Characterization of Large Genomic Rearrangements in BRCA1 and BRCA2 Genes in a Chinese High-Risk Cohort

Large genomic rearrangements (LGRs) account for at least 10% of the mutations in BRCA1 and 5% of BRCA2 mutations in outbred families with hereditary breast and ovarian cancer. A total of 21 probands with breast cancer who carried BRCA1 or BRCA2 LGRs were identified from a cohort of 4678 Chinese patients. There was a total of 13 BRCA1 LGR carriers and 8 BRCA2 LGR carriers, including 12 large genomic deletions and 1 duplication. Ten and three specific breakpoints from BRCA1 and BRCA2, respectively, were identified by either whole-genome sequencing by nanopore sequencing or long-range PCR. Five of these LGRs were recurrent LGRs. Three LGRs were novel founder LGRs in the southeast Chinese population. Chinese LGR carriers exhibited clinical phenotypes that were generally similar to those of non-LGR mutation carriers. However, there was a notable tendency for triple-negative breast cancer to be more prevalent among Chinese LGR carriers (P = 0.007), largely because of the predominance of BRCA1 mutations. This suggests a potential association that warrants further investigation.