How does inheritance work in x-linked recessive diseases?

It's Complicated: In x-linked disorders, the allele for the trait is located on the x chromosome. In recessive traits, both parents must pass on a copy of the recessive allele for the child to be affected. For a son (xy) to be affected, his mom must pass on the recessive allele (since the dad passes the y and is not a factor). For a daughter (xx), both parents must pass it.

Naked X expresssion: The carrier mother has 2 x chromosomes and the 2nd normal chromosome produces enough of the "normal" factors that mother is not symptomatic. The male with only one x chromosome from the mother, has a y that cannot cover up the deficiency in mom's donated x, so the male is affected by whatever the condition is.