BRCA2 and breast cancer: Onco-suppressors BC gene 1 (BRCA1_OMIM 113705) and BC gene 2 (BRCA2_OMIM 600185) are the main genes in HBOC syndrome and play a role in response to DNA damage, and their pathogenic variant carriers account for around 30–50% of cases having a higher risk of HBOC [4].