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Sanoguera-Miralles L, Llinares-Burguet I, Bueno-Martínez E, Ramadane-Morchadi L, Stuani C, Valenzuela-Palomo A, García-Álvarez A, Pérez-Segura P, Buratti E, de la Hoya M, Velasco-Sampedro EA. Comprehensive splicing analysis of the alternatively spliced CHEK2 exons 8 and 10 reveals three enhancer/silencer-rich regions and 38 spliceogenic variants. J Pathol 2024; 262:395-409. [PMID: 38332730 DOI: 10.1002/path.6243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/26/2023] [Accepted: 11/28/2023] [Indexed: 02/10/2024]
Abstract
Splicing is controlled by a large set of regulatory elements (SREs) including splicing enhancers and silencers, which are involved in exon recognition. Variants at these motifs may dysregulate splicing and trigger loss-of-function transcripts associated with disease. Our goal here was to study the alternatively spliced exons 8 and 10 of the breast cancer susceptibility gene CHEK2. For this purpose, we used a previously published minigene with exons 6-10 that produced the expected minigene full-length transcript and replicated the naturally occurring events of exon 8 [Δ(E8)] and exon 10 [Δ(E10)] skipping. We then introduced 12 internal microdeletions of exons 8 and 10 by mutagenesis in order to map SRE-rich intervals by splicing assays in MCF-7 cells. We identified three minimal (10-, 11-, 15-nt) regions essential for exon recognition: c.863_877del [ex8, Δ(E8): 75%] and c.1073_1083del and c.1083_1092del [ex10, Δ(E10): 97% and 62%, respectively]. Then 87 variants found within these intervals were introduced into the wild-type minigene and tested functionally. Thirty-eight of them (44%) impaired splicing, four of which (c.883G>A, c.883G>T, c.884A>T, and c.1080G>T) induced negligible amounts (<5%) of the minigene full-length transcript. Another six variants (c.886G>A, c.886G>T, c.1075G>A, c.1075G>T, c.1076A>T, and c.1078G>T) showed significantly strong impacts (20-50% of the minigene full-length transcript). Thirty-three of the 38 spliceogenic variants were annotated as missense, three as nonsense, and two as synonymous, underlying the fact that any exonic change is capable of disrupting splicing. Moreover, c.883G>A, c.883G>T, and c.884A>T were classified as pathogenic/likely pathogenic variants according to ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology)-based criteria. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Inés Llinares-Burguet
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Lobna Ramadane-Morchadi
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Cristiana Stuani
- Molecular Pathology Lab. International Centre of Genetic Engineering and Biotechnology, Trieste, Italy
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Alicia García-Álvarez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Emanuele Buratti
- Molecular Pathology Lab. International Centre of Genetic Engineering and Biotechnology, Trieste, Italy
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Eladio A Velasco-Sampedro
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biomedicina y Genética Molecular de Valladolid (IBGM), Consejo Superior de Investigaciones Científicas - Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
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2
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Li C, Zhang R, Pan F, Xin Q, Shi X, Guo W, Qiao D, Wang Z, Zhang Y, Liu X, Zhang Y, Shao L. Functional analysis of the CTNS gene exonic variants predicted to affect splicing. Clin Genet 2024; 105:323-328. [PMID: 38009794 DOI: 10.1111/cge.14460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/26/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023]
Abstract
Cystinosis is a severe, monogenic systemic disease caused by variants in CTNS gene. Currently, there is growing evidence that exonic variants in many diseases can affect pre-mRNA splicing. The impact of CTNS gene exonic variants on splicing regulation may be underestimated due to the lack of routine studies at the RNA level. Here, we analyzed 59 exonic variants in the CTNS gene using bioinformatics tools and identified candidate variants that may induce splicing alterations by minigene assays. We identified six exonic variants that induce splicing alterations by disrupting the ratio of exonic splicing enhancers/exonic splicing silencers (ESEs/ESSs) or by interfering with the recognition of classical splice sites, or both. Our results help in the correct molecular characterization of variants in cystinosis and inform emerging therapies. Furthermore, our work suggests that the combination of in silico and in vitro assays facilitates to assess the effects of DNA variants driving rare genetic diseases on splicing regulation and will enhance the clinical utility of variant functional annotation.
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Affiliation(s)
- Changying Li
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Ruixiao Zhang
- Department of Emergency, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Fengjiao Pan
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Qing Xin
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xiaomeng Shi
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Wencong Guo
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Dan Qiao
- Department of Nephrology, Dalian Medical University, Dalian, China
| | - Zhi Wang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yiyin Zhang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xuyan Liu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yan Zhang
- Department of Nephrology, Weifang Medical University, Weifang, China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
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Ning Y, Zhang Y, Tian T, Chen Y, Wang J, Lei K, Cui Z. Reclassifying BRCA1 c.4358-2A > G and BRCA2 c.475 + 5G > C variants from "Uncertain Significance" to "Pathogenic" based on minigene assays and clinical evidence. J Cancer Res Clin Oncol 2024; 150:62. [PMID: 38300310 PMCID: PMC10834553 DOI: 10.1007/s00432-023-05597-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/25/2023] [Indexed: 02/02/2024]
Abstract
BACKGROUND Pathogenic variants in BRCA genes play a crucial role in the pathogenesis of ovarian cancer. Intronic variants of uncertain significance (VUS) may contribute to pathogenicity by affecting splicing. Currently, the significance of many intronic variants in BRCA has not been clarified, impacting patient treatment strategies and the management of familial cases. METHOD A retrospective study was conducted to analyze BRCA intronic VUS in a cohort of 707 unrelated ovarian cancer patients at a single institution from 2018 to 2023. Three splicing predictors were employed to analyze detected intronic VUS. Variants predicted to have splicing alterations were selected for further validation through minigene assays. Patient and familial investigations were conducted to comprehend cancer incidence within pedigrees and the application of poly (ADP-ribose) polymerase inhibitors (PARPi) by the patients. In accordance with the guidelines of the American College of Medical Genetics and Genomics (ACMG), the intronic VUS were reclassified based on minigene assay results and clinical evidence. RESULT Approximately 9.8% (69/707) of patients were identified as carriers of 67 different VUS in BRCA1/2, with four intronic variants accounting for 6% (4/67) of all VUS. Splicing predictors indicated potential splicing alterations in splicing for BRCA1 c.4358-2A>G and BRCA2 c.475+5G>C variants. Minigene assays utilizing the pSPL3 exon trapping vector revealed that these variants induced changes in splicing sites and frameshift, resulting in premature termination of translation (p. Ala1453Glyfs and p. Pro143Glyfs). According to ACMG guidelines, BRCA1 c.4358-2A>G and BRCA2 c.475+5G>C were reclassified as pathogenic variants. Pedigree investigations were conducted on patients with BRCA1 c.4358-2A>G variant, and the detailed utilization of PARPi provided valuable insights into research on PARPi resistance. CONCLUSION Two intronic VUS were reclassified as pathogenic variants. A precise classification of variants is crucial for the effective treatment and management of both patients and healthy carriers.
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Affiliation(s)
- Ying Ning
- Department of Clinical Medicine, Qingdao University, Qingdao, 266003, China
| | - Yu Zhang
- Department of Clinical Medicine, Qingdao University, Qingdao, 266003, China
| | - Tian Tian
- Department of Obstetrics and Gynecology, The Affiliated Hospital of Qingdao University, No. 59 Haier Road, Laoshan District, Qingdao, 266000, China
| | - Yu Chen
- Department of Clinical Medicine, Qingdao University, Qingdao, 266003, China
| | - Jia Wang
- Center of Tumor Immunology and Cytotherapy, Medical Research Center, The Affiliated Hospital of Qingdao University, No. 59 Haier Road, Laoshan District, Qingdao, 266000, China
| | - Ke Lei
- Center of Tumor Immunology and Cytotherapy, Medical Research Center, The Affiliated Hospital of Qingdao University, No. 59 Haier Road, Laoshan District, Qingdao, 266000, China.
| | - Zhumei Cui
- Department of Obstetrics and Gynecology, The Affiliated Hospital of Qingdao University, No. 59 Haier Road, Laoshan District, Qingdao, 266000, China.
