UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Dog Coat Color MC1R - Mask - Grizzle

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MC1R Gene

The production of the two pigments eumelanin (black) and pheomelanin (red/yellow) is controlled by the melanocortin 1 receptor (MC1R) gene, also known as Extension. The six known alleles (variants) of this gene are: melanistic mask (Em), grizzle (Eg), black (E), red/yellow (e1), cream (e2) and pale yellow/white (e3). Some dog breeds are fixed for either black or red pigment, such as the Large Munsterlander for black and Irish Setters for red.

Melanistic face mask is found in a variety of breeds including but not limited to Afghans, Akitas, Boxers, French Bulldogs, German Shepherds, Great Danes, Greyhounds, Pug Dogs and Whippets. Dogs that are overall eumelanistic (black, blue or brown) may have the mask but it is indistinguishable from the body color. Dogs with white muzzles may have the mask gene but expression is overridden by white spotting patterns. The mask phenotype is caused by the Em variant at the MC1R gene.  

Grizzle (also called domino) is a pattern of dark pigment (eumelanin) on the dorsal surface of the head, body and tops of the legs; light pigment (pheomelanin) is present on the lower legs, undersides and up the face around the eyes. The distinctive face pattern is often referred to as a widow’s peak. This variant has only been seen in Afghan and Saluki hounds. Grizzle can only be expressed when the Dominant Black (K Locus) variant is not present (N/N) and the agouti gene is at/at.

Red/Yellow is widespread and found in the homozygous state (two copies of variant) in many dogs that are uniformly yellow,  red or cream-colored. The pale cream color produced by the e2 variant occurs in Australian Cattle Dog and appears limited to this breed and its crossbreds. The pale yellow/white color produced by the e3 variant occurs in Siberian Huskies and appears to be limited to this breed and its crossbreds.

The VGL test for MC1R screens for all 6 variants to provide a complete analysis of the genotype of a dog for this gene and a better understanding of phenotype and breeding expectations. Results are reported as:

Em/Em 2 copies of mask
Em/Eg 1 copy of mask and 1 copy of grizzle
Em/E 1 copy of mask and 1 copy of black
Em/e1 1 copy  of mask and 1 copy of red/yellow/cream
Em/e2 1 copy  of mask and 1 copy of red/yellow/cream
Em/e3 1 copy  of mask and 1 copy of red/yellow/cream
Eg/Eg 2 copies of grizzle
Eg/E 1 copy of grizzle and 1 copy of black
Eg/e1 1 copy of grizzle and 1 copy of red/yellow/cream
E/E 2 copies of black
E/e1 1 copy of black and 1 copy of red/yellow/cream
E/e2 1 copy  of black and 1 copy of red/yellow/cream
E/e3 1 copy  of black and 1 copy of red/yellow/cream
e1/e1 2 copies of red/yellow/cream
e1/e2 2 copies of red/yellow/cream
e1/e3 2 copies of red/yellow/cream
e2/e2 2 copies of red/yellow/cream
e3/e3 2 copies of red/yellow/cream

References

Schmutz SM, TG Berryere, NM Ellinwood, JA Kerns and GS Barsh. MC1R studies in dogs with melanistic mask or brindle patterns. Journal of Heredity 94:69-73 (2003)

Newton JM, AL Wilkie, L He et al. Melanocortin 1 receptor variation in the domestic dog. Mammalian Genome 11:24-30 (2000)

Dreger DL and SM Schmutz.  A new mutation in MC1R explains a coat color phenotype in 2 “old” breeds: Saluki and Afghan hounds. Journal of Heredity 101 (5):644-649 (2010)

Durig N, A Letko, SH Rasouliha, R Loechel, A Kehl, MK Hytonen, H Lohi, N Mauri, J Dietrich, M Wiedmer, M Drogemuller, V Jagannathan, SM Schmutz, T Leeb. 2018. Two MC1R loss-of-function alleles in cream-coloured Australian Cattle Dogs and white Huskies. Animal Genetics 49:284-290.

Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL