Sex-Linked Inheritance and disorders
Hemophilia, an autosomal or sex-linked recessive trait, results from mutations of genes encoding blood clotting proteins.
Affected the royal families of England and Russia prior to World War I. Fig. 7.24
The sex-linked forms are much more common because men only have one gene on the X chromosome and there is no allele on the Y chromosome.
Red-green color-blindness - Genes code for the proteins that make pigments in the eye necessary for absorbing the different-colored wavelengths in light.
Red and green pigments are made by proteins on the X chromosome.
Mutations in the genes for these pigments result in inability to see those colors.
These mutations are recessive because one good copy of the gene is sufficient for color vision.
Effect men much more frequently than women. Because women have two X chromosomes, they can be heterozygous (have one mutant allele) but still have normal color vision (0.5% of women are color blind).
Men have only one X chromosome, so if they have one mutant allele, they will be color blind (8% are color-blind).
SOURCE