3. You are a genetic counselor (named Icktor) for a family that has two differen

Question

3. You are a genetic counselor (named Icktor) for a family that has two different genetic disorders: X-linked dominant vitamin-D resistant Ricketts and also autosomal recessive albinism. Your patients are: A. a man with Ricketts, who has normal skin pigmentation but whose mother was albino, and B. a woman without Ricketts, who has normal skin pigmentation but whose father was albino a. What is the chance that this couple will have a child with albinism? Feel free to use the punnet square provided to draw out your answer b. What is the chance that this couple will have a child with Ricketts? Feel free to use the punnet square provided to draw out your answer c. If these two people have a daughter, what is the chance that she will have both Ricketts and Albinism? d. Is it possible for this couple to have a son who has both Ricketts and Albinism? Why or why not? e. Is the risk of having a child with Ricketts higher than that of having a child with albinism? Explain your answer. f. Whom did the man inherit Ricketts from? Explain your answer.

Explanation / Answer

a. ANS: Man Genotype = XRY Aa (R = rickets)

Woman Genotype = XN XN Aa (N = normal)

aa = albinism

         25% child has albinism

b. ANS:

50% chance child has Rickets (XN XR)

c. ANS: Number of chances for both Ricketts and Albinism:

100% chance daughter has Rickets

25% chance daughter has albinism

25% chance daughter has both

d. ANS: No, The son born with both the Ricketts and Albinism is not possible in this condition. Because the father carries the Ricketts so only his daughters get that trait and the sons get his X chromosome from his mother.

e. ANS:

Yes, the risk of having a child with Ricketts higher than that of having a child with albinism. It is because rickets will automatically be passed on to the daughter but the son doesn’t get it at all. This is a 50%chance to a 25% chance of albinism

f. ANS: The man inherit Ricketts from his mother. That’s where his X chromosome came from.

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