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Value of the loss of heterozygosity to BRCA1 variant classification. NPJ Breast Cancer 2022; 8:9. [PMID: 35039532 PMCID: PMC8764043 DOI: 10.1038/s41523-021-00361-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 09/21/2021] [Indexed: 11/25/2022] Open
Abstract
At least 10% of the BRCA1/2 tests identify variants of uncertain significance (VUS) while the distinction between pathogenic variants (PV) and benign variants (BV) remains particularly challenging. As a typical tumor suppressor gene, the inactivation of the second wild-type (WT) BRCA1 allele is expected to trigger cancer initiation. Loss of heterozygosity (LOH) of the WT allele is the most frequent mechanism for the BRCA1 biallelic inactivation. To evaluate if LOH can be an effective predictor of BRCA1 variant pathogenicity, we carried out LOH analysis on DNA extracted from 90 breast and seven ovary tumors diagnosed in 27 benign and 55 pathogenic variant carriers. Further analyses were conducted in tumors with PVs yet without loss of the WT allele: BRCA1 promoter hypermethylation, next-generation sequencing (NGS) of BRCA1/2, and BRCAness score. Ninety-seven tumor samples were analyzed from 26 different BRCA1 variants. A relatively stable pattern of LOH (65.4%) of WT allele for PV tumors was observed, while the allelic balance (63%) or loss of variant allele (15%) was generally seen for carriers of BV. LOH data is a useful complementary argument for BRCA1 variant classification.
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Ivanov M, Ivanov M, Kasianov A, Rozhavskaya E, Musienko S, Baranova A, Mileyko V. Novel bioinformatics quality control metric for next-generation sequencing experiments in the clinical context. Nucleic Acids Res 2019; 47:e135. [PMID: 31511888 PMCID: PMC6868350 DOI: 10.1093/nar/gkz775] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 07/22/2019] [Accepted: 08/29/2019] [Indexed: 11/23/2022] Open
Abstract
As the use of next-generation sequencing (NGS) for the Mendelian diseases diagnosis is expanding, the performance of this method has to be improved in order to achieve higher quality. Typically, performance measures are considered to be designed in the context of each application and, therefore, account for a spectrum of clinically relevant variants. We present EphaGen, a new computational methodology for bioinformatics quality control (QC). Given a single NGS dataset in BAM format and a pre-compiled VCF-file of targeted clinically relevant variants it associates this dataset with a single arbiter parameter. Intrinsically, EphaGen estimates the probability to miss any variant from the defined spectrum within a particular NGS dataset. Such performance measure virtually resembles the diagnostic sensitivity of given NGS dataset. Here we present case studies of the use of EphaGen in context of BRCA1/2 and CFTR sequencing in a series of 14 runs across 43 blood samples and 504 publically available NGS datasets. EphaGen is superior to conventional bioinformatics metrics such as coverage depth and coverage uniformity. We recommend using this software as a QC step in NGS studies in the clinical context. Availability: https://github.com/m4merg/EphaGen or https://hub.docker.com/r/m4merg/ephagen.
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Affiliation(s)
- Maxim Ivanov
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation
| | - Mikhail Ivanov
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation
| | - Artem Kasianov
- Vavilov Institute of General Genetics, Moscow, Russian Federation
| | - Ekaterina Rozhavskaya
- Vavilov Institute of General Genetics, Moscow, Russian Federation.,Atlas Oncology Diagnostics, Ltd, Moscow, Russian Federation
| | | | - Ancha Baranova
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation.,Atlas Oncology Diagnostics, Ltd, Moscow, Russian Federation.,Research Centre for Medical Genetics, Moscow, Russian Federation.,School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
| | - Vladislav Mileyko
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation.,Atlas Oncology Diagnostics, Ltd, Moscow, Russian Federation
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3
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Li D, Harlan-Williams LM, Kumaraswamy E, Jensen RA. BRCA1-No Matter How You Splice It. Cancer Res 2019; 79:2091-2098. [PMID: 30992324 PMCID: PMC6497576 DOI: 10.1158/0008-5472.can-18-3190] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/09/2019] [Accepted: 03/05/2019] [Indexed: 02/07/2023]
Abstract
BRCA1 (breast cancer 1, early onset), a well-known breast cancer susceptibility gene, is a highly alternatively spliced gene. BRCA1 alternative splicing may serve as an alternative regulatory mechanism for the inactivation of the BRCA1 gene in both hereditary and sporadic breast cancers, and other BRCA1-associated cancers. The alternative transcripts of BRCA1 can mimic known functions, possess unique functions compared with the full-length BRCA1 transcript, and in some cases, appear to function in opposition to full-length BRCA1 In this review, we will summarize the functional "naturally occurring" alternative splicing transcripts of BRCA1 and then discuss the latest next-generation sequencing-based detection methods and techniques to detect alternative BRCA1 splicing patterns and their potential use in cancer diagnosis, prognosis, and therapy.
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Affiliation(s)
- Dan Li
- The University of Kansas Cancer Center, Kansas City, Kansas
| | - Lisa M Harlan-Williams
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Easwari Kumaraswamy
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Roy A Jensen
- The University of Kansas Cancer Center, Kansas City, Kansas.
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
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Walsh MF, Ritter DI, Kesserwan C, Sonkin D, Chakravarty D, Chao E, Ghosh R, Kemel Y, Wu G, Lee K, Kulkarni S, Hedges D, Mandelker D, Ceyhan-Birsoy O, Luo M, Drazer M, Zhang L, Offit K, Plon SE. Integrating somatic variant data and biomarkers for germline variant classification in cancer predisposition genes. Hum Mutat 2018; 39:1542-1552. [PMID: 30311369 PMCID: PMC6310222 DOI: 10.1002/humu.23640] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/29/2018] [Accepted: 08/30/2018] [Indexed: 12/20/2022]
Abstract
In its landmark paper about Standards and Guidelines for the Interpretation of Sequence Variants, the American College of Medical Genetics and Genomics (ACMG), and Association for Molecular Pathology (AMP) did not address how to use tumor data when assessing the pathogenicity of germline variants. The Clinical Genome Resource (ClinGen) established a multidisciplinary working group, the Germline/Somatic Variant Subcommittee (GSVS) with this focus. The GSVS implemented a survey to determine current practices of integrating somatic data when classifying germline variants in cancer predisposition genes. The GSVS then reviewed and analyzed available resources of relevant somatic data, and performed integrative germline variant curation exercises. The committee determined that somatic hotspots could be systematically integrated into moderate evidence of pathogenicity (PM1). Tumor RNA sequencing data showing altered splicing may be considered as strong evidence in support of germline pathogenicity (PVS1) and tumor phenotypic features such as mutational signatures be considered supporting evidence of pathogenicity (PP4). However, at present, somatic data such as focal loss of heterozygosity and mutations occurring on the alternative allele are not recommended to be systematically integrated, instead, incorporation of this type of data should take place under the advisement of multidisciplinary cancer center tumor-normal sequencing boards.
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Affiliation(s)
- Michael F Walsh
- Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | | | | | | | | | | | | | - Yelena Kemel
- Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Gang Wu
- St. Jude Children's Hospital, Memphis, Tennessee, USA
| | - Kristy Lee
- University of North Carolina, Chapel Hill, North Carolina, USA
| | | | - Dale Hedges
- St. Jude Children's Hospital, Memphis, Tennessee, USA
| | - Diana Mandelker
- Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | | | - Minjie Luo
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Liying Zhang
- Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Kenneth Offit
- Memorial Sloan Kettering Cancer Center, New York City, New York, USA
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