delineate common characteristics that make this type of wild type pseudoexons distinct high-risk sites in the human genome.
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Affiliation(s)
- Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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12
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Tomkiewicz TZ, Suárez-Herrera N, Cremers FPM, Collin RWJ, Garanto A. Antisense Oligonucleotide-Based Rescue of Aberrant Splicing Defects Caused by 15 Pathogenic Variants in ABCA4. Int J Mol Sci 2021; 22:ijms22094621. [PMID: 33924840 PMCID: PMC8124656 DOI: 10.3390/ijms22094621] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/16/2022] Open
Abstract
The discovery of novel intronic variants in the ABCA4 locus has contributed significantly to solving the missing heritability in Stargardt disease (STGD1). The increasing number of variants affecting pre-mRNA splicing makes ABCA4 a suitable candidate for antisense oligonucleotide (AON)-based splicing modulation therapies. In this study, AON-based splicing modulation was assessed for 15 recently described intronic variants (three near-exon and 12 deep-intronic variants). In total, 26 AONs were designed and tested in vitro using a midigene-based splice system. Overall, partial or complete splicing correction was observed for two variants causing exon elongation and all variants causing pseudoexon inclusion. Together, our results confirm the high potential of AONs for the development of future RNA therapies to correct splicing defects causing STGD1.
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Affiliation(s)
- Tomasz Z. Tomkiewicz
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands; (T.Z.T.); (N.S.-H.); (F.P.M.C.); (R.W.J.C.)
| | - Nuria Suárez-Herrera
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands; (T.Z.T.); (N.S.-H.); (F.P.M.C.); (R.W.J.C.)
| | - Frans P. M. Cremers
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands; (T.Z.T.); (N.S.-H.); (F.P.M.C.); (R.W.J.C.)
| | - Rob W. J. Collin
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands; (T.Z.T.); (N.S.-H.); (F.P.M.C.); (R.W.J.C.)
| | - Alejandro Garanto
- Departments of Pediatrics and Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands
- Correspondence:
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13
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Latchman K, Brown J, Sineni CJ, Ragin-Dames L, Guo S, Huang J, Thorson W, Hacker S, Barbouth D, Tekin M, Bademci G. A founder noncoding GALT variant interfering with splicing causes galactosemia. J Inherit Metab Dis 2020; 43:1199-1204. [PMID: 32748411 DOI: 10.1002/jimd.12293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/23/2020] [Accepted: 07/28/2020] [Indexed: 11/08/2022]
Abstract
Galactosemia is a rare, treatable hereditary disorder of carbohydrate metabolism. We investigated the etiology of decreased GALT enzyme activity in a cohort of newborns referred by the Florida Newborn Screening Program with no detectable GALT variants in diagnostic molecular tests. Six affected individuals from four families with Guatemalan heritage were included. GALT enzyme activity ranged from 20% to 34% of normal. Clinical findings were unremarkable except for speech delay in two children. Via genome sequencing followed by Sanger confirmation we showed that all affected individuals were homozygous for a deep intronic GALT variant, c.1059+390A>G, which segregated as an autosomal recessive trait in all families. The intronic variant disrupts splicing and leads to a premature termination and is associated with a single haplotype flanking GALT, suggesting a founder effect. In conclusion, we present a deep intronic GALT variant leading to a biochemical variant form of galactosemia. This variant remains undiagnosed until it is specifically targeted in molecular testing.
