BRCA 1

BRCA1 Mutation Test

Mutations in the BRCA1 and BRCA2 genes profoundly increase the risk of developing breast and/or ovarian cancer among women.

Diagomet DNA test can help identify patients with mutations in BRCA1/BRCA2 genes that predispose them to breast/ovarian cancer

Purpose of the Test

Mutations in BRCA1 or BRCA 2 genes will help predict the risk of developing breast and ovarian cancer.

Background

Among a number of genetic risk factors, mutations in the BRCA 1 and BRCA 2 have been associated with a high incidence of breast cancer.1 These tumor suppressing genes can have inherited or accumulated mutations that have been linked to about 5-10% of breast cancer cases, though the true risk depends on the family history.3 BRCA1/BRCA2 genes have been linked to almost 45% of sporadic breast cancers and about 85% of breast cancer and 60% ovarian cancer in families.2 Screening for clinically relevant mutations, those that cause some amino acid change, can provide valuable information needed for preventive monitoring and therapy.4 The whole gene, 23 exons for BRCA 1 and 26 exons for BRCA 2, is examined for any deletions, insertions, or changes that result in nonfunctional proteins that may induce breast cancer.3 In high-risk patients early detection of the disease through regular mammograms, breast self-examinations, and genetic testing can assist in detecting the cancer when as it arises and has not spread.1

It has recently been shown that breast cancer patients with mutations in BRCA1/2 show a positive response to PARP inhibitors, a cellular enzyme.5 Hence BRCA status will be a useful marker for patient selection in clinical trials and also subsequently for identifying patients who are likely to benefit from PARP inhibitors.

Exceptions

Not all patients with BRCA1 or BRCA 2 mutations will develop breast cancer.

Test Method

PCR and sequencing of the BRAC1 coding exons from the patient blood derived DNA.

Sample Requirements

We require 5-8mls of blood collected in EDTA containing tubes. Blood should be shipped within 48 hours after collection of blood on ice. You may send 10ug of genomic DNA derived from blood, prepared using a Qiagen blood DNA preparation kit (or equivalent) and should have an A260/A280 value of 1.8.

References

1. Antoniou, A., Pharoah, P. D., Narod, S., Risch, H. A., Eyfjord, J. E., Hopper, J. L, Loman, N, & Olsson, H. Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history:a combined analysis of 22 studies; Am. J. Hum. Genet.72 1117-1130 (2003).

2. Brose, M. S., Rebbeck, T. R., Calzone, K.A., Stopfer, J. E., Nathanson, K.L, & Weber, B. L. Cancer risk estimates for BRCA1 mutation carriers identified in a risk evaluation program. J. Natl. Cancer Inst. 94 1365-1372 (2002).

3. Fackenthal, J.D, & Olopade, O.I., Breast cancer risk associated with BRCA1 and BRCA2 in diverse populations. Nat Rev Cancer. 7:937-948 (2007).

4. Deffenbaugh, A.M., Frank, T.S., Hoffman, M., Cannon-Albright, L., Neuhausen, S.L. Characterization of common BRCA1 and BRCA2 variants. Genet Test 6:119-121(2002).

5. Helleday, Thomas. "The Underlying Mechanism for the PARP and BRCA Synthetic Lethality: Clearing up the Misunderstandings." Molecular Oncology 5.4 (2011). Oncology Tests