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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 HardyWeinberg 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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#2




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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Claus_CU (05302011) 
#3




Quote:
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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Claus_CU (05302011) 
#4




Quote:
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. 
The above post was thanked by:  
Claus_CU (05302011) 
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Biochemistry, Genetics, Step1Questions 
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