What evidence indicates that mutations in human DNA mismatch repair genes are related to certain forms of cancer?

Video transcript

Hi everybody, let's take a look at this practice problem together, the deficiency of the D. N. A. Mismatch repair system in tumors that are associated with lynch syndrome can be detected by now, lynch syndrome recall is a colorectal cancer and the DNA mismatch repair system repairs mismatched base pairs by exercising out the incorrect base and inserting in the correct one. So a deficiency in the system is going to lead to mutations in D. N. A. Note that all of our answers include the word micro satellite instability. What is a micro satellite? Well, a micro satellite is repeated short DNA sequences occurring in a row. And there's a test called micro satellite instability, which is a test for lynch syndrome, likelihood. The more micro satellite, excuse me, the more micro satellite instability, the more likelihood of the person having lynch syndrome due to an accumulation of mutations that would occur from the deficient DNA repair system. So let's take a look at our options. A low micro satellite instability would be an inconclusive test. It would show that there are some changes in the micro satellite but not enough to determine if the person had lynch syndrome. A stable micro satellite instability indicates that a person is unlikely to have lynch syndrome because they're not having a bunch of mutations occurring. A high micro satellite instability suggests that a person has high likelihood. So it is likely that they have lynched syndrome and that's because there would be a high number of changes. And so our answer is a high micro satellite instability. Alright, everybody, I hope you found this helpful and I'll see you soon for the next practice problem.