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Affiliation(s)
- Kumarie Latchman
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jeanette Brown
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Claire J Sineni
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Lorrien Ragin-Dames
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Shengru Guo
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jingyu Huang
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Willa Thorson
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Stephanie Hacker
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Deborah Barbouth
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Mustafa Tekin
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Guney Bademci
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, USA
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
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14
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Xie Z, Tang L, Xie Z, Sun C, Shuai H, Zhou C, Liu Y, Yu M, Zheng Y, Meng L, Zhang W, Leal SM, Wang Z, Schrauwen I, Yuan Y. Splicing Characteristics of Dystrophin Pseudoexons and Identification of a Novel Pathogenic Intronic Variant in the DMD Gene. Genes (Basel) 2020; 11:genes11101180. [PMID: 33050418 PMCID: PMC7650627 DOI: 10.3390/genes11101180] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/23/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
Pseudoexon (PE) inclusion has been implicated in various dystrophinopathies; however, its splicing characteristics have not been fully investigated. This study aims to analyze the splicing characteristics of dystrophin PEs and compare them with those of dystrophin canonical exons (CEs). Forty-two reported dystrophin PEs were divided into a splice site (ss) group and a splicing regulatory element (SRE) group. Five dystrophin PEs with characteristics of poison exons were identified and categorized as the possible poison exon group. The comparative analysis of each essential splicing signal among different groups of dystrophin PEs and dystrophin CEs revealed that the possible poison exon group had a stronger 3′ ss compared to any other group. As for auxiliary SREs, different groups of dystrophin PEs were found to have a smaller density of diverse types of exonic splicing enhancers and a higher density of several types of exonic splicing silencers compared to dystrophin CEs. In addition, the possible poison exon group had a smaller density of 3′ ss intronic splicing silencers compared to dystrophin CEs. To our knowledge, our findings indicate for the first time that poison exons might exist in DMD (the dystrophin gene) and present with different splicing characteristics than other dystrophin PEs and CEs.
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Affiliation(s)
- Zhiying Xie
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Liuqin Tang
- Science and Technology, Running Gene Inc., Beijing 100085, China; (L.T.); (C.Z.)
| | - Zhihao Xie
- Department of Epidemiology and Biostatistics, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu 610041, China;
| | - Chengyue Sun
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Haoyue Shuai
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA; (H.S.); (S.M.L.)
| | - Chao Zhou
- Science and Technology, Running Gene Inc., Beijing 100085, China; (L.T.); (C.Z.)
| | - Yilin Liu
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Meng Yu
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Yiming Zheng
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Wei Zhang
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Suzanne M. Leal
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA; (H.S.); (S.M.L.)
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA; (H.S.); (S.M.L.)
- Correspondence: (I.S.); (Y.Y.)
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; (Z.X.); (C.S.); (Y.L.); (M.Y.); (Y.Z.); (L.M.); (W.Z.); (Z.W.)
- Correspondence: (I.S.); (Y.Y.)
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15
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Canson D, Glubb D, Spurdle AB. Variant effect on splicing regulatory elements, branchpoint usage, and pseudoexonization: Strategies to enhance bioinformatic prediction using hereditary cancer genes as exemplars. Hum Mutat 2020; 41:1705-1721. [PMID: 32623769 DOI: 10.1002/humu.24074] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/26/2020] [Accepted: 07/02/2020] [Indexed: 12/15/2022]
Abstract
It is possible to estimate the prior probability of pathogenicity for germline disease gene variants based on bioinformatic prediction of variant effect/s. However, routinely used approaches have likely led to the underestimation and underreporting of variants located outside donor and acceptor splice site motifs that affect messenger RNA (mRNA) processing. This review presents information about hereditary cancer gene germline variants, outside native splice sites, with experimentally validated splicing effects. We list 95 exonic variants that impact splicing regulatory elements (SREs) in BRCA1, BRCA2, MLH1, MSH2, MSH6, and PMS2. We utilized a pre-existing large-scale BRCA1 functional data set to map functional SREs, and assess the relative performance of different tools to predict effects of 283 variants on such elements. We also describe rare examples of intronic variants that impact branchpoint (BP) sites and create pseudoexons. We discuss the challenges in predicting variant effect on BP site usage and pseudoexonization, and suggest strategies to improve the bioinformatic prioritization of such variants for experimental validation. Importantly, our review and analysis highlights the value of considering impact of variants outside donor and acceptor motifs on mRNA splicing and disease causation.
