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Old 05-30-2011
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Question Phenylketonuria and genetics

A man with phenylketonuria (PKU) is planning to start a family with his healthy, unaffected & unrelated partner, who has no family history of PKU. PKU shows autosomal recessive inheritance with an incidence of 1 in 10 000. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

a) The probability that his partner is a carrier is 1 in 100.
b) The probability that the man will transmit a mutant allele to his first child is 1 in 2.
c) The probability that his partner will transmit a mutant allele to their first child is 1 in 50.
d) The probability that their first child will be affected is 1 in 100.
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Old 05-30-2011
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answer is D

affected rate is 1/100000
mutant allel frequecy is 1/100
carrier rate is 2/100 (the man's partner)
chances of passing a mutant allel to child is 1/100
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Old 05-30-2011
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Originally Posted by Claus_CU View Post
A man with phenylketonuria (PKU) is planning to start a family with his healthy, unaffected & unrelated partner, who has no family history of PKU. PKU shows autosomal recessive inheritance with an incidence of 1 in 10 000. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

a) The probability that his partner is a carrier is 1 in 100.
b) The probability that the man will transmit a mutant allele to his first child is 1 in 2.
c) The probability that his partner will transmit a mutant allele to their first child is 1 in 50.
d) The probability that their first child will be affected is 1 in 100.
HW eq.
carrier = 1/50
If the partner is a carrier= 50% children normal - 50% with PKU

then, probability that their first child will be affected
1/50 * 1/2 = 1/100

answer D)
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Old 05-30-2011
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Quote:
Originally Posted by Claus_CU View Post
A man with phenylketonuria (PKU) is planning to start a family with his healthy, unaffected & unrelated partner, who has no family history of PKU. PKU shows autosomal recessive inheritance with an incidence of 1 in 10 000. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

a) The probability that his partner is a carrier is 1 in 100.
b) The probability that the man will transmit a mutant allele to his first child is 1 in 2.
c) The probability that his partner will transmit a mutant allele to their first child is 1 in 50.
d) The probability that their first child will be affected is 1 in 100.
D) The probability that their first child will be affected is 1 in 100.

Incidence is 1/10000 = 1%

If the affected individual has one mutant allele (1/2), and he is mating with a homozygous normal (0/2) individual, the chances are the same as amongst the general population.
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