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Sanoguera-Miralles L, Valenzuela-Palomo A, Bueno-Martínez E, Esteban-Sánchez A, Lorca V, Llinares-Burguet I, García-Álvarez A, Pérez-Segura P, Infante M, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco-Sampedro EA. Systematic Minigene-Based Splicing Analysis and Tentative Clinical Classification of 52 CHEK2 Splice-Site Variants. Clin Chem 2024; 70:319-338. [PMID: 37725924 DOI: 10.1093/clinchem/hvad125] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 07/07/2023] [Indexed: 09/21/2023]
Abstract
BACKGROUND Disrupted pre-mRNA splicing is a frequent deleterious mechanism in hereditary cancer. We aimed to functionally analyze candidate spliceogenic variants of the breast cancer susceptibility gene CHEK2 by splicing reporter minigenes. METHODS A total of 128 CHEK2 splice-site variants identified in the Breast Cancer After Diagnostic Gene Sequencing (BRIDGES) project (https://cordis.europa.eu/project/id/634935) were analyzed with MaxEntScan and subsetted to 52 variants predicted to impact splicing. Three CHEK2 minigenes, which span all 15 exons, were constructed and validated. The 52 selected variants were then genetically engineered into the minigenes and assayed in MCF-7 (human breast adenocarcinoma) cells. RESULTS Of 52 variants, 46 (88.5%) impaired splicing. Some of them led to complex splicing patterns with up to 11 different transcripts. Thirty-four variants induced splicing anomalies without any trace or negligible amounts of the full-length transcript. A total of 89 different transcripts were annotated, which derived from different events: single- or multi-exon skipping, alternative site-usage, mutually exclusive exon inclusion, intron retention or combinations of the abovementioned events. Fifty-nine transcripts were predicted to introduce premature termination codons, 7 kept the original open-reading frame, 5 removed the translation start codon, 6 affected the 5'UTR (Untranslated Region), and 2 included missense variations. Analysis of variant c.684-2A > G revealed the activation of a non-canonical TG-acceptor site and exon 6 sequences critical for its recognition. CONCLUSIONS Incorporation of minigene read-outs into an ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology)-based classification scheme allowed us to classify 32 CHEK2 variants (27 pathogenic/likely pathogenic and 5 likely benign). However, 20 variants (38%) remained of uncertain significance, reflecting in part the complex splicing patterns of this gene.
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Affiliation(s)
- Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Ada Esteban-Sánchez
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Víctor Lorca
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Inés Llinares-Burguet
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Alicia García-Álvarez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Mar Infante
- Cancer Genetics, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Douglas F Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, CB1 8RN, Cambridge, United Kingdom
| | - Peter Devilee
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Eladio A Velasco-Sampedro
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid (CSIC-UVa), Valladolid, Spain
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5
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Nesic K, Krais JJ, Vandenberg CJ, Wang Y, Patel P, Cai KQ, Kwan T, Lieschke E, Ho GY, Barker HE, Bedo J, Casadei S, Farrell A, Radke M, Shield-Artin K, Penington JS, Geissler F, Kyran E, Zhang F, Dobrovic A, Olesen I, Kristeleit R, Oza A, Ratnayake G, Traficante N, DeFazio A, Bowtell DDL, Harding TC, Lin K, Swisher EM, Kondrashova O, Scott CL, Johnson N, Wakefield MJ. BRCA1 secondary splice-site mutations drive exon-skipping and PARP inhibitor resistance. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.03.20.23287465. [PMID: 36993400 PMCID: PMC10055590 DOI: 10.1101/2023.03.20.23287465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
BRCA1 splice isoforms Δ11 and Δ11q can contribute to PARP inhibitor (PARPi) resistance by splicing-out the mutation-containing exon, producing truncated, partially-functional proteins. However, the clinical impact and underlying drivers of BRCA1 exon skipping remain undetermined. We analyzed nine ovarian and breast cancer patient derived xenografts (PDX) with BRCA1 exon 11 frameshift mutations for exon skipping and therapy response, including a matched PDX pair derived from a patient pre- and post-chemotherapy/PARPi. BRCA1 exon 11 skipping was elevated in PARPi resistant PDX tumors. Two independent PDX models acquired secondary BRCA1 splice site mutations (SSMs), predicted in silico to drive exon skipping. Predictions were confirmed using qRT-PCR, RNA sequencing, western blots and BRCA1 minigene modelling. SSMs were also enriched in post-PARPi ovarian cancer patient cohorts from the ARIEL2 and ARIEL4 clinical trials. We demonstrate that SSMs drive BRCA1 exon 11 skipping and PARPi resistance, and should be clinically monitored, along with frame-restoring secondary mutations.
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Affiliation(s)
- Ksenija Nesic
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | - Cassandra J. Vandenberg
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | | | | | - Tanya Kwan
- Clovis Oncology Inc., San Francisco, CA, USA
| | - Elizabeth Lieschke
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Gwo-Yaw Ho
- School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
| | - Holly E. Barker
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Justin Bedo
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | - Andrew Farrell
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Marc Radke
- University of Washington, Seattle, WA, USA
| | - Kristy Shield-Artin
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Jocelyn S. Penington
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Franziska Geissler
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Elizabeth Kyran
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Fan Zhang
- University of Melbourne Department of Surgery, Austin Health, Heidelberg, Victoria, Australia
| | - Alexander Dobrovic
- University of Melbourne Department of Surgery, Austin Health, Heidelberg, Victoria, Australia
| | - Inger Olesen
- The Andrew Love Cancer Centre, Barwon Health, Geelong, Victoria, Australia
| | - Rebecca Kristeleit
- Department of Oncology, Guys and St Thomas’ NHS Foundation Trust, London, UK
- National Institute for Health Research, University College London Hospitals Clinical Research Facility, London, UK
| | - Amit Oza
- Princess Margaret Cancer Center, Toronto, ON, Canada
| | | | - Nadia Traficante
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
| | | | - Anna DeFazio
- The Daffodil Centre, The University of Sydney, a joint venture with Cancer Council New South Wales, Sydney, New South Wales, Australia
- The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Department of Gynecological Oncology, Westmead Hospital, Western Sydney Local Health District, New South Wales, Australia
| | - David D. L. Bowtell
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
| | | | - Kevin Lin
- Clovis Oncology Inc., San Francisco, CA, USA
| | | | - Olga Kondrashova
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Clare L. Scott
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
- Royal Women’s Hospital, Parkville, VIC, Australia
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
- Department of Obstetrics and Gynecology, University of Melbourne, Parkville, VIC, Australia
| | | | - Matthew J. Wakefield
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
- Department of Obstetrics and Gynecology, University of Melbourne, Parkville, VIC, Australia
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6
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Sullivan PJ, Gayevskiy V, Davis RL, Wong M, Mayoh C, Mallawaarachchi A, Hort Y, McCabe MJ, Beecroft S, Jackson MR, Arts P, Dubowsky A, Laing N, Dinger ME, Scott HS, Oates E, Pinese M, Cowley MJ. Introme accurately predicts the impact of coding and noncoding variants on gene splicing, with clinical applications. Genome Biol 2023; 24:118. [PMID: 37198692 PMCID: PMC10190034 DOI: 10.1186/s13059-023-02936-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/10/2023] [Indexed: 05/19/2023] Open
Abstract
Predicting the impact of coding and noncoding variants on splicing is challenging, particularly in non-canonical splice sites, leading to missed diagnoses in patients. Existing splice prediction tools are complementary but knowing which to use for each splicing context remains difficult. Here, we describe Introme, which uses machine learning to integrate predictions from several splice detection tools, additional splicing rules, and gene architecture features to comprehensively evaluate the likelihood of a variant impacting splicing. Through extensive benchmarking across 21,000 splice-altering variants, Introme outperformed all tools (auPRC: 0.98) for the detection of clinically significant splice variants. Introme is available at https://github.com/CCICB/introme .
