Familial breast cancer, or breast cancer that runs in families. About 20-25% of breast cancer patients have at least one relative with breast cancer, which means that two related members of a family have breast cancer, which is called familial breast cancer. Breast cancer with a clear genetic predisposition is called hereditary breast cancer. Hereditary breast cancer accounts for 5-10% of the total breast cancer population. Most hereditary breast cancers are familial in nature; however, a small percentage of hereditary breast cancers are sporadic in their epidemiological distribution and have no family history. This may be because the mutated genes associated with breast cancer are carried by male family members who are unable to develop a breast cancer phenotype. Most hereditary breast cancers are associated with BRCA-1 and BRCA-2. The breast cancer susceptibility genes now known are p53 and PTEN in addition to BRCA-1 and BRCA-2. Breast cancers associated with mutations in these genes are all classified as hereditary breast cancer. Domestic and international studies have shown that there is a correlation between BRCA1 gene and familial and early-onset breast cancer in China, and the detection of BRCA1 gene mutation in high-risk groups is beneficial to assess the risk of breast cancer development. To date, more than 1500 germline mutations and polymorphisms in the BRCA1 gene have been reported. Studies have confirmed that the incidence of familial BRCA1 germline mutations in Chinese women is about 8%-10%, and the risk of breast cancer in women with BRCA1 germline mutations is 60%-80%, which is about 10 times higher than the risk in the general population. By testing patients with family history of breast cancer and their normal female members for BRCA1 germline mutations, it is beneficial to detect normal female members carrying BRCA1 germline mutations, and by closely following up and monitoring the high-risk group carrying BRCA1 germline mutations, it is beneficial to early detection, early diagnosis and early treatment of breast cancer, thus obtaining better treatment results.