1
|
O'Neill MJ, Yang T, Laudeman J, Calandranis ME, Harvey ML, Solus JF, Roden DM, Glazer AM. ParSE-seq: a calibrated multiplexed assay to facilitate the clinical classification of putative splice-altering variants. Nat Commun 2024; 15:8320. [PMID: 39333091 PMCID: PMC11437130 DOI: 10.1038/s41467-024-52474-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 09/10/2024] [Indexed: 09/29/2024] Open
Abstract
Interpreting the clinical significance of putative splice-altering variants outside canonical splice sites remains difficult without time-intensive experimental studies. To address this, we introduce Parallel Splice Effect Sequencing (ParSE-seq), a multiplexed assay to quantify variant effects on RNA splicing. We first apply this technique to study hundreds of variants in the arrhythmia-associated gene SCN5A. Variants are studied in 'minigene' plasmids with molecular barcodes to allow pooled variant effect quantification. We perform experiments in two cell types, including disease-relevant induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). The assay strongly separates known control variants from ClinVar, enabling quantitative calibration of the ParSE-seq assay. Using these evidence strengths and experimental data, we reclassify 29 of 34 variants with conflicting interpretations and 11 of 42 variants of uncertain significance. In addition to intronic variants, we show that many synonymous and missense variants disrupted RNA splicing. Two splice-altering variants in the assay also disrupt splicing and sodium current when introduced into iPSC-CMs by CRISPR-Cas9 editing. ParSE-seq provides high-throughput experimental data for RNA-splicing to support precision medicine efforts and can be readily adopted to study other loss-of-function genotype-phenotype relationships.
Collapse
Affiliation(s)
| | - Tao Yang
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Julie Laudeman
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Maria E Calandranis
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - M Lorena Harvey
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Joseph F Solus
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| |
Collapse
|
2
|
Gao M, Chen L, Yang J, Dong S, Cao Q, Cui Z, Dong Y, Liu H, Shen Y, Yang H, Hao Z, Zhang L, Li W, Tie JK, Shen G. Multimodal mechanisms of pathogenic variants in the signal peptide of FIX leading to hemophilia B. Blood Adv 2024; 8:3893-3905. [PMID: 38820490 PMCID: PMC11321298 DOI: 10.1182/bloodadvances.2023012432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/27/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024] Open
Abstract
ABSTRACT Signal peptide (SP) is essential for protein secretion, and pathogenic variants in the SP of factor IX (FIX) have been identified in hemophilia B (HB). However, the underlying mechanism for the genotype-phenotype correlation of these variants has not been well studied. Here, we systematically examined the effects of 13 pathogenic point variants in the SP of FIX using different approaches. Our results showed that these point variants lead to HB by missense variants and/or aberrant premessenger RNA (pre-mRNA) splicing. The missense variants in a hydrophobic core (h-region) mainly affected the cotranslational translocation function of the SP, and those in C-terminal containing cleavage site (c-region) caused FIX deficiency mainly by disturbing the cotranslational translocation and/or cleavage of the SP. Almost absolute aberrant pre-mRNA splicing was only observed in variants of c.82T>G, but a slight change of splicing patterns was found in variants of c.53G>T, c.77C>A, c.82T>C, and c.83G>A, indicating that these variants might have different degrees of impact on pre-mRNA splicing. Although two 6-nt deletion aberrant pre-mRNA splicing products caused FIX deficiency by disturbing the SP cleavage, they could produce some functional mature FIX, and vitamin K could increase the secretion of functional FIX. Taken together, our data indicated that pathogenic variants in the SP of FIX caused HB through diverse molecular mechanisms or even a mixture of several mechanisms, and vitamin K availability could be partially attributed to varying bleeding tendencies in patients carrying the same variant in the SP.
Collapse
Affiliation(s)
- Meng Gao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
| | - Long Chen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
| | - Jinlong Yang
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
| | - Shixia Dong
- Department of Cell Biology, Harbin Medical University, Harbin, People’s Republic of China
| | - Qing Cao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Zihan Cui
- Department of Cell Biology, Harbin Medical University, Harbin, People’s Republic of China
| | - Yanyan Dong
- Department of Cell Biology, Harbin Medical University, Harbin, People’s Republic of China
| | - Hongli Liu
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
- Department of Cell Biology, Harbin Medical University, Harbin, People’s Republic of China
| | - Yan Shen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
| | - Haiping Yang
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
- First Affiliated Hospital of Henan University of Science and Technology, Luoyang, People’s Republic of China
| | - Zhenyu Hao
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, People’s Republic of China
| | - Lei Zhang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
- Tianjin Key Laboratory of Gene Therapy for Blood Diseases, CAMS Key Laboratory of Gene Therapy for Blood Diseases, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Jian-Ke Tie
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Guomin Shen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, People’s Republic of China
- Department of Cell Biology, Harbin Medical University, Harbin, People’s Republic of China
| |
Collapse
|
3
|
Nicolas-Martinez EC, Robinson O, Pflueger C, Gardner A, Corbett MA, Ritchie T, Kroes T, van Eyk CL, Scheffer IE, Hildebrand MS, Barnier JV, Rousseau V, Genevieve D, Haushalter V, Piton A, Denommé-Pichon AS, Bruel AL, Nambot S, Isidor B, Grigg J, Gonzalez T, Ghedia S, Marchant RG, Bournazos A, Wong WK, Webster RI, Evesson FJ, Jones KJ, Cooper ST, Lister R, Gecz J, Jolly LA. RNA variant assessment using transactivation and transdifferentiation. Am J Hum Genet 2024; 111:1673-1699. [PMID: 39084224 PMCID: PMC11339655 DOI: 10.1016/j.ajhg.2024.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/27/2024] [Accepted: 06/28/2024] [Indexed: 08/02/2024] Open
Abstract
Understanding the impact of splicing and nonsense variants on RNA is crucial for the resolution of variant classification as well as their suitability for precision medicine interventions. This is primarily enabled through RNA studies involving transcriptomics followed by targeted assays using RNA isolated from clinically accessible tissues (CATs) such as blood or skin of affected individuals. Insufficient disease gene expression in CATs does however pose a major barrier to RNA based investigations, which we show is relevant to 1,436 Mendelian disease genes. We term these "silent" Mendelian genes (SMGs), the largest portion (36%) of which are associated with neurological disorders. We developed two approaches to induce SMG expression in human dermal fibroblasts (HDFs) to overcome this limitation, including CRISPR-activation-based gene transactivation and fibroblast-to-neuron transdifferentiation. Initial transactivation screens involving 40 SMGs stimulated our development of a highly multiplexed transactivation system culminating in the 6- to 90,000-fold induction of expression of 20/20 (100%) SMGs tested in HDFs. Transdifferentiation of HDFs directly to neurons led to expression of 193/516 (37.4%) of SMGs implicated in neurological disease. The magnitude and isoform diversity of SMG expression following either transactivation or transdifferentiation was comparable to clinically relevant tissues. We apply transdifferentiation and/or gene transactivation combined with short- and long-read RNA sequencing to investigate the impact that variants in USH2A, SCN1A, DMD, and PAK3 have on RNA using HDFs derived from affected individuals. Transactivation and transdifferentiation represent rapid, scalable functional genomic solutions to investigate variants impacting SMGs in the patient cell and genomic context.
Collapse
Affiliation(s)
- Emmylou C Nicolas-Martinez
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia
| | - Olivia Robinson
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia
| | - Christian Pflueger
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA 6009, Australia; The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Alison Gardner
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia
| | - Mark A Corbett
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia; The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Tarin Ritchie
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia
| | - Thessa Kroes
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia
| | - Clare L van Eyk
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia; The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg, VIC 3084, Australia; Murdoch Children's Research Institute, Parkville, VIC 3052, Australia; Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia; Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, VIC 3052, Australia
| | - Michael S Hildebrand
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg, VIC 3084, Australia; Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, VIC 3052, Australia; The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Jean-Vianney Barnier
- Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS, Université Paris-Saclay, Saclay, France
| | - Véronique Rousseau
- Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS, Université Paris-Saclay, Saclay, France
| | - David Genevieve
- Montpellier University, Inserm U1183, Reference Center for Rare Diseases Developmental Anomaly and Malformative Syndromes, Genetics Department, Montpellier Hospital, Montpellier, France
| | - Virginie Haushalter
- Genetic Diagnosis Laboratory, Strasbourg University Hospital, Strasbourg, France
| | - Amélie Piton
- Genetic Diagnosis Laboratory, Strasbourg University Hospital, Strasbourg, France
| | - Anne-Sophie Denommé-Pichon
- CRMRs "Anomalies du Développement et syndromes malformatifs" et "Déficiences Intellectuelles de causes rares", Centre de Génétique, CHU Dijon, Dijon, France; INSERM UMR1231, GAD "Génétique des Anomalies du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France
| | - Ange-Line Bruel
- CRMRs "Anomalies du Développement et syndromes malformatifs" et "Déficiences Intellectuelles de causes rares", Centre de Génétique, CHU Dijon, Dijon, France; INSERM UMR1231, GAD "Génétique des Anomalies du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France
| | - Sophie Nambot
- CRMRs "Anomalies du Développement et syndromes malformatifs" et "Déficiences Intellectuelles de causes rares", Centre de Génétique, CHU Dijon, Dijon, France; INSERM UMR1231, GAD "Génétique des Anomalies du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France
| | - Bertrand Isidor
- CRMRs "Anomalies du Développement et syndromes malformatifs" et "Déficiences Intellectuelles de causes rares", Centre de Génétique, CHU Dijon, Dijon, France; INSERM UMR1231, GAD "Génétique des Anomalies du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France
| | - John Grigg
- Speciality of Ophthalmology, Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia
| | - Tina Gonzalez
- Department of Clinical Genetics, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - Sondhya Ghedia
- Department of Clinical Genetics, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - Rhett G Marchant
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia
| | - Adam Bournazos
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Children's Medical Research Institute, Westmead, NSW 2145, Australia
| | - Wui-Kwan Wong
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Children's Medical Research Institute, Westmead, NSW 2145, Australia; Department of Paediatric Neurology, Children's Hospital at Westmead, Sydney, NSW 2000, Australia
| | - Richard I Webster
- Department of Paediatric Neurology, Children's Hospital at Westmead, Sydney, NSW 2000, Australia
| | - Frances J Evesson
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; Children's Medical Research Institute, Westmead, NSW 2145, Australia
| | - Kristi J Jones
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Children's Medical Research Institute, Westmead, NSW 2145, Australia; Department of Clinical Genetics, Children's Hospital at Westmead, Sydney, NSW 2000, Australia
| | - Sandra T Cooper
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2000, Australia; Children's Medical Research Institute, Westmead, NSW 2145, Australia
| | - Ryan Lister
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Jozef Gecz
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia; South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia.
| | - Lachlan A Jolly
- The Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia.
| |
Collapse
|
4
|
Holm LL, Doktor TK, Flugt KK, Petersen US, Petersen R, Andresen B. All exons are not created equal-exon vulnerability determines the effect of exonic mutations on splicing. Nucleic Acids Res 2024; 52:4588-4603. [PMID: 38324470 PMCID: PMC11077056 DOI: 10.1093/nar/gkae077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 01/05/2024] [Accepted: 01/26/2024] [Indexed: 02/09/2024] Open
Abstract
It is now widely accepted that aberrant splicing of constitutive exons is often caused by mutations affecting cis-acting splicing regulatory elements (SREs), but there is a misconception that all exons have an equal dependency on SREs and thus a similar vulnerability to aberrant splicing. We demonstrate that some exons are more likely to be affected by exonic splicing mutations (ESMs) due to an inherent vulnerability, which is context dependent and influenced by the strength of exon definition. We have developed VulExMap, a tool which is based on empirical data that can designate whether a constitutive exon is vulnerable. Using VulExMap, we find that only 25% of all exons can be categorized as vulnerable, whereas two-thirds of 359 previously reported ESMs in 75 disease genes are located in vulnerable exons. Because VulExMap analysis is based on empirical data on splicing of exons in their endogenous context, it includes all features important in determining the vulnerability. We believe that VulExMap will be an important tool when assessing the effect of exonic mutations by pinpointing whether they are located in exons vulnerable to ESMs.
