Question

Color blindness is a X-linked recessive trait. A couple want to predict whether it would be possible for their child to be color blind. The female is an unaffected carrier and the male is red/green color blind. What percentage of offspring would be color blind? ​

Answer 1

Answer: There is a probability (n.b. NOT certainty) that half of all offspring will be colour blind.

Explanation: The female is XX and as an unaffected carrier we can assign genotype Cc where c is the recessive allele.

The male is XY and colour blind, so genotype cY

Male offspring can be cY or CY so p|colourblind = 50%

Female offspring can be Cc or cc so, again p= 50%

If there is also equal probability of sex of the offspring, there is an overall probability that half the offspring will be colour blind