PS9-11.CA - Bio D137 Human and Eukaryotic Genetics Prob Set...

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Bio D137 Human and Eukaryotic Genetics J.L.Marsh F'11 Prob Set 9 due MONDAY, DEC 5 by 4pm Name/student ID:_______________ 1 1 1] Robinow Syndrome (RS) is an extremely rare genetic disorder characterized by short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral segmentation and is often called fetal face syndrome (shown in Fig 1). Both dominant and recessive forms exist and it has been proposed that the dominant forms may be associated with unique alleles of a gene in the 9q22 region. The family of the woman shown in fig 1 is segregating a fully penetrant dominant form of Robinow syndrome. We wish to map the responsible allele. Two HVRs (HyperVariableRegion) were analyzed in this woman’s family. HVR-A is located @ 9q21.13 and HVR –B @ 9q22.32. Please analyze the pattern of inheritance shown below for each HVR marker. 10 points total Figure 1. Age 19 years. http://www.robinow.org/photos/28.html Map of chromosome 9 A] Is HVR A @ 9q21.13 linked to this disease and if so, what would you estimate the map distance between them to be and what are the parental linkage relationships in person #1? Please explain your work. Answer: 2 pts Yes (0.5 pt) @ 25mu (0.5pt) – 5 recombinants/20 tota l = .25 RF = 25 mu. Parental linkage relationships = M 43/+ 32 (0.5pt ) Show work (0.5 pt)
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Bio D137 Human and Eukaryotic Genetics J.L.Marsh F'11 Prob Set 9 due MONDAY, DEC 5 by 4pm Name/student ID:_______________ 2 2 The disease is dominant and thus, if linked to HVRA, it is linked to the 43 allele because 7/9 affected people have it while only 3 of 11 unaffecteds have it . Female #1 is hypothesized to be M 43/+ 32 and we are testing for independent assortment so the possible combinations in her offspring are: Parental: M 43 of which there are 7 i.e. #3, 4, 8, 11, 15, 16, 22 Parental: + 32 of which there are 8 i.e. #5, 6, 7, 10, 12, 13, 14, 21 Recombinant: M 32 of which there are 2 i.e. #18, 20 Recombinant: + 43 of which there are 3 i.e. #9, 17, 19 Thus, the mutant is linked to the 43 allele at a distance of ~5/20 = 25 map units One point was given for an answer of “unlinked” with a reasonable explanation. B] Is HVR B @ 9q22.32 linked to this disease and if so, what would you estimate the map distance between them to be and what are the parental linkage relationships in person #1? Please explain your work. Answer: 2 pts Yes (0.5pt) @ 5mu (0.5 pt) – 1 recombinant/20 total. Parental linkage relationships = M 23/+ 20 (0.5 pt) Show work (0.5 pt) The disease is dominant and thus if linked to HVRB it is linked to the 23 allele because all 9 affected individuals have the marker and only one unaffected does. Female #1 is hypothesized to be M 23/+ 20 and we are testing for independent assortment so the possible combinations in her offspring are: M 23 of which there are 9 i.e. #3,4,8,11,15,16,18,20,22 + 20 of which there are 10 i.e. #5,7,9,10,12,13,14,17,19,21 M 20 of which there are 0 i.e. + 23
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PS9-11.CA - Bio D137 Human and Eukaryotic Genetics Prob Set...

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