As the NCCN guideline currently recommends genetic counseling and genetic testing for any patient with high risk 10% or more of mutation, the prevalence of BRCA1/2 mutations in high-risk breast cancer patients without family history of breast or ovarian cancer—noted in this study—may play a key role for genetic testing criteria in Korean breast cancer patients with high risk of mutation. The gene discussed is BRCA1; the disease is breast cancer.