Locus Information: D locus
Inheritance: autosomal dominant
→ Horses with one or two copies of this variant (D/nd or D/D) show the diluted coat color and the primitive markings (zebra stripes, dorsal stripe) on their legs and back. Horses with one or two copies of this variant are duns.
- Duns show a diluted coat color depending on their base color, and primitive markings (stripes on legs and one along the back).
- Dun is the original coat color of all horses. Over time, two mutations (nd1 and nd2) caused the now wide-spread undiluted phenotypes most modern horses display.
- nd1 (non-dun1) leaves the gene partially functional and allows a non-diluted coat color but may keep the primitive markings (“pseudo-duns“).
- nd2 (non-dun2) switches the gene off completely and the horse displays a non-diluted coat color without primitive markings → most common phenotype in modern breeds.
- A horse may be D/D, D/nd1, D/nd2, nd1/nd1, nd1/nd2, or nd2/nd2.
- Buckskin (bay+cream) horses are often called “dun”, but a “true dun” has both a diluted coat color and primitive markings.
- Dun is dominant, so a dun horse must have at least one dun parent.
- A horse with a copy of cream and primitive markings from nd1 (“pseudo-dun) may be difficult to distinguish from a “true” dun.
|D/D||Dun (diluted coat color with primitive markings)
|D/nd1||Dun (diluted coat color with primitive markings)|
|D/nd2||Dun (diluted coat color with primitive markings)|
|nd1/nd1||undiluted coat color with primitive markings (dorsal stripe and leg bars)|
|nd1/nd2||undiluted coat color that may have primitive markings (dorsal stripe and leg bars):|
|nd2/nd2:||undiluted coat color without primitive markings (dorsal stripe and leg bars)
Test information: This test detects three different variants:
|1. The Wildtype (Dun).|
|2. The non-dun1 (nd1) mutation, which is caused by the change of a single basepair in the TBX3 gene.|
|3. The non-dun2 (nd2) mutation, which is caused by a deletion in the TBX3 gene.
Imsland, F., McGowan, K., Rubin, C.J., Henegar, C., Sundström, E., Berglund, J., Schwochow, D., Gustafson, U., Imsland, P., Lindblad-Toh, K., Lindgren, G., Mikko, S., Millon, L., Wade, C., Schubert, M., Orlando, L., Penedo, M.C., Barsh, G.S., Andersson, L. :Regulatory mutations in TBX3 disrupt asymmetric hair pigmentation that underlies Dun camouflage color in horses. Nat Genet :, 2015. Pubmed reference: 26691985. DOI: 10.1038/ng.3475.
Further information is available at Online Mendelian Inheritance in Animals verfügbar.
Test #: H219
Samples: Blood, Hair
Price: 35 € (net)
Time required: 7-10 days
|A: Dun = dilution + primitive markings
|B: Pseudo-dun (nd1) = full coat color + primitive markings|
|C: Non-dun (nd2) = full coat color without primitive markings|
|D: Non-dun (nd2) + dilution factor (e.g. Cream) = diluted coat color without primitive markings|
|→ A “pseudo-dun” with another dilution variant will look like a “real” dun.|