Please select one of the following tests for further information:
Red factor testing can be used to differentiate between black horses carrying Ee and those carrying EE. For further information on the inheritance of colours in horses please visit the section about Agouti testing.
The agouti locus directly interacts with the extension locus (red factor), e.g. horses, which are homozygous ee for red factor are reddish in colour independent of the genetic status at the agouti locus.
Accordingly, the interaction of the extension locus and the agouti will create the following situations:
|Phenotype||Genetic status||Possible progenies|
|Chestnut||aa;ee||No bay horse if mated
|Aa;ee||Any coat colour possible|
|Bay||AA;EE||No blacks, no chestnuts|
|Aa;Ee||Any coat colour possible|
|aa;EE||Only blacks if mated with blacks|
GeneControl is currently offering genetic testing of following White spotting variants:
|Variant||Breed / Origin||Phenotype|
|W8||Islandic / Þokkadís vom Rosenhof||variable phenotype ranking from white markings to complete sabino-like pattern|
|W20||quite common in many breeds||Minimal sabino-like piebald pattern. W20 increases the proportion of white caused by other W variants as well as piebald patterns such as Sabino or Tobiano|
|W21||Islandic / Ellert frá Baldurshaga||Moderately expressed sabino-like piebald pattern, different colored eyes possible|
Note: Most combinations of two (different or same) White spotting variants cause embryonic death. This means it is very unlikely that a horse will have two copies of White spotting unless it is a combination with at least one copy of W20.
Another two possible alleles at the Dun locus can influence expression of the dun coat colour:
Nd1 – the non-dun1 allele is caused by a single nucleotide polymorphism in the TBX3 gene. Allele nd1 causes a non-diluted base color in combination with primitive markings of varying degrees (e.g. pseudo- line on the back).
Nd2 - the non-dun2 allele is caused by a complex deletion of bases in the TBX3 gene. Allele nd2 is quite common in most horse breeds, today. It causes a non-diluted base color without primitive markings.
Allele D acts dominant over nd1 and nd2. Allele nd1 is dominant over nd2.
|Falbe||D/D||homozygous dun; diluted base colour and primitve markings|
|D/nd1||heterozygous dun; diluted base colour and primitve markings|
|D/nd2||heterozygous dun; diluted base colour and primitve markings|
|Non-dun||nd2/nd2||non-diluted base colour, no primitve markings|
|Pseudo-Dun||nd1/nd1||non-diluted base colour with primitve markings|
|nd1/nd2||non-diluted base colour, primitve markings possible|
Champagne colors can resemble other diluted colors, e.g., cream dilutions and can also occur in combination. Horses which are heterozygous for the cream dilution gene will be classic ivory champagne (black), amber ivory champagne (bay) or gold ivory champagne (red) when carrying one or two copies of the champagne gene.
Champagne also modifies the phenotype of dun and silver dapple. For example, bay horses carrying silver dapple will be diluted to amber silver champagne and black dun horses will be diluted to classic dun champagne by the champagne gene.
At the cream dilution locus there are two possible allelic states: CCr and C. The semi-dominant allele CCr causes brightening of the basic coat colour which in single dose results in palominos, buckskins or smoky blacks and in double dose causes pale cream colours seen in cremello, perlino or smoky cream horses.
In contrast, the recessive allele C has no influence hair pigmentation. Animals being homozygous for allele C are non-dilute and show basic colours like chestnut, bay or black in the absence of other modifying genes.
Horses carrying two copies of the pearl gene appear similar to champagne diluted horses. Horses carrying one copy of the pearl gene and one copy of cream will have a diluted color which can resemble champagne dilution or double diluted cream horses.
The pearl gene, originally discovered in Andalusian and Paint Horses, is present in Quarter Horses, Paints and related breeds, today.
Please note: The offered test does not distinguish between homozygous and heterozygous carriers of the Grey gene, but discriminates presence and absence of the Grey gene.
Recent research revealed 3 mutations (SW1, SW2 and SW3) that cause splashed white spotting pattern in horses.
Variant SW1 is found in several breeds, e.g. Quarter and Paint Horse, Trakehner, Miniature Horse, Icelandic Horse and Shetland Pony. Homozygous SW1 splashed horses have been identified, which suggests that this variant is not lethal in homozygous state.
Occurrence of SW2 and the rare SW3 mutation is confined to certain lines of Quarter Horses and Paints. Both mutations are suggested to have a lethal effect in homozygous state. Thus breeding two horses that carry SW2 or SW3 should be avoided due to the risk of generating nonviable embryos.
Horses that carry two or more splashed white mutations or a combination of tobiano or lethal white overo and splashed white may display extensive white markings up to being completely white.
In chestnuts, the gene causes a lightened sepia color of the body as well as a flaxen mane and tail. In bay horses milder gene effects are seen with normally pigmented mane and tail and a sepia diluted body due to lack of red pigment.
Mushroom can show similarities to cream and silver dilutions, although these have different genetic background.