Phenylketonuria is an autosomal recessive human disease. Suppose that both membe
ID: 48355 • Letter: P
Question
Phenylketonuria is an autosomal recessive human disease. Suppose that both members of a couple are heterozygous for Pku and have children.
a. If the couple has four children with phenylketonuria, what is the probability that their next child will have phenylketonuria?
b. If they have four children, what is the probability that none of the four will have phenylketonuria?
c. If the couple has four children what is the probability that the second child will have phenyketonuria and the first, third and fourth will not.
d. If the couple has four children, what is the probability that just one of the four children will have phenylketonuria and regardless of the order?
e. Compare the different numbers obtained for c) and d), and explain why you think they are different.
f. If they have four children, what is the probability that at least one or more of their children will have phenylketonuria. (Hint: There is a simple, fast way to get the answer. It involves subtracting some probability from the sum of all the probabilities.)
Explanation / Answer
a. the couple will have 1 in 4 children affected. so fifth child will not be affected.
b. if they have 4 children , only one of the child will be affected.
c. second child will not have phenylketonuria , its genetic make up will be heterozygous.
d. 25% willl be the probability .