human genetics
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hw8.linkage.mmg404.fs16.docx
MMG 404 FS16 NAME:_____________________
Homework #8 22 pts due Oct. 25, 2016
DO BOTH SIDES OF THE PAGE
The pedigree below is for an autosomal dominant disorder that has 100% penetrance.
Determine the genotype for each individual and write in the box below their symbol. (3pts)
Which allele for the STRP is most likely in coupling with the disease allele?______ (1pt) NOTE: We also say this allele is in phase with the disease allele
In the same box, indicate whether each of the seven grandkids is a recombinant (R) or non-recombinant (NR) between the STRP and the disease allele.
How many recombinant individuals?_________(1pt)
How many non-recombinant individuals?_________(1pt)
Estimate the value of Θmax for this pedigree? _________ (1pt) (HINT: It is equal to the fraction of recombinants over total.)
Based on data from #4, write the equation relating Z to Θ for this pedigree . (2pt)
Calculate Z for Θ = 0. __________(2πτ)
Calculate Zmax (i.e., Z value at Θmax).__________(2pt)
Circle your interpretation for the value of Zmax for this pedigree? (1pt)
linked ii) suggestive linkage iii) not linked
What is your rationale? (1pt)
|
Θ |
0 |
0.05 |
0.1 |
0.15 |
0.2 |
|
Z(A) |
-3.0 |
-2.0 |
-1 |
0 |
0.3 |
|
Z(B) |
0.1 |
0.2 |
1.0 |
0.6 |
0.3 |
|
Z(C) |
4.0 |
3.0 |
2.0 |
0.8 |
0.2 |
|
Z(D) |
-∞ |
2.0 |
4.0 |
4.2 |
2.5 |
11. The table above gives the Z scores for four different marker loci (A, B, C and D) with respect to possible linkage to a monogenic, fully penetrant trait.
a. Which markers is/are significantly linked to the trait allele anywhere within 0≤Θ≤0.2? ________(1pt)
b. Which marker appears to be closest (fewest cM away) to the trait allele? _________(1pt)
c. Which markers, if any, definitely is/are NOT linked to the trait allele specifically at Θ=0? ________(1pt)
(they may be linked at other values of Θ)
d. For which markers, if any, can we make no definite conclusion about linkage? ________(1pt)
|
Θ |
0 |
0.05 |
0.1 |
0.15 |
0.2 |
|
Z(family1) |
0.2 |
0.3 |
0.5 |
0.3 |
0.2 |
|
Z(family2) |
-0.2 |
2.2 |
1.5 |
1.0 |
0.5 |
|
Z(family3) |
-∞ |
3.8 |
3.6 |
2.5 |
2.0 |
|
Z(family4) |
-∞ |
-2.5 |
-2.8 |
-2.5 |
-2.0 |
|
Z(family5) |
-∞ |
2.7 |
3.2 |
2.0 |
1.5 |
|
total |
-∞ |
6.5 |
6.0 |
3.3 |
2.2 |
3. The table above shows the Z vs. Θ curves for a single marker but for five different family pedigrees.
a. Is this marker likely to be linked to the causal trait allele (within Θ≤0.2)? Yes No (1pt)
b. If so, about how far (in cM) from the marker do you think the trait allele is?_________cM (1pt)
c. The Z value in family 4 is negative at all Θ? Suggest an explanation. (1pt)
