The pedigree below is for an autosomal dominant disorder that has 100% penetrance.

  1. 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 Èmax 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 È for this pedigree. (2pt)
  • Calculate Zfor È = 0. __________(2ðô)
  • Calculate Zmax (i.e., Z value at Èmax).__________(2pt)
  • Circle your interpretation for the value of Zmax for this pedigree? (1pt)
  1.  linked      ii)  suggestive linkage             iii) not linked
  1. What is your rationale? (1pt)
È00.050.10.150.2
Z(A)-3.0-2.0-100.3
Z(B)0.10.21.00.60.3
Z(C)4.03.02.00.80.2
Z(D)-∞2.04.04.22.5

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≤È≤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 È=0? ________(1pt)

            (they may be linked at other values of È)

d. For which markers, if any, can we make no definite conclusion about linkage? ________(1pt)

È00.050.10.150.2
Z(family1)0.20.30.50.30.2
Z(family2)-0.22.21.51.00.5
Z(family3)-∞3.83.62.52.0
Z(family4)-∞-2.5-2.8-2.5-2.0
Z(family5)-∞2.73.22.01.5
total-∞6.56.03.32.2

3. The table above shows the Z vs. È 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 È≤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 È?  Suggest an explanation. (1pt)