Question 1 - The pedigree below indicates the transmission pattern of an X-linked disease.
Part A. For the above pedigree indicate whether an X-linked dominant or X-linked recessive mode of inheritance is compatible with the transmission pattern.
Part B. Assume the compatible mode of inheritance inferred in Part A. What is the probability that individual 1 is affected with the disorder?
What is the probability that individual 2 is NOT affected with the disorder?
What is the probability that individual 3 is affected with the disorder?
Question 2 - A dismembered right foot in a size 11 running shoe washes up on a beach in Vancouver. Three months later a dismembered left foot in size 11 running shoe washes up on a beach in Victoria. Both feet appear to be Caucasian. DNA profiling is applied to both samples to determine whether the two feet are from the same person. The results for 3 genetic loci located on different chromosomes are as follows:
|
Locus
|
Left foot genotypes
|
Right foot genotypes
|
|
TPOX
|
112/114
|
112/114
|
|
TH01
|
113/115
|
113/115
|
|
D2S11
|
111/111
|
111/111
|
The population allele frequencies at the 3 markers in Caucasians of European descent are:
TPOX: f(112) = 0.3, f(114) = 0.2
TH01: f(113) = 0.02, f(115) = 0.23
D2S11: f(111) = 0.06
Can we exclude the possibility that the feet come from the same individual based on the observed genotypes?
What is the probability of a random match of the genotypes at these loci if the two feet came from unrelated individuals in a randomly mating population of Caucasians of European descent?
Question 3 - A sample of 380 individuals are chosen from a population and genotyped for a SNP locus with 2 alleles T and C. The genotype counts are as follows:
T/T: 133 T/C: 127 C/C: 120
(a) Estimate the frequencies of alleles T and C in the population.
(b) Using the estimated allele frequencies predict the expected frequencies of genotypes T/T, T/C and C/C assuming that the population is in Hardy-Weinberg equilibrium (HWE).
(c) [BONUS QUESTION] Do the sampled genotype frequencies appear to fit (an acceptable fit is <= +/- 0.01 difference between predicted vs observed frequencies) the frequencies predicted assuming HWE? If not, give a possible explanation for the discrepancy.