Compared with sporadic breast cancers, the expression levels of BRCA2 were significantly elevated in BRCA1-mutated samples (p = 5e-4, t-test), the expression level of BRCA1 was significantly elevated in BRCA2-mutated cancers (p = 9e-5, t-test), and the expression level of RAD51 was significantly elevated in both BRCA1-mutated and BRCA2-mutated cancers (p = 5e-7 and p = 1e-4, t-test) (Additional file 1: Figure S6). Here, BRCA2 is linked to cancer.