The purpose of this study is to collect a blood sample from patients that may be used for research purposes. These blood samples will be used by researchers at this institution to study the causes of breast and ovarian cancer, and to better understand how these cancers develop. We are trying to discover differences in the ways cells work in women with a high genetic risk of developing breast or ovarian cancer. Early data suggest that some genes may be turned on or off in different ways based upon whether or not a woman has a high genetic risk of developing breast or ovarian cancer. The primary objective is to test the hypothesis that BRCA1 haploinsufficiency regulates gene expression on the X chromosome. This hypothesis will be tested by comparing the gene expression profiles of BRCA1 heterozygotes (cases) to an age-matched group of unaffected women who are not BRCA1 mutation carriers (controls).