The BRCA Genes: What are they, and why are they seemingly in control of my life?
“BRCA” stands for Breast Cancer–creative, I know. There are two BRCA genes: breast cancer susceptibility gene 1 (BRCA1) and breast cancer susceptibility gene 2 (BRCA2). They are tumor suppressor genes, which are essentially in charge of regulating cell division. Mutations in either of these genes are linked to higher chances of developing breast cancer and ovarian cancer.
I inherited a BRCA2 mutation from my mother. The specific mutation, 6056delC, is a frameshift mutation with a missing cytosine that creates a stop codon, preventing the rest of the gene from being written correctly. (Didn’t you love learning all about DNA in high school?) Therefore my tumor suppressor gene doesn’t work; there is nothing preventing cells from dividing rapidly.
People with a BRCA mutation have a much higher chance of being diagnosed with breast cancer and ovarian cancer. According to Myriad Genetics & Laboratories, BRCA carriers have:
- a 33-50% chance of being diagnosed with breast cancer by age 50, compared with the 2% chance of the mutation-free population.
- a 56-87% chance of being diagnosed with breast cancer by age 70, compared with the 7% chance of the mutation-free population.
- a 27-44% chance of being diagnosed with ovarian cancer by age 70, compared with the <2% chance of the mutation-free population.
- For male carriers, there is a 6% chance of being diagnosed with breast cancer by age 70, compared with the .05% chance of the mutation-free population.
How do you know if you have a BRCA mutation?
Since the BRCA genes are hereditary, a family history of breast cancer or ovarian cancer should be the first sign of a possible BRCA mutation. If these type of cancers appear sporadically in your family (say your grandmother on your father’s side had breast cancer and your aunt on your mother’s side has ovarian cancer) the likelihood of there being a BRCA gene at work is probably not very high. However, if your family history is strong or certain individuals (like my mom, for example) have had repeated instances of cancer, it might be a sign of a BRCA mutation.
If you are concerned, talk to a genetic counselor. A genetic counselor will do risk assessment based on your family medical history. A blood test determines if an individual has a BRCA mutation. In my case, the lab knew what kind of mutation they were looking for (based on my mom’s results) so they only did a single site analysis.
Once my test results came back, my genetic counselor was able to talk to me about my options. She’s been a great resource for me.
Who is usually a BRCA carrier?
Anyone can be a BRCA carrier. Some people have BRCA mutations and don’t even know it because cancer has (thankfully) not affected them. Men are just as likely as women to have a BRCA mutation, and even though breast cancer is far less likely to strike them, they can still pass that mutation onto their children.
Certain populations are more likely to have BRCA mutations. Ashkenazi Jews, for example, have a higher occurrence of BRCA mutations compared to that of the general population. One study found that in a group of 5,318 participating Ashkenazi Jews, 120 carried one of three particular BRCA mutations. (I always found this to be interesting: I am an Ashkenazi Jew, but my BRCA mutation is from my non-Jewish side!)