Collapse
Affiliation(s)
- Lise L Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Katharina K Flugt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Rikke Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Guo Q, Ji S, Takeuchi K, Urasaki W, Suzuki A, Iwasaki Y, Saito H, Xu Z, Arai M, Nakamura S, Momozawa Y, Chiba N, Miki Y, Matsuura M, Sunada S. Functional evaluation of BRCA1/2 variants of unknown significance with homologous recombination assay and integrative in silico prediction model. J Hum Genet 2023; 68:849-857. [PMID: 37731132 DOI: 10.1038/s10038-023-01194-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 08/01/2023] [Accepted: 08/29/2023] [Indexed: 09/22/2023]
Abstract
Numerous variants of unknown significance (VUSs) exist in hereditary breast and ovarian cancers. Although multiple methods have been developed to assess the significance of BRCA1/2 variants, functional discrepancies among these approaches remain. Therefore, a comprehensive functional evaluation system for these variants should be established. We performed conventional homologous recombination (HR) assays for 50 BRCA1 and 108 BRCA2 VUSs and complementarily predicted VUSs using a statistical logistic regression prediction model that integrated six in silico functional prediction tools. BRCA1/2 VUSs were classified according to the results of the integrative in vitro and in silico analyses. Using HR assays, we identified 10 BRCA1 and 4 BRCA2 VUSs as low-functional pathogenic variants. For in silico prediction, the statistical prediction model showed high accuracy for both BRCA1 and BRCA2 compared with each in silico prediction tool individually and predicted nine BRCA1 and seven BRCA2 variants to be pathogenic. Integrative functional evaluation in this study and the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines strongly suggested that seven BRCA1 variants (p.Glu272Gly, p.Lys1095Glu, p.Val1653Leu, p.Thr1681Pro, p.Phe1761Val, p.Thr1773Ile, and p.Gly1803Ser) and four BRCA2 variants (p.Trp31Gly, p.Ser2616Phe, p.Tyr2660Cys, and p.Leu2792Arg) were pathogenic. This study demonstrates that integrative evaluation using conventional HR assays and optimized in silico prediction comprehensively classified the significance of BRCA VUSs for future clinical applications.
Collapse
Affiliation(s)
- Qianqian Guo
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Shuting Ji
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kazuma Takeuchi
- Graduate School of Public Health, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan
| | - Wataru Urasaki
- Department of Information Sciences, Tokyo University of Science, 2641 Yamazaki, Noda City, Chiba, 278-8510, Japan
| | - Asuka Suzuki
- Graduate School of Public Health, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan
| | - Yusuke Iwasaki
- Laboratory for Genotyping Development, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama City, Kanagawa, 230-0045, Japan
| | - Hiroko Saito
- Department of Genetic Diagnosis, The Cancer Institute, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan
| | - Zeyu Xu
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Masami Arai
- Department of Clinical Genetics, Juntendo University, Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Seigo Nakamura
- Division of Breast Surgical Oncology, Department of Surgery, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Yukihide Momozawa
- Laboratory for Genotyping Development, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama City, Kanagawa, 230-0045, Japan
| | - Natsuko Chiba
- Department of Cancer Biology; Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai, 980-8575, Japan
| | - Yoshio Miki
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
- Department of Genetic Diagnosis, The Cancer Institute, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
| | - Masaaki Matsuura
- Graduate School of Public Health, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan.
| | - Shigeaki Sunada
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
- Juntendo Advanced Research Institute for Health Science, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
- Department of Oncology, School of Medicine, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| |
Collapse
|
7
|
Cao Q, Hao Z, Li C, Chen X, Gao M, Jiang N, Liu H, Shen Y, Yang H, Zhang S, Yang A, Li W, Tie JK, Shen G. Molecular basis of inherited protein C deficiency results from genetic variations in the signal peptide and propeptide regions. J Thromb Haemost 2023; 21:3124-3137. [PMID: 37393002 PMCID: PMC10592384 DOI: 10.1016/j.jtha.2023.06.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 07/03/2023]
Abstract
BACKGROUND Inherited protein C deficiency (PCD) caused by mutations in protein C (PC) gene (PROC) increases the risk of thrombosis. Missense mutations in PC's signal peptide and propeptide have been reported in patients with PCD, but their pathogenic mechanisms, except mutations in R42 residue, remain unclear. OBJECTIVES To investigate the pathogenic mechanisms of inherited PCD caused by 11 naturally occurring missense mutations in PC's signal peptide and propeptide. METHODS Using cell-based assays, we evaluated the impact of these mutations on various aspects such as activities and antigens of secreted PC, intracellular PC expression, subcellular localization of a reporter protein, and propeptide cleavage. Additionally, we investigated their effect on pre-messenger RNA (pre-mRNA) splicing using a minigene splicing assay. RESULTS Our data revealed that certain missense mutations (L9P, R32C, R40C, R38W, and R42C) disrupted PC secretion by impeding cotranslational translocation to the endoplasmic reticulum or causing endoplasmic reticulum retention. Additionally, some mutations (R38W and R42L/H/S) resulted in abnormal propeptide cleavage. However, a few missense mutations (Q3P, W14G, and V26M) did not account for PCD. Using a minigene splicing assay, we observed that several variations (c.8A>C, c.76G>A, c.94C>T, and c.112C>T) increased the incidence of aberrant pre-mRNA splicing. CONCLUSION Our findings suggest that variations in PC's signal peptide and propeptide have varying effects on the biological process of PC, including posttranscriptional pre-mRNA splicing, translation, and posttranslational processing. Additionally, a variation could affect the biological process of PC at multiple levels. Except for W14G, our results provide a clear understanding of the relationship between PROC genotype and inherited PCD.
Collapse
Affiliation(s)
- Qing Cao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Zhenyu Hao
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Cheng Li
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China
| | - Xuejie Chen
- Department of Biology, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Meng Gao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China
| | - Nan Jiang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Hongli Liu
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China; Department of Cell Biology, Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Yan Shen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China
| | - Haiping Yang
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China; First Affiliated Hospital, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China
| | - Shujuan Zhang
- Department of Cell Biology, Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Aiying Yang
- Department of Cell Biology, Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA.
| | - Jian-Ke Tie
- Department of Biology, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
| | - Guomin Shen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang, Henan, People's Republic of China; Department of Cell Biology, Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
| |
Collapse
|
8
|
O'Neill MJ, Yang T, Laudeman J, Calandranis M, Solus J, Roden DM, Glazer AM. ParSE-seq: A Calibrated Multiplexed Assay to Facilitate the Clinical Classification of Putative Splice-altering Variants. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.04.23295019. [PMID: 37732247 PMCID: PMC10508793 DOI: 10.1101/2023.09.04.23295019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Background Interpreting the clinical significance of putative splice-altering variants outside 2-base pair canonical splice sites remains difficult without functional studies. Methods We developed Parallel Splice Effect Sequencing (ParSE-seq), a multiplexed minigene-based assay, to test variant effects on RNA splicing quantified by high-throughput sequencing. We studied variants in SCN5A, an arrhythmia-associated gene which encodes the major cardiac voltage-gated sodium channel. We used the computational tool SpliceAI to prioritize exonic and intronic candidate splice variants, and ClinVar to select benign and pathogenic control variants. We generated a pool of 284 barcoded minigene plasmids, transfected them into Human Embryonic Kidney (HEK293) cells and induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), sequenced the resulting pools of splicing products, and calibrated the assay to the American College of Medical Genetics and Genomics scheme. Variants were interpreted using the calibrated functional data, and experimental data were compared to SpliceAI predictions. We further studied some splice-altering missense variants by cDNA-based automated patch clamping (APC) in HEK cells and assessed splicing and sodium channel function in CRISPR-edited iPSC-CMs. Results ParSE-seq revealed the splicing effect of 224 SCN5A variants in iPSC-CMs and 244 variants in HEK293 cells. The scores between the cell types were highly correlated (R2=0.84). In iPSCs, the assay had concordant scores for 21/22 benign/likely benign and 24/25 pathogenic/likely pathogenic control variants from ClinVar. 43/112 exonic variants and 35/70 intronic variants with determinate scores disrupted splicing. 11 of 42 variants of uncertain significance were reclassified, and 29 of 34 variants with conflicting interpretations were reclassified using the functional data. SpliceAI computational predictions correlated well with experimental data (AUC = 0.96). We identified 20 unique SCN5A missense variants that disrupted splicing, and 2 clinically observed splice-altering missense variants of uncertain significance had normal function when tested with the cDNA-based APC assay. A splice-altering intronic variant detected by ParSE-seq, c.1891-5C>G, also disrupted splicing and sodium current when introduced into iPSC-CMs at the endogenous locus by CRISPR editing. Conclusions ParSE-seq is a calibrated, multiplexed, high-throughput assay to facilitate the classification of candidate splice-altering variants.
Collapse
Affiliation(s)
| | - Tao Yang
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Julie Laudeman
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Maria Calandranis
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Joseph Solus
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| |
Collapse
|
9
|
Duan Y, Xiong J, Lai Z, Zhong Y, Tian C, Du Z, Luo Z, Yu J, Li W, Xu W, Wang Y, Ding T, Zhong X, Pan M, Qiu Y, Lan X, Chen T, Li P, Liu K, Gao M, Hu Y, Liu Z. Analysis of the genetic contribution to thoracic aortic aneurysm or dissection in a prospective cohort of patients with familial and sporadic cases in East China. Orphanet J Rare Dis 2023; 18:251. [PMID: 37644562 PMCID: PMC10466872 DOI: 10.1186/s13023-023-02855-7] [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: 04/15/2022] [Accepted: 07/26/2023] [Indexed: 08/31/2023] Open
Abstract
BACKGROUND Thoracic aortic aneurysm or dissections (TAADs) represent a group of life-threatening diseases. Genetic aetiology can affect the age of onset, clinical phenotype, and timing of intervention. We conducted a prospective trial to determine the prevalence of pathogenic variants in TAAD patients and to elucidate the traits related to harbouring the pathogenic variants. One hundred and one unrelated TAAD patients underwent genetic sequencing and analysis for 23 TAAD-associated genes using a targeted PCR and next-generation sequencing-based panel. RESULTS A total of 47 variants were identified in 52 TAAD patients (51.5%), including 5 pathogenic, 1 likely pathogenic and 41 variants of uncertain significance. The pathogenic or likely pathogenic (P/LP) variants in 4 disease-causing genes were carried by 1 patient with familial and 5 patients with sporadic TAAD (5.9%). In addition to harbouring one variant causing familial TAAD, the FBN1 gene harboured half of the P/LP variants causing sporadic TAAD. Individuals with an age of onset less than 50 years or normotension had a significantly increased genetic risk. CONCLUSIONS TAAD patients with a younger age at diagnosis or normotension were more likely to carry a P/LP variant; thus, routine genetic testing will be beneficial to a better prognosis through genetically personalized care prior to acute rupture or dissection.
Collapse
Affiliation(s)
- Yanyu Duan
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Ganzhou Cardiovascular Rare Disease Diagnosis and Treatment Technology Innovation Center, Gannan Medical University, Ganzhou, China
| | - Jianxian Xiong
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Zhenghong Lai
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Yiming Zhong
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Ganzhou Cardiovascular Rare Disease Diagnosis and Treatment Technology Innovation Center, Gannan Medical University, Ganzhou, China
| | - Chengnan Tian
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Zhiming Du
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Zhifang Luo
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Junjian Yu
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Wentong Li
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Weichang Xu
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Yabing Wang
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
| | - Ting Ding
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Xuehong Zhong
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Mengmeng Pan
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
| | - Yu Qiu
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Ganzhou Cardiovascular Rare Disease Diagnosis and Treatment Technology Innovation Center, Gannan Medical University, Ganzhou, China
| | - Xuemei Lan
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Ganzhou Cardiovascular Rare Disease Diagnosis and Treatment Technology Innovation Center, Gannan Medical University, Ganzhou, China
| | - Taihua Chen
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Peijun Li
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Kang Liu
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Meng Gao
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Yanqiu Hu
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Ziyou Liu
- Engineering Research Center of Intelligent Acoustic Signals of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, 341000, China.
