Two mothers give birth to sons at the same time at a busy urban hospital. The son of mother 1 is afflicted with hemophilia, a disease caused by an X-linked recessive allele. Neither parent has the disease. Mother 2 has a normal son, despite the fact that the father has hemophilia. Several years later, couple 1 sues the hospital, claiming that these two newborns were swapped in the nursery following their birth. As a genetic counselor, you are called to testify. What information can you provide the jury concerning the allegation?

Question

Accepted Answer

Hello everyone welcome back. Let's look at our next question in which of the following conditions does a carrier female pass the disorder onto her male child? Well looking at this question, we've got a big clue in the word carrier, a carrier of course is a person that is heterosexual. For a recessive I will for a condition. So in this case our disorder is carried on a recessive gene and the carrier female has only one copy of the alley. So we can go ahead and eliminate choice. A autism all dominant and choice C. X linked dominant. Because of course a dominant disorder. There are no carriers. If you have even one copy of the affected value, all you have the disorder then our second key. Now we need to choose between choice B autism will recess it and choice the excellent recess it is that our question says we have a carrier female passing the disorder onto a male child. Well in autism disorders, the sex of the individual does not matter. Male female, they all have the same autism all chromosomes. So the inheritance of the disease will not be affected by sex. So that gives us our clue that we're not talking about choice be autism. A recessive. We'd be looking at a sex linked trait. And since we have a carrier female. So the female is hetero passing the disorder to her male child. So the male child of course has only a single X chromosome. So even if he only inherits one copy of that recessive gene, it doesn't matter that it's recessive. Since he has no second X to provide the dominant unaffected alil. Uh it's in the case of a female child because the female has two X chromosomes, it can only, the disorder can only be passed on from two parents with the affected a little. So when we have a carrier female that can pass the disorder itself, not just um not just carrier status onto her male child, we're talking about an excellent recessive trait. So choice D excellent recessive. See you in the next video.

Verified video answer for a similar problem:

Key Concepts

X-linked Recessive Inheritance

Genetic Probability and Carrier Status

Paternity and Maternity Testing Using Genetic Markers