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Reclassification of BRCA1 and BRCA2 variants of uncertain significance: a multifactorial analysis of multicentre prospective cohort
  1. Jee-Soo Lee1,2,
  2. Sohee Oh3,
  3. Sue Kyung Park4,
  4. Min-Hyuk Lee5,
  5. Jong Won Lee6,
  6. Sung-Won Kim7,
  7. Byung Ho Son6,
  8. Dong-Young Noh8,
  9. Jeong Eon Lee9,
  10. Hai-Lin Park10,
  11. Man Jin Kim2,
  12. Sung Im Cho2,
  13. Young Kyung Lee1,11,
  14. Sung Sup Park2,
  15. Moon-Woo Seong2,8
  1. 1 Department of Laboratory Medicine, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea
  2. 2 Department of Laboratory Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea
  3. 3 Department of Biostatistics SMG-SNU Boramae Medical Center, Seoul, Republic of Korea
  4. 4 Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
  5. 5 Department of Surgery, College of Medicine, Soonchunhyang University, Seoul, Republic of Korea
  6. 6 Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seongnam, Republic of Korea
  7. 7 Department of Surgery, Seoul National University Bundang Hospital, Seoul, Republic of Korea
  8. 8 Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
  9. 9 Department of Surgery, Samsung Medical Center, Sungkyunkwan University, Seoul, Republic of Korea
  10. 10 Department of Surgery, Kangnam CHA Hospital, Seoul, Republic of Korea
  11. 11 Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Republic of Korea
  1. Correspondence to Professor Moon-Woo Seong, Department of Laboratory Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; mwseong{at}


Background BRCA1 and BRCA2 (BRCA1/2) variants classified ambiguously as variants of uncertain significance (VUS) are a major challenge for clinical genetic testing in breast cancer; their relevance to the cancer risk is unclear and the association with the response to specific BRCA1/2-targeted agents is uncertain. To minimise the proportion of VUS in BRCA1/2, we performed the multifactorial likelihood analysis and validated this method using an independent cohort of patients with breast cancer.

Methods We used a data set of 2115 patients with breast cancer from the nationwide multicentre prospective Korean Hereditary Breast Cancer study. In total, 83 BRCA1/2 VUSs (BRCA1, n=26; BRCA2, n=57) were analysed. The multifactorial probability was estimated by combining the prior probability with the overall likelihood ratio derived from co-occurrence of each VUS with pathogenic variants, personal and family history, and tumour characteristics. The classification was compared with the interpretation according to the American College of Medical Genetics and Genomics–Association for Molecular Pathology (ACMG/AMP) guidelines. An external validation was conducted using independent data set of 810 patients.

Results We were able to redefine 38 VUSs (BRCA1, n=10; BRCA2, n=28). The revised classification was highly correlated with the ACMG/AMP guideline-based interpretation (BRCA1, p for trend=0.015; BRCA2, p=0.001). Our approach reduced the proportion of VUS from 19% (154/810) to 8.9% (72/810) in the retrospective validation data set.

Conclusion The classification in this study would minimise the ‘uncertainty’ in clinical interpretation, and this validated multifactorial model can be used for the reliable annotation of BRCA1/2 VUSs.

  • brca1
  • brca2
  • variant of uncertain significance
  • breast cancer

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  • Contributors J-SL, M-WS and SSP designed the study. J-SL, MJK and SIC validated the mutations and analysed the genetic data. J-SL and SO performed the statistical analysis. SKP, MHL, JWL, S-WK, BHS, D-YN, JEL, H-LP and YKL provided patients’ clinical information. J-SL and MWS wrote the manuscript.

  • Funding This study was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology (NRF-2010-0014167 and 2009-0093820).

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Seoul National University Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.