Cream is dominant and has a dosage effect in that a single copy of the cream allele ( N/Cr) produces palominos on a chestnut background and buckskin on a bay background. Molecular characterization of six different dilution phenotypes in horses include Cream, Champagne, Dun, Pearl, Silver, and Mushroom. Some dilute both the coat and the points (mane, tail, lower legs, ear rims), while others primarily dilute the points, and still others leave the points unaffected and only dilute the coat. Some of these dilution genes affect only one type of pigment (red or black) while others affect both (red and black). There are several genes that that have been shown to reduce the amount of pigment produced and/or reduce the amount transferred from the pigment cell to the hair follicular cells, and these are know as dilution genes. The genetics behind the variability in shade in horses is something we still have a lot to learn about. While, over 300 different genes have been identified that contribute to mammalian pigmentation, for many of these their contribution to equine pigmentation variation remains unknown. For example, some horses are a very dark chestnut known as liver chestnut while others are a much lighter yellow shade. 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. Equine Coat Color Genetics Base Coat Color
0 kommentar(er)
