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Mesman RLS, Calléja FMGR, Hendriks G, Morolli B, Misovic B, Devilee P, van Asperen CJ, Vrieling H, Vreeswijk MPG. The functional impact of variants of uncertain significance in BRCA2. Genet Med 2018; 21:293-302. [PMID: 29988080 PMCID: PMC6752316 DOI: 10.1038/s41436-018-0052-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/20/2018] [Indexed: 11/30/2022] Open
Abstract
Purpose Genetic testing has uncovered large numbers of variants in the BRCA2 gene for which the clinical significance is unclear. Cancer risk prediction of these variants of uncertain significance (VUS) can be improved by reliable assessment of the extent of impairment of the tumor suppressor function(s) of BRCA2. Methods Here, we evaluated the performance of the mouse embryonic stem cell (mESC)-based functional assay on an extensive set of BRCA2 missense variants. Results Whereas all 20 nonpathogenic (class 1/2) variants were able to complement the cell lethal phenotype induced by loss of endogenous mouse Brca2, only 1 out of 15 pathogenic (class 4/5) variants (p.Gly2609Asp) was able to do so. However, in this variant the major tumor suppressive activity of BRCA2, i.e., homology directed repair (HDR), was severely abrogated. Among 43 evaluated VUS (class 3), 7 were unable to complement the lethal phenotype of mouse Brca2 loss while 7 other variants displayed a more severe reduction of HDR activity than observed for class 1/ 2 variants. Conclusion The mESC-based BRCA2 functional assay can reliably determine the functional impact of VUS, distinguish between pathogenic and nonpathogenic variants, and may contribute to improved cancer risk estimation for BRCA2 VUS carriers.
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Affiliation(s)
- Romy L S Mesman
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Fabienne M G R Calléja
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Giel Hendriks
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Bruno Morolli
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Branislav Misovic
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Peter Devilee
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands.,Department of Pathology, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Christi J van Asperen
- Department of Clinical Genetics, Leiden University Medical Center, PO Box 9600, 2300RC, Leiden, The Netherlands
| | - Harry Vrieling
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands
| | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands.
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