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Affiliation(s)
- Daffodil Canson
- Genetics and Computational Biology Department, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
| | - Dylan Glubb
- Genetics and Computational Biology Department, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Amanda B Spurdle
- Genetics and Computational Biology Department, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
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16
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Weisschuh N, Sturm M, Baumann B, Audo I, Ayuso C, Bocquet B, Branham K, Brooks BP, Catalá-Mora J, Giorda R, Heckenlively JR, Hufnagel RB, Jacobson SG, Kellner U, Kitsiou-Tzeli S, Matet A, Martorell Sampol L, Meunier I, Rudolph G, Sharon D, Stingl K, Streubel B, Varsányi B, Wissinger B, Kohl S. Deep-intronic variants in CNGB3 cause achromatopsia by pseudoexon activation. Hum Mutat 2019; 41:255-264. [PMID: 31544997 DOI: 10.1002/humu.23920] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/20/2019] [Accepted: 09/16/2019] [Indexed: 01/18/2023]
Abstract
Our comprehensive cohort of 1100 unrelated achromatopsia (ACHM) patients comprises a considerable number of cases (~5%) harboring only a single pathogenic variant in the major ACHM gene CNGB3. We sequenced the entire CNGB3 locus in 33 of these patients to find a second variant which eventually explained the patients' phenotype. Forty-seven intronic CNGB3 variants were identified in 28 subjects after a filtering step based on frequency and the exclusion of variants found in cis with pathogenic alleles. In a second step, in silico prediction tools were used to filter out those variants with little odds of being deleterious. This left three variants that were analyzed using heterologous splicing assays. Variant c.1663-1205G>A, found in 14 subjects, and variant c.1663-2137C>T, found in two subjects, were indeed shown to exert a splicing defect by causing pseudoexon insertion into the transcript. Subsequent screening of further unsolved CNGB3 subjects identified four additional cases harboring the c.1663-1205G>A variant which makes it the eighth most frequent CNGB3 variant in our cohort. Compound heterozygosity could be validated in ten cases. Our study demonstrates that whole gene sequencing can be a powerful approach to identify the second pathogenic allele in patients apparently harboring only one disease-causing variant.
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Affiliation(s)
- Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Marc Sturm
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Britta Baumann
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Isabelle Audo
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.,CHNO des Quinze-Vingts, INSERM-DHOS CIC1423, Paris, France.,Institute of Ophthalmology, University College of London, London, United Kingdom
| | - 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), ISCIII, Madrid, Spain
| | - Beatrice Bocquet
- Centre National de Référence «Maladies Sensorielles Génétiques», Service Ophtalmologie, Hôpital Gui de Chauliac, CHRU de Montpellier, Montpellier, France.,INSERM U1051, Institute for Neurosciences of Montpellier, Montpellier, France
| | - Kari Branham
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Brian P Brooks
- National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | | | - Roberto Giorda
- Molecular Biology Lab, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Italy
| | - John R Heckenlively
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Robert B Hufnagel
- National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Samuel G Jacobson
- Department of Ophthalmology, Perelman School of Medicine, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ulrich Kellner
- Rare Retinal Disease Center, Augenzentrum Siegburg, MVZ ADTC Siegburg GmbH, Siegburg, Germany
| | - Sofia Kitsiou-Tzeli
- Department of Medical Genetics, National & Kapodistrian University of Athens, Athens, Greece
| | - Alexandre Matet
- Department of Ophthalmology, Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | | | - Isabelle Meunier
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain.,Centre National de Référence «Maladies Sensorielles Génétiques», Service Ophtalmologie, Hôpital Gui de Chauliac, CHRU de Montpellier, Montpellier, France
| | - Günther Rudolph
- Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Katarina Stingl
- University Eye Hospital, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Berthold Streubel
- Department of Pathology, Medical University of Vienna, Vienna, Austria
| | - Balázs Varsányi
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary.,Department of Ophthalmology, University of Pécs Medical School, Pécs, Hungary
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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Ajeawung NF, Nguyen TTM, Lu L, Kucharski TJ, Rousseau J, Molidperee S, Atienza J, Gamache I, Jin W, Plon SE, Lee BH, Teodoro JG, Wang LL, Campeau PM. Mutations in ANAPC1, Encoding a Scaffold Subunit of the Anaphase-Promoting Complex, Cause Rothmund-Thomson Syndrome Type 1. Am J Hum Genet 2019; 105:625-30. [PMID: 31303264 DOI: 10.1016/j.ajhg.2019.06.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 06/11/2019] [Indexed: 11/21/2022] Open
Abstract
Rothmund-Thomson syndrome (RTS) is an autosomal-recessive disorder characterized by poikiloderma, sparse hair, short stature, and skeletal anomalies. Type 2 RTS, which is defined by the presence of bi-allelic mutations in RECQL4, is characterized by increased cancer susceptibility and skeletal anomalies, whereas the genetic basis of RTS type 1, which is associated with juvenile cataracts, is unknown. We studied ten individuals, from seven families, who had RTS type 1 and identified a deep intronic splicing mutation of the ANAPC1 gene, a component of the anaphase-promoting complex/cyclosome (APC/C), in all affected individuals, either in the homozygous state or in trans with another mutation. Fibroblast studies showed that the intronic mutation causes the activation of a 95 bp pseudoexon, leading to mRNAs with premature termination codons and nonsense-mediated decay, decreased ANAPC1 protein levels, and prolongation of interphase. Interestingly, mice that were heterozygous for a knockout mutation have an increased incidence of cataracts. Our results demonstrate that deficiency in the APC/C is a cause of RTS type 1 and suggest a possible link between the APC/C and RECQL4 helicase because both proteins are involved in DNA repair and replication.
