Males are More Often Affected by Sex-Linked Traits Than Females

Question

Males are more often affected by sex-linked traits than females because
A)male hormones such as testosterone often alter the effects of mutations on the X chromosome.
B)female hormones such as estrogen often compensate for the effects of mutations on the X chromosome.
C)X chromosomes in males generally have more mutations than X chromosomes in females.
D)males are hemizygous for the X chromosome.
E)mutations on the Y chromosome often worsen the effects of X-linked mutations.

Accepted Answer

Males have only one X chromosome, making them hemizygous for the X-linked gene. If they inherit a recessive allele that causes a particular trait, they will express the trait because they have no second copy of the X chromosome to provide the dominant allele that would mask the recessive one. In contrast, females have two X chromosomes and would need to inherit two copies of the recessive allele to exhibit the trait.