- Heart Medical Centre, First Affiliated Hospital of Gannan Medical University, Ganzhou, China.
- Ganzhou Cardiovascular Rare Disease Diagnosis and Treatment Technology Innovation Center, Gannan Medical University, Ganzhou, China.
| |
Collapse
|
10
|
Debbabi I, Vacher S, Neuzillet C, Cros J, Revillon F, Petitalot A, Turpin A, Antonio S, Girard E, Dupain C, Kamal M, Hammel P, Bièche I, Masliah-Planchon J, Caputo SM. Identification of a large intra-exonic deletion in BRCA2 exon 18 in a pancreatic ductal adenocarcinoma. Ther Adv Med Oncol 2023; 15:17588359221146132. [PMID: 36700131 PMCID: PMC9869184 DOI: 10.1177/17588359221146132] [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: 07/01/2022] [Accepted: 11/30/2022] [Indexed: 01/19/2023] Open
Abstract
By 2030, pancreatic cancer will become the second leading cause of cancer-related deaths in the United States and in Europe. The management of patients with advanced pancreatic cancer relies on chemotherapy and poly (ADP-ribose) polymerase inhibitors for patients who carry BRCA1/2 inactivating alterations. Some variants, such as large insertion/deletions (Indels), inactivating BRCA1/2 and therefore of clinical relevance can be hard to detect by next-generation sequencing techniques. Here we report a 47-year-old patient presenting with pancreatic cancer whose tumour harbours a large somatic intra-exonic deletion of BRCA2 of 141 bp. This BRCA2 deletion, located in the C-terminal domain, can be considered as pathogenic and consequently affect tumorigenesis because it is involved in the interaction between the DSS1 protein and DNA. Thanks to the optimized bioinformatics algorithm, this intermediate size deletion in BRCA2 was identified, enabling personalized patient management via the inclusion of the patients in a clinical trial.
Collapse
Affiliation(s)
- Inès Debbabi
- Department of Genetics, Institut Curie, Paris, France
| | - Sophie Vacher
- Department of Genetics, Institut Curie, Paris, France,PSL Research University, Paris, France
| | - Cindy Neuzillet
- Department of Medical Oncology, Curie Institute, Versailles Saint Quentin University, Paris, France
| | - Jérome Cros
- INSERM UMR1149, Beaujon University Hospital, Paris University, Paris, France,Department of Pathology, Beaujon University, Hospital Paris 7 Diderot University, Paris, France
| | | | - Ambre Petitalot
- Department of Genetics, Institut Curie, Paris, France,PSL Research University, Paris, France
| | - Anthony Turpin
- ULR9020-UMR-S 1277 Canther-Cancer Heterogeneity, Plasticity and Resistance to Therapies, University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, France,Medical Oncology Department, CHU Lille, University of Lille, France
| | - Samantha Antonio
- Department of Genetics, Institut Curie, Paris, France,PSL Research University, Paris, France
| | | | - Célia Dupain
- Department of Drug Development and Innovation, Institut Curie, PSL Research University, Paris
| | - Maud Kamal
- Department of Drug Development and Innovation, Institut Curie, PSL Research University, Paris
| | - Pascal Hammel
- Department of Digestive and Medical Oncology, Paris-Saclay University, Hôpital Paul Brousse, Villejuif, France
| | - Ivan Bièche
- Department of Genetics, Institut Curie, Paris, France,Université de Paris, Paris, France
| | | | | |
Collapse
|
11
|
O’Neill MJ, Wada Y, Hall LD, Mitchell DW, Glazer AM, Roden DM. Functional Assays Reclassify Suspected Splice-Altering Variants of Uncertain Significance in Mendelian Channelopathies. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2022; 15:e003782. [PMID: 36197721 PMCID: PMC9772980 DOI: 10.1161/circgen.122.003782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/12/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND Rare protein-altering variants in SCN5A, KCNQ1, and KCNH2 are major causes of Brugada syndrome and the congenital long QT syndrome. While splice-altering variants lying outside 2-bp canonical splice sites can cause these diseases, their role remains poorly described. We implemented 2 functional assays to assess 12 recently reported putative splice-altering variants of uncertain significance and 1 likely pathogenic variant without functional data observed in Brugada syndrome and long QT syndrome probands. METHODS We deployed minigene assays to assess the splicing consequences of 10 variants. Three variants incompatible with the minigene approach were introduced into control induced pluripotent stem cells by CRISPR genome editing. We differentiated cells into induced pluripotent stem cell-derived cardiomyocytes and studied splicing outcomes by reverse transcription-polymerase chain reaction. We used the American College of Medical Genetics and Genomics functional assay criteria (PS3/BS3) to reclassify variants. RESULTS We identified aberrant splicing, with presumed disruption of protein sequence, in 8/10 variants studied using the minigene assay and 1/3 studied in induced pluripotent stem cell-derived cardiomyocytes. We reclassified 8 variants of uncertain significance to likely pathogenic, 1 variant of uncertain significance to likely benign, and 1 likely pathogenic variant to pathogenic. CONCLUSIONS Functional assays reclassified splice-altering variants outside canonical splice sites in Brugada Syndrome- and long QT syndrome-associated genes.
Collapse
Affiliation(s)
- Matthew J. O’Neill
- Vanderbilt University School of Medicine, Medical Scientist
Training Program, Vanderbilt University
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics
(VanCART), Division of Clinical Pharmacology, Department of Medicine
| | - Lynn D. Hall
- Vanderbilt Center for Arrhythmia Research and Therapeutics
(VanCART), Division of Clinical Pharmacology, Department of Medicine
| | - Devyn W. Mitchell
- Vanderbilt Center for Arrhythmia Research and Therapeutics
(VanCART), Division of Clinical Pharmacology, Department of Medicine
| | - Andrew M. Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics
(VanCART), Division of Clinical Pharmacology, Department of Medicine
| | - Dan M. Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics
(VanCART), Departments of Medicine, Pharmacology, and Biomedical Informatics,
Vanderbilt University Medical Center, Nashville, TN
| |
Collapse
|
12
|
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.
Collapse
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:
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Opitz syndrome: improving clinical interpretation of intronic variants in MID1 gene. Pediatr Res 2022; 93:1208-1215. [PMID: 35953512 DOI: 10.1038/s41390-022-02237-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 07/12/2022] [Accepted: 07/24/2022] [Indexed: 03/05/2023]
Abstract
BACKGROUND Loss-of-function variants in MID1 are the most common cause of Opitz G/BBB syndrome (OS). The interpretation of intronic variants affecting the splicing is a rising issue in OS. METHODS Exon sequencing of a 2-year-old boy with OS showed that he was a carrier of the de novo c.1286-10G>T variant in MID1. In silico predictions and minigene assays explored the effect of the variant on splicing. The minigene approach was also applied to two previously identified MID1 c.864+1G>T and c.1285+1G>T variants. RESULTS Minigene assay demonstrated that the c.1286-10G>T variant generated the inclusion of eight nucleotides that predicted generation of a frameshift. The c.864+1G>T and c.1285+1G>T variants resulted in an in-frame deletion predicted to generate a shorter MID1 protein. In hemizygous males, this allowed reclassification of all the identified variants from "of unknown significance" to "likely pathogenic." CONCLUSIONS Minigene assay supports functional effects from MID1 intronic variants. This paves the way to the introduction of similar second-tier investigations in the molecular diagnostics workflow of OS. IMPACT Causative intronic variants in MID1 are rarely investigated in Opitz syndrome. MID1 is not expressed in blood and mRNA studies are hardly accessible in routine diagnostics. Minigene assay is an alternative for assessing the effect of intronic variants on splicing. This is the first study characterizing the molecular consequences of three MID1 variants for diagnostic purposes and demonstrating the efficacy of minigene assays in supporting their clinical interpretation. Review of the criteria according to the American College of Medical Genetics reassessed all variants as likely pathogenic.
Collapse
|
15
|
Zhang H, Chen C, Wu X, Lou C, Liang Q, Wu W, Wang X, Ding Q. Effects of 14 F9 synonymous codon variants on hemophilia B expression: Alteration of splicing along with protein expression. Hum Mutat 2022; 43:928-939. [PMID: 35391506 DOI: 10.1002/humu.24377] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 01/25/2023]
Abstract
There is growing evidence that synonymous codon variants (SCVs) can cause disease through the disruption of different processes of protein production. The aim of the study is to investigate whether the 14 SCVs reported in the F9 variant database were the pathogenic causes of hemophilia B. The impacts of SCVs on splicing and protein expression were detected using a combination of in silico prediction, in vitro minigene splicing assay and cell expression detection. The splicing transcripts were identified and quantified by co-amplification fluorescent PCR. The mechanism of splicing was verified by a modified pU1snRNA and pU7snRNA approach. Aberrant splicing patterns were found in eight SCVs. Five of the 8 SCVs produced almost all aberrant splicing isoforms, which were expected to truncate protein, three of them presented a partial defect on both splicing and protein secretion, the overall effects were consistent with the residual Factor IX activity of the affected cases. Neither the pre-messenger RNA (mRNA) splicing process nor the protein function was impaired in the rest six SCVs. In conclusion, our study firstly revealed the pathogenic mechanism of the 14 F9 SCVs and highlighted the importance of performing mRNA splicing analysis and protein expression studies of SCVs in inherited disorders.
Collapse
Affiliation(s)
- Huayang Zhang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Changming Chen
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xi Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Can Lou
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qian Liang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Wenman Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Collaborative Innovation Center of Hematology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xuefeng Wang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Collaborative Innovation Center of Hematology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qiulan Ding
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Collaborative Innovation Center of Hematology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| |
Collapse
|
16
|
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.
Collapse
|
17
|
Functional analysis of variants in DMD exon/intron 10 predicted to affect splicing. J Hum Genet 2022; 67:495-501. [DOI: 10.1038/s10038-022-01035-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 11/08/2022]
|
18
|
Tumor BRCA Testing in Epithelial Ovarian Cancers: Past and Future-Five-Years' Single-Institution Experience of 762 Consecutive Patients. Cancers (Basel) 2022; 14:cancers14071638. [PMID: 35406410 PMCID: PMC8996829 DOI: 10.3390/cancers14071638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/04/2022] [Accepted: 03/16/2022] [Indexed: 02/04/2023] Open
Abstract
Simple Summary Tumor BRCA testing is crucial in the clinical management of women affected by epithelial ovarian cancer (EOC). In the present study, we aimed to report the results of five years of experience in tumor BRCA testing performed in a single-institution diagnostic setting. We profiled 762 consecutive EOC patients with a failure rate of less than 1% and less than two weeks of turnaround time, which is consistent with the clinical needs. We identified 23.4% of cases with pathogenic/likely pathogenic mutations, including 76% of patients affected by germline and 24% by somatic alterations. Here, we proposed a comprehensive and multidisciplinary clinical workflow that could be successfully followed for the identification of somatic as well as germline alterations, maximizing the benefit of BRCA testing both from a therapeutic and risk assessment perspective. Abstract The establishment of PARP inhibitors in the treatment of epithelial ovarian carcinoma (EOC) has prompt BRCA assessment at the time of diagnosis. We described our five years of experience of tumor BRCA testing, as part of a multidisciplinary workflow for the management of EOC patients. We used a BRCA next-generation sequencing (NGS) test for profiling formalin-fixed, paraffin-embedded (FFPE) EOCs of 762 consecutive patients, with a success rate of 99.7% and a median turnaround time of 12 days. We found 178 (23.4%) cases with pathogenic/likely pathogenic (P/LP) mutations, 74 (9.7%) cases with variants of uncertain significance and 508 (66.8%) wild type tumors. Among 174 patients without P/LP mutations and investigated with multiple-ligation probe-amplification analysis on peripheral blood, two (1.1%) were positive for large rearrangements. Patients with P/LP alterations and/or with positive family history were referred to genetic counselling. Comparing tumor and blood NGS test results of 256 patients, we obtained a tumor test negative predictive value of 100% and we defined 76% of P/LP alterations as germline and 24% as somatic variants. The proposed workflow may successfully identify EOC patients with BRCA1/2 alteration, guiding both therapeutic and risk assessment clinical decisions.
