Ataxia telangiectasia (OMIM 208900) is a human inherited disorder characterized by poor coordination (ataxia), red marks on the face (telangiectasia), increased sensitivity to X-rays and other radiation, and an increased susceptibility to cancer. Recent studies have shown that this disorder occurs as a result of mutation of the ATM gene. Propose a mechanism for how a mutation in the ATM gene leads to the characteristics associated with the disorder. Be sure to relate the symptoms of this disorder to functions of the ATM protein. Further, explain why DNA repair mechanisms cannot correct this problem.

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Accepted Answer

Welcome back, everyone. Let's look at our next problem. Bloom syndrome is a rare genetic condition that is inherited in an autosomal recessive pattern. It is characterized by short stature. Some might induce skin changes and an increased risk of cancer. The disorder is caused by mutations in the B L M gene which provides instructions for making the Bloom Syndrome protein. This protein is important for repairing damaged DNA and maintaining genomic stability particularly in the repair of double strand of brakes. Which of the following statements is true regarding the correlation between genetic mutation of the B L M gene and sunlight skin sensitivity choice. It's a sun sensitive skin changes are caused directly by the B L M gene mutation. Choice B, sun sensitive skin changes are the primary symptom of Bloom Syndrome. Choice. C. Mutations in the B L M gene can cause a decrease in the ability of cells to repair DNA damage caused by exposure to ultraviolet U V radiation from the sun or choice D mutation. The B L M gene causes increased production of melanin leading to sun sensitive skin changes. So we had a lot of information thrown at us in our question. But let's focus in on what it's asking us, which is saying we're looking for a true statement regarding the correlation between the mutation in that B L M gene and sunlight skin sensitivity. So between this particular symptom, when we look at our answer choices or excuse me, when we look at our problem, we notice it tells us that the protein generated by this gene is important for repairing, damaged DNA and maintaining genomic stability. Well, when we think about sensitivity to the sun or what happens when the skin is exposed to the sun too long, the key issue is that U V light leads to DNA damage. The body has means of repairing damage caused to DNA by U V light. But our question has told us that this protein which has a mutation in it is important for the process of repairing that DNA damage. So with that, in mind, we want to look at choice C mutations in that gene cause a decrease in the ability of cells to repair DNA damage caused by exposure to U V radiation. Let's take a look at our other answer. Choices to understand why they are not correct choice. A says sun sensitive skin changes are caused directly by the B L M G mutation. But that is not a true answer because the mutation does not directly cause the changes to the skin. It's the fact that the mutation causes the body to be unable to repair the U V damage to the skin the way it usually does. Then choice B says that the skin changes are the primary symptom of Blue Bloom syndrome. But this is not a true statement we saw in our problem that we see symptoms of short stature, the skin changes and increased risk of cancer. So there are many other symptoms that come along with this syndrome. And finally, choice D says that the mutation in the gene causes increased production of melanin leading to some sensitive skin changes. But this is not true. That's not what this mutation does. Again, it affects the protein that is important in the repair of damaged DNA. So again, our answer choice which of the following statements is true regarding the correlation between gene, the genetic mutation and sunlight, skin sensitivity choice C mutations in the B L M gene can cause a decrease in the ability of the cells to repair DNA DNA damage caused by exposure to U V radiation from the sun. See you in the next video.

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Key Concepts

ATM Gene and Protein Function

DNA Repair Mechanisms

Genetic Inheritance and Disorders