Question

. A normal vision male marries a female who is a carrier of the color-blind gene and she becomes pregnant. What will a genetic counselor tell the parents regarding the a) percentage of having a daughter who is color-blind; b) what is the percentage of having a son who is color-blind? Consider a different couple with a female with normal vision and a male with normal vision. Would it be possible for their daughter to be a carrier for color-blindness? Explain your answer.

Answer 1

Step-by-step explanation:

a, The genetic counselor should explain that color-blindness is a sex-linked disorder, that is its expression is related to a particular sex-cells.

a) The percentage is 0% . This is because your husband is normal, so no sex-linked alleleis attached to his only X-chromosomes.However either of your X-chromosomes can bear the allele for color blind. Since a girl child sex-chromosomes combination is XX, and your husband X chromosomes is normal,hence your daughters can only be carries (XCX, XCX)like you if they inherited any of your X -chromosomes color blind allele.But none will be colorblind.

b)Because you are carrier for this alllele, and your husband is normal; chances are all your sons be colourblind is 50% proportion(YXC/YXC). This is because your husband Y chromosomes determines a male child, and you can bear the defective(carrier allele) for colourblind on either of your X-chromosmes to give a male child as XY. Thus either of the male child assuming with Mendelian fashion of inheritance, will be colour blind in 50% proportion.

No. A girl child can only be a carrier for color blindness if the inherited the color blind gene from her carrier mother or the father is color-blind. None of this is present in this scenario. The two parents are normal Therefore there is no chance of their daughter emerging a carrier.