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
Li J, Wang P, Zhang C, Han S, Xiao H, Liu Z, Wang X, Liu W, Wei B, Ma J, Li H, Guo Y. Characterization of Synonymous BRCA1:c.132C>T as a Pathogenic Variant. Front Oncol 2022; 11:812656. [PMID: 35087763 PMCID: PMC8789006 DOI: 10.3389/fonc.2021.812656] [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: 11/10/2021] [Accepted: 12/08/2021] [Indexed: 11/26/2022] Open
Abstract
Breast cancer gene 1 (BRCA1) and BRCA2 are tumor suppressors involved in DNA damage response and repair. Carriers of germline pathogenic or likely pathogenic variants in BRCA1 or BRCA2 have significantly increased lifetime risks of breast cancer, ovarian cancer, and other cancer types; this phenomenon is known as hereditary breast and ovarian cancer (HBOC) syndrome. Accurate interpretation of BRCA1 and BRCA2 variants is important not only for disease management in patients, but also for determining preventative measures for their families. BRCA1:c.132C>T (p.Cys44=) is a synonymous variant recorded in the ClinVar database with “conflicting interpretations of its pathogenicity”. Here, we report our clinical tests in which we identified this variant in two unrelated patients, both of whom developed breast cancer at an early age with ovarian presentation a few years later and had a family history of relevant cancers. Minigene assay showed that this change caused a four-nucleotide loss at the end of exon 3, resulting in a truncated p.Cys44Tyrfs*5 protein. Reverse transcription-polymerase chain reaction identified two fragments (123 and 119 bp) using RNA isolated from patient blood samples, in consistency with the results of the minigene assay. Collectively, we classified BRCA1:c.132C>T (p.Cys44=) as a pathogenic variant, as evidenced by functional studies, RNA analysis, and the patients’ family histories. By analyzing variants recorded in the BRCA Exchange database, we found synonymous changes at the ends of exons could potentially influence splicing; meanwhile, current in silico tools could not predict splicing changes efficiently if the variants were in the middle of an exon, or in the deep intron region. Future studies should attempt to identify variants that influence gene expression and post-transcription modifications to improve our understanding of BRCA1 and BRCA2, as well as their related cancers.
Collapse
Affiliation(s)
- Jun Li
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| | - Ping Wang
- Department of Pathophysiology, School of Basic Medical Science, Zhengzhou University, Zhengzhou, China
| | - Cuiyun Zhang
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| | - Sile Han
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China
| | - Han Xiao
- Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zhiyuan Liu
- Amoy Diagnostics Co., Ltd. (AmoyDx), Xiamen, China
| | - Xiaoyan Wang
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| | - Weiling Liu
- Department of Medical Oncology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzou, China
| | - Bing Wei
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| | - Jie Ma
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| | - Hongle Li
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China
| | - Yongjun Guo
- Department of Molecular Pathology, The Affiliated Cancer Hospital of Zhengzhou University and Henan Cancer Hospital, Zhengzhou, China.,Henan Key Laboratory of Molecular Pathology, Zhengzhou, China.,Henan International Joint Laboratory of Cancer Genetics, Zhengzhou, China
| |
Collapse
|
21
|
Zhu L, Miao B, Dymerska D, Kuswik M, Bueno-Martínez E, Sanoguera-Miralles L, Velasco EA, Paramasivam N, Schlesner M, Kumar A, Yuan Y, Lubinski J, Bandapalli OR, Hemminki K, Försti A. Germline Variants of CYBA and TRPM4 Predispose to Familial Colorectal Cancer. Cancers (Basel) 2022; 14:cancers14030670. [PMID: 35158942 PMCID: PMC8833488 DOI: 10.3390/cancers14030670] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/17/2022] [Accepted: 01/26/2022] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Whole-genome sequencing and bioinformatics analysis on unique colorectal cancer families revealed two attractive candidate predisposition genes, CYBA and TRPM4, each with a loss-of-function variant. Supported by our functional studies, we suggest that the two gene defects mechanistically involve intestinal barrier integrity through reactive oxygen species and mucus biology, which converges in chronic bowel inflammation, a known risk factor for colorectal cancer. Abstract Familial colorectal cancer (CRC) is only partially explained by known germline predisposing genes. We performed whole-genome sequencing in 15 Polish families of many affected individuals, without mutations in known CRC predisposing genes. We focused on loss-of-function variants and functionally characterized them. We identified a frameshift variant in the CYBA gene (c.246delC) in one family and a splice site variant in the TRPM4 gene (c.25–1 G > T) in another family. While both variants were absent or extremely rare in gene variant databases, we identified four additional Polish familial CRC cases and two healthy elderly individuals with the CYBA variant (odds ratio 2.46, 95% confidence interval 0.48–12.69). Both variants led to a premature stop codon and to a truncated protein. Functional characterization of the variants showed that knockdown of CYBA or TRPM4 depressed generation of reactive oxygen species (ROS) in LS174T and HT-29 cell lines. Knockdown of TRPM4 resulted in decreased MUC2 protein production. CYBA encodes a component in the NADPH oxidase system which generates ROS and controls, e.g., bacterial colonization in the gut. Germline CYBA variants are associated with early onset inflammatory bowel disease, supported with experimental evidence on loss of intestinal mucus barrier function due to ROS deficiency. TRPM4 encodes a calcium-activated ion channel, which, in a human colonic cancer cell line, controls calcium-mediated secretion of MUC2, a major component of intestinal mucus barrier. We suggest that the gene defects in CYBA and TRPM4 mechanistically involve intestinal barrier integrity through ROS and mucus biology, which converges in chronic bowel inflammation.
Collapse
Affiliation(s)
- Lizhen Zhu
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Department of Medical Oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310009, China;
| | - Beiping Miao
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), D-69120 Heidelberg, Germany
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), D-69120 Heidelberg, Germany
| | - Dagmara Dymerska
- Department of Genetics and Pathology, Hereditary Cancer Center, Pomeranian Medical University, Unii Lubelskiej 1, 71-252 Szczecin, Poland; (D.D.); (M.K.); (J.L.)
| | - Magdalena Kuswik
- Department of Genetics and Pathology, Hereditary Cancer Center, Pomeranian Medical University, Unii Lubelskiej 1, 71-252 Szczecin, Poland; (D.D.); (M.K.); (J.L.)
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (E.A.V.)
| | - Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (E.A.V.)
| | - Eladio A. Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), 47003 Valladolid, Spain; (E.B.-M.); (L.S.-M.); (E.A.V.)
| | - Nagarajan Paramasivam
- Computational Oncology, Molecular Diagnostics Program, National Center for Tumor Diseases (NCT), D-69120 Heidelberg, Germany;
| | - Matthias Schlesner
- Bioinformatics and Omics Data Analytics, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany;
| | - Abhishek Kumar
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Institute of Bioinformatics, International Technology Park, Bengaluru 560066, India
- Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Ying Yuan
- Department of Medical Oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310009, China;
| | - Jan Lubinski
- Department of Genetics and Pathology, Hereditary Cancer Center, Pomeranian Medical University, Unii Lubelskiej 1, 71-252 Szczecin, Poland; (D.D.); (M.K.); (J.L.)
| | - Obul Reddy Bandapalli
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), D-69120 Heidelberg, Germany
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), D-69120 Heidelberg, Germany
- Medical Faculty Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany
- Correspondence: (O.R.B.); (K.H.)
| | - Kari Hemminki
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Faculty of Medicine and Biomedical Center in Pilsen, Charles University in Prague, 30605 Pilsen, Czech Republic
- Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany
- Correspondence: (O.R.B.); (K.H.)
| | - Asta Försti
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; (L.Z.); (B.M.); (A.K.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), D-69120 Heidelberg, Germany
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), D-69120 Heidelberg, Germany
| |
Collapse
|
22
|
Billaud A, Chevalier LM, Augereau P, Frenel JS, Passot C, Campone M, Morel A. Functional pre-therapeutic evaluation by genome editing of variants of uncertain significance of essential tumor suppressor genes. Genome Med 2021; 13:174. [PMID: 34749799 PMCID: PMC8576946 DOI: 10.1186/s13073-021-00976-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/23/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Targeted therapies in oncology are promising but variants of uncertain significance (VUS) limit their use for clinical management and necessitate functional testing in vitro. Using BRCA1 and BRCA2 variants, which have consequences on PARP inhibitor sensitivity, and POLE variants, potential biomarkers of immunotherapy response, we developed a rapid functional assay based on CRISPR-Cas9 genome editing to determine the functional consequences of these variants having potentially direct implications on patients' access to targeted therapies. METHODS We first evaluated the functional impact of 26 BRCA1 and 7 BRCA2 variants by editing and comparing NGS results between the variant of interest and a silent control variant. Ten of these variants had already been classified as benign or pathogenic and were used as controls. Finally, we extended this method to the characterization of POLE VUS. RESULTS For the 23 variants that were unclassified or for which conflicting interpretations had been reported, 15 were classified as functionally normal and 6 as functionally abnormal. Another two variants were found to have intermediate consequences, both with potential impacts on splicing. We then compared these scores to the patients' responses to PARP inhibitors when possible. Finally, to prove the application of our method to the classification of variants from other tumor suppressor genes, we exemplified with three POLE VUS. Among them, two were classified with an intermediate functional impact and one was functionally abnormal. Eventually, four POLE variants previously classified in databases were also evaluated. However, we found evidence of a discordance with the classification, variant p.Leu424Val being found here functionally normal. CONCLUSIONS Our new rapid functional assay can be used to characterize the functional implication of BRCA1 and BRCA2 variants, giving patients whose variants were evaluated as functionally abnormal access to PARP inhibitor treatment. Retrospective analysis of patients' responses to PARP inhibitors, where accessible, was consistent with our functional score evaluation and confirmed the accuracy of our protocol. This method could potentially be extended to the classification of VUS from all essential tumor suppressor genes and can be performed within a timeframe compatible with clinical applications, thereby having a direct theranostic impact.
Collapse
Affiliation(s)
- Amandine Billaud
- Université d'Angers, Inserm, CRCINA, SFR ICAT, F-49000, Angers, France
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
| | - Louise-Marie Chevalier
- Université d'Angers, Inserm, CRCINA, SFR ICAT, F-49000, Angers, France
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
| | - Paule Augereau
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
| | - Jean-Sebastien Frenel
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
- Université de Nantes, Inserm, CRCINA, F-44000, Nantes, France
| | - Christophe Passot
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
| | - Mario Campone
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France
- Université de Nantes, Inserm, CRCINA, F-44000, Nantes, France
| | - Alain Morel
- Université d'Angers, Inserm, CRCINA, SFR ICAT, F-49000, Angers, France.
- Institut de Cancérologie de l'Ouest Nantes-Angers, F-49000, Angers, France.
| |
Collapse
|
23
|
Lin JH, Wu H, Zou WB, Masson E, Fichou Y, Le Gac G, Cooper DN, Férec C, Liao Z, Chen JM. Splicing Outcomes of 5' Splice Site GT>GC Variants That Generate Wild-Type Transcripts Differ Significantly Between Full-Length and Minigene Splicing Assays. Front Genet 2021; 12:701652. [PMID: 34422003 PMCID: PMC8375439 DOI: 10.3389/fgene.2021.701652] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/13/2021] [Indexed: 12/18/2022] Open
Abstract
Combining data derived from a meta-analysis of human disease-associated 5' splice site GT>GC (i.e., +2T>C) variants and a cell culture-based full-length gene splicing assay (FLGSA) of forward engineered +2T>C substitutions, we recently estimated that ∼15-18% of +2T>C variants can generate up to 84% wild-type transcripts relative to their wild-type counterparts. Herein, we analyzed the splicing outcomes of 20 +2T>C variants that generate some wild-type transcripts in two minigene assays. We found a high discordance rate in terms of the generation of wild-type transcripts, not only between FLGSA and the minigene assays but also between the different minigene assays. In the pET01 context, all 20 wild-type minigene constructs generated the expected wild-type transcripts; of the 20 corresponding variant minigene constructs, 14 (70%) generated wild-type transcripts. In the pSPL3 context, only 18 of the 20 wild-type minigene constructs generated the expected wild-type transcripts whereas 8 of the 18 (44%) corresponding variant minigene constructs generated wild-type transcripts. Thus, in the context of a particular type of variant, we raise awareness of the limitations of minigene splicing assays and emphasize the importance of sequence context in regulating splicing. Whether or not our findings apply to other types of splice-altering variant remains to be investigated.
