Question

Zubeda's father is colorblind, as is her maternal grandfather (her mother's father). Zubeda herself has normal color vision. Zubeda and her husband, Martin, who is also colorblind, have just had their first child, a son they have named Mickey.

5 marks

Please answer the following questions about this small family.

a. What is the probability that this child will be colorblind?

b. Using proper pedigree format, diagram the available information about the four generations of

this family described, assuming that Mickey is colorblind.

c. If Martin were not colorblind, how would this affect the prediction about Mickey?​

Answer 1

a. The probability that Mickey will be colorblind is 0.5 (50%). A son inherits it's X chromosome from his mother and Marian has the one with the C allele and one with the c allele. He has an equivalent chance of receiving either one.

b. Mickey's colorblindness allele came from Marian's father. Mickey's Direct source of allele was Marian. Mickey didn't get it from Martin, his father, because he had to get his Y chromosome from Martin and the Y chromosome has No Allele for his gene on it.

c. It wouldn't Martin has nothing to do with Mickey being or not being colorblind. It's all up to Marian.

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