Olivia S. was born with a rare recessive disorder called tyrosinemia.The next day, Olivia M. was born in a neighboringstate with the same disorder. Tyrosinemia is causedby the lack of an enzyme in the degradation pathway of the aminoacid tyrosine. Accumulation of metabolic intermediates causesprogressive liver dysfunction and kidney problems. One-year-oldOlivia S. is healthy and has no symptoms of the disorder. At thesame age, Olivia M. developed total liver failure. Olivia S. was bornin a state where newborns are tested for tyrosinemia, but Olivia M.was born in a state where newborns are not tested for this disorder.A week after diagnosis, Olivia S. was placed on a low-tyrosinediet and prescribed a drug to block the accumulation of metabolicintermediates. Olivia M. was not diagnosed until she was in liverfailure; she then was placed on a low-tyrosine diet, was prescribedmedication, and underwent a liver transplant. She faces a lifetimeof antirejection drug therapy and may require a kidney transplant.In the United States, newborn screening programs are developedindependently by each state and are often based on a cost–benefitanalysis to decide which diseases are included in testing. In theUnited States, tyrosinemia occurs in only 1/100,000 births, and inthis case, two states made different decisions about newborn testingfor this disorder. Question: In a region of Quebec, Canada, 1 in 22 people are heterozygousfor the mutant tyrosinemia allele. Using the frequencyof heterozygotes, calculate the frequency of recessive homozygotesin this population. What might explain the differencebetween the frequency of tyrosinemia in the U.S. populationand in this particular Canadian population?
Olivia S. was born with a rare recessive disorder called tyrosinemia.
The next day, Olivia M. was born in a neighboring
state with the same disorder. Tyrosinemia is caused
by the lack of an enzyme in the degradation pathway of the amino
acid tyrosine. Accumulation of
progressive liver dysfunction and kidney problems. One-year-old
Olivia S. is healthy and has no symptoms of the disorder. At the
same age, Olivia M. developed total liver failure. Olivia S. was born
in a state where newborns are tested for tyrosinemia, but Olivia M.
was born in a state where newborns are not tested for this disorder.
A week after diagnosis, Olivia S. was placed on a low-tyrosine
diet and prescribed a drug to block the accumulation of metabolic
intermediates. Olivia M. was not diagnosed until she was in liver
failure; she then was placed on a low-tyrosine diet, was prescribed
medication, and underwent a liver transplant. She faces a lifetime
of antirejection drug therapy and may require a kidney transplant.
In the United States, newborn screening programs are developed
independently by each state and are often based on a cost–benefit
analysis to decide which diseases are included in testing. In the
United States, tyrosinemia occurs in only 1/100,000 births, and in
this case, two states made different decisions about newborn testing
for this disorder.
Question:
In a region of Quebec, Canada, 1 in 22 people are heterozygous
for the mutant tyrosinemia allele. Using the frequency
of heterozygotes, calculate the frequency of recessive homozygotes
in this population. What might explain the difference
between the frequency of tyrosinemia in the U.S. population
and in this particular Canadian population?
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
