An x-linked gene means that the mutation occurs on a gene in the x-chromosome. For males, the single recessive gene on that chromosome is more likely to cause a disorder since males have one x and one y chromosome. Females, who have two x chromosomes, are less likely to show the recessive gene. 

For females to receive x-linked gene disorders, both parents must be x-linked carriers of the condition. A woman who has the condition on one x-chromosome will be a carrier.