A horse that inherits a Grey coat colour can be born in any colour. El gen gris causa la despigmentación progresiva (decoloración) del cabello y se considera que es el más fuerte de todos los genes modificadores del color del pelaje. El proceso de despigmentación puede durar años, pero una vez que se despigmenta el cabello, el color original nunca regresará. Algunos caballos grises se vuelven completamente blancos, mientras que otros mantendrán pequeñas manchas sin decoloración (también llamadas pulgas). A horse can also carry mutations for other modifying genes which can further affect its coat colour.
The Coat Colour Grey test (P807) tests for the genetic status of the STX17 gene. Este gen tiene dos variantes (alelos). El alelo dominante G da como resultado el color de la capa gris y el alelo recesivo N no tiene un efecto sobre el color básico. El alelo dominante G tiene una duplicación de una parte del ADN. The test does not discriminate between horses carrying 1 or 2 copies of the duplication (N/G or G/G). Todos los caballos que lleven la duplicación se volverán grises.
The Coat Colour Grey test encloses the following results, in this scheme the results of the Coat Colour Grey test are shown in combination with the possible results for the tests that determine the basic Coat Colour (Coat Colour Chestnut and Coat Colour Agouti test):
|
Result Grey |
Result Chestnut + Agouti |
Coat Colour |
Descripción |
|---|---|---|---|
|
N/N |
e/e + A/A, A/a or a/a
|
Chestnut, Sorrel |
Horse will not turn grey. The basic colour chestnut/sorrel is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/N |
E/E or E/e + A/A or A/a |
Bay, Brown |
Horse will not turn grey. The basic colour bay/brown is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/N |
E/E or E/e + a/a |
Black |
Horse will not turn grey. The basic colour black is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/G or G/G |
e/e + A/A, A/a or a/a
|
Grey (born chestnut/sorrel) |
Horse is born with basic colour chestnut/sorrel (unless modified by other colour modifying genes) and will turn grey. One copy or two copies of the G allele. It can pass on either allele N or G to its offspring. |
|
N/G or G/G |
E/E or E/e + A/A or A/a |
Grey (born bay/brown) |
Horse is born with basic colour bay/brown (unless modified by other colour modifying genes) and will turn grey. One copy or two copies of the G allele. It can pass on either allele N or G to its offspring. |
|
N/G or G/G |
E/E or E/e + a/a |
Grey (born black) |
Horse is born with basic colour black (unless modified by other colour modifying genes) and will turn grey. One copy or two copies of the G allele. It can pass on either allele N or G to its offspring. |