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18
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Montalban G, Bonache S, Moles-Fernández A, Gisbert-Beamud A, Tenés A, Bach V, Carrasco E, López-Fernández A, Stjepanovic N, Balmaña J, Diez O, Gutiérrez-Enríquez S. Screening of BRCA1/2 deep intronic regions by targeted gene sequencing identifies the first germline BRCA1 variant causing pseudoexon activation in a patient with breast/ovarian cancer. J Med Genet 2018; 56:63-74. [PMID: 30472649 DOI: 10.1136/jmedgenet-2018-105606] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/16/2018] [Accepted: 10/28/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND Genetic analysis of BRCA1 and BRCA2 for the diagnosis of hereditary breast and ovarian cancer (HBOC) is commonly restricted to coding regions and exon-intron boundaries. Although germline pathogenic variants in these regions explain about ~20% of HBOC cases, there is still an important fraction that remains undiagnosed. We have screened BRCA1/2 deep intronic regions to identify potential spliceogenic variants that could explain part of the missing HBOC susceptibility. METHODS We analysed BRCA1/2 deep intronic regions by targeted gene sequencing in 192 high-risk HBOC families testing negative for BRCA1/2 during conventional analysis. Rare variants (MAF <0.005) predicted to create/activate splice sites were selected for further characterisation in patient RNA. The splicing outcome was analysed by RT-PCR and Sanger sequencing, and allelic imbalance was also determined when heterozygous exonic loci were present. RESULTS A novel transcript was detected in BRCA1 c.4185+4105C>T variant carrier. This variant promotes the inclusion of a pseudoexon in mature mRNA, generating an aberrant transcript predicted to encode for a non-functional protein. Quantitative and allele-specific assays determined haploinsufficiency in the variant carrier, supporting a pathogenic effect for this variant. Genotyping of 1030 HBOC cases and 327 controls did not identify additional carriers in Spanish population. CONCLUSION Screening of BRCA1/2 intronic regions has identified the first BRCA1 deep intronic variant associated with HBOC by pseudoexon activation. Although the frequency of deleterious variants in these regions appears to be low, our study highlights the importance of studying non-coding regions and performing comprehensive RNA assays to complement genetic diagnosis.
