Red-green colorblindness is caused by a recessive X-linked allele (rg). The dominant allele (RG) at this gene locus confers normal red-green color vision. Blue color blindness is a different form of defective color vision caused by an autosomal gene. The rare dominant allele (B) causes an inability to see the color blue, while the recessive allele (b) confers normal blue color vision. A woman who is heterozygous at both loci has a child with a man who has red-green colorblindness but is normal for blue vision (as in the question above). What is the probability they will have the following: A son who is red-green and blue colorblind

the probability of a red-green and blue colorblind child is 1/8

Explanation:

We know according to the exercise that we parents have

XRG Xrg (Bb) (woman) x (man) Xrg (b)

the data is as follows

X-linked recessive allele (rg)

dominant allele (RG) normal vision

blue disability dominant allele (B)

blue normal vision recessive allele (b)

Xgr B. Yb

XGR B. XRGXrg(Bb) XRGY(Bb)

XGR b. XRGXrg(bb) XRGXrg( bb)

Xgr B. XrgXrg( Bb) XrgY(Bb)

Xgr b. XrgXrg(bb) XrgY( bb)

As we can see in the previous graph, the probabilities that we can have are registered and that the probability of having a child with the characteristic colorblind red-green and blue or XRGY (Bb) will be 1/8