OMIA:000201-9796 : Coat colour, agouti in Equus caballus (horse)

In other species: Tasmanian devil , gray wolf , coyote , dog , red fox , domestic cat , leopard , ass (donkey) , pig , Arabian camel , llama , Western roe deer , impala , taurine cattle , goat , sheep , rabbit , tassel-eared squirrel , North American deer mouse , Mongolian gerbil , meadow voles , domestic guinea pig , alpaca , leopard cat , oldfield mouse , Kodkod , Colocolo , Asiatic golden cat , Northern mole vole , Eurasian water mole

Categories: Pigmentation phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 611742 (trait) , 600201 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2001

Cross-species summary: This locus, ASIP, encodes the agouti signalling protein, a peptide antagonist of the melanocyte-stimulating hormone receptor (MC1R), which is the product of the extension locus. As explained by Schneider et al. (PLoS Genet 10(2): e1004892; 2015), "The most common causes of melanism (black coat) mutations are gain-of-function alterations in MC1R, or loss-of function alterations in ASIP, which encodes Agouti signaling protein, a paracrine signaling molecule that inhibits MC1R signaling".

Molecular basis: By cloning and sequencing a very likely comparative candidate gene (based on the known molecular basis of the agouti locus in other species), Rieder et al. (2001) identified recessive black in nine breeds as being due "an 11-bp deletion in exon 2 (ADEx2) [of the ASIP gene, OMIAvariantID:509]. . . . The frameshift initiated by ADEx2 is believed to alter the regular coding sequence, acting as a loss-of-function ASIP mutation." The same authors also state that they consider the deletion to be "between position 2174–2184 on genomic DNA level or at position 191–201, with regard to the start codon, if only exonic sequences are taken into account".

Breeds: American Trotter (Horse) (VBO_0000899), Arab (Horse) (VBO_0000905), Belgian Draft (Horse) (VBO_0000915), Clydesdale (Horse) (VBO_0000934), Freiberger (Horse) (VBO_0000965), Icelandic Horse (Horse) (VBO_0000991), Morgan (Horse) (VBO_0001022), Quarter Horse (Horse) (VBO_0001057), Shetland Pony (Horse) (VBO_0001066), Warmblood (Horse) (VBO_0017483), Welsh Pony (Horse) (VBO_0001091).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
ASIP agouti signaling protein Equus caballus 22 NC_009165.3 (26009341..26072655) ASIP Homologene, Ensembl , NCBI gene


By default, variants are sorted chronologically by year of publication, to provide a historical perspective. Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the second, third etc relevant column headers.

WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.

OMIA Variant ID Breed(s) Variant Phenotype Gene Allele Type of Variant Source of Genetic Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
509 American Trotter (Horse) Arab (Horse) Belgian Draft (Horse) Clydesdale (Horse) Freiberger (Horse) Icelandic Horse (Horse) Morgan (Horse) Quarter Horse (Horse) Shetland Pony (Horse) Thoroughbred (Horse) Warmblood (Horse) Welsh Pony (Horse) Coat colour, recessive black ASIP a deletion, small (<=20) Naturally occurring variant EquCab3.0 22 NC_009165.3:g.26067463_26067473del NM_001164017.1:c.187_197del published as g.2174_2184del and c.191_201del - coordinates in the table updated to a recent reference genome. rs3091770233 2001 11353392 Coordinates in EquCab3.0 kindly provided by Haley Rutstein, working under the guidance of Professor Ernie Bailey. Breed information based on PMID: 38600096

Cite this entry

Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2024). OMIA:000201-9796: Online Mendelian Inheritance in Animals (OMIA) [dataset].


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.

