Why Do X-Linked Conditions Appear More Frequently in Males Than

Question

Why do X-linked conditions appear more frequently in males than in females?
A) A male with a nonfunctioning allele on the X chromosome does not have another allele of that gene on the Y chromosome that could cover up the nonfunctioning one.
B) Males have no X chromosomes.
C) The Y chromosome carries many alleles that are recessive to alleles on the X chromosome.
D) Males are more likely to inherit an extra chromosome than females.
E) Females have no X chromosomes.

Accepted Answer

Males only have one X chromosome, so if they inherit a nonfunctioning allele on that chromosome, they have no backup copy to compensate. Females, on the other hand, have two X chromosomes, so if one X chromosome has a nonfunctioning allele, the other X chromosome can often compensate.