Genetic Counseling for Families With Inherited Susceptibility to Breast and Ovarian Cancer

TLDR

BRCA1, located on chromosome 17q12‑21, is a gene whose mutations confer an ~85 % lifetime risk of breast cancer and an increased but uncertain risk of ovarian cancer, with an estimated carrier frequency of 1 in 200–400 American women, and while current testing is limited to rare families, this work anticipates the challenges of future population screening. The study aimed to prospectively identify BRCA1 mutation carriers within linked families and to offer this information to an extended family by developing a protocol addressing the clinical and logistical issues of service delivery. The authors implemented a protocol that enabled prospective identification of likely carriers in linked families and facilitated the delivery of genetic counseling and testing services to the target family. They identified several families with linkage between breast and/or ovarian cancer and BRCA1‑flanking markers, and their experience highlights the complexities that will arise as population screening for BRCA1 mutations becomes feasible.

Abstract

Efforts are under way to isolate a gene (BRCA1) on chromosome 17q12-21. Mutations in this gene predispose women to breast and ovarian cancer. Women with germline mutations in BRCA1 are estimated to have an 85% lifetime risk of developing breast cancer and an increased but as yet undetermined risk of ovarian cancer. It is estimated that one in 200 to 400 American women may be carriers of BRCA1 mutations. We have identified several families that show linkage between breast and/or ovarian cancer and genetic markers that flank BRCA1. It is now possible, within these linked families, to prospectively identify family members likely to be carrying BRCA1 mutations. Because of profound and immediate clinical ramifications, we offered to provide this information to one such extended family. To provide information to this family, we developed a protocol to address the many issues that arise in the delivery of these services. Although testing for BRCA1 mutation carriers is currently limited to very rare families being analyzed for research purposes, this experience presages the complexities of the much larger scale availability of population screening for BRCA1 mutations, which is likely to become a reality in the next few years.