A particular type of anemia in humans, called β-thalassemia, results from a severe reduction or absence of the normal β-globin chain of hemoglobin. However, the γ-globin chain, normally only expressed during fetal development, can functionally substitute for β-globin. A variety of studies have explored the use of the nucleoside 5-azacytidine for the expression of γ-globin in adult patients with β-thalassemia.

Explain why this drug may also have some adverse side effects.

Video transcript

Hi everyone welcome back. Here's our next question. Gamma Globe in is expressed during fetal development but become silenced in adults due to methylation of side iodine in a CPG island in or near the promoter. Which of the following do you believe will stimulate its expression in adult patients if incorporated into DNA. So we have the expression of a gene that's expressed in fetal development, silenced and adults by methylation. So the addition of a methyl group of sighting. So our question says what then would be most likely to cause the expression to be stimulated in adult patients if it's incorporated into their DNA. And we've got four different answer choices with four different chemicals here. Or compounds choice A €50 ill be five sided in C. Two amino peering and D. A. Cycle iguanas seen. Well, since our silencing occurs by the methylation of cytosine, that leads us to the correct answer here, which is choice B. Five as a sideline. And that's because this is a sighting analog that can't be methylated. So if you incorporate that into the adults, D. N. A. Since the the mechanism silencing is meth relating aside indian residue. If you've got this analog incorporated in the D. N. A. That can't be methylated, you have the most likelihood of causing expression of this gene in adult patients. Since the silent silencing mechanism will no longer work. So let's just quickly look at our other answer choices choice A €5 ill. Um Not our answer choices of a euros L. Analog. It can substitute for thinning and D. N. A. And gets used as an artificial mutation and scientific experiments but not our answer choice since it's not going to be likely to cause this expression in adult patients. Since it's an analog €2 ill and not going to affect that methylation of sitting Choice C. is two amino pureeing and this gets used as a fluorescent marker for D. N. A. Actually. Um It's an analog, an artificial analog of guanine and adenine as this being this. Oops okay, there we go. We're adding that in the wrong place to amino pureeing is an analog of guanine. Adami gets used as a fluorescent marker. It compare with timing. Um It also gets used as an artificial mutation but not what we're looking for since it's not an analog of the cited in here. So I see, not correct. And finally a cyclo guana seen as we can see by looking at the name here as its name indicates. It's a guana zine analog and interestingly is a medication for HSV or herpes and that's because it interferes in substituting here with the action of HSV. D. N. A. Prelim race so prevents the um inc generation of the D. N. A. From that retrovirus that will incorporate into the cell's DNA. So it's kind of interesting little note there but not the answer we're looking for. So again we've got gamma globe in as expressed during fetal development will become silenced and adults do the methylation of cytosine which the following do you believe will stimulate its expression in adult patients if incorporated into DNA. And that's just B5 is a sight to see you in the next video.