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Affiliation(s)
- Patricia J Sullivan
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, UNSW Medicine & Health, UNSW Sydney, Sydney, NSW, Australia
- University of New South Wales Centre for Childhood Cancer Research, UNSW Sydney, Sydney, NSW, Australia
| | - Velimir Gayevskiy
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, Australia
| | - Ryan L Davis
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, Australia
- Department of Neurogenetics, Kolling Institute, St. Leonards, NSW, Australia
- Sydney Medical School-Northern, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Marie Wong
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, UNSW Medicine & Health, UNSW Sydney, Sydney, NSW, Australia
| | - Chelsea Mayoh
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, UNSW Medicine & Health, UNSW Sydney, Sydney, NSW, Australia
| | - Amali Mallawaarachchi
- Division of Genomics and Epigenetics, Garvan Institute of Medical Research, Sydney, Australia
- Clinical Genetics Unit, Institute of Precision Medicine and Bioinformatics, Sydney Local Health District, Sydney, Australia
| | - Yvonne Hort
- Division of Genomics and Epigenetics, Garvan Institute of Medical Research, Sydney, Australia
| | - Mark J McCabe
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, Australia
| | - Sarah Beecroft
- Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA, Australia
| | - Matilda R Jackson
- Department of Genetics and Molecular Pathology, Centre for Cancer Biology, An Alliance Between SA Pathology and the University of South Australia, Adelaide, Australia
- Australian Genomics, Parkville, VIC, Australia
| | - Peer Arts
- Department of Genetics and Molecular Pathology, Centre for Cancer Biology, An Alliance Between SA Pathology and the University of South Australia, Adelaide, Australia
| | - Andrew Dubowsky
- Department of Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia
| | - Nigel Laing
- Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA, Australia
| | - Marcel E Dinger
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, Australia
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Hamish S Scott
- Department of Genetics and Molecular Pathology, Centre for Cancer Biology, An Alliance Between SA Pathology and the University of South Australia, Adelaide, Australia
- Australian Genomics, Parkville, VIC, Australia
- School of Medicine, University of Adelaide, Adelaide, SA, Australia
- ACRF Cancer Genomics Facility, Centre for Cancer Biology, An Alliance Between SA Pathology and the University of South Australia, Adelaide, SA, Australia
| | - Emily Oates
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Mark Pinese
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Clinical Medicine, UNSW Medicine & Health, UNSW Sydney, Sydney, NSW, Australia
| | - Mark J Cowley
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia.
- School of Clinical Medicine, UNSW Medicine & Health, UNSW Sydney, Sydney, NSW, Australia.
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7
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Thomassen M, Mesman RLS, Hansen TVO, Menendez M, Rossing M, Esteban‐Sánchez A, Tudini E, Törngren T, Parsons MT, Pedersen IS, Teo SH, Kruse TA, Møller P, Borg Å, Jensen UB, Christensen LL, Singer CF, Muhr D, Santamarina M, Brandao R, Andresen BS, Feng B, Canson D, Richardson ME, Karam R, Pesaran T, LaDuca H, Conner BR, Abualkheir N, Hoang L, Calléja FMGR, Andrews L, James PA, Bunyan D, Hamblett A, Radice P, Goldgar DE, Walker LC, Engel C, Claes KBM, Macháčková E, Baralle D, Viel A, Wappenschmidt B, Lazaro C, Vega A, Vreeswijk MPG, de la Hoya M, Spurdle AB. Clinical, splicing, and functional analysis to classify BRCA2 exon 3 variants: Application of a points-based ACMG/AMP approach. Hum Mutat 2022; 43:1921-1944. [PMID: 35979650 PMCID: PMC10946542 DOI: 10.1002/humu.24449] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 08/05/2022] [Accepted: 08/09/2022] [Indexed: 01/25/2023]
Abstract
Skipping of BRCA2 exon 3 (∆E3) is a naturally occurring splicing event, complicating clinical classification of variants that may alter ∆E3 expression. This study used multiple evidence types to assess pathogenicity of 85 variants in/near BRCA2 exon 3. Bioinformatically predicted spliceogenic variants underwent mRNA splicing analysis using minigenes and/or patient samples. ∆E3 was measured using quantitative analysis. A mouse embryonic stem cell (mESC) based assay was used to determine the impact of 18 variants on mRNA splicing and protein function. For each variant, population frequency, bioinformatic predictions, clinical data, and existing mRNA splicing and functional results were collated. Variant class was assigned using a gene-specific adaptation of ACMG/AMP guidelines, following a recently proposed points-based system. mRNA and mESC analysis combined identified six variants with transcript and/or functional profiles interpreted as loss of function. Cryptic splice site use for acceptor site variants generated a transcript encoding a shorter protein that retains activity. Overall, 69/85 (81%) variants were classified using the points-based approach. Our analysis shows the value of applying gene-specific ACMG/AMP guidelines using a points-based approach and highlights the consideration of cryptic splice site usage to appropriately assign PVS1 code strength.
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Affiliation(s)
- Mads Thomassen
- Department of Clinical GeneticsOdense University HospitalOdence CDenmark
| | - Romy L. S. Mesman
- Department of Human GeneticsLeiden University Medical CenterLeidenthe Netherlands
| | - Thomas V. O. Hansen
- Department of Clinical Genetics, RigshospitaletCopenhagen University HospitalCopenhagenDenmark
| | - Mireia Menendez
- Hereditary Cancer ProgramCatalan Institute of Oncology, ONCOBELL‐IDIBELL‐IDTP, CIBERONCHospitalet de LlobregatSpain
| | - Maria Rossing
- Center for Genomic Medicine, RigshospitaletCopenhagen University HospitalCopenhagenDenmark
| | - Ada Esteban‐Sánchez
- Molecular Oncology Laboratory, CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Emma Tudini
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | - Therese Törngren
- Division of Oncology, Department of Clinical Sciences LundLund UniversityLundSweden
| | - Michael T. Parsons
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | - Inge S. Pedersen
- Molecular Diagnostics, Aalborg University HospitalAalborgDenmark
- Clinical Cancer Research CenterAalborg University HospitalAalborgDenmark
- Department of Clinical MedicineAalborg UniversityAalborgDenmark
| | - Soo H. Teo
- Breast Cancer Research ProgrammeCancer Research MalaysiaSubang JayaSelangorMalaysia
- Department of Surgery, Faculty of MedicineUniversity of MalayaKuala LumpurMalaysia
| | - Torben A. Kruse
- Department of Clinical GeneticsOdense University HospitalOdence CDenmark
| | - Pål Møller
- Department of Tumour BiologyThe Norwegian Radium Hospital, Oslo University HospitalOsloNorway
| | - Åke Borg
- Division of Oncology, Department of Clinical Sciences LundLund UniversityLundSweden
| | - Uffe B. Jensen
- Department of Clinical GeneticsAarhus University HospitalAarhus NDenmark
| | | | - Christian F. Singer
- Department of OB/GYN and Comprehensive Cancer CenterMedical University of ViennaViennaAustria
| | - Daniela Muhr
- Department of OB/GYN and Comprehensive Cancer CenterMedical University of ViennaViennaAustria
| | - Marta Santamarina
- Fundación Pública Galega de Medicina XenómicaSantiago de CompostelaSpain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Complejo Hospitalario Universitario de Santiago, SERGASSantiago de CompostelaSpain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER)MadridSpain
| | - Rita Brandao
- Department of Clinical GeneticsMaastricht University Medical CenterMaastrichtthe Netherlands
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical SciencesUniversity of Southern DenmarkOdenseDenmark
| | - Bing‐Jian Feng
- Department of DermatologyHuntsman Cancer Institute, University of Utah School of MedicineSalt Lake CityUtahUSA
| | - Daffodil Canson
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | | | | | | | | | | | | | | | | | - Lesley Andrews
- Hereditary Cancer Clinic, Nelune Comprehensive Cancer Care CentreSydneyNew South WalesAustralia
| | - Paul A. James
- Parkville Familial Cancer Centre, Peter MacCallum Cancer CenterMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyThe University of MelbourneMelbourneVictoriaAustralia
| | - Dave Bunyan
- Human Development and Health, Faculty of MedicineUniversity of SouthamptonSouthamptonUK
| | - Amanda Hamblett
- Middlesex Health Shoreline Cancer CenterWestbrookConnecticutUSA
| | - Paolo Radice
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of ResearchFondazione IRCCS Istituto Nazionale dei Tumori (INT)MilanItaly
| | - David E. Goldgar
- Department of DermatologyHuntsman Cancer Institute, University of Utah School of MedicineSalt Lake CityUtahUSA
| | - Logan C. Walker
- Department of Pathology and Biomedical ScienceUniversity of OtagoChristchurchNew Zealand
| | - Christoph Engel
- Institute for Medical Informatics, Statistics and EpidemiologyUniversity of LeipzigLeipzigGermany
| | | | - Eva Macháčková
- Department of Cancer Epidemiology and GeneticsMasaryk Memorial Cancer InstituteBrnoCzech Republic
| | - Diana Baralle
