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?

ASO testing determines that an individual is a carrier for the mutant β-globin allele (βˢ) found in sickle-cell anemia.

Accepted Answer

Hello, everyone. Let's look at our next problem. It says a little specific ala go nucleotide hybridization or dot blotting as a method for testing known mutations identify and correctly describe the version of this technique that is widely used for the routine screening of genes that have numerous mutant alleles, including alpha thalassemia, beta thalassemia and cystic fibrosis. So dot plotting, you have uh you're using short nucleotide probes to look for complementary sequences in a PCR amplified D N A sample. So when you have a single mutation, you're looking for, you tend to immobilize your D N A sample on a nitrocellulose membrane. And then you have labeled Olivo nucleotide probes that you wash over this membrane to see where they hybridize, to look for that complementary sequence with that mutation. However, it's a little more complicated when we have conditions like the ones listed in our problems that have numerous mutant aliens because you're not just looking for a single DNA sequence of a single mutation, you're looking for the presence of one of several mutations. In that case, you have a technique called reverse dot blotting. And in that case, you actually immobilize the algo nucleotide probes. And that way you can have multiple probes with each of your different mutations on your membrane. And then your sample is what's labeled rather than your probes and washed over that membrane. And you can see where your sample hybridize is to see which mutation you're looking at. So in this case, the PCR products are labeled, whereas in the forward version, you have the robes that are labeled and this reverse form is the one we want when we have numerous mutant alleles. So let's work our way through our answer choices to see where the correct description is of this reverse stop bonding that we'd be looking for. Choice. A says the PCR amplified DNA fragments are immobilized onto a filter and labeled Allah go nucleotide probes that are complementary and specific forgiven DNA sequence or hybridized the filter called forward A S O format. Well, this is a correct description of the forward um dot blotting where you have labeled probes and your D N A samples are mobilized in multiple dots on a memory, but that is not what we want to use, not for numerous mutations. So choice A is not going to be our answer. Eliminate that choice B says different A S O probes get immobilized onto a filter or membrane and hybridization filter to labeled PCR amplified DNA takes place which is called reverse A S O format. And everything lines up here. The probes are what gets immobilized the D N A samples what's labeled and that is the reverse format. So choice B is going to be our correct answer here for the correct description identification of the technique will use when there's numerous mutant albiol's. So just to be thorough, let's look at our other answer choices and see why they're incorrect. Choice. C says the PCR amplified DNA fragments are immobilized onto a filter membrane and labeled ala go nucleotide probes that are complementary and specific to a given D N A sequence are hybridized. The filter called reverse A S O format. Well, the reverse part is correct, that's what we want. But this is an incorrect description of the reverse format because in that reverse format, we have Allah go nucleotides on the membrane and labeled PCR DNA fragments. So that's why choice C isn't our answer? Eliminate that. And then finally, choice D says different S O probes get immobilized onto a filter, our membrane and hybridization filter to labeled PCR amplified DNA takes place which is called forward A S O format. Well, we've got a correct description of the technique. The probes get immobilized, the PCR amplified DNA is labeled, but it's incorrectly called the foreword of format. So choice D is not our answer. So again, when we're talking about dot blotting, identifying correctly, describe the version of this technique widely used to the routine screening of genes that have numerous mutant alleles. And our answer is choice be different A S O probes get immobilized onto a filter or a membrane and hybridization of the filter to label PCR amplified DNA takes place which is called reverse A S O format. See you in the next video.

Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
ASO testing determines that an individual is a carrier for the mutant β-globin allele (βˢ) found in sickle-cell anemia.

Key Concepts

Prognostic Testing

Diagnostic Testing

Carrier Testing

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