The red factor and agouti panel offers diagnostic tests for these two coat color markers.
The extension gene, or red factor, determines whether a horse will have a chestnut base coat color or a black or bay base coat color.
The agouti gene controls the distribution of black pigment, and determines whether a horse will have a bay or black base coat color.
Mode of Inheritance: Autosomal dominant
Alleles: A = Dominant agouti allele (responsible for bay)
a = Recessive agouti allele (causes black)
Explanation of Results:
- If black pigment is present, horses with A/A genotype have black pigment restricted to the points. They will transmit the dominant agouti allele to all of their offspring.
- If black pigment is present, horses with A/a genotype have black pigment restricted to the points. They will transmit the dominant agouti allele to 50% of offspring and the recessive agouti allele to 50% of offspring.
- Horses with a/a genotype will have black pigment distributed uniformly over the body and will transmit the recessive agouti allele to all of their offspring.
Please Note: All DNA parentage verification and mandatory health testing results, whether purchased through the EBRA or transferred into the EBRA system, will become permanent record, which the documented owner may access at any time upon request. The EBRA is not responsible for providing non-mandatory DNA test results, therefore the release of any additional testing performed by past or present owners must be negotiated between the private parties at time of purchase.
Red Factor and Black Agouti Test
Roan is a white patterning coat color trait of intermixed white and colored hairs in the body while the head, lower legs, mane, and tail remain colored. Roan horses are born with the pattern, though it may not be obvious until the foal coat is shed. The white and colored hairs are evenly mixed in horses that inherit the classic Roan gene, which can differentiate this from several mimic patterns called roaning. Roaning patterns tend to be uneven in the distribution of white hairs, and the inheritance of roaning has not been defined. The Roan gene is found in a variety of breeds such as Quarter Horse, Paints, Peruvian Paso, Paso Fino, Welsh Pony, Miniature and Belgian, but not in Thoroughbreds or Arabians.
Although it has been suggested that Roan is a homozygous lethal, evidence from the Quarter Horse breed indicates otherwise. Production records have documented the existence of Roan Quarter Horses that produce 100% Roan foals. DNA tests have confirmed homozygosity in the genomic region that contains the Roan gene.
Note: Roan is inherited as a dominant gene but the specific mutation has not yet been identified, so there is no direct test for the gene. VGL has identified DNA markers in Quarter Horses and Paints associated with Roan that can be used to determine if a horse has the roan gene and how many copies. The following additional materials should be included to provide a complete analysis:
Materials Needed for Complete Analysis
- Hair sample from at least one parent
- Color photo of the subject horse, labeled with the horse’s name
- Three generation pedigree with color and patterns listed