Four high-penetrance genes are tested in clinical practice when genetic susceptibility to breast cancer is suspected: BRCA1, BRCA2, TP53 and CDH1. Germline mutations in BRCA1 and TP53 are predominantly associated with IDC, BRCA2 mutations are associated with both ductal and lobular tumors, while mutations in CDH1 are exclusively associated with ILC. Here, BRCA1 is linked to breast cancer.