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Affiliation(s)
- Gemma Montalban
- Oncogenetics Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain
| | - Sandra Bonache
- Oncogenetics Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain
| | | | | | - Anna Tenés
- Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Vanessa Bach
- Oncogenetics Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain
| | - Estela Carrasco
- High Risk and Cancer Prevention Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain
| | - Adrià López-Fernández
- High Risk and Cancer Prevention Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain
| | - Neda Stjepanovic
- High Risk and Cancer Prevention Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain.,Medical Oncology Department, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Judith Balmaña
- High Risk and Cancer Prevention Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain.,Medical Oncology Department, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Orland Diez
- Oncogenetics Group, Vall d'Hebron Institut d'Oncologia, Barcelona, Spain.,Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
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19
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Albert S, Garanto A, Sangermano R, Khan M, Bax NM, Hoyng CB, Zernant J, Lee W, Allikmets R, Collin RW, Cremers FP. Identification and Rescue of Splice Defects Caused by Two Neighboring Deep-Intronic ABCA4 Mutations Underlying Stargardt Disease. Am J Hum Genet 2018. [PMID: 29526278 DOI: 10.1016/j.ajhg.2018.02.008] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sequence analysis of the coding regions and splice site sequences in inherited retinal diseases is not able to uncover ∼40% of the causal variants. Whole-genome sequencing can identify most of the non-coding variants, but their interpretation is still very challenging, in particular when the relevant gene is expressed in a tissue-specific manner. Deep-intronic variants in ABCA4 have been associated with autosomal-recessive Stargardt disease (STGD1), but the exact pathogenic mechanism is unknown. By generating photoreceptor precursor cells (PPCs) from fibroblasts obtained from individuals with STGD1, we demonstrated that two neighboring deep-intronic ABCA4 variants (c.4539+2001G>A and c.4539+2028C>T) result in a retina-specific 345-nt pseudoexon insertion (predicted protein change: p.Arg1514Leufs∗36), likely due to the creation of exonic enhancers. Administration of antisense oligonucleotides (AONs) targeting the 345-nt pseudoexon can significantly rescue the splicing defect observed in PPCs of two individuals with these mutations. Intriguingly, an AON that is complementary to c.4539+2001G>A rescued the splicing defect only in PPCs derived from an individual with STGD1 with this but not the other mutation, demonstrating the high specificity of AONs. In addition, a single AON molecule rescued splicing defects associated with different neighboring mutations, thereby providing new strategies for the treatment of persons with STGD1. As many genes associated with human genetic conditions are expressed in specific tissues and pre-mRNA splicing may also rely on organ-specific factors, our approach to investigate and treat splicing variants using differentiated cells derived from individuals with STGD1 can be applied to any tissue of interest.
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20
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Nieminen TT, Pavicic W, Porkka N, Kankainen M, Järvinen HJ, Lepistö A, Peltomäki P. Pseudoexons provide a mechanism for allele-specific expression of APC in familial adenomatous polyposis. Oncotarget 2016; 7:70685-98. [PMID: 27683109 DOI: 10.18632/oncotarget.12206] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 09/12/2016] [Indexed: 12/11/2022] Open
Abstract
Allele-specific expression (ASE) of the Adenomatous Polyposis Coli (APC) gene occurs in up to one-third of families with adenomatous polyposis (FAP) that have screened mutation-negative by conventional techniques. To advance our understanding of the genomic basis of this phenomenon, 54 APC mutation-negative families (21 with classical FAP and 33 with attenuated FAP, AFAP) were investigated. We focused on four families with validated ASE and scrutinized these families by sequencing of the blood transcriptomes (RNA-seq) and genomes (WGS). Three families, two with classical FAP and one with AFAP, revealed deep intronic mutations associated with pseudoexons. In all three families, intronic mutations (c.646-1806T>G in intron 6, c.1408+729A>G in intron 11, and c.1408+731C>T in intron 11) created new splice donor sites resulting in the insertion of intronic sequences (of 127 bp, 83 bp, and 83 bp, respectively) in the APC transcript. The respective intronic mutations were absent in the remaining polyposis families and the general population. Premature stop of translation as the predicted consequence as well as co-segregation with polyposis supported the pathogenicity of the pseudoexons. We conclude that next generation sequencing on RNA and genomic DNA is an effective strategy to reveal and validate pseudoexons that are regularly missed by traditional screening methods and is worth considering in apparent mutation-negative polyposis families.
