Hereditary breast and ovarian cancer syndrome (Orphanet_145) is an autosomal dominant inherited syndrome caused by mutations in the BRCA1 or BRCA2 genes. Patients are at high risk of developing breast cancer, particularly before the age of fifty, high risk of developing a second primary breast cancer, and high risk of developing both breast and ovarian cancer. Also known as: BRCA1- and BRCA2-associated hereditary breast and ovarian cancer, BRCA1- and BRCA2-associated hereditary breast and ovarian cancer (HBOC), breast-ovarian cancer, familial, susceptibility to, familial breast and ovarian cancer syndrome, familial breast/ovarian cancer (BRCA1, BRCA2), hereditary breast and ovarian cancer, hereditary breast and ovarian cancer syndrome, hereditary breast ovarian cancer syndrome.