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Understanding Genetic Mutations

“I want to do genetic testing to see if I have the cancer gene”. This is a common phrase I hear from my patients as a genetic counselor working in the cancer space. So much so, that I have even incorporated it into my sessions to ensure that my patients fully understand genetic testing, and what it is actually looking for. This is a phrase that most of my patients have heard before, and one that makes sense to them. If you have the cancer gene, then you are at an increased risk for cancer. If you don’t have the cancer gene, then you are at general population risk. Makes sense. However, this is not actually correct.

These “cancer genes” (e.g. BRCA1 and BRCA2) are genes that every individual in the world has, and they are very important genes that keep us healthy. When functioning properly, these genes actually protect us from cancer, acting as a tumor suppressor. As a tumor suppressor, their job is really in their name, as they function to stop cancer from developing within our bodies (like I said, important genes to have).

What causes an increased risk for cancer is an individual having a mutation (also called variant) within one of these genes, which is like a spelling mistake in the DNA. When these tumor suppressor genes like BRCA1 and BRCA2 have a mutation within them, they are not able to function properly and cannot provide as much protection to cancer as they normally would.

Through genetic testing, we are able to analyze these genes via a saliva or blood sample, and “spell check” these genes like you would a sentence on Microsoft Word. If a mutation is then identified on this testing, we would know that the individual is at an increased risk for cancer, with the specific cancer risks depending on which gene has the mutation. For the individual themselves, a physician would be able to use this information to make medical management recommendations which can include increased cancer screening or preventative surgeries.

As this testing is looking for mutations which are associated with hereditary (inherited) cancer conditions, this information would also be important for any family members. Any blood relative, male or female, of an individual who has a mutation identified on genetic testing would then be at risk of having that same mutation themselves. As such, family members may use this information to pursue their own genetic testing, which can then help determine their own medical management recommendations, or ensure that they did not inherit the same mutation, and would not be at an increased risk for cancer.

If you or any of your family members have questions about previous genetic testing, or if you should pursue genetic testing yourself, please discuss this with a genetics healthcare professional such as a genetic counselor. If you are interested in meeting with a genetic counselor at the Cancer Risk Evaluation Program at the University of Pennsylvania, you may contact 215-349-9093. To find a genetic counselor more local to you, you may visit

Editor; Derek Mann, LS, MCGC


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