bio genetics blood type

Question

A man files his wife for divorce on the grounds of infidelity. Both man and wife have normal eyes, but there is a baby daughter who has coloboma iridis (a fissure in the iris of the eye). This characteristic is known to be inherited as a sex-linked, recessive trait. If you were the man’s lawyer, could you use this fact as evidence? If so, how would you explain the case to the jury?

1. no, it is unsure to use this information
2. yes, but the information given is unsure to come to a conclusion
3. yes, as there is no condition called carrier in this case

Answer 1

Hello! :)

Your answer would depend on both the sex to which the trait is linked, as well as to the status of grandparents and great grandparents on both sides of the equation.

Answer 2

If the baby girl has the condition then she got a X chromosome from each parent. And it is known that it is the sex linked form of the disease in this case.Then the mutated X chromosome could have come from either parent. However, we are told that the girl baby has sex linked recessive form which means that the mother has 2 mutated X chromosomes which is extremely unlikely but possible. Here is a quotation about the condition from the National Institutes of Health, " X-linked recessive means that in females, a mutation would have to occur in both copies of a gene to cause the disorder. In males, one altered copy of a gene in each cell is sufficient to cause the condition. Because it is unlikely that females will have two altered copies of a particular gene, males are affected by X-linked recessive disorders much more frequently than females."

So, I would choose answer B, "yes, but the information given is unsure to come to a conclusion"