Go to the OMIM website (https://www.ncbi.nlm.nih.gov/omim) and...

Question

Go to the OMIM website (https://www.ncbi.nlm.nih.gov/omim) and type 'dyskeratosis congenita autosomal dominant 1' (DKCA1) into the search bar. The result will include a clickable link to the disorder that has an OMIM number of 127550. Review the OMIM information you retrieve and notice that this disorder is caused by a mutation of a telomerase gene that results in abnormally rapid shortening of telomeres and the appearance of disease symptoms at progressively younger ages in successive generations of the affected families. Use this and other information on OMIM to assist with this problem. Go to reference number 15 at the bottom of the OMIM page for a link to a 2004 paper by Tom Vulliamy and colleagues that appeared in the journal Nature Genetics. Click on the 'Full text' option and download a copy of the paper. Look at Table 1 of the paper on page 448. This table lists the lengths of telomeres measured in members of the families in this study. Telomeres shorten with age, and the telomere lengths in Table 1 are age-adjusted. The negative numbers for telomere lengths in the table indicate that telomeres are shorter than average for age, and the more negative the number, the shorter the telomere. Based on Table 1, the discussion in the Vulliamy et al. (2004) paper, and information available on OMIM, answer the following:
How do telomere lengths in children compare with telomere lengths of their parents?

How do telomere lengths in children compare with telomere lengths of their parents?

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next question. Familial melanoma, pancreatic cancer syndrome increases the risk of melanoma, skin cancer and pancreatic cancer. It is caused by a mutation in the P O T one gene protection of telomeres. One, the P O T one helps regulate the length of telomeres and prevent them from being recognized as damaged DNA, which could trigger cellular aging or death. Studies have shown that an affected individual with a mutated copy of P O T one has a 50% chance of passing the syndrome to their offspring, which pattern of inheritance is associated with mutation in the P O T one gene choice. A autosomal recessive B, autosomal dominant C link dominant or D linked recessive. Well, first of all, we can eliminate choices C and D because there's no mention of that inheritance depending on the sex of the offspring or the sex of the parent. So choices C and D are not our answer because link traits, whether dominant or assess show differences in inheritance patterns based on the sex of the affected individuals. Since obviously, males and females have different numbers of X chromosomes. So we know it's an autosomal gene and we just have to ask whether it's recessive or dominant. Well, our problem tells us that an affected individual with a mutated copy of the gene has a 50% chance of passing the syndrome to the offspring. So I've underlined the word A and a mutated copy and syndrome because this is key. It tells us our individual in question is affected by the syndrome with just a single mutated copy of the gene. And then this person who is affected with a single copy. So presumably has one mutated copy and one unaffected copy has a 50% chance of passing the syndrome to their offspring. Well, they have a 50% chance of passing that mutated copy of the gene and that's matched with a 50% chance of inheriting the syndrome. And that tells us that you only need one mutated copy of the gene to be affected by the syndrome. And that would indicate choice B an autism dominant condition with a recessive condition you need or autosomal recessive, you need two copies of the mutated gene to be affected by the syndrome. So that's why choice. A autosomal recessive is not our answer. So again, with an affected individual with a mutated copy of P O T, one has a 50% chance of passing the syndrome to their offspring, which pattern of inheritance is associated with the mutation in P O T one gene. Choice B, autosomal dominant see you in the next video.

Key Concepts

Telomeres

Genetic Mutations

Age-Adjusted Telomere Lengths

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