BRCA1-related and sporadic ovarian cancer in the same family: implications for genetic testing

Objective. The aim of this study was to present a family with both BRCA1-related and sporadic ovarian cancer and address current difficulties in genetic testing. Methods. BRCA1 mutation detection was performed on a family having four confirmed cases of ovarian cancer, two cases of breast cancer, and one case each of colon, stomach, and prostate cancer. The incidence and types of cancer were consistent with a BRCA1 mutation although previous linkage analysis had excluded this family as being due to BRCA1. Results. A protein-truncating mutation in BRCA1, denoted 2799delAA, was identified in the germline DNA of each of the women affected with breast and ovarian cancer in this family except the proband, who was diagnosed with ovarian cancer at age 65. Conclusions. In an earlier study, which sought to determine the proportion of site-specific ovarian cancer due to BRCA1, the family described in this report was wrongly identified as not being due to BRCA1 when, in fact, all but one of the breast and ovarian cancer cases carry a deleterious BRCA1 mutation. Our analysis suggests that the proband, who was the first of the women in this family to seek genetic counseling, developed ovarian cancer by chance and not as the result of an inherited mutation. We describe the results of our analysis in light of current issues that face clinicians who may be involved in genetic testing for breast and ovarian cancer predisposition.