Question

Oral-facial-digital syndrome type I is an X-linked dominant disorder (X^C). Consider a cross between a normal female and a male with the disorder. What is the genotype of these parents? What percentage of their female offspring would have the disorder? What about the male offspring? Show all your work.

Answer 1

Here I am taking the normal X allele as X and the dominant disordered allele as X*.

So, the genotype of the normal female is XX and the genotype of the disordered male will be X*Y.

Now, after the cross between them the punnet square diagram will be:

	X*	Y
X	X*X	XY
X	X*X	XY

So, from the punnet square diagram, we can see that 100% of the female offspring have the disorder (heterozygous for the diseased allele X*X).

We can see from the punnet square diagram that 0% of the male will be affected.