- Human Development and Health, Faculty of MedicineUniversity of SouthamptonSouthamptonUK
| | - Alessandra Viel
- Division of Functional Onco‐genomics and GeneticsCentro di Riferimento Oncologico di Aviano (CRO), IRCCSAvianoItaly
| | - Barbara Wappenschmidt
- Center for Familial Breast and Ovarian Cancer, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
- Center for Integrated Oncology (CIO), Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Conxi Lazaro
- Hereditary Cancer ProgramCatalan Institute of Oncology, ONCOBELL‐IDIBELL‐IDTP, CIBERONCHospitalet de LlobregatSpain
| | - Ana Vega
- Fundación Pública Galega de Medicina XenómicaSantiago de CompostelaSpain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Complejo Hospitalario Universitario de Santiago, SERGASSantiago de CompostelaSpain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER)MadridSpain
| | - ENIGMA Consortium
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | | | - Miguel de la Hoya
- Molecular Oncology Laboratory, CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Amanda B. Spurdle
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
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Valenzuela-Palomo A, Sanoguera-Miralles L, Bueno-Martínez E, Esteban-Sánchez A, Llinares-Burguet I, García-Álvarez A, Pérez-Segura P, Gómez-Barrero S, de la Hoya M, Velasco-Sampedro EA. Splicing Analysis of 16 PALB2 ClinVar Variants by Minigene Assays: Identification of Six Likely Pathogenic Variants. Cancers (Basel) 2022; 14:cancers14184541. [PMID: 36139699 PMCID: PMC9496955 DOI: 10.3390/cancers14184541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/12/2022] [Accepted: 09/15/2022] [Indexed: 11/29/2022] Open
Abstract
PALB2 loss-of-function variants are associated with significant increased risk of breast cancer as well as other types of tumors. Likewise, splicing disruptions are a common mechanism of disease susceptibility. Indeed, we previously showed, by minigene assays, that 35 out of 42 PALB2 variants impaired splicing. Taking advantage of one of these constructs (mgPALB2_ex1-3), we proceeded to analyze other variants at exons 1 to 3 reported at the ClinVar database. Thirty-one variants were bioinformatically analyzed with MaxEntScan and SpliceAI. Then, 16 variants were selected for subsequent RNA assays. We identified a total of 12 spliceogenic variants, 11 of which did not produce any trace of the expected minigene full-length transcript. Interestingly, variant c.49-1G > A mimicked previous outcomes in patient RNA (transcript ∆(E2p6)), supporting the reproducibility of the minigene approach. A total of eight variant-induced transcripts were characterized, three of which (∆(E1q17), ∆(E3p11), and ∆(E3)) were predicted to introduce a premature termination codon and to undergo nonsense-mediated decay, and five (▼(E1q9), ∆(E2p6), ∆(E2), ▼(E3q48)-a, and ▼(E3q48)-b) maintained the reading frame. According to an ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology)-based classification scheme, which integrates mgPALB2 data, six PALB2 variants were classified as pathogenic/likely pathogenic, five as VUS, and five as likely benign. Furthermore, five ±1,2 variants were catalogued as VUS because they produced significant proportions of in-frame transcripts of unknown impact on protein function.
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Affiliation(s)
- Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
| | - Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
| | - Ada Esteban-Sánchez
- Molecular Oncology Laboratory, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain
| | - Inés Llinares-Burguet
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
| | - Alicia García-Álvarez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain
| | - Susana Gómez-Barrero
- Facultad de Ciencias de la Salud, Universidad Alfonso X “El Sabio”, Avda. de la Universidad 1, Villanueva de la Cañada, 28691 Madrid, Spain
| | - Miguel de la Hoya
- Molecular Oncology Laboratory, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain
| | - Eladio A. Velasco-Sampedro
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain
- Correspondence:
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9
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Bueno‐Martínez E, Sanoguera‐Miralles L, Valenzuela‐Palomo A, Esteban‐Sánchez A, Lorca V, Llinares‐Burguet I, Allen J, García‐Álvarez A, Pérez‐Segura P, Durán M, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco‐Sampedro EA. Minigene-based splicing analysis and ACMG/AMP-based tentative classification of 56 ATM variants. J Pathol 2022; 258:83-101. [PMID: 35716007 PMCID: PMC9541484 DOI: 10.1002/path.5979] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/11/2022] [Accepted: 06/08/2022] [Indexed: 12/29/2022]
Abstract
The ataxia telangiectasia-mutated (ATM) protein is a major coordinator of the DNA damage response pathway. ATM loss-of-function variants are associated with 2-fold increased breast cancer risk. We aimed at identifying and classifying spliceogenic ATM variants detected in subjects of the large-scale sequencing project BRIDGES. A total of 381 variants at the intron-exon boundaries were identified, 128 of which were predicted to be spliceogenic. After further filtering, we ended up selecting 56 variants for splicing analysis. Four functional minigenes (mgATM) spanning exons 4-9, 11-17, 25-29, and 49-52 were constructed in the splicing plasmid pSAD. Selected variants were genetically engineered into the four constructs and assayed in MCF-7/HeLa cells. Forty-eight variants (85.7%) impaired splicing, 32 of which did not show any trace of the full-length (FL) transcript. A total of 43 transcripts were identified where the most prevalent event was exon/multi-exon skipping. Twenty-seven transcripts were predicted to truncate the ATM protein. A tentative ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology)-based classification scheme that integrates mgATM data allowed us to classify 29 ATM variants as pathogenic/likely pathogenic and seven variants as likely benign. Interestingly, the likely pathogenic variant c.1898+2T>G generated 13% of the minigene FL-transcript due to the use of a noncanonical GG-5'-splice-site (0.014% of human donor sites). Circumstantial evidence in three ATM variants (leakiness uncovered by our mgATM analysis together with clinical data) provides some support for a dosage-sensitive expression model in which variants producing ≥30% of FL-transcripts would be predicted benign, while variants producing ≤13% of FL-transcripts might be pathogenic. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Elena Bueno‐Martínez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Lara Sanoguera‐Miralles
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Alberto Valenzuela‐Palomo
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Ada Esteban‐Sánchez
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Víctor Lorca
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Inés Llinares‐Burguet
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Jamie Allen
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Alicia García‐Álvarez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Pedro Pérez‐Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Mercedes Durán
- Cancer Genetics, Instituto de Biología y Genética MolecularValladolidSpain
| | - Douglas F Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Peter Devilee
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Maaike PG Vreeswijk
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Eladio A Velasco‐Sampedro
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
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Minigene Splicing Assays Identify 20 Spliceogenic Variants of the Breast/Ovarian Cancer Susceptibility Gene RAD51C. Cancers (Basel) 2022; 14:cancers14122960. [PMID: 35740625 PMCID: PMC9221245 DOI: 10.3390/cancers14122960] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 12/11/2022] Open
Abstract
RAD51C loss-of-function variants are associated with an increased risk of breast and ovarian cancers. Likewise, splicing disruptions are a frequent mechanism of gene inactivation. Taking advantage of a previous splicing-reporter minigene with exons 2-8 (mgR51C_ex2-8), we proceeded to check its impact on the splicing of candidate ClinVar variants. A total of 141 RAD51C variants at the intron/exon boundaries were analyzed with MaxEntScan. Twenty variants were selected and genetically engineered into the wild-type minigene. All the variants disrupted splicing, and 18 induced major splicing anomalies without any trace or minimal amounts (<2.4%) of the minigene full-length (FL) transcript. Twenty-seven transcripts (including the wild-type and r.904A FL transcripts) were identified by fluorescent fragment electrophoresis; of these, 14 were predicted to truncate the RAD51C protein, 3 kept the reading frame, and 8 minor isoforms (1.1−4.7% of the overall expression) could not be characterized. Finally, we performed a tentative interpretation of the variants according to an ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology)-based classification scheme, classifying 16 variants as likely pathogenic. Minigene assays have been proven as valuable tools for the initial characterization of potential spliceogenic variants. Hence, minigene mgR51C_ex2-8 provided useful splicing data for 40 RAD51C variants.
