Definition: X-linked dominant inheritance refers to one of the ways in which a trait or disorder can be inherited. X-linked disorders are caused by mutations in one of the genes on the X chromosome. In females (who have two X chromosomes), a mutation in one of the two copies of the gene in each cell is enough to cause the disorder. In males (who only have one X chromosome), a mutation in the only copy of the gene in each cell causes the disorder. In most cases, male experience more severe symptoms of the disorder than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits or disorders to their sons because with this pattern of inheritance there is no male-to-male transmission.