Collapse
Affiliation(s)
- Jin-Huan Lin
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Hao Wu
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Wen-Bin Zou
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Emmanuelle Masson
- Univ Brest, Inserm, EFS, UMR 1078, GGB, Brest, France.,Service de Génétique Médicale et de Biologie de la Reproduction, CHRU Brest, Brest, France
| | - Yann Fichou
- Univ Brest, Inserm, EFS, UMR 1078, GGB, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Gerald Le Gac
- Univ Brest, Inserm, EFS, UMR 1078, GGB, Brest, France.,Service de Génétique Médicale et de Biologie de la Reproduction, CHRU Brest, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Claude Férec
- Univ Brest, Inserm, EFS, UMR 1078, GGB, Brest, France.,Service de Génétique Médicale et de Biologie de la Reproduction, CHRU Brest, Brest, France
| | - Zhuan Liao
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.,Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Jian-Min Chen
- Univ Brest, Inserm, EFS, UMR 1078, GGB, Brest, France
| |
Collapse
|
24
|
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.
Collapse
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.)
| |
Collapse
|
25
|
Jimenez-Sainz J, Jensen RB. Imprecise Medicine: BRCA2 Variants of Uncertain Significance (VUS), the Challenges and Benefits to Integrate a Functional Assay Workflow with Clinical Decision Rules. Genes (Basel) 2021; 12:genes12050780. [PMID: 34065235 PMCID: PMC8161351 DOI: 10.3390/genes12050780] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/20/2022] Open
Abstract
Pathological mutations in homology-directed repair (HDR) genes impact both future cancer risk and therapeutic options for patients. HDR is a high-fidelity DNA repair pathway for resolving DNA double-strand breaks throughout the genome. BRCA2 is an essential protein that mediates the loading of RAD51 onto resected DNA breaks, a key step in HDR. Germline mutations in BRCA2 are associated with an increased risk for breast, ovarian, prostate, and pancreatic cancer. Clinical findings of germline or somatic BRCA2 mutations in tumors suggest treatment with platinum agents or PARP inhibitors. However, when genetic analysis reveals a variant of uncertain significance (VUS) in the BRCA2 gene, precision medicine-based decisions become complex. VUS are genetic changes with unknown pathological impact. Current statistics indicate that between 10–20% of BRCA sequencing results are VUS, and of these, more than 50% are missense mutations. Functional assays to determine the pathological outcome of VUS are urgently needed to provide clinical guidance regarding cancer risk and treatment options. In this review, we provide a brief overview of BRCA2 functions in HDR, describe how BRCA2 VUS are currently assessed in the clinic, and how genetic and biochemical functional assays could be integrated into the clinical decision process. We suggest a multi-step workflow composed of robust and accurate functional assays to correctly evaluate the potential pathogenic or benign nature of BRCA2 VUS. Success in this precision medicine endeavor will offer actionable information to patients and their physicians.
Collapse
Affiliation(s)
- Judit Jimenez-Sainz
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
| | - Ryan B. Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
| |
Collapse
|
26
|
Genetic testing results in Slovenian male breast cancer cohort indicate the BRCA2 7806-2A > G founder variant could be associated with higher male breast cancer risk. Breast Cancer Res Treat 2021; 188:811-820. [PMID: 33891299 PMCID: PMC8272709 DOI: 10.1007/s10549-021-06224-5] [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: 11/15/2020] [Accepted: 04/08/2021] [Indexed: 10/26/2022]
Abstract
PURPOSE To analyze the prevalence of pathogenic/likely pathogenic variants (P/LPVs) in BRCA1 and BRCA2 genes in the largest cohort of Slovenian male breast cancer (MBC) patients to date and to explore a possible correlation between the Slovenian founder variant BRCA2:c.7806-2A > G and predisposition to MBC. METHODS We performed a retrospective analysis of 81 MBC cases who underwent genetic counseling and/or testing between January 1999 and May 2020. To explore a possible genotype-phenotype correlation, we performed additional analyses of 203 unrelated families with P/LPVs in BRCA2 and 177 cases of female breast cancer (FBC) in carriers of P/LPVs in BRCA2. RESULTS Detection rate of P/LPVs in the BRCA1 and BRCA2 genes was 24.7% (20/81) with 95% of them in BRCA2 gene. The only two recurrent P/LPVs were BRCA2:c.7806-2A > G and BRCA2:c.3975_3978dupTGCT (9 and 5 MBC cases, respectively). In families with BRCA2:c.7806-2A > G, the incidence of MBC cases was higher compared to families with other P/LPVs in BRCA2; however, the difference did not reach statistical significance (17.8% vs. 8.9%, p = 0.105). BRCA2:c.7806-2A > G was detected in both families with multiple cases of MBC. This splice-site variant represented a significantly higher proportion of all BRCA2 P/LPVs detected in MBC carriers compared to FBC carriers (47.4% vs. 26%, p = 0.049). CONCLUSION We observed a high mutation detection rate and conclude this may be due to the prevalent BRCA2:c.7806-2A > G variant in Slovenia. Our results indicate a possible association between this variant and higher risk of breast cancer in males compared to other identified P/LPVs in BRCA2.
Collapse
|
27
|
Morbidoni V, Baschiera E, Forzan M, Fumini V, Ali DS, Giorgi G, Buson L, Desbats MA, Cassina M, Clementi M, Salviati L, Trevisson E. Hybrid Minigene Assay: An Efficient Tool to Characterize mRNA Splicing Profiles of NF1 Variants. Cancers (Basel) 2021; 13:cancers13050999. [PMID: 33673681 PMCID: PMC7957615 DOI: 10.3390/cancers13050999] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 02/08/2023] Open
Abstract
Neurofibromatosis type 1 (NF1) is caused by heterozygous loss of function mutations in the NF1 gene. Although patients are diagnosed according to clinical criteria and few genotype-phenotype correlations are known, molecular analysis remains important. NF1 displays allelic heterogeneity, with a high proportion of variants affecting splicing, including deep intronic alleles and changes outside the canonical splice sites, making validation problematic. Next Generation Sequencing (NGS) technologies integrated with multiplex ligation-dependent probe amplification (MLPA) have largely overcome RNA-based techniques but do not detect splicing defects. A rapid minigene-based system was set up to test the effects of NF1 variants on splicing. We investigated 29 intronic and exonic NF1 variants identified in patients during the diagnostic process. The minigene assay showed the coexistence of multiple mechanisms of splicing alterations for seven variants. A leaky effect on splicing was documented in one de novo substitution detected in a sporadic patient with a specific phenotype without neurofibromas. Our splicing assay proved to be a reliable and fast method to validate novel NF1 variants potentially affecting splicing and to detect hypomorphic effects that might have phenotypic consequences, avoiding the requirement of patient's RNA.
Collapse
Affiliation(s)
- Valeria Morbidoni
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
| | - Elisa Baschiera
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
| | - Monica Forzan
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Valentina Fumini
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Dario Seif Ali
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Gianpietro Giorgi
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Lisa Buson
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
| | - Maria Andrea Desbats
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
| | - Matteo Cassina
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Maurizio Clementi
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
| | - Leonardo Salviati
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
| | - Eva Trevisson
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (V.M.); (E.B.); (M.F.); (V.F.); (D.S.A.); (G.G.); (L.B.); (M.A.D.); (M.C.); (M.C.); (L.S.)
- Istituto di Ricerca Pediatrica—IRP, Fondazione Città della Speranza, 35127 Padova, Italy
- Correspondence: ; Tel.: + 39-(04)-9821-1402
| |
Collapse
|
28
|
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.
Collapse
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
| |
Collapse
|
29
|
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.
Collapse
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.)
| |
Collapse
|
30
|
Biswas K, Lipton GB, Stauffer S, Sullivan T, Cleveland L, Southon E, Reid S, Magidson V, Iversen ES, Sharan SK. A computational model for classification of BRCA2 variants using mouse embryonic stem cell-based functional assays. NPJ Genom Med 2020; 5:52. [PMID: 33293522 PMCID: PMC7722754 DOI: 10.1038/s41525-020-00158-5] [Citation(s) in RCA: 13] [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: 07/16/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022] Open
Abstract
Sequencing-based genetic tests to identify individuals at increased risk of hereditary breast and ovarian cancers have resulted in the identification of more than 40,000 sequence variants of BRCA1 and BRCA2. A majority of these variants are considered to be variants of uncertain significance (VUS) because their impact on disease risk remains unknown, largely due to lack of sufficient familial linkage and epidemiological data. Several assays have been developed to examine the effect of VUS on protein function, which can be used to assess their impact on cancer susceptibility. In this study, we report the functional characterization of 88 BRCA2 variants, including several previously uncharacterized variants, using a well-established mouse embryonic stem cell (mESC)-based assay. We have examined their ability to rescue the lethality of Brca2 null mESC as well as sensitivity to six DNA damaging agents including ionizing radiation and a PARP inhibitor. We have also examined the impact of BRCA2 variants on splicing. In addition, we have developed a computational model to determine the probability of impact on function of the variants that can be used for risk assessment. In contrast to the previous VarCall models that are based on a single functional assay, we have developed a new platform to analyze the data from multiple functional assays separately and in combination. We have validated our VarCall models using 12 known pathogenic and 10 neutral variants and demonstrated their usefulness in determining the pathogenicity of BRCA2 variants that are listed as VUS or as variants with conflicting functional interpretation.
Collapse
Affiliation(s)
- Kajal Biswas
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Gary B Lipton
- Department of Statistical Science, Duke University, Durham, NC, 27708, USA
| | - Stacey Stauffer
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Teresa Sullivan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Linda Cleveland
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Eileen Southon
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Susan Reid
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Valentin Magidson
- Optical Microscopy and Analysis Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Edwin S Iversen
- Department of Statistical Science, Duke University, Durham, NC, 27708, USA.
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| |
Collapse
|
31
|
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.
Collapse
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
| |
Collapse
|
32
|
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: 15] [Impact Index Per Article: 3.8] [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.
Collapse
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
| |
Collapse
|
33
|
Chase A, Score J, Lin F, Bryant C, Waghorn K, Yapp S, Carreno-Tarragona G, Aranaz P, Villasante A, Ernst T, Cross NCP. Mutational mechanisms of EZH2 inactivation in myeloid neoplasms. Leukemia 2020; 34:3206-3214. [PMID: 32322039 PMCID: PMC7610374 DOI: 10.1038/s41375-020-0816-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 03/20/2020] [Accepted: 03/26/2020] [Indexed: 12/18/2022]
Abstract
EZH2, a component of the polycomb repressive complex 2, catalyses the trimethylation of histone H3 lysine 27, a chromatin mark associated with transcriptional repression. EZH2 loss-of-function mutations are seen in myeloid neoplasms and are associated with an adverse prognosis. Missense mutations in the SET/CXC domain abrogate catalytic activity as assessed by in vitro histone methylation assays, but missense mutations clustering in the conserved DI and DII regions retain activity. To understand the role of DI and DII mutations, we initially developed a cell-based histone methylation assay to test activity in a cellular context. Murine induced pluripotent stem cells lacking EZH2 were transiently transfected with wild type or mutant EZH2 (n=15) and any resulting histone methylation was measured by flow cytometry. All DI mutations (n=5) resulted in complete or partial loss of methylation activity whilst 5/6 DII mutations retained activity. Next, we assessed the possibility of splicing abnormalities induced by exon 8 mutations (encoding DII) using RT-PCR from primary patient samples and mini-gene assays. Exon 8 mutations resulted in skipping of exon 8 and an out-of-frame transcript. We have therefore shown that mutations within regions encoding EZH2 domains DI and DII are pathogenic by loss of function and exon skipping, respectively.