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11
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Valenzuela‐Palomo A, Bueno‐Martínez E, Sanoguera‐Miralles L, Lorca V, Fraile‐Bethencourt E, Esteban‐Sánchez A, Gómez‐Barrero S, Carvalho S, Allen J, García‐Álvarez A, Pérez‐Segura P, Dorling L, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco EA. Splicing predictions, minigene analyses, and ACMG-AMP clinical classification of 42 germline PALB2 splice-site variants. J Pathol 2022; 256:321-334. [PMID: 34846068 PMCID: PMC9306493 DOI: 10.1002/path.5839] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/18/2021] [Accepted: 11/26/2021] [Indexed: 12/18/2022]
Abstract
PALB2 loss-of-function variants confer high risk of developing breast cancer. Here we present a systematic functional analysis of PALB2 splice-site variants detected in approximately 113,000 women in the large-scale sequencing project Breast Cancer After Diagnostic Gene Sequencing (BRIDGES; https://bridges-research.eu/). Eighty-two PALB2 variants at the intron-exon boundaries were analyzed with MaxEntScan. Forty-two variants were selected for the subsequent splicing functional assays. For this purpose, three splicing reporter minigenes comprising exons 1-12 were constructed. The 42 potential spliceogenic variants were introduced into the minigenes by site-directed mutagenesis and assayed in MCF-7/MDA-MB-231 cells. Splicing anomalies were observed in 35 variants, 23 of which showed no traces or minimal amounts of the expected full-length transcripts of each minigene. More than 30 different variant-induced transcripts were characterized, 23 of which were predicted to truncate the PALB2 protein. The pathogenicity of all variants was interpreted according to an in-house adaptation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) variant classification scheme. Up to 23 variants were classified as pathogenic/likely pathogenic. Remarkably, three ±1,2 variants (c.49-2A>T, c.108+2T>C, and c.211+1G>A) were classified as variants of unknown significance, as they produced significant amounts of either in-frame transcripts of unknown impact on the PALB2 protein function or the minigene full-length transcripts. In conclusion, we have significantly contributed to the ongoing effort of identifying spliceogenic variants in the clinically relevant PALB2 cancer susceptibility gene. Moreover, we suggest some approaches to classify the findings in accordance with the ACMG-AMP rationale. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Alberto Valenzuela‐Palomo
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Elena Bueno‐Martínez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Lara Sanoguera‐Miralles
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Víctor Lorca
- Molecular Oncology Laboratory, Hospital Clínico San CarlosIdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Eugenia Fraile‐Bethencourt
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
- Knight Cancer Research BuildingPortlandORUSA
| | - Ada Esteban‐Sánchez
- Molecular Oncology Laboratory, Hospital Clínico San CarlosIdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | | | - Sara Carvalho
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Jamie Allen
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Alicia García‐Álvarez
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
| | - Pedro Pérez‐Segura
- Molecular Oncology Laboratory, Hospital Clínico San CarlosIdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Leila Dorling
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Douglas F Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary CareUniversity of CambridgeCambridgeUK
| | - Peter Devilee
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Maaike PG Vreeswijk
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Miguel de la Hoya
- Molecular Oncology Laboratory, Hospital Clínico San CarlosIdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Eladio A Velasco
- Splicing and Genetic Susceptibility to Cancer, Unidad de Excelencia Instituto de Biología y Genética MolecularConsejo Superior de Investigaciones Científicas (CSIC‐UVa)ValladolidSpain
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12
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Yin J, Zhou J, Chen J, Xu T, Zhang Z, Zhang H, Yuan C, Cheng X, Qin Y, Zheng B, Wang C, Yang S, Jia Z. Case Report: A Novel Variant c.2262+3A>T of the SCN5A Gene Results in Intron Retention Associated With Incessant Ventricular Tachycardias. Front Med (Lausanne) 2021; 8:659119. [PMID: 34422849 PMCID: PMC8371685 DOI: 10.3389/fmed.2021.659119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/30/2021] [Indexed: 11/18/2022] Open
Abstract
Objective: Voltage-gated sodium channel Nav1.5 encoded by the SCN5A gene plays crucial roles in cardiac electrophysiology. Previous genetic studies have shown that mutations in SCN5A are associated with multiple inherited cardiac arrhythmias. Here, we investigated the molecular defect in a Chinese boy with clinical manifestations of arrhythmias. Methods: Gene variations were screened using whole-exome sequencing and validated by direct Sanger sequencing. A minigene assay and reverse transcription PCR (RT-PCR) were performed to confirm the effects of splice variants in vitro. Western blot analysis was carried out to determine whether the c.2262+3A>T variant produced a truncated protein. Results: By genetic analysis, we identified a novel splice variant c.2262+3A>T in SCN5A gene in a Chinese boy with incessant ventricular tachycardias (VT). This variant was predicted to activate a new cryptic splice donor site and was identified by in silico analysis. The variant retained 79 bp at the 5′ end of intron 14 in the mature mRNA. Furthermore, the mutant transcript that created a premature stop codon at 818 amino acids [p.(R818*)] could be produced as a truncated protein. Conclusion: We verified the pathogenic effect of splicing variant c.2262+3A>T, which disturbed the normal mRNA splicing and caused a truncated protein, suggesting that splice variants play an important role in the molecular basis of early onset incessant ventricular tachycardias, and careful molecular profiling of these patients will be essential for future effective personalized treatment options.
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Affiliation(s)
- Jie Yin
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jia Zhou
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jinlong Chen
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Ting Xu
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Zhongman Zhang
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Han Zhang
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Chang Yuan
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xueying Cheng
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Yuming Qin
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Shiwei Yang
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Zhanjun Jia
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
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13
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Bueno-Martínez E, Sanoguera-Miralles L, Valenzuela-Palomo A, Lorca V, Gómez-Sanz A, Carvalho S, Allen J, Infante M, Pérez-Segura P, Lázaro C, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco EA. RAD51D Aberrant Splicing in Breast Cancer: Identification of Splicing Regulatory Elements and Minigene-Based Evaluation of 53 DNA Variants. Cancers (Basel) 2021; 13:2845. [PMID: 34200360 PMCID: PMC8201001 DOI: 10.3390/cancers13112845] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 12/18/2022] Open
Abstract
RAD51D loss-of-function variants increase lifetime risk of breast and ovarian cancer. Splicing disruption is a frequent pathogenic mechanism associated with variants in susceptibility genes. Herein, we have assessed the splicing and clinical impact of splice-site and exonic splicing enhancer (ESE) variants identified through the study of ~113,000 women of the BRIDGES cohort. A RAD51D minigene with exons 2-9 was constructed in splicing vector pSAD. Eleven BRIDGES splice-site variants (selected by MaxEntScan) were introduced into the minigene by site-directed mutagenesis and tested in MCF-7 cells. The 11 variants disrupted splicing, collectively generating 25 different aberrant transcripts. All variants but one produced negligible levels (<3.4%) of the full-length (FL) transcript. In addition, ESE elements of the alternative exon 3 were mapped by testing four overlapping exonic microdeletions (≥30-bp), revealing an ESE-rich interval (c.202_235del) with critical sequences for exon 3 recognition that might have been affected by germline variants. Next, 26 BRIDGES variants and 16 artificial exon 3 single-nucleotide substitutions were also assayed. Thirty variants impaired splicing with variable amounts (0-65.1%) of the FL transcript, although only c.202G>A demonstrated a complete aberrant splicing pattern without the FL transcript. On the other hand, c.214T>C increased efficiency of exon 3 recognition, so only the FL transcript was detected (100%). In conclusion, 41 RAD51D spliceogenic variants (28 of which were from the BRIDGES cohort) were identified by minigene assays. We show that minigene-based mapping of ESEs is a powerful approach for identifying ESE hotspots and ESE-disrupting variants. Finally, we have classified nine variants as likely pathogenic according to ACMG/AMP-based guidelines, highlighting the complex relationship between splicing alterations and variant interpretation.
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Affiliation(s)
- Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer Laboratory, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (A.V.-P.)
| | - Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer Laboratory, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (A.V.-P.)
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer Laboratory, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (A.V.-P.)
| | - Víctor Lorca
- Molecular Oncology Laboratory CIBERONC, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Hospital Clinico San Carlos, 28040 Madrid, Spain; (V.L.); (A.G.-S.); (P.P.-S.)
| | - Alicia Gómez-Sanz
- Molecular Oncology Laboratory CIBERONC, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Hospital Clinico San Carlos, 28040 Madrid, Spain; (V.L.); (A.G.-S.); (P.P.-S.)
| | - Sara Carvalho
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Jamie Allen
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Mar Infante
- Cancer Genetics, Unidad de Excelencia Instituto de Biología y Genética Molecular (CSIC-UVa), 47003 Valladolid, Spain;
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Hospital Clinico San Carlos, 28040 Madrid, Spain; (V.L.); (A.G.-S.); (P.P.-S.)
| | - Conxi Lázaro
- Hereditary Cancer Program, Catalan Institute of Oncology, IDIBELL and CIBERONC, 08908 Hospitalet de Llobregat, Spain;
| | - Douglas F. Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Peter Devilee
- Department of Human Genetics, Leiden University Medical Center, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Maaike P. G. Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Hospital Clinico San Carlos, 28040 Madrid, Spain; (V.L.); (A.G.-S.); (P.P.-S.)
| | - Eladio A. Velasco
- Splicing and Genetic Susceptibility to Cancer Laboratory, Unidad de Excelencia Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (A.V.-P.)