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21
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Lee M, Roos P, Sharma N, Atalar M, Evans TA, Pellicore MJ, Davis E, Lam ATN, Stanley SE, Khalil SE, Solomon GM, Walker D, Raraigh KS, Vecchio-Pagan B, Armanios M, Cutting GR. Systematic Computational Identification of Variants That Activate Exonic and Intronic Cryptic Splice Sites. Am J Hum Genet 2017; 100:751-765. [PMID: 28475858 DOI: 10.1016/j.ajhg.2017.04.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/30/2017] [Indexed: 12/30/2022] Open
Abstract
We developed a variant-annotation method that combines sequence-based machine-learning classification with a context-dependent algorithm for selecting splice variants. Our approach is distinctive in that it compares the splice potential of a sequence bearing a variant with the splice potential of the reference sequence. After training, classification accurately identified 168 of 180 (93.3%) canonical splice sites of five genes. The combined method, CryptSplice, identified and correctly predicted the effect of 18 of 21 (86%) known splice-altering variants in CFTR, a well-studied gene whose loss-of-function variants cause cystic fibrosis (CF). Among 1,423 unannotated CFTR disease-associated variants, the method identified 32 potential exonic cryptic splice variants, two of which were experimentally evaluated and confirmed. After complete CFTR sequencing, the method found three cryptic intronic splice variants (one known and two experimentally verified) that completed the molecular diagnosis of CF in 6 of 14 individuals. CryptSplice interrogation of sequence data from six individuals with X-linked dyskeratosis congenita caused by an unknown disease-causing variant in DKC1 identified two splice-altering variants that were experimentally verified. To assess the extent to which disease-associated variants might activate cryptic splicing, we selected 458 pathogenic variants and 348 variants of uncertain significance (VUSs) classified as high confidence from ClinVar. Splice-site activation was predicted for 129 (28%) of the pathogenic variants and 75 (22%) of the VUSs. Our findings suggest that cryptic splice-site activation is more common than previously thought and should be routinely considered for all variants within the transcribed regions of genes.
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Affiliation(s)
- Melissa Lee
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | - Neeraj Sharma
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Melis Atalar
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taylor A Evans
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Matthew J Pellicore
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Emily Davis
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anh-Thu N Lam
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Susan E Stanley
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sara E Khalil
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - George M Solomon
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35233 USA
| | - Doug Walker
- Pediatric Pulmonary Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Karen S Raraigh
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Briana Vecchio-Pagan
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mary Armanios
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Garry R Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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22
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Liquori A, Vaché C, Baux D, Blanchet C, Hamel C, Malcolm S, Koenig M, Claustres M, Roux AF. Whole USH2A Gene Sequencing Identifies Several New Deep Intronic Mutations. Hum Mutat 2015; 37:184-93. [PMID: 26629787 DOI: 10.1002/humu.22926] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/19/2015] [Indexed: 01/01/2023]
Abstract
Deep intronic mutations leading to pseudoexon (PE) insertions are underestimated and most of these splicing alterations have been identified by transcript analysis, for instance, the first deep intronic mutation in USH2A, the gene most frequently involved in Usher syndrome type II (USH2). Unfortunately, analyzing USH2A transcripts is challenging and for 1.8%-19% of USH2 individuals carrying a single USH2A recessive mutation, a second mutation is yet to be identified. We have developed and validated a DNA next-generation sequencing approach to identify deep intronic variants in USH2A and evaluated their consequences on splicing. Three distinct novel deep intronic mutations have been identified. All were predicted to affect splicing and resulted in the insertion of PEs, as shown by minigene assays. We present a new and attractive strategy to identify deep intronic mutations, when RNA analyses are not possible. Moreover, the bioinformatics pipeline developed is independent of the gene size, implying the possible application of this approach to any disease-linked gene. Finally, an antisense morpholino oligonucleotide tested in vitro for its ability to restore splicing caused by the c.9959-4159A>G mutation provided high inhibition rates, which are indicative of its potential for molecular therapy.
