This variability has been described as shade. Variability exists among the three basic coat colors. The dominant allele ( A) restricts black pigment to the points of the horse (mane, tail, lower legs, ear rims), while the recessive form ( a) distributes black pigment uniformly over the body.Ĭurrently, genetic tests for the three basic coat colors include: Agouti and Red Factor ASIP, also known as Agouti, controls the distribution of black pigment. In homozygous individuals ( e/e or e a/e a) only red pigment is produced, hence the name red factor. The e and e aalleles are recessive to E and are considered to be loss of function mutations in MC1R. To date, there are three versions ( alleles) of this gene that have been identified at the molecular level: E, e, and e a. MC1R, which has also been referred to as the extension or red factor locus, controls the production of red and black pigment.

These are controlled by the interaction between two genes: Melanocortin 1 Receptor ( MC1R) and Agouti Signaling Protein ( ASIP). The basic coat colors of horses include chestnut, bay, and black. Below are the current genetic tests offered by the Veterinary Genetics Laboratory for dog coat color.Equine Coat Color Genetics Base Coat Color As new discoveries are made we will update our information and educational resources.

Additional genes have been shown to also dilute the coat and add white patterns some of which are specific to certain breeds. The dilution gene ( MLPH) dilutes both black and red pigments. Beta-defensin ( CBD-103), which so far has been found to be unique to dogs, is responsible for dominant black (K locus). While Agouti ( ASIP) organizes the distribution of black and red pigments. For example, the Brown gene, Tyrosinase-Related Protein 1 ( TYRP1), is a modifier that dilutes black pigment to brown but does not affect red pigment. Other genes modify how much eumelanin and phaeomelanin are produced and this results in the variety of colors and patterns found in the domestic dog.

One of the genes involved in the production of these pigments in many species including dogs is Melanocortin 1 Receptor ( MC1R) which is also known as the Extension locus. Mammals have two pigments that are the basis of hair color: eumelanin (black) and phaeomelanin (red or yellow).

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