In 1994, Mary-Claire King, PhD, a University of Washington professor of genome sciences and medicine, discovered the “breast cancer gene,” BRCA1, on chromosome 17, which is responsible for a number of different inherited breast and ovarian cancers. The hunt for a genetic link in breast cancer took 17 years to complete. It began in the early 1970s when the National Cancer Institute (NCI) allowed Dr. King to add a question on family history to its epidemiological study on oral contraceptives and breast cancer risk.

In 1995, scientists identified a second breast-cancer gene, BRCA2, and showed that women inheriting mutations in this or BRCA1 have increased susceptibility to breast and ovarian cancers.