Practice

Question 1

If Paula and Simon are first cousins and they have a child that is affected with CFN, what is the chance that the child inherited both abnormal alleles from a common ancestor?

Answer 1

The COR for first cousins is 1/8. So, COI (COR) 1/2 (1/8) (1/2) 1/16 (6%). This can be interpreted as a 1/16 (6%) chance that the CFN affected child inherited both abnormal alleles from a common ancestor.

Question 2

You’re seeing a two year old boy who has poor growth, chronic cough, food particles are often found in the stool. How is this condition most likely inherited?

Answer 2

autosomal recessive

cystic fibrosis

Question 3

Hereditary hemochromatosis is an autosomal recessive disorder (1/10000), square root is 1/100) that affects males greater than females that exhibit low penetrance (approximately 2% in females penetrance0. IF two carriers of heterozygous mutant alleles have a male child, what is the boy’s risk for developing hereditary hemochromatosis? For female child?

Answer 3

female is 2% penetrance
males are 5x greater than females that exhibit low penetrance

2% x5 = 10%

If its autosomal recessive, the child having the disorder if both parents are carriers is 1/4.

So 1/4 x 10%= 1/4 x 1/10= 1/40

For female 1/4 x 2%

What is the frequency of hereditary hemochromatosis in population? is 1/100

Question 4

frequency of alleles in a population

risk of a person

Answer 4

AA allele frequence A= P= p^2

Aa Aa x Aa (out of this there is a 1/4
chance of child being rr)

aa a=q q^2

Question 5

Hereditary breast cancer is inherited as autosomal dominant wit reduced penetrance. Females with a mutant allele have about 80%

Answer 5

1/2 x 80%= 2/5

Most homozygous recessive and dominant are lethal.

Question 6

Bobby
when we dont have family history or anything we just assume population
Hardy Weinberg

Answer 6

q=1/50
p= 49/50 =1

2pq= 2 x 1 x 1/50

1 x 1/25 x 1/4 x 1/10= 1/1000