Friday, November 25, 2011

What exactly is this BRCA gene mutation?

What exactly is this BRCA gene mutation? How is it related to cancers?

All of the cells that make up your body divide and grow throughout your life. Cells are replaced that wear out or are injured.  When cells divide normally, they follow their genetic instructions on how fast to grow and when to stop.  But cancer grows when this normal process is disrupted. Instead of following orders, the cells begin to grow abnormal or out of control. It might start with just a few abnormalities.  This doesn't mean cancer.  However this abnormal cell growth left unchecked, will lead to cancer.

Everyone has these genes.  Actually, we have two copies of each gene, a BRCA1 and BRCA2 from your mother and also one of each from your father. As long as at least one gene in each set works normally, cancer won’t form in your breasts or ovaries. The two copies of each gene act as a backup for the other; if one is damaged, the other still handles repairs.  However, if either BRCA1 or BRCA2 are damaged, cancer is free to grow. This damage can come from exposure to any number of the known carcinogens a person experience in a lifetime.  This is how people born with two normal copies of each BRCA gene can develop breast or ovarian cancer. 

However in our family, some people are not born with normal BRCA genes.  I inherited an abnormal genetic change, called a "mutation," on my BRCA1 gene.  Because we have two sets of these genes, I still have the working set that I inherited from my mom; I just lack the back up protection. 

This leads to a much higher risk of developing breast and ovarian.  The general population has a 12% risk of developing breast cancer over their lifetime.  Those with a mutation on their BRCA genes, instead have an 87% lifetime risk.  The general population has a 2% risk of developing ovarian cancer, BRCA positive have 54% risk.
People with an inherited gene change have a 50% chance of passing the mutation to each of their children.  My girls have 2 sets of both of these genes; one set from me, one set from Mitch.  From me, they could have gotten the perfectly normal one that I received from my mom.  However, there is a risk that they may have gotten my mutated genes as well. 

The only way to know for sure if a person has these mutated genes, is for a genetic test to be performed.  The company Myriad has a patent on these genes and is the only place outside of medical studies that this test can be performed.  I have some strong opinions on Myriad and their patents that I will save for another post.

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