A woman's father has ornithine transcarbamylase deficien...

Question

A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.

If the woman has a son with a man who does not have OTD, what is the chance the son will have OTD?

Accepted Answer

Hey, everyone. Let's take a look at this question together if both the mother and the father have ex linked recessive disorders, which of the following is correct. Is it answer choice. A half of their Children will get affected. Answer choice. B all of their Children will be carriers. Answer choice. C, only the daughters will get affected or answer choice. D all Children will get affected. Let's work this problem out together to try to figure out which of the following answer choices is the correct answer. So we know that both the mother and the father have this X linked recessive disorder. So let's go ahead and represent the mother by having two X chromosomes. And we have the father, which we know that the father is represented as that one X and the Y. And since both the mother and the father have this excellent recessive disorder, we can go ahead and put the mutant allele on the mother and the father to represent that they both have that X linked recessive disorder. And let's go ahead and set up a punt square cross between this mother and father in order to determine more information about what their offspring might look like. So on the top of the pundit square, we will have the mother, which is represented as having two X chromosomes with the immune allele attached to both. And then on the left, we will have father, which we know is represented as having that one X and the Y with the X chromosome having that muti as well. And so when we do a cross between this mother and the father, we know that we end up with having 50% of the offspring being female because of the two X chromosomes and 50% being male because of that X and Y chromosome. And we go ahead and add our mule to all of the XX chromosomes since it is an ex linked recessive disorder. And in order for both the mother and the father to have it, they need to have that recessive disorder on every single X chromosome, which is why you see that the mother has two mut and the father has one on his singular X chromosome and the mother on both XX chromosomes. So now that we have this pundit square cross between the mother and the father, we can determine that the correct answer is answer choice. D all Children will get affected because we know that answer choice A is an incorrect statement since all of their Children will be affected. And answer choice B and C are also both in correct statements because all of their Children will not be carriers and will have the disorder as well as the males and the females having the disorder. So answer choice C is also incorrect and answer choice. D all Children will get affected is the only correct answer. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

X-Linked Recessive Inheritance

Genotype of the Parents

Punnett Square Analysis

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