(A) Is recessive or dominant? (B) Is it X-linked or autosomal? (C) Mark and Jill
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Question
(A) Is recessive or dominant?
(B) Is it X-linked or autosomal?
(C) Mark and Jill's genotypes are _______ and ________, respectively
(D) What is the probability that Mary and Will's first child will be a boy with the disease?
(2) Cystic fibrosis is caused by an autosomal recessive mutation. A man with cystic fibrosis marries a healthy woman whose biological mother had the disease. Approximately what percentage of their children will have cystic fibrosis?
You are a genetic counselor who is trying to determine the probability that Will and Mary will have a child with a genetic disease. The disease is caused by a mutation in the R gene. Mary has the disease but Will does not. Their family pedigree is shown below: Bob Sue Kai Mark Jill Juan Sally Pete Ann Rick Mary WillExplanation / Answer
Please find the answers below:
Answer A: Since not all the offsprings from the affected couple are affected, the disease is inherited in recessive manner.
Answer B: Since both males and females are affected from the disease and not all males/females of same generation are being affected, the disease is inherited in autosomal manner.
Answer C: As the disease is inherited in autosomal recessive manner, it is very likely that Mark is homozygous whereas Jill is heterozygous for this allele.
Answer D: Will must have carried at least a single allele from her mother and Marry too is affected, so their genotypes are Aa and aa, respectively. Thus, the Punnett square can be formulated as below:
Genotype: Aa : aa :: 1:1
Phenotype: Normal : affected :: 1:1
Thus, there are 50% chances that their offspring would be affected.
A a a Aa aa a Aa aaRelated Questions
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