Collapse
Affiliation(s)
- Andrew Chase
- Faculty of Medicine, University of Southampton, Southampton, UK. .,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK.
| | - Joannah Score
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Feng Lin
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Catherine Bryant
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Katherine Waghorn
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Sarah Yapp
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | | | - Paula Aranaz
- Centre for Nutrition Research, University of Navarra, Pamplona, Spain
| | - Aranzazu Villasante
- Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.,Department of Electronics and Biomedical Engineering, University of Barcelona, Barcelona, Spain
| | - Thomas Ernst
- Abteilung Hämatologie/Onkologie, Klinik für Innere Medizin II, Universitätsklinikum Jena, Jena, Germany
| | - Nicholas C P Cross
- Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| |
Collapse
|
34
|
Wang C, Han Y, Zhou J, Zheng B, Zhou W, Bao H, Jia Z, Zhang A, Huang S, Ding G, Zhao F. Splicing Characterization of CLCNKB Variants in Four Patients With Type III Bartter Syndrome. Front Genet 2020; 11:81. [PMID: 32153641 PMCID: PMC7047732 DOI: 10.3389/fgene.2020.00081] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/24/2020] [Indexed: 12/22/2022] Open
Abstract
Objective Type III Bartter syndrome (BS) is caused by loss-of-function mutations in the gene encoding basolateral chloride channel ClC-Kb (CLCNKB), and is characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here, we investigated the molecular defects in four Chinese children with clinical manifestations of Bartter syndrome. Methods The genomic DNA of the four patients was screened for gene variations using whole-exome sequencing (WES). The candidate variants were validated by direct Sanger sequencing. Quantitative PCR (qPCR) was subsequently performed to confirm the whole CLCNK gene deletion mutation. A minigene assay and reverse transcription PCR (RT-PCR) were performed to analyze the effect of splice variants in vitro. Results Our patients showed early onset age with hyponatremia, hypokalemia, hypochloremia, repeated vomiting and growth retardation, suggesting Bartter syndrome. Genetic analysis revealed that all patients carried compound heterozygous or homozygous truncating variants in the CLCNKB gene. In particular, we identified a novel nonsense variant c.239G > A (p.(Trp80*)), two splice site variants (c.1053-1 G > A and c.1228-2A > G), a whole gene deletion, and a novel synonymous variant c.228A > C (p.(Arg76Arg)) which located -2 bp from the 5′ splice donor site in exon 3. Furthermore, our in vitro minigene analysis revealed c.228A > C, c.1053-1G > A, and c.1228-2A > G cause the skipping of exon 3, exon 12, and exon 13, respectively. Conclusion Our results support that the whole CLCNKB gene deletion is the most common mutation in Chinese patients with type III BS, and truncating and whole gene deletion variants may account for a more severe phenotype of patients. We verified the pathogenic effect of three splicing variants (c.228A > C, c.1053-1G > A, and c.1228-2A > G) which disturbed the normal mRNA splicing, suggesting that splice variants play an important role in the molecular basis of type III BS, and careful molecular profiling of these patients will be essential for future effective personalized treatment options.
Collapse
Affiliation(s)
- Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Yuan Han
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jiaran Zhou
- Department of Nephrology, 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
| | - Wei Zhou
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Huaying Bao
- Department of Nephrology, 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
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Songming Huang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Guixia Ding
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Fei Zhao
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| |
Collapse
|
35
|
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.
Collapse
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
| |
Collapse
|
36
|
Apostolou P, Fostira F, Kouroussis C, Kalfakakou D, Delimitsou A, Agelaki S, Androulakis N, Christodoulou C, Kalbakis K, Kalykaki A, Sanidas E, Papadimitriou C, Vamvakas L, Georgoulias V, Mavroudis D, Yannoukakos D, Konstantopoulou I, Saloustros E. BRCA1 and BRCA2 germline testing in Cretan isolates reveals novel and strong founder effects. Int J Cancer 2020; 147:1334-1342. [PMID: 32022259 DOI: 10.1002/ijc.32903] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/15/2020] [Accepted: 01/23/2020] [Indexed: 12/14/2022]
Abstract
Germline BRCA1 and BRCA2 loss-of-function variants have been linked to increased breast and ovarian cancer risk, with more than 5,000 distinct pathogenic variants being reported worldwide. Among individuals of Greek descent, the BRCA1/2 variant spectrum is heterogeneous, but characterized by strong founder effects. As patients from certain geographical regions of Greece (like Crete) were underrepresented in previous studies, we hypothesized that isolated Cretans, a southern Greece islanders' population with distinct demographic, cultural and genetic features, could harbor founder BRCA1/2 mutations. A total of 304 breast or/and ovarian cancer patients of Cretan descent, fulfilling NCCN criteria for genetic testing, were tested by NGS or Sanger sequencing, followed by MLPA. Haplotype analysis was subsequently performed to investigate potential founder effects of recurrent alleles. Overall, 16.5% (50/304) of the tested patients carried 22 different pathogenic variants; 48% in BRCA1, 52% in BRCA2. Three variants, namely two in BRCA2 (Δexons 12 and 13 and c.7806-2A>T) and one in BRCA1 (c.5492del), constituting approximately half (48%) of all detected pathogenic variants, were shown to have a founder effect, with all carriers sharing common haplotypes. Remarkably, these variants were confined to Cretans and have not been identified in other regions of Greece. The high prevalence of specific BRCA1/2 pathogenic variants among Cretans, provides the possibility of cost- and time-efficient screening of the Cretan population. Integrating this knowledge in local public health services may have a significant impact on cancer prevention, and may serve as a starting point for the implementation of testing on a population level.
Collapse
Affiliation(s)
- Paraskevi Apostolou
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Florentia Fostira
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | | | - Despoina Kalfakakou
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Angeliki Delimitsou
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Sofia Agelaki
- Laboratory of Translational Oncology, School of Medicine, University of Crete, Heraklion, Crete, Greece.,Department of Medical Oncology, School of Medicine, University Hospital of Heraklion, Crete, Greece
| | | | | | - Konstantinos Kalbakis
- Department of Medical Oncology, School of Medicine, University Hospital of Heraklion, Crete, Greece
| | - Antonia Kalykaki
- Department of Medical Oncology, School of Medicine, University Hospital of Heraklion, Crete, Greece
| | - Elias Sanidas
- Department of Surgery, School of Medicine, University of Crete, Heraklion, Greece
| | - Christos Papadimitriou
- Oncology Unit, Second Department of Surgery, Aretaieion Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Lambros Vamvakas
- Department of Medical Oncology, School of Medicine, University Hospital of Heraklion, Crete, Greece
| | | | - Dimitris Mavroudis
- Laboratory of Translational Oncology, School of Medicine, University of Crete, Heraklion, Crete, Greece.,Department of Medical Oncology, School of Medicine, University Hospital of Heraklion, Crete, Greece
| | - Drakoulis Yannoukakos
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Irene Konstantopoulou
- Molecular Diagnostics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Emmanouil Saloustros
- Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| |
Collapse
|
37
|
Montalban G, Bonache S, Moles-Fernández A, Gadea N, Tenés A, Torres-Esquius S, Carrasco E, Balmaña J, Diez O, Gutiérrez-Enríquez S. Incorporation of semi-quantitative analysis of splicing alterations for the clinical interpretation of variants in BRCA1 and BRCA2 genes. Hum Mutat 2019; 40:2296-2317. [PMID: 31343793 DOI: 10.1002/humu.23882] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 07/21/2019] [Accepted: 07/22/2019] [Indexed: 12/15/2022]
Abstract
BRCA1 and BRCA2 (BRCA1/2) genetic variants that disrupt messenger RNA splicing are commonly associated with increased risks of developing breast/ovarian cancer. The majority of splicing studies published to date rely on qualitative methodologies (i.e., Sanger sequencing), but it is necessary to incorporate semi-quantitative or quantitative approaches to accurately interpret the clinical significance of spliceogenic variants. Here, we characterize the splicing impact of 31 BRCA1/2 variants using semi-quantitative capillary electrophoresis of fluorescent amplicons (CE), Sanger sequencing and allele-specific assays. A total of 14 variants were found to disrupt splicing. Allelic-specific assays could be performed for BRCA1 c.302-1G>A and BRCA2 c.516+2T>A, c.1909+1G>A, c.8332-13T>G, c.8332-2A>G, c.8954-2A>T variants, showing a monoallelic contribution to full-length transcript expression that was concordant with semi-quantitative data. The splicing fraction of alternative and aberrant transcripts was also measured by CE, facilitating variant interpretation. Following Evidence-based Network for the Interpretation of Germline Mutant Alleles criteria, we successfully classified eight variants as pathogenic (Class 5), five variants as likely pathogenic (Class 4), and 14 variants as benign (Class 1). We also provide splicing data for four variants classified as uncertain (Class 3), which produced a "leaky" splicing effect or introduced a missense change in the protein sequence, that will require further assessment to determine their clinical significance.
Collapse
Affiliation(s)
- Gemma Montalban
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Sandra Bonache
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | | | - Neus Gadea
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Medical Oncology Department, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Anna Tenés
- Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Sara Torres-Esquius
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Estela Carrasco
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Judith Balmaña
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Medical Oncology Department, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Orland Diez
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
| | | |
Collapse
|
38
|
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.
Collapse
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
| |
Collapse
|
39
|
Wangensteen T, Felde CN, Ahmed D, Mæhle L, Ariansen SL. Diagnostic mRNA splicing assay for variants in BRCA1 and BRCA2 identified two novel pathogenic splicing aberrations. Hered Cancer Clin Pract 2019; 17:14. [PMID: 31143303 PMCID: PMC6532242 DOI: 10.1186/s13053-019-0113-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/16/2019] [Indexed: 12/15/2022] Open
Abstract
Background Pathogenic variants in BRCA1 and BRCA2 cause hereditary breast and ovarian cancer. Screening of these genes has become easily accessible in diagnostic laboratories. Sequencing and copy number analyses are used to detect pathogenic variants, but also lead to identification of variants of unknown clinical significance (VUS). If the effect of a VUS can be clarified, it has direct consequence for the clinical management of the patient and family members. A splicing assay is one of several tools that might help in the classification of VUS. We therefore established mRNA analyses for BRCA1 and BRCA2 in the diagnostic laboratory in 2015. We hereby report the results of mRNA analysis variants in BRCA1 and BRCA2 after three years. Methods Variants predicted to alter splicing and variants within the canonical splice sites were selected for splicing analyses. Splicing assays were performed by reverse transcription-PCR of patient RNA. A biallalic expression analysis was carried out whenever possible. Results Twenty-five variants in BRCA1 and BRCA2 were analyzed by splicing assays; nine showed altered transcripts and 16 showed normal splicing patterns. The two novel pathogenic variants in BRCA1 c.4484 + 3 A > C and c.5407–10G > A were characterized. Conclusions We conclude that mRNA analyses are useful in characterization of variants that may affect splicing. The results can guide classification of variants from unknown clinical significance to pathogenic or benign in a diagnostic laboratory, and thus be of direct clinical importance.
