OMIA 001199-9838 : Coat colour, extension in Camelus dromedarius

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 , Kodkod , Colocolo , ass , Mongolian gerbil

Possibly relevant human trait(s) and/or gene(s) (MIM number): 266300

Mendelian trait/disorder: yes

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2018

Cross-species summary: The extension locus encodes the melanocyte-stimulating hormone receptor (MSHR; also 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.

Molecular basis: Adopting the comparative candidate gene approach, Almathen et al. (2018) sequenced the MC1R 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 a missense variant (c.901C>T; p.R301C) associated with white versus non-white: "All nonwhite individuals (black, dark, and light brown, n = 70) were homozygous for the 901C allele, whereas all white dromedaries (Wodh population, n = 21) were either homozygous for the 901T (n = 8) or heterozygous (n = 13) for the 901C/T alleles . . . (P < 0.0001, df = 1)."

Alshanbari et al. (2019) reported that "heterozygosity for . . . [the] missense mutation c.901C > T in MC1R is sufficient for the white coat color suggesting a possible dominant negative effect."

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
MC1R melanocortin 1 receptor (alpha melanocyte stimulating hormone receptor) Camelus dromedarius - no genomic information (-..-) MC1R Homologene, Ensembl, NCBI gene

Variants

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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.

Breed(s) Variant Phenotype Gene Allele Type of Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
White coat colour MC1R missense KU179867 c.901C>T p.R301C 2018 29893870

References


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 <i>MC1R</i>, <i>ASIP</i>, and <i>TYRP1</i> in New and Old World Camelids and Association Analysis With Coat Color Phenotypes in the Dromedary (<i>Camelus dromedarius</i>). 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.

Edit History


  • Created by Frank Nicholas on 28 Aug 2018
  • Changed by Frank Nicholas on 05 Jun 2019