Since 1994, many thousands of women with breast cancer from families severely affected with the disease have been tested for inherited mutations in BRCA1 and BRCA2. The vast majority of those patients were told that their gene sequences were normal.
With the development of modern genomics sequencing tools, the discovery of additional genes implicated in breast cancer and the change in the legal status of genetic testing for BRCA1 and BRCA2, it is now possible to determine how often families in these circumstances actually do carry cancer-predisposing mutations in BRCA1, BRCA2, or another gene implicated in breast cancer, despite the results of their previous genetic tests.
This was the challenge addressed by Mary-Claire King, Ph.D., American Cancer Society Professor of Medicine and Genome Sciences, and Tomas Walsh, Ph.D., Associate Research Professor of Medical Genetics, both at the University of Washington, Seattle. They conducted complete genomic sequencing of all genes implicated in breast cancer on DNA samples from breast cancer patients who had normal BRCA1 and BRCA2 commercial test results. The commercial testing occurred because the patients had a severe family history of breast cancer, defined as a family with three or more relatives affected by breast or ovarian cancer.
The results were presented today, Oct. 24, by Dr. Walsh at the American Society of Human Genetics 2013 meeting in Boston.
The researchers found that over 25 percent of index patients with normal results from commercial testing of BRCA1 and BRCA2, but with families severely affected by breast cancer, could be resolved by sequencing all genes known to be involved in breast cancer.
Sequencing was carried out using BROCA, an openly available, targeted capture and genomic sequencing approach that was developed and validated by Drs. Walsh and King in 2010. BROCA detects all single base substitutions, insertions and deletions and copy number varia
|Contact: Cathy Yarbrough|
American Society of Human Genetics