OMIA 000201-9838 : Coat colour, agouti in Camelus dromedarius
In other species: horse , cattle , meadow voles , red fox , pig , sheep , domestic cat , rabbit , dog , gray wolf , coyote , goat , Eurasian water mole , Northern mole vole , North American deer mouse , alpaca , leopard , Asiatic golden cat , leopard cat , ass , impala , Colocolo , Kodkod , Mongolian gerbil , domestic guinea pig , Western roe deer , llama , oldfield mouse
Category: Pigmentation phene
Links to MONDO diseases: No links.
Mendelian trait/disorder: yes
Considered a defect: no
Key variant known: yes
Year key variant first reported: 2018
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: Adopting the comparative candidate gene approach, Almathen et al. (2018) sequenced the ASIP gene in "91 animals from ten Arabian camel populations, that included the four predominant coat color phenotypes observed in the dromedary (light brown, dark brown, black and white)". They identified two variants "a 1-bp deletion (23delT/T) and a SNP (25G/A) in exon 2 of ASIP" that exist as two haplotypes, namely "23delT-25A and 23T-25G". Noting that the "23delT-25A haplotype results in a frame shift mutation, which changes the amino acid sequence and introduces a premature stop codon at position 24", Almathen et al. (2018) reported that this haplotype is associated with black and dark-brown coat colour: "Animals with black and dark-brown coat colors (n = 40, Magaheem and Sofor [populations]) were homozygous for haplotype 23delT-25A, whereas all light-brown and white individuals (n = 51) were homozygous for the 23T-25G haplotype".
Alshanbari et al. (2019) "confirmed that the majority [with 4 exceptions] of black dromedaries were homozygous for . . . [the 23delT-25A] frameshift mutation in ASIP exon 2"
|Symbol||Description||Species||Chr||Location||OMIA gene details page||Other Links|
|ASIP||agouti signaling protein||Camelus dromedarius||19||NC_044529.1 (21604597..21537069)||ASIP||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|
|1010||Black and dark-brown coat colour||ASIP||haplotype||Naturally occurring variant||c.[23delT;c.25G>A]||KU179868; c.[23delT;c.25G>A]. As described by Almathen et al. (2018), this haplotype comprises "a 1-bp deletion (23delT/T) and a SNP (25G/A) in exon 2 of ASIP".||2018||29893870|
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.
|2019||Alshanbari, F., Castaneda, C., Juras, R., Hillhouse, A., Mendoza, M.N., Gutiérrez, G.A., Ponce de León, F.A., Raudsepp, T. :|
|Comparative FISH-mapping of MC1R, ASIP, and TYRP1 in New and Old World camelids and association analysis with coat color phenotypes in the dromedary (Camelus dromedarius). Front Genet 10:340, 2019. Pubmed reference: 31040864. DOI: 10.3389/fgene.2019.00340.|
|2018||Almathen, F., Elbir, H., Bahbahani, H., Mwacharo, J., Hanotte, O., Almathen, F., Elbir, H., Bahbahani, H., Mwacharo, J., Hanotte, O. :|
|Polymorphisms in MC1R and ASIP genes are associated with coat color variation in the Arabian camel. J Hered 109:700-706, 2018. Pubmed reference: 29893870. DOI: 10.1093/jhered/esy024.|
- Created by Frank Nicholas on 28 Aug 2018
- Changed by Frank Nicholas on 28 Aug 2018
- Changed by Frank Nicholas on 05 Jun 2019