8. Li Fraumeni syndrome is a loss of heterogeneity in p53. Why would a pedigree
ID: 269022 • Letter: 8
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8. Li Fraumeni syndrome is a loss of heterogeneity in p53. Why would a pedigree of the condition appear dominant? What is the function of p53? o. Would you use multiplex ligation probe amplification or triple repeat primed PCR to diagnose Huntington disease? Why? 10. How would you distinguish promoter methylat tion from chromatin remodeling experimentally to understand how a gene of interest was silenced? 11. List the preferred method to test for the following genetic traits a. PKU screening: b. CF ?.SCA: d. DMD: 12. Give an example of a specific genetic disease that could be detected/diagnosed genetically for each of the following genetic disorders: a. CML (Bcr-Abl): b. Down syndrome c. Breast Cancer:Explanation / Answer
Answer 9) for Huntington disease triple repeat primed PCR is used.
Diagnostic and predictive testing for Huntington disease (HD) requires an accurate determination of the number of CAG repeats in the Huntingtin (HHT) gene. Currently, when a sample appears to be homozygous for a normal allele, additional testing is required to confirm amplification from both alleles. If the sample still appears homozygous, Southern blot analysis is performed to rule out an undetected expanded HTT allele. Southern blot analysis is expensive, time-consuming, and labor-intensive and requires high concentrations of DNA. We have developed a chimeric PCR process where true homozygous alleles are easily distinguished by this simplified method, and only very large expanded alleles still require Southern blot analysis.
Two hundred forty-six HD samples, previously run with a different fragment analysis method, were analyzed with our new method. All samples were correctly genotyped, resulting in 100% concordance between the methods. The chimeric PCR assay was able to identify expanded alleles up to >150 CAG repeats. This method offers a simple strategy to differentiate normal from expanded CAG alleles, thereby reducing the number of samples reflexed to Southern blot analysis. It also provides assurance that expanded alleles are not routinely missed because of allele dropout.
Answer 11) Cystic fibrosis
Answer 12) CML:
Chronic myelogenous leukemia (CML) accounts of about 20% of all leukemias affecting adults. It typically affects middle-aged individuals and rarely adolescents or children. CML is a slowly progressing blood and bone marrow disorder, characterized by the excessive development of white blood cells in the spongy tissue found inside large bones of the body (bone marrow), spleen, liver and blood. As the disease progresses, the leukemic (blast) cells invade other areas of the body including the intestinal tract, kidneys, lungs, gonads and lymph nodes. These diseased cells do not grow old and eventually die like normal cells. They build up in huge numbers, overwhelm healthy blood cells and damage the bone marrow. Since CML progresses slowly, many people are first diagnosed during routine blood exams before they even show symptoms. There is no cure for CML because it is not possible to eliminate all of the diseased cells in the body, however, there are many approved treatments that can achieve a long-term remission
Downsyndrome:
They also have an increased risk to develop gastroesophageal reflux, celiac disease, hypothyroidism, hearing and vision problems, leukemia, and Alzheimer disease. Down syndrome is caused by having three copies of chromosome 21 .
Breast cancer:
Cancer-causing genetic changes can also be acquired during one’s lifetime, as the result of errors that occur as cells divide or from exposure to carcinogenic substances that damage DNA, such as certain chemicals in tobacco smoke, and radiation, such as ultraviolet rays from the sun. Genetic changes that occur after conception are called somatic (or acquired) changes.
Answer 13) d) Fragile X can be diagnosed by Southern Blot og genomic DNA and PCR amplification.
HD can be diagnose by triplet primed PCR.
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