Which of the examples of genetic testing below are prognostic ...

Question

Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?

DNA sequencing of a breast tumor reveals mutations in the BRCA1 gene.

Accepted Answer

Hi, everyone. Welcome back. Here's our next question. It says triple negative. Breast cancer comprises 15 to 20% of all breast cancer cases and affects women with a mutation in the B R C A one gene more than other breast cancers, TNBC is breast cancer that lacks or shows low levels of. Well, we'll want to recall what characterizes triple negative breast cancer. And to do that, we want to remember that all breast cancer tumors are classified as one of four different classifications. So I'm going to put that up here and those are estrogen receptor, positive progesterone receptor positive H E R two over expression positive h er to being human epidermal growth factor receptor two and triple negative. And as we can see, looking at our names, we've got three positives here. Tumors that are positive for one of these three factors. And then our fourth classification, triple negative. So that just means negative for the other three classifications. So it's missing any of those three characteristics. Well, if we're thinking about negative or missing, um what we want to look at is that our, our problem here says TNBC is breast cancer that lacks or shows low levels of. So, since it's negative for these three things that are present, that's where we want to zoom in on for answer. And these classifications are very important because they represent whether a patient is a candidate for targeted therapies. So for instance, um estrogen receptor positive means the tumor has estrogen receptors on its surface. So therapies that would block estrogen from binding those receptors would treat that cancer and prevent that tumor from growing. So let's look at our answer. Choices here, Knowing that we want to look for estrogen receptor, progesterone receptor and HER two over expression as the things that triple negative breast cancer is lacking. So choice a says BRCA one gene mutation, estrogen receptor progesterone receptor. Well, We know here that women with the BRCA- one mutation are more likely to have triple negative breast cancer. So that would make that incorrect since we're looking for something that it lacks or shows low levels up. So that's not our answer. Choice. B says BRCA one gene mutation, progesterone receptor, human epidermal growth factor receptor two gene amplification. So that's not a correct answer because that also has that B R C A one gene mutation. So choice B is not correct. I see again, we see right away B R C A one gene mutation, estrogen receptor B R C A two gene mutation again, triple negative, more likely to have BRC one gene mutation. So choice C is not correct. So now we have Joyce D and it does say estrogen receptor progesterone receptor, human epidermal growth factor receptor two gene amplification gene amplification. Of course, would mean the same thing as when we look at our classifications over expression. So choice d is going to be our correct answer describing triple negative breast cancer as lacking or showing low levels of estrogen receptor progesterone receptor and HER two amplification. See you in our next video.

Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
DNA sequencing of a breast tumor reveals mutations in the BRCA1 gene.

Key Concepts

Prognostic vs. Diagnostic Testing

BRCA1 Gene and Its Role in Cancer

DNA Sequencing

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