Pedigree Analysis and Population Genetics Workshop

Question 1

What does Hardy-Weinberg tell us?

There are 2 (kinda) equations for this. What is the purpose of each?

Answer 1

Hardy-Weinberg is used to estimate frequency of gene variants in a randomly mating population.

p²+2pq+q²=1 (people)

p+q=1 (genes)

p=frequency of “normal” allele

q=frequency of mutation

q²=frequency of affected

Question 2

If 1 in 40,000 is affected by a genetic disorder, give me

affected

frequency of mutation

frequency of normal allele

Answer 2

If 1 in 40,000 affected

then q² = 1/40,000

q = 1/200 which is 0.005 (Bradbury trick- half the zeros and take square root of nonzero)

And p = 0.995

Question 3

Define these basic population genetics terms:

Natural Selection

Genetic Drift

Gene Flow

Founder Effect

Answer 3

Natural selection: survival or reproductive advantage

Genetic drift: change with time

Gene flow: mixing populations

Founder effect: small numbers of people with large effects

Question 4

What population genetics idea is malaria and sickle cell an example of?

Answer 4

Selective advantage

Heterozygotes for sickle cell are not as affected by malaria, and live longer

Because of this they live longer and are able to pass on their genes, increasing gene frequency

Question 5

When making a pedigree what symbols would be used to show

male

female

unknown sex

multiple individuals in a small space on the chart (?)

Answer 5

Question 6

When making a pedigree what symbols would you use to indicate

fraternal twins

identical twins

Consanguinity

Answer 6

Question 7

What symbols would you use to indicate the genetic status of individuals in a pedigree?

Answer 7

Question 8

What is the relationship between consanguinity and the probability of a recessive disorder?

Answer 8

The rarer the recessive disorder the more likely parents are consanguineous