2024 Durward-Akhurst, S.A., Marlowe, J.L., Schaefer, R.J., Springer, K., Grantham, B., Carey, W.K., Bellone, R.R., Mickelson, J.R., McCue, M.E. :
Predicted genetic burden and frequency of phenotype-associated variants in the horse. Sci Rep 14:8396, 2024. Pubmed reference: 38600096. DOI: 10.1038/s41598-024-57872-8.
Mura, M.C., Carcangiu, V., Cosso, G., Columbano, N., Sanna Passino, E., Luridiana, S. :
Discrepancies between genetic and visual coat color assignment in Sarcidano horse. Animals (Basel) 14:543, 2024. Pubmed reference: 38396512. DOI: 10.3390/ani14040543.
2021 Cieslak, J., Brooks, S.A., Wodas, L., Mantaj, W., Borowska, A., Sliwowska, J.H., Ziarniak, K., Mackowski, M. :
Genetic background of the Polish primitive horse (Konik) coat color variation-new insight into dun dilution phenotypic effect. J Hered 112:436-442, 2021. Pubmed reference: 34432873. DOI: 10.1093/jhered/esab034.
2020 Corbin, L.J., Pope, J., Sanson, J., Antczak, D.F., Miller, D., Sadeghi, R., Brooks, S.A. :
An independent locus upstream of ASIP controls variation in the shade of the bay coat colour in horses. Genes (Basel) 11:606, 2020. Pubmed reference: 32486210. DOI: 10.3390/genes11060606.
Nguyen, T.B., Paul, R.C., Okuda, Y., LE, T.N.A., Pham, P.T.K., Kaissar, K.J., Kazhmurat, A., Bibigul, S., Bakhtin, M., Kazymbet, P., Maratbek, S.Z., Meldebekov, A., Nishibori, M., Ibi, T., Tsuji, T., Kunieda, T. :
Genetic characterization of Kushum horses in Kazakhstan based on haplotypes of mtDNA and Y chromosome, and genes associated with important traits of the horses. J Equine Sci 31:35-43, 2020. Pubmed reference: 33061782. DOI: 10.1294/jes.31.35.
2019 Mackowski, M., Wodas, L., Brooks, S.A., Cieslak, J. :
TBX3 and ASIP genotypes reveal discrepancies in officially recorded coat colors of Hucul horses. Animal 13:1811-1816, 2019. Pubmed reference: 30614426. DOI: 10.1017/S1751731118003506.
Shang, S., Yu, Y., Zhao, Y., Dang, W., Zhang, J., Qin, X., Irwin, D.M., Wang, Q., Liu, F., Wang, Z., Zhang, S., Wang, Z. :
Synergy between MC1R and ASIP for coat color in horses (Equus caballus)1. J Anim Sci 97:1578-1585, 2019. Pubmed reference: 30785190. DOI: 10.1093/jas/skz071.
2016 Jacobs, L.N., Staiger, E.A., Albright, J.D., Brooks, S.A. :
The MC1R and ASIP coat color loci may impact behavior in the horse. J Hered 107:214-9, 2016. Pubmed reference: 26884605. DOI: 10.1093/jhered/esw007.
Reissmann, M., Musa, L., Zakizadeh, S., Ludwig, A. :
Distribution of coat-color-associated alleles in the domestic horse population and Przewalski's horse. J Appl Genet 57:519-525, 2016. Pubmed reference: 27194311. DOI: 10.1007/s13353-016-0352-7.
2013 Teixeira, R.B., Rendahl, A.K., Anderson, S.M., Mickelson, J.R., Sigler, D., Buchanan, B.R., Coleman, R.J., McCue, M.E. :
Coat color genotypes and risk and severity of melanoma in gray Quarter horses. J Vet Intern Med 27:1201-8, 2013. Pubmed reference: 23875712. DOI: 10.1111/jvim.12133.
2010 Bellone, RR. :
Pleiotropic effects of pigmentation genes in horses. Anim Genet 41 Suppl 2:100-10, 2010. Pubmed reference: 21070283. DOI: 10.1111/j.1365-2052.2010.02116.x.
Li, B., He, XL., Zhao, YP., Wang, XJ., Manglai, D., Zhang, YR. :
[Molecular basis and applicability in equine color genetics]. Yi Chuan 32:1133-40, 2010. Pubmed reference: 21513164.
2009 Kakoi, H., Tozaki, T., Nagata, S., Gawahara, H., Kijima-Suda, I. :
Development of a method for simultaneously genotyping multiple horse coat colour loci and genetic investigation of basic colour variation in Thoroughbred and Misaki horses in Japan. J Anim Breed Genet 126:425-31, 2009. Pubmed reference: 19912416. DOI: 10.1111/j.1439-0388.2009.00841.x.
Lewin, H.A. :
Genetics. It's a bull's market. Science 324:478-9, 2009. Pubmed reference: 19390037. DOI: 10.1126/science.1173880.
Ludwig, A., Pruvost, M., Reissmann, M., Benecke, N., Brockmann, G.A., Castaños, P., Cieslak, M., Lippold, S., Llorente, L., Malaspinas, A.S., Slatkin, M., Hofreiter, M. :
Coat color variation at the beginning of horse domestication. Science 324:485, 2009. Pubmed reference: 19390039. DOI: 10.1126/science.1172750.
Rieder, S. :
Molecular tests for coat colours in horses. J Anim Breed Genet 126:415-24, 2009. Pubmed reference: 19912415. DOI: 10.1111/j.1439-0388.2009.00832.x.
2008 Royo, L.J., Fernández, I., Azor, P.J., Alvarez, I., Pérez-Pardal, L., Goyache, F. :
Technical note: a novel method for routine genotyping of horse coat color gene polymorphisms. J Anim Sci 86:1291-5, 2008. Pubmed reference: 18310485. DOI: 10.2527/jas.2007-0498.
2002 Henner, J., Poncet, P.A., Aebi, L., Hagger, C., Stranzinger, G., Rieder, S. :
Horse breeding: genetic tests for the coat colors chestnut, bay and black. Results from a first study in the Swiss Franches-Montagnes horse breed. Schweiz Arch Tierheilkd 144:405-12, 2002. Pubmed reference: 12224446. DOI: 10.1024/0036-7281.144.8.405.
2001 Rieder, S., Taourit, S., Mariat, D., Langlois, B., Guerin, G. :
Mutations in the agouti (ASIP), the extension (MC1R), and the brown (TYRP1) loci and their association to coat color phenotypes in horses (Equus caballus) Mammalian Genome 12:450-455, 2001. Pubmed reference: 11353392. DOI: 10.1007/s003350020017.
1948 Castle, W.E. :
The Abc of color inheritance in horses. Genetics 33:22-35, 1948. Pubmed reference: 17247268. DOI: 10.1093/genetics/33.1.22.

Edit History

  • Created by Frank Nicholas on 12 Sep 2010
  • Changed by Frank Nicholas on 11 Sep 2011
  • Changed by Frank Nicholas on 09 Dec 2011
  • Changed by Frank Nicholas on 18 Sep 2012
  • Changed by Frank Nicholas on 19 Sep 2012
  • Changed by Imke Tammen2 on 27 Mar 2024
  • Changed by Imke Tammen2 on 04 Jun 2024