Cat Coat Genetics

Identifying the genes that regulate cat coat genetics, is not an easy job, as there are many genes regulating different aspects of a cat’s coat and they usually interact with each other. There are genes for color, pattern and fur length. The combination of all these results in a certain type of coat. This article discusses the genes for:

• Color,
• Pattern, and
• Fur length.

Genes for Color

An important aspect of cat coat genetics are the genes determining coat color. Primary genes that can be discerned are:

• The colorpoint restriction gene: this determines the production of melanin. There are four alleles of this gene: C (full color, dominant over the other alleles), cb (Burmese, or sepia color), cs (Siamese color, and the very rare c allele (Albino, white coat and blue eyes).
• The brown gene: this gene affects the amount of melanin produced. There are three alleles: B (Full color, dominant allele), b (Brown color, recessive compared to B, dominant over bl), bl (Light bron, or cinnamon).
• The orange gene: this gene determines the production of phaeomelanin. There are two alleles: O (Orange color, dominant), and o (shade of black, depending on the brown gene).
• The white gene: this gene determines whether or not the pigment producing cells reach the skin and are able to produce a coat color. There are two alleles: W (White color, dominant), and w (Any color, depending and the aforementioned genes).

Genes for Pattern

A second aspect of cat coat genetics, is the distribution of the coat color. Here also, several genes are involved:

• The agouti gene: this gene regulates the distribution of the black pigment in the hairs. There are two alleles: A (Agouti, bands of color on the hairs, dominant) and a (Solid color).
• The dilute gene: this gene causes an uneven distribution of the pigment in the hairs, resulting in a ‘diluted’ effect. There are two alleles: D (Full color, dominant), and d (Dilute).
• The melanin inhibition gene: this gene can inhibit the expression of melanin. There are two alleles: I (Inhibition, dominant) and I (No inhibition).
• The tabby marking gene: this gene determines the occurrence of stripes in the coat. There are three alleles: T (Striped, referred to as mackerel or tiger, dominant), Ta (ticked fur and tabby stripes on the face, also dominant), and tb (Blotchy or classic pattern).
• The spotting gene: this gene regulates the expression of white patches and has variable expression. There are two alleles; S (Spotted), and s (Not spotted). Due to the variable expression an SS cat has more and larger patches than an Ss one.

Genes for Fur Length

• The hair length gene: determines the length of the cat’s hairs. There are two alleles: L (Short hair, dominant) and l (Long hair).

There are some other genes that affect the length and presence of the hairs in specific cat breeds. For example, Sphinx cats posses a ‘hairless’ gene, and several cat breeds (such as the Cornish Rex and the Devonshire Rex) posses a ‘curly’ gene.

References

• Eizerik, E.; Yuhki, N.; Johnson, W.E.; Menotti-Raymond, M.; Hannah, S.S & O’Brien S.J. (2003) Molecular Genetics and Evolution of Melanism in the Cat Family. Current Biology. 13(5), pp. 448 – 453.
• UC Davis, Veterinary Genetics Laboratory: https://www.vgl.ucdavis.edu/services/coatcolorcat.php
• University of Saskatchewan, Department of Animal and Poultry Science: https://homepage.usask.ca/~schmutz/catcolors.html
• Wageningen University, Laboratory of Genetics: https://www.gen.wur.nl/UK/education/Courses/Simplified+cat+coat+color+genetics/?wbc_purpose=Basic&WBCMODE=PresentationUnpublished