If anyone can help me with some genetic questions from my review, it\'ll be grea
ID: 57783 • Letter: I
Question
If anyone can help me with some genetic questions from my review, it'll be greatly appericated.
1. Before Mary does Genetic test for this RFLP marker, what is the probability of Mary as a carrier of the death gene and being a heterozygote for the RFLP marker? (This question asking for the probability of Mary as a carrier of the death gene and also being a heterozygote for the RFLP marker- NOT the probability of Mary being a heterozygote for the death gene).
2. After Mary did her RFLP test and found out that she was indeed a heterozygote for the marker, then what is the probability of Mary as a carrier of the death gene?
3. What is the probability of sister 3 as a carrier of the death gene?
In genetic counseling, it is difficult to directly test if an individual has a recessive allele that is associated with an inherited disease. However, the individual many be tested for the presence of a particular DNA marker that is located at a known distance from the disease gene. It is often possible to calculate the probability that the individual possesses the disease allele One recessive mutation in human chromosome 12 can cause a rare disease that leads to death within the first year. This gene is located approximately 20 cM from the centromere. ARFLP marker is identified to be as close as 5 cM to this lethal gene. The RFLP markers results from the presence or absence of a BamHI restriction enzyme site. The presence of the BamHI site results in the production of 5 kb and 3 kb restriction fragment that can be visualized on an agarose gel. The absence of the HindIII site results in | 3kb Sister! Sism2 Siser3 Mary an 8.0Kb fragment. Falher Wcter Sister1 Sisle? Sise^ Vary Mary came from a family, which unfortunately carry this horrible gene. One of Mary sisters (sisterl) passed away in her 6-month age. Mary is now 25 year old and planning a child. She is so concened about passing this recessive allele to her child. So she collected DNAs from all her families to do the RFLP test. The results are shown as above. Based on this information, please answer the following questions 1, Before Mary does Genetic test for this RFLP marker, what is the probability of Mary as a carrier of the death gene and being a heterozygote for the RFLP marker (5pts)'?Explanation / Answer
1.
From the pedigree shown, it is clear that both the parents are carriers for the gene. That’s why Mary’s first sister got both recessive alleles. Now for Mary being a carrier there is 50% chance. If she had received both normal genes from her parents, then she is not a carrier. If she had received one affected gene and one normal gene, then she would be a carrier. Thus, there is 50% probability for Mary being a carrier of this death gene and heterozygote for RFLP marker.
2.
If Mary was found positive as a heterozygote for the marker, then there is 100% probability that she is a carrier of the death gene.
3.
There is 50% probability for Mary’s sister 3 to be a carrier for death gene. If Mary’s sister 2 is wildtype for both the gene, then sister 3 would be a carrier. In case, if sister 2 is a carrier, then sister 3 would be normal. Thus, there is 50% probability.