Answer to Question #59167 in Genetics for Rafael Leahu

Question

Red-green color blindness is the inability to distinguish between the colors red and green. This characteristic is a X-linked recessive trait in humans and is 16 times more common in males than in females. Two people both have normal color vision have a color-blind son. What are the genotypes of the parents? Be sure to define the allele symbols you chose to use.

Answer 1

X* states for disorder, X is the normal allele.
Color-blind son must have genotype X*Y. The X chromosome was provided by mother. Thus, as she is healthy, her genotype is XX*.
The father is healthy and thus, his genotype is XY.