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Hu C, Huang H, Na J, Lumby C, Abozaid M, Holdren MA, Rao TJ, Karam R, Pesaran T, Weyandt JD, Csuy CM, Seelaus CA, Young CC, Fulk K, Heidari Z, Morais Lyra PC, Couch RE, Persons B, Polley EC, Gnanaolivu RD, Boddicker NJ, Monteiro ANA, Yadav S, Domchek SM, Richardson ME, Couch FJ. Functional analysis and clinical classification of 462 germline BRCA2 missense variants affecting the DNA binding domain. Am J Hum Genet 2024; 111:584-593. [PMID: 38417439 PMCID: PMC10940015 DOI: 10.1016/j.ajhg.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 02/01/2024] [Accepted: 02/01/2024] [Indexed: 03/01/2024] Open
Abstract
Variants of uncertain significance (VUSs) in BRCA2 are a common result of hereditary cancer genetic testing. While more than 4,000 unique VUSs, comprised of missense or intronic variants, have been identified in BRCA2, the few missense variants now classified clinically as pathogenic or likely pathogenic are predominantly located in the region encoding the C-terminal DNA binding domain (DBD). We report on functional evaluation of the influence of 462 BRCA2 missense variants affecting the DBD on DNA repair activity of BRCA2 using a homology-directed DNA double-strand break repair assay. Of these, 137 were functionally abnormal, 313 were functionally normal, and 12 demonstrated intermediate function. Comparisons with other functional studies of BRCA2 missense variants yielded strong correlations. Sequence-based in silico prediction models had high sensitivity, but limited specificity, relative to the homology-directed repair assay. Combining the functional results with clinical and genetic data in an American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP)-like variant classification framework from a clinical testing laboratory, after excluding known splicing variants and functionally intermediate variants, classified 431 of 442 (97.5%) missense variants (129 as pathogenic/likely pathogenic and 302 as benign/likely benign). Functionally abnormal variants classified as pathogenic by ACMG/AMP rules were associated with a slightly lower risk of breast cancer (odds ratio [OR] 5.15, 95% confidence interval [CI] 3.43-7.83) than BRCA2 DBD protein truncating variants (OR 8.56, 95% CI 6.03-12.36). Overall, functional studies of BRCA2 variants using validated assays substantially improved the variant classification yield from ACMG/AMP models and are expected to improve clinical management of many individuals found to harbor germline BRCA2 missense VUS.
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Affiliation(s)
- Chunling Hu
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Huaizhi Huang
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Jie Na
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | - Carolyn Lumby
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Mohamed Abozaid
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Megan A Holdren
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Tara J Rao
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | | | | | | | | | | | | | - Kelly Fulk
- Ambry Genetics, Aliso Viejo, CA 92656, USA
| | | | | | - Ronan E Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Benjamin Persons
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Eric C Polley
- Department of Public Health Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Rohan D Gnanaolivu
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | - Nicholas J Boddicker
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | | | - Siddhartha Yadav
- Department of Medical Oncology, Mayo Clinic, Rochester, MN 55902, USA
| | - Susan M Domchek
- Division of Hematology Oncology, Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Fergus J Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA; Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA.
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Huang H, Couch RE, LaDuca H, Yadav S, Polley EC, Boddicker NJ, Na J, Gnanaolivu RD, Goldgar DE, Pesaran T, Hart SN, Dolinsky JS, Palmer JR, Teras L, Patel AV, Ruddy KJ, Olson JE, Vachon CM, Kraft P, Yao S, Trentham-Dietz A, Nathanson KL, Weitzel JN, Domchek SM, Couch FJ, Hu C. Abstract A003: Risks of ductal carcinoma in situ of the breast associated with pathogenic variants in cancer predisposition genes. Cancer Prev Res (Phila) 2022. [DOI: 10.1158/1940-6215.dcis22-a003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Abstract
Introduction: The relationship between germline pathogenic variants (PVs) in cancer predisposition genes and ductal carcinoma in situ (DCIS) is not well established. The objective of this study is to determine the risks of DCIS and contralateral breast cancer among women with DCIS associated with germline PVs in cancer predisposition genes. Methods: Associations between pathogenic variants in 11 cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, MSH6, PALB2, RAD51C, and RAD51D) and DCIS were determined in case control analyses of a population-based cohort of 3876 women with DCIS and age-matched unaffected women, and in a clinical cohort of 9887 DCIS cases undergoing clinical genetic testing at Ambry Genetics and unaffected reference controls. The incidence of contralateral breast cancer risk in BRCA1, BRCA2, and PALB2 PV carriers with DCIS was also evaluated in a time-to-event analysis. Results: The mean age at diagnosis of DCIS was 50 years in the clinical testing cohort and 59 years in the population-based cohort. The frequency of PVs in 11 predisposition genes among DCIS cases was 6.9% in the clinical testing cohort and 4.9% in the population-based cohort. PVs in ATM, BRCA1, BRCA2, CHEK2, MSH6, PALB2, and RAD51D were associated with significantly increased risks (Odds Ratio (OR) >2) of DCIS in the clinical testing cohort whereas only PVs in BRCA1, CHEK2, PALB2, and ATM were associated with significantly increased risks of DCIS in the population-based cohort. The cumulative incidence of contralateral breast cancer among BRCA1, BRCA2, and PALB2 PV carriers with DCIS was 11% in 5-years and 20% in 15-years. Conclusions: This study provides new insights into PVs that predispose to DCIS. In addition, it establishes an increased risk of contralateral breast cancer risk among women with DCIS who are carriers of PVs in BRCA1, BRCA2, or PALB2. These findings will guide surveillance and risk reducing strategies in germline PV carriers with DCIS.
Citation Format: Huaizhi Huang, Ronan E. Couch, Holly LaDuca, Siddhartha Yadav, Eric C. Polley, Nicholas J. Boddicker, Jie Na, Rohan D. Gnanaolivu, David E. Goldgar, Tina Pesaran, Steven N. Hart, Jill S. Dolinsky, Julie R. Palmer, Lauren Teras, Alpa V. Patel, Kathryn J. Ruddy, Janet E. Olson, Celine M. Vachon, Peter Kraft, Song Yao, Amy Trentham-Dietz, Katherine L. Nathanson, Jeffrey N. Weitzel, Susan M. Domchek, Fergus J. Couch, Chunling Hu. Risks of ductal carcinoma in situ of the breast associated with pathogenic variants in cancer predisposition genes [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr A003.
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Affiliation(s)
| | | | | | | | | | | | - Jie Na
- 1Mayo Clinic, Rochester, MN,
| | | | | | | | | | | | | | | | | | | | | | | | | | - Song Yao
- 8Roswell Park Comprehensive Cancer Center, Buffalo, NY,
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