Collapse
Affiliation(s)
| | | | - Deeqa Ahmed
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Lovise Mæhle
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | | |
Collapse
|
40
|
Fraile-Bethencourt E, Valenzuela-Palomo A, Díez-Gómez B, Goina E, Acedo A, Buratti E, Velasco EA. Mis-splicing in breast cancer: identification of pathogenic BRCA2 variants by systematic minigene assays. J Pathol 2019; 248:409-420. [PMID: 30883759 DOI: 10.1002/path.5268] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/21/2019] [Accepted: 03/11/2019] [Indexed: 12/21/2022]
Abstract
Splicing disruption is a common mechanism of gene inactivation associated with germline variants of susceptibility genes. To study the role of BRCA2 mis-splicing in hereditary breast/ovarian cancer (HBOC), we performed a comprehensive analysis of variants from BRCA2 exons 2-9, as well as the initial characterization of the regulatory mechanisms of such exons. A pSAD-based minigene with exons 2-9 was constructed and validated in MCF-7 cells, producing the expected transcript (1016-nt/V1-BRCA2_exons_2-9-V2). DNA variants from mutational databases were analyzed by NNSplice and Human Splicing Finder softwares. To refine ESE-variant prediction, we mapped the regulatory regions through a functional strategy whereby 26 exonic microdeletions were introduced into the minigene and tested in MCF-7 cells. Thus, we identified nine spliceogenic ESE-rich intervals where ESE-variants may be located. Combining bioinformatics and microdeletion assays, 83 variants were selected and genetically engineered in the minigene. Fifty-three changes impaired splicing: 28 variants disrupted the canonical sites, four created new ones, 10 abrogated enhancers, eight created silencers and three caused a double-effect. Notably, nine spliceogenic-ESE variants were located within ESE-containing intervals. Capillary electrophoresis and sequencing revealed more than 23 aberrant transcripts, where exon skipping was the most common event. Interestingly, variant c.67G>A triggered the usage of a noncanonical GC-donor 4-nt upstream. Thirty-six variants that induced severe anomalies (>60% aberrant transcripts) were analyzed according to the ACMG guidelines. Thus, 28 variants were classified as pathogenic, five as likely pathogenic and three as variants of uncertain significance. Interestingly, 13 VUS were reclassified as pathogenic or likely pathogenic variants. In conclusion, a large fraction of BRCA2 variants (∼64%) provoked splicing anomalies lending further support to the high prevalence of this disease-mechanism. The low accuracy of ESE-prediction algorithms may be circumvented by functional ESE-mapping that represents an optimal strategy to identify spliceogenic ESE-variants. Finally, systematic functional assays by minigenes depict a valuable tool for the initial characterization of splicing anomalies and the clinical interpretation of variants. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Collapse
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
| | - Elisa Goina
- Molecular Pathology Group, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Alberto Acedo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Emanuele Buratti
- Molecular Pathology Group, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Eladio A Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| |
Collapse
|
41
|
Usefulness and Limitations of Comprehensive Characterization of mRNA Splicing Profiles in the Definition of the Clinical Relevance of BRCA1/2 Variants of Uncertain Significance. Cancers (Basel) 2019; 11:cancers11030295. [PMID: 30832263 PMCID: PMC6468917 DOI: 10.3390/cancers11030295] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/18/2019] [Accepted: 02/20/2019] [Indexed: 12/12/2022] Open
Abstract
Highly penetrant variants of BRCA1/2 genes are involved in hereditary predisposition to breast and ovarian cancer. The detection of pathogenic BRCA variants has a considerable clinical impact, allowing appropriate cancer-risk management. However, a major drawback is represented by the identification of variants of uncertain significance (VUS). Many VUS potentially affect mRNA splicing, making transcript analysis an essential step for the definition of their pathogenicity. Here, we characterize the impact on splicing of ten BRCA1/2 variants. Aberrant splicing patterns were demonstrated for eight variants whose alternative transcripts were fully characterized. Different events were observed, including exon skipping, intron retention, and usage of de novo and cryptic splice sites. Transcripts with premature stop codons or in-frame loss of functionally important residues were generated. Partial/complete splicing effect and quantitative contribution of different isoforms were assessed, leading to variant classification according to Evidence-based Network for the Interpretation of Mutant Alleles (ENIGMA) consortium guidelines. Two variants could be classified as pathogenic and two as likely benign, while due to a partial splicing effect, six variants remained of uncertain significance. The association with an undefined tumor risk justifies caution in recommending aggressive risk-reduction treatments, but prevents the possibility of receiving personalized therapies with potential beneficial effect. This indicates the need for applying additional approaches for the analysis of variants resistant to classification by gene transcript analyses.
Collapse
|
42
|
Farber-Katz S, Hsuan V, Wu S, Landrith T, Vuong H, Xu D, Li B, Hoo J, Lam S, Nashed S, Toppmeyer D, Gray P, Haynes G, Lu HM, Elliott A, Tippin Davis B, Karam R. Quantitative Analysis of BRCA1 and BRCA2 Germline Splicing Variants Using a Novel RNA-Massively Parallel Sequencing Assay. Front Oncol 2018; 8:286. [PMID: 30101128 PMCID: PMC6072868 DOI: 10.3389/fonc.2018.00286] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/09/2018] [Indexed: 12/27/2022] Open
Abstract
Clinical genetic testing for hereditary breast and ovarian cancer (HBOC) is becoming widespread. However, the interpretation of variants of unknown significance (VUS) in HBOC genes, such as the clinically actionable genes BRCA1 and BRCA2, remain a challenge. Among the variants that are frequently classified as VUS are those with unclear effects on splicing. In order to address this issue we developed a high-throughput RNA-massively parallel sequencing assay—CloneSeq—capable to perform quantitative and qualitative analysis of transcripts in cell lines and HBOC patients. This assay is based on cloning of RT-PCR products followed by massive parallel sequencing of the cloned transcripts. To validate this assay we compared it to the RNA splicing assays recommended by members of the ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) consortium. This comparison was performed using well-characterized lymphoblastoid cell lines (LCLs) generated from carriers of the BRCA1 or BRCA2 germline variants that have been previously described to be associated with splicing defects. CloneSeq was able to replicate the ENIGMA results, in addition to providing quantitative characterization of BRCA1 and BRCA2 germline splicing alterations in a high-throughput fashion. Furthermore, CloneSeq was used to analyze blood samples obtained from carriers of BRCA1 or BRCA2 germline sequence variants, including the novel uncharacterized alteration BRCA1 c.5152+5G>T, which was identified in a HBOC family. CloneSeq provided a high-resolution picture of all the transcripts induced by BRCA1 c.5152+5G>T, indicating it results in significant levels of exon skipping. This analysis proved to be important for the classification of BRCA1 c.5152+5G>T as a clinically actionable likely pathogenic variant. Reclassifications such as these are fundamental in order to offer preventive measures, targeted treatment, and pre-symptomatic screening to the correct individuals.
Collapse
Affiliation(s)
- Suzette Farber-Katz
- Translational Genomics Laboratory, Ambry Genetics, Aliso Viejo, CA, United States
| | - Vickie Hsuan
- Translational Genomics Laboratory, Ambry Genetics, Aliso Viejo, CA, United States
| | - Sitao Wu
- Department of Bioinformatics, Ambry Genetics, Aliso Viejo, CA, United States
| | - Tyler Landrith
- Translational Genomics Laboratory, Ambry Genetics, Aliso Viejo, CA, United States
| | - Huy Vuong
- Department of Bioinformatics, Ambry Genetics, Aliso Viejo, CA, United States
| | - Dong Xu
- Department of Bioinformatics, Ambry Genetics, Aliso Viejo, CA, United States
| | - Bing Li
- Department of Bioinformatics, Ambry Genetics, Aliso Viejo, CA, United States
| | - Jayne Hoo
- Department of Research and Development, Ambry Genetics, Aliso Viejo, CA, United States
| | - Stephanie Lam
- Department of Research and Development, Ambry Genetics, Aliso Viejo, CA, United States
| | - Sarah Nashed
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Deborah Toppmeyer
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Phillip Gray
- Department of Research and Development, Ambry Genetics, Aliso Viejo, CA, United States
| | - Ginger Haynes
- Translational Genomics Laboratory, Ambry Genetics, Aliso Viejo, CA, United States
| | - Hsiao-Mei Lu
- Department of Bioinformatics, Ambry Genetics, Aliso Viejo, CA, United States
| | - Aaron Elliott
- Department of Research and Development, Ambry Genetics, Aliso Viejo, CA, United States
| | - Brigette Tippin Davis
- Department of Research and Development, Ambry Genetics, Aliso Viejo, CA, United States
| | - Rachid Karam
- Translational Genomics Laboratory, Ambry Genetics, Aliso Viejo, CA, United States
| |
Collapse
|
43
|
Vendrell JA, Vilquin P, Larrieux M, Van Goethem C, Solassol J. Benchmarking of Amplicon-Based Next-Generation Sequencing Panels Combined with Bioinformatics Solutions for Germline BRCA1 and BRCA2 Alteration Detection. J Mol Diagn 2018; 20:754-764. [PMID: 30055349 DOI: 10.1016/j.jmoldx.2018.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/27/2018] [Accepted: 06/05/2018] [Indexed: 11/16/2022] Open
Abstract
The recent deployment of next-generation sequencing approaches in routine laboratory analysis has considerably modified the landscape of BRCA1 and BRCA2 germline alteration detection in patients with a high risk of developing breast and/or ovarian cancer. Several commercial multiplex amplicon-based panels and bioinformatics solutions are currently available. In this study, we evaluated the combinations of several BRCA testing assays and bioinformatics solutions for the identification of single-nucleotide variants, insertion/deletion variants, and copy number variations (CNVs). Four assays (BRCA Tumor, BRCA HC, Ion AmpliSeq BRCA, and Access Array BRCA) and two commercial bioinformatics solutions (SeqNext software version 4.3.1 and Sophia DDM version 5.0.13) were tested on a set of 28 previously genotyped samples. All solutions exhibited accurate detection of single-nucleotide variants and insertion/deletion variants, except for Ion AmpliSeq BRCA, which exhibited a decrease in coverage. Of interest, for CNV analysis, the best accuracy was observed with the Sophia DDM platform regardless of the BRCA kit used. Finally, the performance of the most relevant combination (BRCA Tumor and Sophia DDM) was blindly validated on an independent set of 152 samples. Altogether, our results emphasize the need to accurately compare and control both molecular next-generation sequencing approaches and bioinformatics pipelines to limit the number of discrepant alterations and to provide a powerful tool for reliable detection of genetic alterations in BRCA1 and BRCA2, notably CNVs.
Collapse
Affiliation(s)
- Julie A Vendrell
- Solid Tumor Laboratory, Department of Pathology and Oncobiology, CHU Montpellier, University of Montpellier, Montpellier, France
| | - Paul Vilquin
- Solid Tumor Laboratory, Department of Pathology and Oncobiology, CHU Montpellier, University of Montpellier, Montpellier, France
| | - Marion Larrieux
- Solid Tumor Laboratory, Department of Pathology and Oncobiology, CHU Montpellier, University of Montpellier, Montpellier, France
| | - Charles Van Goethem
- Solid Tumor Laboratory, Department of Pathology and Oncobiology, CHU Montpellier, University of Montpellier, Montpellier, France
| | - Jérôme Solassol
- Solid Tumor Laboratory, Department of Pathology and Oncobiology, CHU Montpellier, University of Montpellier, Montpellier, France; The Institute of Cancer Research of Montpellier, INSERM U1194, University of Montpellier, Montpellier, France.
| |
Collapse
|
44
|
Montalban G, Fraile-Bethencourt E, López-Perolio I, Pérez-Segura P, Infante M, Durán M, Alonso-Cerezo MC, López-Fernández A, Diez O, de la Hoya M, Velasco EA, Gutiérrez-Enríquez S. Characterization of spliceogenic variants located in regions linked to high levels of alternative splicing: BRCA2 c.7976+5G > T as a case study. Hum Mutat 2018; 39:1155-1160. [PMID: 29969168 DOI: 10.1002/humu.23583] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 06/04/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022]
Abstract
Many BRCA1 and BRCA2 (BRCA1/2) genetic variants have been studied at mRNA level and linked to hereditary breast and ovarian cancer due to splicing alteration. In silico tools are reliable when assessing variants located in consensus splice sites, but we may identify variants in complex genomic contexts for which bioinformatics is not precise enough. In this study, we characterize BRCA2 c.7976 + 5G > T variant located in intron 17 which has an atypical donor site (GC). This variant was identified in three unrelated Spanish families and we have detected exon 17 skipping as the predominant transcript occurring in carriers. We have also detected several isoforms (Δ16-18, Δ17,18, Δ18, and ▼17q224 ) at different expression levels among carriers and controls. This study remarks the challenge of interpreting genetic variants when multiple alternative isoforms are present, and that caution must be taken when using in silico tools to identify potential spliceogenic variants located in GC-AG introns.
