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E-Locus (E-LOCUS)

E Locus (E-LOCUS)

E/e Locus, Extension Locus, Red Coat Color, Yellow Coat Color, Apricot/Cream/Red/Yellow

A mutation in the MC1R gene (E locus) is responsible for the presence of yellow to red coats in many different domestic dog breeds. The normal form of the gene (“E” allele) allows the dog to produce a black pigment called Eumelanin. A mutation in the MC1R gene causes the pigment-producing cells to generate a yellow pigment called Pheomelanin. A dog must have two copies of the MC1R recessive mutation (represented as the “e” allele) to express the solid yellow coat color. This “ee” genotype can vary in expression ranging from yellow or red coloring to more subtle differences (apricot, cream, or white) depending on the breed. There are additional breed-specific mutations that exist for yellow to red coat color that are not detected by this test. It is important to note that the genetic cause of what is termed “Red” in some breeds (Dobermans, Australian Shepherds, etc.) is due to a mutation in B Locus and not E Locus.

Reading Your Results


These dogs have two copies of the normal gene, will have a black-based coat and will not pass the mutation to their offspring.


These dogs have one copy of the normal gene and one copy of the mutation associated with yellow to red coloring. They will have a black-based coat but will, if bred, pass the mutation to 50% of its offspring, on average.


These dogs have two copies of the MC1R mutation associated with a yellow coat which results in a yellow to red coat coloring that varies by breed.

Additional Details


Autosomal Recessive

Affected gene



Ch. 5




Everts RE, Rothuizen J, van Oost BA. Identification of a premature stop codon in the melanocyte-stimulating hormone receptor gene (MC1R) in Labrador and Golden retrievers with yellow coat color. Animal Genetics. 2000 Jun; 31(3):194-99. [PubMed: 10895310]