BRCA1 and breast cancer: Hereditary breast and ovarian cancer (HBOC) syndrome is an autosomal dominant genetic disorder that is caused by the predisposition of pathogenic variants in breast cancer gene 1 (BRCA1) and BRCA2. It is characterized by an increased lifetime risk of developing breast cancer, ovarian cancer (OC) and prostate cancer, as well as other cancers to a lower extent, such as pancreatic cancer (1).