There is increased awareness of hereditary breast and ovarian cancer syndrome (HBOC) among medical professionals, and it has become clear that a relatively high number of Japanese patients have hereditary breast cancer with pathological variants in BRCA1 or BRCA2. [12] A nationwide registry of BRCA genetic test examinees has begun, and the clinical and genetic characteristics of BRCA1 and BRCA2 pathological variant carriers are starting to be clarified. This evidence concerns the gene BRCA1 and breast carcinoma.