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Biology and Genetics - BRCA1/2 Hereditary Breast Cancer Genes

Worldwide, women have a 10% risk of developing breast cancer within their lifetime, or up to age 80 years, making breast cancer the most common carcinoma in women. 

The mapping of two genes, BRCA1 (an abbreviation for Breast Cancer 1) and BRCA2, lead to the discovery that any mutations in either one of these two genes account for approximately 5-10% of breast cancer cases and 10% of ovarian cancer cases.  Patients with hereditary breast cancer inherit a mutated BRCA1 or BRCA2 gene putting them at a higher risk of developing cancer. The likelihood of getting the disease may also be influenced by other genes as well as by the environment.

Estimates of the population prevalence of the BRCA gene mutations have ranged from 1 in 300 women to 1 in 500, except in several sub-populations known to harbor a much higher rate of mutation.  Several risk management options are available to carriers of BRCA1 and BRCA2 gene mutations.  These are surveillance, chemoprevention, and prophylactic surgery. It is important to note that no risk management option will offer complete protection against cancer and a decrease in breast cancer risk does not necessary mean a reduction in mortality.  Evidently, careful consideration of the risks, benefits, and strength of evidence of each risk management strategy is essential before making any risk management decision.

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Contributor: Jessica Dennis

Last reviewed: June 2, 2010


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