BRCA1 and BRCA2 are genes that repair damage in cells and prevent them from growing and dividing too rapidly. All of us have two copies of these genes. Mutations in these genes can cause cells to become abnormal and grow in an uncontrolled way.
Having a mutation in one of these genes can increase a woman’s risk of both breast and ovarian cancer. This can mean that a woman has an 80% chance of developing breast and a 35-60% chance of developing ovarian cancer in her lifetime. There’s an increased risk of melanoma too but as yet, the percentage of this increased risk is unknown.
For men, a BRCA2 gene mutation increases the risk of developing prostate cancer and BRCA1/2 gene mutations have also been linked to pancreatic cancer and melanoma in men and women.
Those from Ashkenazi Jewish, Dutch, Icelandic, Norwegian, Pakistani, Polish and Swedish populations are more likely to have a BRCA1/2 gene mutation than some other populations.
How many people do BRCA1/2 gene mutations effect?
It is thought that, in the general population, around 1 in every 1000 people carry a BRCA1/2 gene mutation. This figure is, however, significantly higher in certain backgrounds. For example, it rises to 1 in 40 for people from an Ashkenazi Jewish background.
Why is BRCA1/2 testing important?
There can be benefits to genetic testing, regardless of whether a person receives a positive or a negative result.
The potential benefits of a true negative result, which is where the test results show that you do not carry a mutation, include a sense of relief regarding the future risk of cancer, learning that one's children are not at risk of inheriting the family's cancer susceptibility, and the possibility that special check-ups, tests, or preventive surgeries may not be needed.
A positive test result may bring relief by resolving uncertainty regarding future cancer risk and may allow people to make informed decisions about their future, including taking steps to reduce their cancer risk.
In addition, people who have a positive test result may choose to participate in medical research that could, in the long run, help reduce deaths from hereditary breast and ovarian cancer.
Sometimes genetic testing will not give a clear positive or negative result. Some BRCA1/2 gene mutations are yet to be linked with an increased risk of breast and ovarian cancer, these are known as ‘variants of uncertain significance’ (VUS). Read more about VUS in the section entitled ‘After the test: What’s next?’