Analysis of BRCA1/2 variants of unknown significance in patients with breast cancer from a prospective KOHBRA study

Abstract

Background Genetic testing for BRCA1 and BRCA2 genes is crucial for diagnosing hereditary breast and ovarian cancer syndromes (HBOC). Testing for such genes has been on the rise due to the development of multigene panel tests. However, results classified as variants of uncertain significance (VUS) present challenges to clinicians trying to interpret their functions and choose appropriate management plans.Methods We reviewed a total of 676 breast cancer patients who had VUS on BRCA mutation tests between November 2007 and April 2013 in the KOHBRA study. These results were compared to the ClinVar database. We calculated the incidence and odds ratios for these variants using the Korean Reference Genome Database (KRGDB).Results A total of 58 and 91 distinct VUS in BRCA1 and 2 were identified in the KOHBRA study (comprising 258 and 453 patients, respectively). A total of 27 variants in the KOHBRA study were not registered in the SNP database. Of the BRCA1 VUS, 20 variants were reclassified as benign or likely benign, 4 variants were reclassified as pathogenic or likely pathogenic, and 8 variants remained as VUS according to the ClinVar database. Of the BRCA2 VUS variants, 25 variants were reclassified as benign or likely benign, two variants were reclassified as pathogenic or likely pathogenic, and 33 variants remained as VUS according to the Clinvar database. There were 12 variants with conflicting interpretations of pathogenicity for BRCA1 and 18 variants for BRCA2. Among them, p.Leu1780Pro showed a particularly high odds ratio.Conclusions Six pathogenic variants and one conflicting variant identified using ClinVar could be reclassified as pathogenic variants in this study. Using updated ClinVar and calculating odds ratios can be helpful when reclassifying VUS in BRCA1/2.