Novel and recurrent BRCA2 mutations in Italian breast/ovarian cancer families widen the ovarian cancer cluster region boundaries to exons 13 and 14

abstract

Hereditary breast and ovarian cancer are mainly linked to mutations in BRCA1 and BRCA2 genes which confer a similar cumulative risk of developing breast cancer. Importantly, while BRCA2 mutation carriers generally have a lower cumulative risk for ovarian cancer, mutations clustered in the central portion of BRCA2 are associated with a higher proportion of ovarian compared with breast cancer cases. The boundaries of this ovarian cancer cluster region (OCCR) have been tentatively defined within a 3.3 kb region of BRCA2 exon 11, and herein, we reassessed these boundaries using our series of Italian breast/ovarian cancer families.
We used direct sequencing to investigate BRCA mutations in 367 breast/ovarian cancer families. We also studied the association between the location of the mutations and the ovarian cancer phenotype in our cohort of BRCA2-mutated families. We observed the novel c.7309_7309delA frameshift mutation and the c.7007G>A deleterious mutation in BRCA2 exons 14 and 13, respectively, in five independent Italian families characterized by a high proportion of ovarian cancer cases. Of note, a significantly higher proportion of ovarian versus breast cancer cases was associated not only with mutations in the previously defined OCCR (OR = 5.91; p = 0.004), but also with the exon 13-14 region (OR = 7.37; p = 0.001) in our BRCA2-mutated families. Our data provide initial evidence for a novel putative OCCR in BRCA2 exons 13-14.