Bayesian Genetics

Question 1

Hardy Weinberg Equilibrium assumptions

(5)

Answer 1

1. Randomly mating population
2. Large population
3. Negligible amount of mutation
4. negligible amount of migration (in and out)
5. Negligible amount of selection, all genotypes equally viable and fertile

Question 2

Calculating carrier frequencies

*Hardy Weinberg equilibrium*

Answer 2

p² + 2pq + q² = 1

AA frequency: p² (assume p ≈ 1)

Aa frequency: 2pq

aa frequency: q² (disease freq)

*autosomal genes*

population incidence must be known

Question 3

Bayes Analysis Purpose

Answer 3

Used to calculate recurrence risks (revision of Mendelian carrier risk)

Take into account:

• Likelihood of new mutation
• penetrance
• information from pedigree
• test results

Determines probability risk that individual has the gene (is a carrier or will be affected)

Question 4

Prior probability

&

Conditional Probability

Answer 4

Prior: Mendelian risk (1/2 for autosomal dominant)

Conditional: chance of an observed outcome

*due to penetrance, test results

Question 5

Joint Probability

&

Posterior probability

Answer 5

Joint: Multiply prior and conditional probabilities

Posterior: one joint probability weight against the other

joint probability carrier chance

joint carrier + non carrier