Genetic testing for BRCA mutations

BRCA1 and BRCA2 are human genes that belong to a class of genes known as tumor suppressors. Mutation of these genes has been linked to hereditary breast and ovarian cancer. – National Cancer Insitute

A woman’s risk of developing breast and/or ovarian cancer is greatly increased if she inherits a deleterious (harmful) BRCA1 or BRCA2 mutation. – National Cancer Insitute

Having a BRCA gene mutation is uncommon. Inherited BRCA gene mutations are responsible for about 5 percent of breast cancers and about 10 to 15 percent of ovarian cancers. – Mayo Clynic

My mom, who was diagnosed with ovarian cancer in June ’12, just got the results of her genetic tests. The news is good, in that there were no mutations detected, however the test looked for only three mutations/variants on the BRCA1 gene (300T/G, 4153delA, and 5382insC). Only three out of hundreds of different types of mutations that have been identified! And the test only checked the BRCA1 gene. I’m inclined to chalk this up to the fact that she’s in Europe and maybe genetic testing isn’t as common practice there as it is in the US, but nonetheless I am dumbfounded. She has submitted another blood sample with a request to run a more thorough analysis.

This made me take a closer look at my own negative BRACAnalysis test results. The tests done were: BRCA1 sequencing (5-site rearrangement panel) and BRCA2 sequencing. The narrative explains: “there are other, uncommon genetic abnormalities in BRCA1 and BRCA2 that this test will not detect. This result, however, rules out the majority of abnormalities believed to be responsible for hereditary susceptibility to breast and ovarian cancer.”

So … what now? As far as further testing (BRACAnalysis Rearrangement TestBART), I’m not sure that it is necessary. Per Myriad: “there is, on average, a less than 1% chance that BART will identify a mutation in a patient who has already had a negative result from Comprehensive BRACAnalysis.” I’m going to wait and see what my mom’s results are. In any case, this doesn’t change my decision to move forward with the prophylactic bilateral mastectomy in January, but creeps back another variable thought to have already been checked off the list.

Side note: In this blog, I’m only addressing my choice to have a prophylactic bilateral mastectomy to reduce my risk of breast cancer. I am conscious of our family’s history with ovarian cancer. That is another topic for another day. At this time, I have decided to keep a close eye and wait until I hit menopause to seriously consider an oophorectomy.

Update 10/16: Mom’s second genetic test results, which also checked for PTEN mutations, were negative. I gave blood for BART anyway and my results were also negative.

Advertisements

One thought on “Genetic testing for BRCA mutations

  1. Pingback: BRCA mutations and me | Saying NOPE to Breast Cancer

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s