X-linked

An X-linked gene is agene which is coded for on the X chromosome. Mutations of said gene are therefore more likely to be presented in males as males have only one copy of the gene.

Patterns of inheritance in X-linked diseases are complicated by the fact that fathers always pass their X chromosome to their daughters where-as mothers pass the X chromosome to daughters and sons equally.

Colourblindness is an example of an X-linked recessive disease. Which is much more prevelent in males.