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Affiliation(s)
- Alessandro Liquori
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France
| | - Christel Vaché
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France.,Laboratoire de Génétique Moléculaire, CHRU Montpellier, Montpellier, France
| | - David Baux
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France.,Laboratoire de Génétique Moléculaire, CHRU Montpellier, Montpellier, France
| | - Catherine Blanchet
- Service ORL, CHRU Montpellier, Montpellier, France.,CHU Montpellier, Centre National de Référence Maladies Rares, "Affections Sensorielles Génétiques, France
| | - Christian Hamel
- CHU Montpellier, Centre National de Référence Maladies Rares, "Affections Sensorielles Génétiques, France
| | - Sue Malcolm
- Genetics and Genomic Medicine Programme, Institute of Child Health, UCL, London, UK
| | - Michel Koenig
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France.,Laboratoire de Génétique Moléculaire, CHRU Montpellier, Montpellier, France
| | - Mireille Claustres
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France.,Laboratoire de Génétique Moléculaire, CHRU Montpellier, Montpellier, France
| | - Anne-Françoise Roux
- Laboratoire de Génétique de Maladies Rares EA 7402, Université de Montpellier, Montpellier, France.,Laboratoire de Génétique Moléculaire, CHRU Montpellier, Montpellier, France
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23
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Greer K, Mizzi K, Rice E, Kuster L, Barrero RA, Bellgard MI, Lynch BJ, Foley AR, O Rathallaigh E, Wilton SD, Fletcher S. Pseudoexon activation increases phenotype severity in a Becker muscular dystrophy patient. Mol Genet Genomic Med 2015; 3:320-6. [PMID: 26247048 PMCID: PMC4521967 DOI: 10.1002/mgg3.144] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 01/16/2023] Open
Abstract
We report a dystrophinopathy patient with an in-frame deletion of DMD exons 45-47, and therefore a genetic diagnosis of Becker muscular dystrophy, who presented with a more severe than expected phenotype. Analysis of the patient DMD mRNA revealed an 82 bp pseudoexon, derived from intron 44, that disrupts the reading frame and is expected to yield a nonfunctional dystrophin. Since the sequence of the pseudoexon and canonical splice sites does not differ from the reference sequence, we concluded that the genomic rearrangement promoted recognition of the pseudoexon, causing a severe dystrophic phenotype. We characterized the deletion breakpoints and identified motifs that might influence selection of the pseudoexon. We concluded that the donor splice site was strengthened by juxtaposition of intron 47, and loss of intron 44 silencer elements, normally located downstream of the pseudoexon donor splice site, further enhanced pseudoexon selection and inclusion in the DMD transcript in this patient.
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Affiliation(s)
- Kane Greer
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Kayla Mizzi
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Emily Rice
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Lukas Kuster
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Roberto A Barrero
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia
| | - Matthew I Bellgard
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia
| | - Bryan J Lynch
- Children's University Hospital Temple Street, Dublin, Ireland
| | | | | | - Steve D Wilton
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia ; Western Australian Neuroscience Institute Nedlands, Western Australia, 6009, Australia
| | - Sue Fletcher
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia ; Western Australian Neuroscience Institute Nedlands, Western Australia, 6009, Australia
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24
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Blázquez L, Aiastui A, Goicoechea M, Martins de Araujo M, Avril A, Beley C, García L, Valcárcel J, Fortes P, López de Munain A. In vitro correction of a pseudoexon-generating deep intronic mutation in LGMD2A by antisense oligonucleotides and modified small nuclear RNAs. Hum Mutat 2013; 34:1387-95. [PMID: 23864287 DOI: 10.1002/humu.22379] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 07/08/2013] [Indexed: 12/25/2022]
Abstract
Limb-girdle muscular dystrophy type 2A (LGMD2A) is the most frequent autosomal recessive muscular dystrophy. It is caused by mutations in the calpain-3 (CAPN3) gene. The majority of the mutations described to date are located in the coding sequence of the gene. However, it is estimated that 25% of the mutations are present at exon-intron boundaries and modify the pre-mRNA splicing of the CAPN3 transcript. We have previously described the first deep intronic mutation in the CAPN3 gene: c.1782+1072G>C mutation. This mutation causes the pseudoexonization of an intronic sequence of the CAPN3 gene in the mature mRNA. In the present work, we show that the point mutation generates the inclusion of the pseudoexon in the mRNA using a minigene assay. In search of a treatment that restores normal splicing, splicing modulation was induced by RNA-based strategies, which included antisense oligonucleotides and modified small-nuclear RNAs. The best effect was observed with antisense sequences, which induced pseudoexon skipping in both HeLa cells cotransfected with mutant minigene and in fibroblasts from patients. Finally, transfection of antisense sequences and siRNA downregulation of serine/arginine-rich splicing factor 1 (SRSF1) indicate that binding of this factor to splicing enhancer sequences is involved in pseudoexon activation.
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Affiliation(s)
- Lorea Blázquez
- Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain; Neuroscience Area, Health Research Institute Biodonostia, San Sebastian, Spain
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