E Locus (E-LOCUS)
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 dominant non-mutated 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. 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.
A (CLEAR/NORMAL): These dogs have two copies of the normal gene, will have a black-based coat and will not pass the mutation to their offspring.
B (CARRIER/NOT AFFECTED): 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.
C (AT RISK/AFFECTED): 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.
E Locus (E‑LOCUS)
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