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14
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Nix P, Mundt E, Coffee B, Goossen E, Warf BM, Brown K, Bowles K, Roa B. Interpretation of BRCA2 Splicing Variants: A Case Series of Challenging Variant Interpretations and the Importance of Functional RNA Analysis. Fam Cancer 2021; 21:7-19. [PMID: 33469799 PMCID: PMC8799590 DOI: 10.1007/s10689-020-00224-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 12/15/2020] [Indexed: 11/13/2022]
Abstract
A substantial proportion of pathogenic variants associated with an increased risk of hereditary cancer are sequence variants affecting RNA splicing. The classification of these variants can be complex when both non-functional and functional transcripts are produced from the variant allele. We present four BRCA2 splice site variants with complex variant interpretations (BRCA2 c.68-3T>G, c.68-2A>G, c.425G>T, c.8331+2T>C). Evidence supporting a pathogenic classification is available for each variant, including in silico models, absence in population databases, and published functional data. However, comprehensive RNA analysis showed that some functional transcript may be produced by each variant. BRCA2 c.68-3T>G results in a partial splice defect. For BRCA2 c.68-2A>G and c.425G>T, aberrant splicing was shown to produce a potentially functional, in-frame transcript. BRCA2 c.8331+2T>C may utilize a functional GC donor in place of the wild-type GT donor. The severity of cancer history for carriers of these variants was also assessed using a history weighting algorithm and was not consistent with pathogenic controls (carriers of known pathogenic variants in BRCA2). Due to the conflicting evidence, our laboratory classifies these BRCA2 variants as variants of uncertain significance. This highlights the importance of evaluating new and existing evidence to ensure accurate variant classification and appropriate patient care.
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Affiliation(s)
- Paola Nix
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA.
| | - Erin Mundt
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA
| | - Bradford Coffee
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA
| | | | - Bryan M Warf
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA.,Third Wave Analytics, Inc., San Francisco, CA, USA
| | - Krystal Brown
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA
| | - Karla Bowles
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA
| | - Benjamin Roa
- Myriad Genetics, Inc., 320 Wakara Way, Salt Lake City, UT, USA
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15
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Sanoguera-Miralles L, Valenzuela-Palomo A, Bueno-Martínez E, Llovet P, Díez-Gómez B, Caloca MJ, Pérez-Segura P, Fraile-Bethencourt E, Colmena M, Carvalho S, Allen J, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco EA. Comprehensive Functional Characterization and Clinical Interpretation of 20 Splice-Site Variants of the RAD51C Gene. Cancers (Basel) 2020; 12:E3771. [PMID: 33333735 PMCID: PMC7765170 DOI: 10.3390/cancers12123771] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 12/12/2022] Open
Abstract
Hereditary breast and/or ovarian cancer is a highly heterogeneous disease with more than 10 known disease-associated genes. In the framework of the BRIDGES project (Breast Cancer Risk after Diagnostic Gene Sequencing), the RAD51C gene has been sequenced in 60,466 breast cancer patients and 53,461 controls. We aimed at functionally characterizing all the identified genetic variants that are predicted to disrupt the splicing process. Forty RAD51C variants of the intron-exon boundaries were bioinformatically analyzed, 20 of which were selected for splicing functional assays. To test them, a splicing reporter minigene with exons 2 to 8 was designed and constructed. This minigene generated a full-length transcript of the expected size (1062 nucleotides), sequence, and structure (Vector exon V1- RAD51C exons_2-8- Vector exon V2). The 20 candidate variants were genetically engineered into the wild type minigene and functionally assayed in MCF-7 cells. Nineteen variants (95%) impaired splicing, while 18 of them produced severe splicing anomalies. At least 35 transcripts were generated by the mutant minigenes: 16 protein-truncating, 6 in-frame, and 13 minor uncharacterized isoforms. According to ACMG/AMP-based standards, 15 variants could be classified as pathogenic or likely pathogenic variants: c.404G > A, c.405-6T > A, c.571 + 4A > G, c.571 + 5G > A, c.572-1G > T, c.705G > T, c.706-2A > C, c.706-2A > G, c.837 + 2T > C, c.905-3C > G, c.905-2A > C, c.905-2_905-1del, c.965 + 5G > A, c.1026 + 5_1026 + 7del, and c.1026 + 5G > T.
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Affiliation(s)
- Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Patricia Llovet
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Beatriz Díez-Gómez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - María José Caloca
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain;
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Eugenia Fraile-Bethencourt
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
- Knight Cancer Research Building, 2720 S Moody Ave, Portland, OR 97201, USA
| | - Marta Colmena
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Sara Carvalho
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Jamie Allen
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Douglas F. Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Peter Devilee
- Leiden University Medical Center, Department of Human Genetics, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Maaike P. G. Vreeswijk
- Leiden University Medical Center, Department of Human Genetics, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Eladio A. Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
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16
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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: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [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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17
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Tubeuf H, Caputo SM, Sullivan T, Rondeaux J, Krieger S, Caux-Moncoutier V, Hauchard J, Castelain G, Fiévet A, Meulemans L, Révillion F, Léoné M, Boutry-Kryza N, Delnatte C, Guillaud-Bataille M, Cleveland L, Reid S, Southon E, Soukarieh O, Drouet A, Di Giacomo D, Vezain M, Bonnet-Dorion F, Bourdon V, Larbre H, Muller D, Pujol P, Vaz F, Audebert-Bellanger S, Colas C, Venat-Bouvet L, Solano AR, Stoppa-Lyonnet D, Houdayer C, Frebourg T, Gaildrat P, Sharan SK, Martins A. Calibration of Pathogenicity Due to Variant-Induced Leaky Splicing Defects by Using BRCA2 Exon 3 as a Model System. Cancer Res 2020; 80:3593-3605. [PMID: 32641407 DOI: 10.1158/0008-5472.can-20-0895] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/14/2020] [Accepted: 07/02/2020] [Indexed: 12/25/2022]
Abstract
BRCA2 is a clinically actionable gene implicated in breast and ovarian cancer predisposition that has become a high priority target for improving the classification of variants of unknown significance (VUS). Among all BRCA2 VUS, those causing partial/leaky splicing defects are the most challenging to classify because the minimal level of full-length (FL) transcripts required for normal function remains to be established. Here, we explored BRCA2 exon 3 (BRCA2e3) as a model for calibrating variant-induced spliceogenicity and estimating thresholds for BRCA2 haploinsufficiency. In silico predictions, minigene splicing assays, patients' RNA analyses, a mouse embryonic stem cell (mESC) complementation assay and retrieval of patient-related information were combined to determine the minimal requirement of FL BRCA2 transcripts. Of 100 BRCA2e3 variants tested in the minigene assay, 64 were found to be spliceogenic, causing mild to severe RNA defects. Splicing defects were also confirmed in patients' RNA when available. Analysis of a neutral leaky variant (c.231T>G) showed that a reduction of approximately 60% of FL BRCA2 transcripts from a mutant allele does not cause any increase in cancer risk. Moreover, data obtained from mESCs suggest that variants causing a decline in FL BRCA2 with approximately 30% of wild-type are not pathogenic, given that mESCs are fully viable and resistant to DNA-damaging agents in those conditions. In contrast, mESCs producing lower relative amounts of FL BRCA2 exhibited either null or hypomorphic phenotypes. Overall, our findings are likely to have broader implications on the interpretation of BRCA2 variants affecting the splicing pattern of other essential exons. SIGNIFICANCE: These findings demonstrate that BRCA2 tumor suppressor function tolerates substantial reduction in full-length transcripts, helping to determine the pathogenicity of BRCA2 leaky splicing variants, some of which may not increase cancer risk.
