The E Locus in Dogs

This webpage is part of a series on Dog Coat Color Genetics and was last updated on June 22, 2017 by Sheila Schmutz

Clear Red

The gene known as the E locus is the Melanocortin Receptor 1 gene (MC1R), formerly called the Melanocyte Stimulating Hormone Receptor Gene (MSHr). The MC1R gene has been mapped to dog chromosome 5.

This gene has two common alleles E and e. Dogs that are e/e are red or yellow due to phaeomelanin production, and this is the recessive genotype. When E is present in a dog, it usually has some black or brown in its coat because of the production of eumelanin. The E allele is dominant to the e allele.

Although the e/e genotype is the most recessive at this locus, it is epistatic or masks other genotypes at other loci, such as the K and A locus. See more about those loci on separate pages.

These 2 Dachshunds exemplify two genotypes at this locus. The red dog has a black nose but is a clear red and has the genotype e/e at MC1R. The black is a black-and-tan and has an E allele, however his black-and-tan pattern is due an agouti allele (at)(see the agouti page for more details).

There are Dachshunds, such as the one shown, and dogs of other breeds that have red hairs with darker or black tips on them. These dogs do not have an e/e genotype. This non-solid red is caused by an allele at the agouti locus, ay. Other breeds such as Chows also fall into the category of not being red because of an e/e genotype. The colors tan or fawn, typically associated with agouti, are not always that easily distinguishable from the red of an Irish Setter. Depending on the breed, one red or the other is more common and in most breeds only one or the other red occurs.

In some breeds, such as Labrador Retrievers the dogs are more yellow than red. The shade varies as is illustrated by the two littermates above whose parents were also both yellow.

Little did not include the Hungarian Vizsla in his studies. They are hunting dogs which are typically gold to red and typically have brown noses because they are also homozygous for the recessive brown allele/s at the B locus. (see Brown for further details)

This very white coat color is desirable in English Setters but it makes it difficult to tell what color the pigmented part of her coat is. By MC1r testing, she is e/e and therefore red.

Breeds in which yellow-to-red dogs of the "e/e" genotype have been detected

Note that in some breeds dogs with an e/e genotype are more often cream to white than yellow to red (see page on white for a discussion of these breeds).

  • Newton, J., A. Wilkie, L. He, S. Jordan, D. Metallinos, N. Holmes, I. Jackson and G. Barsh. 2000. Melanocortin 1 receptor variation in the domestic dog. Mamm. Genome 11:24-30.
  • Everts, RE, Rothuizen,J. and van Oost,B.A. 2000. Identification of a premature stop codon in the melanocyte-stimulating hormone receptor gene (MC1R) in Labrador and Golden retrievers with yellow coat colour. Anim. Genet. 31: 194-199.
  • Schmutz, S.M., J. S. Moker, T. G. Berryere, and K. M. Christison. 2001. A SNP is used to map MC1r on dog chromosome 5. Animal Genetics 32:43-44.
  • Thomas, R., M. Breen, P. Deloukas, N. G. Holmes and M. M. Binns. 2001. An integrated cytogenetic, radiation-hybrid and comparative map of dog Chromosome 5. Mamm. Genome 12:371-3100.

  • Black versus Red

    Black, or black and white is a very common coat color in many dog breeds. It would appear that most of the hunting dogs that have black variants, such as German Shorthairs, German Wirehairs, and Pudelpointers are black because they have an E alllele at the MC1r gene. The Large Munsterlander is "always" E/E and black. However the American Brittany and the Irish Setter are always e/e and red or orange or yellow. But the Small Munsterlander and German Longhair are brown, not red, and are also E/E due to the interaction of another gene B, explained on the page about brown.

    Note that for a dog like Charlie, shown here, to be black it must also have a KB allele. KB is discussed on the page about the K locus.

    Grizzle and Domino

    There is an allele EG which was decribed for the first time in 2010. This allele is relatively common in both Salukis and Afghans Hounds but is not found in other breeds. When EG occurs in dogs with an at/at and no KB or EM allele the phenotype of grizzle or domino results.

    See the page about Salukis for more information and photos of the grizzle phenotype.

    The manuscript describing this will be published in Journal of Heredity in Fall, 2010 but is available as "online early". A free PDF copy of the manuscript is available for download

    Melanistic Mask

    There is a fourth allele at the E locus, EM which is discussed on the page about Melanistic Mask. Melanistic masks are rare in the hunting breeds, but are relatively common in many other breeds. The mask caused by this allele is not visible on solid colored dogs which are black, brown, or gray.

    EM is the top dominant allele in this series.

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