K Locus

For an overview of dog coat color hierarchy continue to the article Introduction into coat color in dogs.

In K locus, three alleles with the following hierarchy have been identified: K^B (dominant black) > k^br (brindle - causing the change of eumelanin and phaeomelanin production) > k^y (recessive yellow) (Kerns et al. 2007, Candille et al. 2007).

If a dog has a genotype with at least one wild-type E-allele that maintains the gene function and at least one K^B allele was detected at the same time, the eumelanin pigment is produced and the resulting colour is black or brown.

In case of genotypes k^y/k^y ,k^y/k^br , k^br/k^br , the resulting coat colour is controlled by A-locus:

• the presence of a-allele (so-called non-agouti allele, recessive black) in homozygote condition (genotype a/a) allows the expression of  the eumelanin pigment (the resulting colour is black or brown)
• in the presence of A-allele (A/a, A/A) the resulting colour is given by the production of phaeomelanin  (the resulting colour is fawn, brown-black or red or brindle, provided there is at least one   k^br-allele).

This test is suitable for the most breeds.

What is the relationship of K-locus to A and E loci?  Continue and have a look at the dominance hierarchy of allele affecting the coat colour in dogs.

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References:

Kerns JA, Cargill EJ, Clark LA, Candille SI, Berryere TG, Oliver M, Lust G, Todhunter RJ, Schmutz SM, Murphy KE, Barsh GS (2007) Linkage and segregation analysis of black and brindle coat color in domestic dogs. Genetics 176, 1679-1689

Candille SI, Kaelin CHB, Cattanach BM, Yu B, Thopson DA, Nix MA, Kerns JA, Schmutz SM, Millhauser GL, Barsh GS (2007) A ß-defensin mutation cause black coat color in domestic dogs. Science 318, 1418-1423