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Affiliation(s)
- Hélène Tubeuf
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Interactive Biosoftware, Rouen, France
| | - Sandrine M Caputo
- Department of Genetics, Institut Curie, Paris, France.,PSL Research University, Paris, France
| | - Teresa Sullivan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Julie Rondeaux
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Sophie Krieger
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Laboratory of Cancer Biology and Genetics, Centre François Baclesse, Caen, France - Normandie University, UNICAEN, Caen, France
| | | | - Julie Hauchard
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Gaia Castelain
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Alice Fiévet
- Department of Genetics, Institut Curie, Paris, France.,INSERM U830, University Paris Descartes, Paris, France.,Service Génétique des Tumeurs, Gustave Roussy, Villejuif, France
| | - Laëtitia Meulemans
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | | | | | | | | | - Linda Cleveland
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Susan Reid
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Eileen Southon
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Omar Soukarieh
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Aurélie Drouet
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Daniela Di Giacomo
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Myriam Vezain
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Violaine Bourdon
- Department of Genetics, Institut Paoli-Calmettes, Marseille, France
| | - Hélène Larbre
- Laboratoire d'Oncogénétique Moléculaire, Institut Godinot, Reims, France
| | - Danièle Muller
- Unité d'Oncogénétique, Centre Paul Strauss, Strasbourg, France
| | - Pascal Pujol
- Unité d'Oncogénétique, CHU Arnaud de Villeneuve, Montpellier, France
| | - Fátima Vaz
- Breast Cancer Risk Evaluation Clinic, Portuguese Institute of Oncology of Lisbon, Lisbon, Portugal
| | | | - Chrystelle Colas
- Department of Genetics, Institut Curie, Paris, France.,PSL Research University, Paris, France
| | | | - Angela R Solano
- Genotipificacion y Cancer Hereditario, Departmento de Analisis Clinicos, Centro de Educacion Medica e Investigaciones Clinicas (CEMIC), Ciudad Autonoma de Buenos Aires, Argentina
| | - Dominique Stoppa-Lyonnet
- Department of Genetics, Institut Curie, Paris, France.,INSERM U830, University Paris Descartes, Paris, France
| | - Claude Houdayer
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Department of Genetics, University Hospital, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Thierry Frebourg
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Department of Genetics, University Hospital, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Pascaline Gaildrat
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Alexandra Martins
- Inserm U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.
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18
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Horinouchi T, Yamamura T, Minamikawa S, Nagano C, Sakakibara N, Nakanishi K, Shima Y, Morisada N, Ishiko S, Aoto Y, Nagase H, Takeda H, Rossanti R, Ishimori S, Kaito H, Matsuo M, Iijima K, Nozu K. Pathogenic evaluation of synonymous COL4A5 variants in X-linked Alport syndrome using a minigene assay. Mol Genet Genomic Med 2020; 8:e1342. [PMID: 32543079 PMCID: PMC7434753 DOI: 10.1002/mgg3.1342] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/13/2020] [Accepted: 05/19/2020] [Indexed: 12/20/2022] Open
Abstract
Background X‐linked Alport syndrome (XLAS) is a progressive, hereditary glomerular nephritis of variable severity caused by pathogenic COL4A5 variants. Currently, genetic testing is widely used for diagnosing XLAS; however, determining the pathogenicity of variants detected by such analyses can be difficult. Intronic variants or synonymous variants may cause inherited diseases by inducing aberrant splicing. Transcript analysis is necessary to confirm the pathogenicity of such variants, but it is sometimes difficult to extract mRNA directly from patient specimens. Methods In this study, we conducted in vitro splicing analysis using a hybrid minigene assay and specimens from three XLAS patients with synonymous variants causing aberrant splicing, including previously reported pathogenic mutations in the same codon. The variants were c.876 A>T (p.Gly292=), c.2358 A>G (p.Pro786=), and c.3906 A>G (p.Gln1302=). Results The results from our hybrid minigene assay were sufficient to predict splicing abnormalities; c.876 A>T cause 17‐bp del and 35‐bp del, c.2358 A>G cause exon 29 skipping, c.3906 A>G cause exon 42 skipping, which are very likely to cause pathogenicity. Further, patients carrying c.2358 A>G exhibited a mild phenotype that may have been associated with the presence of both normal and abnormally spliced transcripts. Conclusion The minigene system was shown to be a sensitive assay and a useful tool for investigating the pathogenicity of synonymous variants.
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Affiliation(s)
- Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shogo Minamikawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Nishihara, Japan
| | - Yuko Shima
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroki Takeda
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shingo Ishimori
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroshi Kaito
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masafumi Matsuo
- Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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19
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Lian DS, Chen XY, Zeng HS, Wang YY. Capillary electrophoresis based on nucleic acid analysis for diagnosing inherited diseases. Clin Chem Lab Med 2020; 59:249-266. [PMID: 32374277 DOI: 10.1515/cclm-2020-0186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/04/2020] [Indexed: 11/15/2022]
Abstract
Most hereditary diseases are incurable, but their deterioration could be delayed or stopped if diagnosed timely. It is thus imperative to explore the state-of-the-art and high-efficient diagnostic techniques for precise analysis of the symptoms or early diagnosis of pre-symptoms. Diagnostics based on clinical presentations, hard to distinguish different phenotypes of the same genotype, or different genotypes displaying similar phenotypes, are incapable of pre-warning the disease status. Molecular diagnosis is ahead of harmful phenotype exhibition. However, conventional gold-standard molecular classifications, such as karyotype analysis, Southern blotting (SB) and sequencing, suffer drawbacks like low automation, low throughput, prolonged duration, being labor intensive and high cost. Also, deficiency in flexibility and diversity is observed to accommodate the development of precise and individualized diagnostics. The aforementioned pitfalls make them unadaptable to the increasing clinical demand for detecting and interpreting numerous samples in a rapid, accurate, high-throughput and cost-effective manner. Nevertheless, capillary electrophoresis based on genetic information analysis, with advantages of automation, high speed, high throughput, high efficiency, high resolution, digitization, versatility, miniature and cost-efficiency, coupled with flexible-designed PCR strategies in sample preparation (PCR-CE), exhibit an excellent power in deciphering cryptic molecular information of superficial symptoms of genetic diseases, and can analyze in parallel a large number of samples in a single PCR-CE, thereby providing an alternative, accurate, customized and timely diagnostic tool for routine screening of clinical samples on a large scale. Thus, the present study focuses on CE-based nucleic acid analysis used for inherited disease diagnosis. Also, the limitations and challenges of this PCR-CE for diagnosing hereditary diseases are discussed.
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Affiliation(s)
- Dong-Sheng Lian
- Guangzhou Women and Children's Medical Center of Guangzhou Medical University, NO. 9 at Jinsui Rd., Tianhe District, Guangzhou, Guangdong, P.R. China.,Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China
| | - Xiang-Yuan Chen
- Guangzhou Women and Children's Medical Center of Guangzhou Medical University, NO. 9 at Jinsui Rd., Tianhe District, Guangzhou, Guangdong, P.R. China
| | - Hua-Song Zeng
- Guangzhou Women and Children's Medical Center of Guangzhou Medical University, NO. 9 at Jinsui Rd., Tianhe District, Guangzhou, Guangdong, P.R. China
| | - Yan-Yi Wang
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China
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20
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Gailite L, Valenzuela-Palomo A, Sanoguera-Miralles L, Rots D, Kreile M, Velasco EA. UGT1A1 Variants c.864+5G>T and c.996+2_996+5del of a Crigler-Najjar Patient Induce Aberrant Splicing in Minigene Assays. Front Genet 2020; 11:169. [PMID: 32211025 PMCID: PMC7067894 DOI: 10.3389/fgene.2020.00169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 02/12/2020] [Indexed: 11/13/2022] Open
Abstract
A large fraction of DNA variants impairs pre-mRNA splicing in human hereditary disorders. Crigler-Najjar syndrome (CNS) is characterized by a severe unconjugated hyperbilirubinemia caused by variants in the UGT1A1 gene. We previously reported one CNS-type II patient with two splice-site variants in trans (c.864+5G>T and c.996+2_996+5del). According to MaxEntScan, both disrupt their corresponding donor sites (c.864+5G>T: 6.99 → 2.28; c.996+2_996+5del: 5.96 → -11.02), so they were selected for subsequent functional tests. Given the unavailability of patient RNA, we constructed an UGT1A1 splicing-reporter minigene with exons 1-4 to characterize the underlying splicing anomaly. The variant c.996+2_996+5del generated two aberrant transcripts, Δ(E2) (exon 2 skipping/64%) and ▼(E2q135) (intron retention of 135-nt/36%), which lead to the loss of 18 conserved amino-acids and the gain of 45 new ones of a critical functional domain, respectively. The c.864+5G>T variant mainly produced the aberrant transcript Δ(E1q141) (141-nt deletion/70.4%) and the full-length isoform (29.6%). Δ(E1q141) would provoke the loss of 47 amino-acids of the N-terminal domain that encodes for substrate specificity. Thus, the three anomalous transcripts are likely to inactivate UGT1A1. Moreover, this patient is also homozygous for the promoter variant A(TA)7TAA that decreases UGT1A1 expression by 70%, so the full-length transcript produced by c.864+5G>T would be even more reduced (<9%), thus supporting the diagnosis of CNS-type II. Therefore, minigenes represent valuable tools for the functional and clinical classifications of genetic variants.
