Each horse has a basic coat colour, which can be black, bay/brown or chestnut. These basic coat colours are controlled by the Extension and Agouti genes. The Extension gene controls the production of black and red pigment while the distribution of black pigment is controlled by the agouti gene.
The rest of the colour genes act as modifiers (dilution or depigmentation) on the basic coat colour of the horse. There are at least five genes that dilute the coat colour of the horse: Cream, Champagne, Dun, Pearl, and Silver. The pattern genes modify the colour of the horse by deleting colour (depigmentation). These genes include Overo, Sabino, Tobiano, Grey, dominant white, white spotting, Appaloosa spotting and Pattern-1. For Appaloosa spotting VHLGenetics doesn’t offer a test yet.
Within the above described coat colour genes, three genes explain the major differences; the Agouti, Extension and Cream dilution genes. In the table below the possible combinations of the genes are indicated.
|
Coat Colour |
Agouti |
Extension |
Cream Dilution |
|---|---|---|---|
|
Black |
a/a |
E/E of E/e |
N/N |
|
Brown or Bay |
A/A of A/a |
E/E of E/e |
N/N |
|
Chestnut |
A/A, A/a of a/a |
e/e |
N/N |
|
Smoky black |
a/a |
E/E of E/e |
N/Cr |
|
Buckskin |
A/A of A/a |
E/E of E/e |
N/Cr |
|
Palomino |
A/A, A/a of a/a |
e/e |
N/Cr |
|
Smoky cream |
a/a |
E/E of E/e |
Cr/Cr |
|
Perlino |
A/A of A/a |
E/E of E/e |
Cr/Cr |
|
Cremello |
A/A, A/a of a/a |
e/e |
Cr/Cr |
