OMIA 001199-9793 : Coat colour, extension in Equus asinus
In other species: cattle , dog , horse , red fox , pig , sheep , jaguar , jaguarundi , American black bear , woolly mammoth , domestic cat , rabbit , domestic guinea pig , goat , Arctic fox , rock pocket mouse , oldfield mouse , gray squirrel , lesser earless lizard , little striped whiptail , water buffalo , domestic yak , alpaca , , coyote , reindeer , Geoffroy's cat , Colocolo , Arabian camel , Mongolian gerbil , raccoon dog , fallow deer , zebu , lorises , antarctic fur seal
Category: Pigmentation phene
Links to MONDO diseases: No links.
Mendelian trait/disorder: yes
Mode of inheritance: Autosomal recessive
Considered a defect: no
Key variant known: yes
Year key variant first reported: 2014
Cross-species summary: The extension locus encodes the melanocyte-stimulating hormone receptor (MSHR; now known as MC1R). This receptor controls the level of tyrosinase within melanocytes. Tyrosinase is the limiting enzyme involved in synthesis of melanins: high levels of tyrosinase result in the production of eumelanin (dark colour, e.g. brown or black), while low levels result in the production of phaeomelanin (light colour, e.g. red or yellow). When melanocyte-stimulating hormone (MSH) binds to its receptor, the level of tyrosinase is increased, leading to production of eumelanin. The wild-type allele at the extension locus corresponds to a functional MSHR, and hence to dark pigmentation in the presence of MSH. 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". Mutations in MC1R have been associated with white colouring in several species.
Molecular basis: Abitbol et al. (2014) "used a panel of 124 donkeys to identify a recessive missense c.629T>C variant in MC1R that showed a perfect association with the red coat colour. This variant leads to a methionine to threonine substitution at position 210 in the protein . . . , [a location in which] methionine 210 is highly conserved among vertebrate melanocortin receptors. Abitbol et al. (2014) proposed "to name the c.629T>C allele in donkeys the e allele". FN is grateful to Corinne Benavides for informing him of this paper describing red coat colour in donkeys, and a likely causal variant.
|Symbol||Description||Species||Chr||Location||OMIA gene details page||Other Links|
|MC1R||melanocortin 1 receptor (alpha melanocyte stimulating hormone receptor)||Equus asinus||28||NC_052204.1 (63567120..63571274)||MC1R||Homologene, Ensembl, NCBI gene|
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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||Inferred EVA rsID||Year Published||PubMed ID(s)||Acknowledgements|
|996||Âne normand, France (Ass) Miniature, United States of America (Ass)||Red coat colour||MC1R||e||missense||Naturally occurring variant||c.629T>C||p.(M210T)||2014||25155046|
|2014||Abitbol, M., Legrand, R., Tiret, L. :>|
|A missense mutation in melanocortin 1 receptor is associated with the red coat colour in donkeys. Anim Genet 45:878-80, 2014. Pubmed reference: 25155046. DOI: 10.1111/age.12207.|
- Created by Frank Nicholas on 22 Jul 2018
- Changed by Frank Nicholas on 22 Jul 2018