Question

Red-green color blindness is due to a mutant gene in the X chromosome. An XX female with normal color vision and an XY male with normal color vision have a child with karyotype XXY who is color blind. The likely explanation is that the:

a. father was heterozygous for the color-blindness mutation.
b. mother was heterozygous for the color-blind mutation.
c. father had CNV of the color-blind mutation.
d. mother had CNV of the color-blind mutation.
e. None of the other answer options is correct

Answer 1

e. None of the other answer options is correct

Step-by-step explanation:

Red-green color blindness is due to a mutant gene in the X chromosome.

An XY male with normal color vision => the X chromosome of the father is normal.

The child has karyotype XXY and is color blind. This means he or she receives one Y from the father and two X's from the mother.

This then means that the mother has two X's with two mutant genes.

However, in this question, the mother's color vision is normal.

Therefore, the answer is e.