ABSTRACT
This study defines the incidence of BRCA1 mutations among patients seen in a clinically relevant population drawn from high-risk breast cancer evaluation clinics. Genomic DNA samples were obtained from 263 women with breast cancer and used for mutation screening. BRCA1 mutations were identified in 16% of women with a family history of breast cancer, with the frequency of mutations significantly higher among women from families with a history of both breast and ovarian cancer. Among family members, an early average age of breast cancer diagnosis, the presence of ovarian cancer in the families, the presence of breast and ovarian cancer in a single individual, and Ashkenazi Jewish ancestry were all predictors of detecting a BRCA1 mutation. No association was found between the presence of bilateral breast cancer or the number of breast cancers in a family and the detection of a BRCA1 mutation, or between the position of the mutation in the BRCA1 gene and the presence of ovarian cancer in the family.