Collapse
Affiliation(s)
- Gemma Montalban
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Eugenia Fraile-Bethencourt
- Splicing and genetic susceptibility to cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Irene López-Perolio
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico 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
| | - Mercedes Durán
- Cancer Genetics, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - María Concepción Alonso-Cerezo
- Genética Clínica. Servicio Análisis Clínicos. Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria Hospital Universitario de la Princesa, Madrid, Spain
| | - Adrià López-Fernández
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Orland Diez
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Eladio A Velasco
- Splicing and genetic susceptibility to cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | | |
Collapse
|
45
|
Fraile-Bethencourt E, Valenzuela-Palomo A, Díez-Gómez B, Acedo A, Velasco EA. Identification of Eight Spliceogenic Variants in BRCA2 Exon 16 by Minigene Assays. Front Genet 2018; 9:188. [PMID: 29881398 PMCID: PMC5977032 DOI: 10.3389/fgene.2018.00188] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/08/2018] [Indexed: 11/17/2022] Open
Abstract
Genetic testing of BRCA1 and BRCA2 identifies a large number of variants of uncertain clinical significance whose functional and clinical interpretations pose a challenge for genetic counseling. Interestingly, a relevant fraction of DNA variants can disrupt the splicing process in cancer susceptibility genes. We have tested more than 200 variants throughout 19 BRCA2 exons mostly by minigene assays, 54% of which displayed aberrant splicing, thus confirming the utility of this assay to check genetic variants in the absence of patient RNA. Our goal was to investigate BRCA2 exon 16 with a view to characterizing spliceogenic variants recorded at the mutational databases. Seventy-two different BIC and UMD variants were analyzed with NNSplice and Human Splicing Finder, 12 of which were selected because they were predicted to disrupt essential splice motifs: canonical splice sites (ss; eight variants) and exonic/intronic splicing enhancers (four variants). These 12 candidate variants were introduced into the BRCA2 minigene with seven exons (14–20) by site-directed mutagenesis and then transfected into MCF-7 cells. Seven variants (six intronic and one missense) induced complete abnormal splicing patterns: c.7618-2A>T, c.7618-2A>G, c.7618-1G>C, c.7618-1G>A, c.7805G>C, c.7805+1G>A, and c.7805+3A>C, as well as a partial anomalous outcome by c.7802A>G. They generated at least 10 different transcripts: Δ16p44 (alternative 3’ss 44-nt downstream; acceptor variants), Δ16 (exon 16-skipping; donor variants), Δ16p55 (alternative 3’ss 55-nt downstream), Δ16q4 (alternative 5’ss 4-nt upstream), Δ16q100 (alternative 5’ss 4-nt upstream), ▾16q20 (alternative 5’ss 20-nt downstream), as well as minor (Δ16p93 and Δ16,17p69) and uncharacterized transcripts of 893 and 954 nucleotides. Isoforms Δ16p44, Δ16, Δ16p55, Δ16q4, Δ16q100, and ▾16q20 introduced premature termination codons which presumably inactivate BRCA2. According to the guidelines the American College of Medical Genetics and Genomics these eight variants could be classified as pathogenic or likely pathogenic whereas the Evidence-based Network for the Interpretation of Germline Mutant Alleles rules suggested seven class 4 and one class 3 variants. In conclusion, our study highlights the relevance of splicing functional assays by hybrid minigenes for the clinical classification of genetic variations. Hence, we provide new data about spliceogenic variants of BRCA2 exon 16 that are directly correlated with breast cancer susceptibility.
Collapse
Affiliation(s)
- Eugenia Fraile-Bethencourt
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Beatriz Díez-Gómez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Alberto Acedo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain.,Biome Makers Inc., San Francisco, CA, United States
| | - Eladio A Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| |
Collapse
|
46
|
Fraile-Bethencourt E, Valenzuela-Palomo A, Díez-Gómez B, Infante M, Durán M, Marcos G, Lastra E, Gómez-Barrero S, Velasco EA. Genetic dissection of the BRCA2 promoter and transcriptional impact of DNA variants. Breast Cancer Res Treat 2018; 171:53-63. [PMID: 29766361 DOI: 10.1007/s10549-018-4826-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/16/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE Promoter mutations may affect transcription and can be associated with human diseases. However, the promoters of the breast cancer (BC) genes are not regularly screened. Our goal was to investigate the BRCA2 promoter in order to study a possible correlation between impaired transcription and disease. METHODS The proximal and core promoter of the BRCA2 gene was sequenced in 95 high-risk BC patients. A BRCA2-promoter insert [- 938 to + 312 from the transcription start site (TSS)] was generated and cloned into the firefly luciferase vector pGL4.10. Promoter variants and deletions were introduced by site-directed mutagenesis and quantified by Dual-Luciferase assays and semi-quantitative RT-PCR. RESULTS Three different variants were detected in high-risk BC patients: rs3092989, rs206118, and rs563971900. Functional mapping of 13 overlapping deletions revealed four down-regulating segments (TSS positions): -59_-10del/µdel3 (16% of activity of the wild-type construct), -104_-55del/µdel4 (62%), -239_-190del/µdel7 (39%), -464_-415/µdel12 (78%), suggesting the presence therein of putative transcriptional activator motifs. Additionally, six microdeletions rendered luciferase overexpression: +32_+81del/µdel1 (356%), -14_+36del/µdel2 (180%), -194_-145del/µdel6 (154%), -284_-235del/µdel8 (168%), -329_-280del/µdel9 (111%), and -509_-460del/µdel13 (139%), which is indicative of repressor elements. Functional assays of 15 promoter variants (including those detected in patients) showed that ten of them significantly altered expression with seven up-regulating (113-163%) and three down-regulating (rs551887850_G, rs570548398_T, rs55880202_T; 72-83%) SNPs. Eight of them were located in an ENCODE-DNase Hypersensitive Cluster (TSS - 185 to + 105) where most active transcriptional motifs are known to be placed. CONCLUSIONS BRCA2 expression is highly sensitive to promoter variations as most of them induced relevant changes. Moreover, we mapped critical regions of the BRCA2 promoter that may constitute potential targets for regulatory variants. Three SNPs moderately decreased luciferase activity, but confirmation of its potential pathogenicity requires further analysis. These data reinforce the need to screen the promoter regions of breast cancer genes with a view to discovering novel deleterious mutations.
Collapse
Affiliation(s)
- Eugenia Fraile-Bethencourt
- Grupo de Splicing y Cáncer, Instituto de Biología y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC-UVa), Sanz y Forés 3, 47003, Valladolid, Spain
| | - Alberto Valenzuela-Palomo
- Grupo de Splicing y Cáncer, Instituto de Biología y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC-UVa), Sanz y Forés 3, 47003, Valladolid, Spain
| | - Beatriz Díez-Gómez
- Grupo de Splicing y Cáncer, Instituto de Biología y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC-UVa), Sanz y Forés 3, 47003, Valladolid, Spain
| | - Mar Infante
- Cancer Genetics, Instituto de Biología y Genética Molecular (UVa-CSIC), Valladolid, Spain
| | - Mercedes Durán
- Cancer Genetics, Instituto de Biología y Genética Molecular (UVa-CSIC), Valladolid, Spain
| | - Germán Marcos
- Servicio de Oncología, Hospital Río Hortega, Valladolid, Spain
| | - Enrique Lastra
- Servicio de Oncología, Hospital Universitario de Burgos, Burgos, Spain
| | | | - Eladio A Velasco
- Grupo de Splicing y Cáncer, Instituto de Biología y Genética Molecular (IBGM), Consejo Superior de Investigaciones Científicas (CSIC-UVa), Sanz y Forés 3, 47003, Valladolid, Spain.
| |
Collapse
|
47
|
Villate O, Ibarluzea N, Fraile-Bethencourt E, Valenzuela A, Velasco EA, Grozeva D, Raymond FL, Botella MP, Tejada MI. Functional Analyses of a Novel Splice Variant in the CHD7 Gene, Found by Next Generation Sequencing, Confirm Its Pathogenicity in a Spanish Patient and Diagnose Him with CHARGE Syndrome. Front Genet 2018; 9:7. [PMID: 29434620 PMCID: PMC5790995 DOI: 10.3389/fgene.2018.00007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/08/2018] [Indexed: 01/30/2023] Open
Abstract
Mutations in CHD7 have been shown to be a major cause of CHARGE syndrome, which presents many symptoms and features common to other syndromes making its diagnosis difficult. Next generation sequencing (NGS) of a panel of intellectual disability related genes was performed in an adult patient without molecular diagnosis. A splice donor variant in CHD7 (c.5665 + 1G > T) was identified. To study its potential pathogenicity, exons and flanking intronic sequences were amplified from patient DNA and cloned into the pSAD® splicing vector. HeLa cells were transfected with this construct and a wild-type minigene and functional analysis were performed. The construct with the c.5665 + 1G > T variant produced an aberrant transcript with an insert of 63 nucleotides of intron 28 creating a premature termination codon (TAG) 25 nucleotides downstream. This would lead to the insertion of 8 new amino acids and therefore a truncated 1896 amino acid protein. As a result of this, the patient was diagnosed with CHARGE syndrome. Functional analyses underline their usefulness for studying the pathogenicity of variants found by NGS and therefore its application to accurately diagnose patients.
Collapse
Affiliation(s)
- Olatz Villate
- Biocruces Health Research Institute, Barakaldo, Spain.,Molecular Genetics Laboratory, Genetics Service, Cruces University Hospital, Barakaldo, Spain
| | | | - Eugenia Fraile-Bethencourt
- Splicing and Cancer Laboratory, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Alberto Valenzuela
- Splicing and Cancer Laboratory, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Eladio A Velasco
- Splicing and Cancer Laboratory, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
| | - Detelina Grozeva
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - F L Raymond
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - María P Botella
- Department of Pediatrics, Araba University Hospital, Vitoria, Spain
| | - María-Isabel Tejada
- Biocruces Health Research Institute, Barakaldo, Spain.,Molecular Genetics Laboratory, Genetics Service, Cruces University Hospital, Barakaldo, Spain.,Clinical Group, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
| |
Collapse
|
48
|
Grodecká L, Buratti E, Freiberger T. Mutations of Pre-mRNA Splicing Regulatory Elements: Are Predictions Moving Forward to Clinical Diagnostics? Int J Mol Sci 2017; 18:ijms18081668. [PMID: 28758972 PMCID: PMC5578058 DOI: 10.3390/ijms18081668] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 07/24/2017] [Accepted: 07/27/2017] [Indexed: 02/08/2023] Open
Abstract
For more than three decades, researchers have known that consensus splice sites alone are not sufficient regulatory elements to provide complex splicing regulation. Other regulators, so-called splicing regulatory elements (SREs) are needed. Most importantly, their sequence variants often underlie the development of various human disorders. However, due to their variable location and high degeneracy, these regulatory sequences are also very difficult to recognize and predict. Many different approaches aiming to identify SREs have been tried, often leading to the development of in silico prediction tools. While these tools were initially expected to be helpful to identify splicing-affecting mutations in genetic diagnostics, we are still quite far from meeting this goal. In fact, most of these tools are not able to accurately discern the SRE-affecting pathological variants from those not affecting splicing. Nonetheless, several recent evaluations have given appealing results (namely for EX-SKIP, ESRseq and Hexplorer predictors). In this review, we aim to summarize the history of the different approaches to SRE prediction, and provide additional validation of these tools based on patients' clinical data. Finally, we evaluate their usefulness for diagnostic settings and discuss the challenges that have yet to be met.
Collapse
Affiliation(s)
- Lucie Grodecká
- Centre for Cardiovascular Surgery and Transplantation, Brno 65691, Czech Republic.
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology, 34149 Trieste, Italy.
| | - Tomáš Freiberger
- Centre for Cardiovascular Surgery and Transplantation, Brno 65691, Czech Republic.
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.
| |
Collapse
|