Refers to an inheritance pattern in which an individual has mutations
on the X chromosome
. In males (who have only one X chromosome
), one mutated copy of the gene in each cell
is enough to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the condition. Because it is unlikely that females will have two mutated copies of this gene, males are affected by X-linked
recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits
to their sons (no male-to=male transmission).