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Affiliation(s)
- Linda Gailite
- Scientific Laboratory of Molecular Genetics, Riga Stradins University, Riga, Latvia
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Dmitrijs Rots
- Scientific Laboratory of Molecular Genetics, Riga Stradins University, Riga, Latvia
| | - Madara Kreile
- Scientific Laboratory of Molecular Genetics, Riga Stradins University, Riga, Latvia
| | - Eladio A Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
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21
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Variants of uncertain significance in the era of high-throughput genome sequencing: a lesson from breast and ovary cancers. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2020; 39:46. [PMID: 32127026 PMCID: PMC7055088 DOI: 10.1186/s13046-020-01554-6] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023]
Abstract
The promising expectations about personalized medicine have opened the path to routine large-scale sequencing and increased the importance of genetic counseling for hereditary cancers, among which hereditary breast and ovary cancers (HBOC) have a major impact. High-throughput sequencing, or Next-Generation Sequencing (NGS), has improved cancer patient management, ameliorating diagnosis and treatment decisions. In addition to its undeniable clinical utility, NGS is also unveiling a large number of variants that we are still not able to clearly define and classify, the variants of uncertain significance (VUS), which account for about 40% of total variants. At present, VUS use in the clinical context is challenging. Medical reports may omit this kind of data and, even when included, they limit the clinical utility of genetic information. This has prompted the scientific community to seek easily applicable tests to accurately classify VUS and increase the amount of usable information from NGS data. In this review, we will focus on NGS and classification systems for VUS investigation, with particular attention on HBOC-related genes and in vitro functional tests developed for ameliorating and accelerating variant classification in cancer.
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22
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Landrith T, Li B, Cass AA, Conner BR, LaDuca H, McKenna DB, Maxwell KN, Domchek S, Morman NA, Heinlen C, Wham D, Koptiuch C, Vagher J, Rivera R, Bunnell A, Patel G, Geurts JL, Depas MM, Gaonkar S, Pirzadeh-Miller S, Krukenberg R, Seidel M, Pilarski R, Farmer M, Pyrtel K, Milliron K, Lee J, Hoodfar E, Nathan D, Ganzak AC, Wu S, Vuong H, Xu D, Arulmoli A, Parra M, Hoang L, Molparia B, Fennessy M, Fox S, Charpentier S, Burdette J, Pesaran T, Profato J, Smith B, Haynes G, Dalton E, Crandall JRR, Baxter R, Lu HM, Tippin-Davis B, Elliott A, Chao E, Karam R. Splicing profile by capture RNA-seq identifies pathogenic germline variants in tumor suppressor genes. NPJ Precis Oncol 2020; 4:4. [PMID: 32133419 PMCID: PMC7039900 DOI: 10.1038/s41698-020-0109-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/30/2020] [Indexed: 12/12/2022] Open
Abstract
Germline variants in tumor suppressor genes (TSGs) can result in RNA mis-splicing and predisposition to cancer. However, identification of variants that impact splicing remains a challenge, contributing to a substantial proportion of patients with suspected hereditary cancer syndromes remaining without a molecular diagnosis. To address this, we used capture RNA-sequencing (RNA-seq) to generate a splicing profile of 18 TSGs (APC, ATM, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, MLH1, MSH2, MSH6, MUTYH, NF1, PALB2, PMS2, PTEN, RAD51C, RAD51D, and TP53) in 345 whole-blood samples from healthy donors. We subsequently demonstrated that this approach can detect mis-splicing by comparing splicing profiles from the control dataset to profiles generated from whole blood of individuals previously identified with pathogenic germline splicing variants in these genes. To assess the utility of our TSG splicing profile to prospectively identify pathogenic splicing variants, we performed concurrent capture DNA and RNA-seq in a cohort of 1000 patients with suspected hereditary cancer syndromes. This approach improved the diagnostic yield in this cohort, resulting in a 9.1% relative increase in the detection of pathogenic variants, demonstrating the utility of performing simultaneous DNA and RNA genetic testing in a clinical context.
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Affiliation(s)
| | - Bing Li
- Ambry Genetics, Aliso Viejo, CA USA
| | | | | | | | | | | | | | | | | | - Deborah Wham
- Aurora St. Luke’s Medical Center, Milwaukee, WI USA
| | | | | | - Ragene Rivera
- Texas Oncology, El Paso, Fort Worth, and Austin, TX USA
| | - Ann Bunnell
- Texas Oncology, El Paso, Fort Worth, and Austin, TX USA
| | - Gayle Patel
- Texas Oncology, El Paso, Fort Worth, and Austin, TX USA
| | | | | | | | | | | | | | - Robert Pilarski
- Ohio State University Wexner Medical Center and James Comprehensive Cancer Center, Columbus, OH USA
| | - Meagan Farmer
- University of Alabama at Birmingham, Birmingham, AL USA
| | | | | | - John Lee
- Cedars-Sinai Medical Center, Los Angeles, CA USA
| | | | | | | | - Sitao Wu
- Ambry Genetics, Aliso Viejo, CA USA
| | | | - Dong Xu
- Ambry Genetics, Aliso Viejo, CA USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Elizabeth Chao
- Ambry Genetics, Aliso Viejo, CA USA
- University of California at Irvine, Irvine, CA USA
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23
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Fraile-Bethencourt E, Valenzuela-Palomo A, Díez-Gómez B, Caloca MJ, Gómez-Barrero S, Velasco EA. Minigene Splicing Assays Identify 12 Spliceogenic Variants of BRCA2 Exons 14 and 15. Front Genet 2019; 10:503. [PMID: 31191615 PMCID: PMC6546720 DOI: 10.3389/fgene.2019.00503] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 05/07/2019] [Indexed: 12/11/2022] Open
Abstract
A relevant fraction of BRCA2 variants is associated with splicing alterations and with an increased risk of hereditary breast and ovarian cancer (HBOC). In this work, we have carried out a thorough study of variants from BRCA2 exons 14 and 15 reported at mutation databases. A total of 294 variants from exons 14 and 15 and flanking intronic sequences were analyzed with the online splicing tools NNSplice and Human Splicing Finder. Fifty-three out of these 294 variants were selected as candidate splicing variants. All variants but one, were introduced into the minigene MGBR2_ex14-20 (with exons 14–20) by site-directed mutagenesis and assayed in MCF-7 cells. Twelve of the remaining 52 variants (23.1%) impaired splicing at different degrees, yielding from 5 to 100% of aberrant transcripts. Nine variants affected the natural acceptor or donor sites of both exons and three affected putative enhancers or silencers. Fluorescent capillary electrophoresis revealed at least 10 different anomalous transcripts: (E14q5), Δ (E14p10), Δ(E14p246), Δ(E14q256), Δ(E14), Δ(E15p12), Δ(E15p13), Δ(E15p83), Δ(E15) and a 942-nt fragment of unknown structure. All transcripts, except for Δ(E14q256) and Δ(E15p12), are expected to truncate the BRCA2 protein. Nine variants induced severe splicing aberrations with more than 90% of abnormal transcripts. Thus, according to the guidelines of the American College of Medical Genetics and Genomics, eight variants should be classified as pathogenic (c.7008-2A > T, c.7008-1G > A, c.7435+1G > C, c.7436-2A > T, c.7436-2A > G, c.7617+1G > A, c.7617+1G > T, and c.7617+2T > G), one as likely pathogenic (c.7008-3C > G) and three remain as variants of uncertain clinical significance or VUS (c.7177A > G, c.7447A > G and c.7501C > T). In conclusion, functional assays by minigenes constitute a valuable strategy to primarily check the splicing impact of DNA variants and their clinical interpretation. While bioinformatics predictions of splice site variants were accurate, those of enhancer or silencer variants were poor (only 3/23 spliceogenic variants) which showed weak impacts on splicing (∼5–16% of aberrant isoforms). So, the Exonic Splicing Enhancer and Silencer (ESE and ESS, respectively) prediction algorithms require further improvement.
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Affiliation(s)
- Eugenia Fraile-Bethencourt
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Beatriz Díez-Gómez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - María José Caloca
- Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | | | - Eladio A Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
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