X-lined disorders are inherent disorders due to mutation in the X-chromosome which causes the phenotype to be always expressed in male and in female only in homozygous condition.

Colour blindness and haemophilia are X-linked recessive disorder. In colour blindness, the affected individual has is not able to distinguish colour especially read and green. In haemophilia, the individual has delayed clotting time for blood which can be fatal.

Colour blind father $\left({\mathrm{X}}^{\mathrm{c}}\mathrm{Y}\right)$ and hemophilic $\left({\mathrm{X}\mathrm{X}}^{\mathrm{h}}\right)$ . carrier mother will produce the following combination of progenies-

Probabilities of son - $\mathrm{X}\mathrm{Y}/{\mathrm{X}}^{\mathrm{h}}\mathrm{Y}$

Probabilities of daughter - ${\mathrm{X}}^{\mathrm{c}}\mathrm{X}/{{\mathrm{X}}^{\mathrm{c}}\mathrm{X}}^{\mathrm{h}}$

25% female progenies carry the genes for both haemophilia and colourblindness.

25% male progenies carry only the gene for haemophilia.

25% female progenies carry only the gene for colourblindness.

25% male progenies are normal without any X-linked disorder.