Genetic Risks
(Reproduced with permission from Ovarian Cancer Australia)
The BRCA1 and BRCA2 genes are thought to be responsible for nearly all cases of familial ovarian cancer and approximately half of all cases of familial breast cancer.
Genes are small pieces of DNA, the material that acts as a master "blue print" for all the cells in the body. Your genes determine such things as what colour hair and eyes you have, how tall you are, and what you look like on the inside. They also instruct the body how to build all the chemical substances in the body and keep it running smoothly. Sometimes there is an error in one of your genes that will cause it not to do its job properly. This can lead to disease and is called a "genetic defect".
The BRCA1 and BRCA2 genes make a chemical substance that helps your body prevent cancer. Most men and women have two normal copies of BRCA1 gene or BRCA 2 gene, both of which produce this cancer preventing substance. Some women have a genetic defect in one copy of their two BRCA 1 genes, or BRCA 2 gene and don't produce a normal amount of this cancer fighting substance. These women are at high risk of getting breast or ovarian cancer, as high as 50 - 80% risk for breast cancer over the course of their lifetime.
You inherit one copy of each of your genes from your mother and a second copy of each of your genes from your father. Even though you may look or behave more like one of your parents than the other. If one of your parents has a defective BRCA1 gene or BRCA 2 gene, there is a 50% chance you may inherit their defective copy and a 50% chance you may inherit their normal copy. If you inherit a defective BRCA 1gene or BRCA 2 gene, then each of your children has a 50% chance of inheriting it from you. Either your mother or father can pass on the BRCA gene. (Even though your father doesn't have ovaries).
Although there is a genetic test to detect a defective BRCA1 or BRCA2 gene, only women with strong family history of ovarian or breast cancer should consult with their physicians about the test. A sample of DNA from an affected relative will also be necessary for the test to be performed.
When to consider testing:
(These are the recommendations of the NBCC of Australia)
2 or more first or second degree relatives with breast or ovarian cancer plus:
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Additional relatives with breast or ovarian cancer.
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Breast and ovarian cancer in same person
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Bilateral breast cancer
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Breast cancer in a male relative.
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Breast cancer diagnosed before age 40 years.
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Ovarian cancer diagnosed before age 50 years.
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Jewish ancestry.
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Member of family with confirmed BRCA abnormality.
Note: A first degree relative is defined as mother, sister or daughter. A second degree relative is defined as aunt, nephew, niece, or grandparent.
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