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Price: $40.00Price: £25.00
Breeds: All
Description
The E-Locus test looks for the variants behind cream, yellow and red coat colors and the black (melanistic) mask in dogs. MC1R, also known as the extension gene, controls the production of pigment in melanocytes, the cells that control the coloration of skin and fur. The dominant form of the gene, the “E” allele, allows the dog to produce eumelanin, which is a black pigment. A dog that is E/E or E/e can produce eumelanin.
A mutation in the MC1R gene causes the pigment-producing cells to produce only phaeomelanin instead of eumelanin. This turns all the eumelanin in the coat to phaeomelanin. This form of the gene is the “e” allele. The “e” allele is recessive, meaning that a dog must have two copies of the MC1R mutation (e/e) to express the yellow or red coat color. Recessive red can mask other color variants. It can even mask the merle coloration.
A third allele exists in the extension gene: EM. It causes the dog to have a black mask on its face, also known as a melanistic mask. EM is dominant, so a dog needs only one copy to express the mask. This allele acts similarly to the E allele in that it produces a black-based coat. In solid black dogs with a copy of the EM allele, the mask is hidden, because the mask and the coat are both black and the mask becomes “invisible.” However, the dog can still pass the melanistic mask on to its offspring, even if the mask cannot be seen.
The e/e genotype can vary in expression between breeds. In some breeds, such as the Labrador Retriever, the difference between a black or brown dog and a yellow dog is obvious. In other breeds, such as the Cocker Spaniel, the difference may be more subtle. Other breeds express the e/e phenotype as a red color.
It is important to note that the extension gene is only one of several important genes that determine a dog’s coat color. Dogs that are e/e will always be yellow to red. However, there is a great deal of variation in dogs that are E/E or E/e, depending on the B-Locus, A-Locus, K-Locus and D-Locus. To find out more about these variations, read the pages for those tests.
Possible results
| Genotype | Description |
|---|---|
| E/E | Dog is negative for cream/yellow, mask and ancient red. |
| E/EM | Dog is negative for cream/yellow and ancient red, and has one copy of mask. |
| E/e | Dog carries one copy of cream/yellow and is negative for ancient red and mask. |
| E/eW | Dog carries one copy of cream/yellow and is negative for mask. |
| E/eA | Dog carries one copy of ancient red and is negative for cream/yellow and mask. |
| EM/EM | Dog is negative for cream/yellow and ancient red, and has two copies of mask. |
| EM/e | Dog carries one copy of cream/yellow and one copy of mask, and is negative for ancient red. |
| EM/eA | Dog carries one copy of ancient red and one copy of mask. |
| EM/eW | Dog carries one copy of cream/yellow and has one copy of mask. |
| e/e | Dog has two copies of cream/yellow. |
| e/eW | Dog has two copies of cream/yellow that may express as white. |
| eA/e | Dog carries one copy of ancient red and one copy of cream/yellow. |
| eA/eA | Dog has two copies of ancient red. |
| eA/eW | Dog carries one copy of cream/yellow and one copy of ancient red. |
| eW/eW | Dog has two copies of cream/yellow that may express as white. |
Reference
[PMID: 10895310]