A-AY Locus (A-AY-LOCUS)
Agouti, Sable, Fawn
The A Locus (agouti series) interacts closely with the E, K, and B Loci which can lead to a dog’s overall coat color and pattern. A-Locus mutations are only expressed if the dog is “Clear” or “Carrier” at the E locus and “Clear” at the K-KB locus. Four potential mutations at the A Locus can each have a different effect on coat color. The mutations are known as A-AY, A-AW, A-AT, and A-A and can determine whether a dog is a Carrier of sable/fawn, wolf sable/gray, black and tan/tricolor/tan points coloration or a recessive form of a solid black or bicolor coat color. The A-AY gene mutation produces a coat color that can range from a light fawn to darker red to a sable based on variation in gene expression. Dogs that are “Clear” at the K-KB Locus and have one or two copies of the A-AY mutation will always express a sable/fawn coat color. This means a dog that appears fawn or sable can carry any of the other A-locus alleles (A-AW, A-AT, or A-A) and would not express them. The A-Locus alleles are expressed in a hierarchical manner with A-AY being dominant to and expressed over A-AW, A-AT, and A-A. It is important to note that the dog’s coat color is also dependent on the dog’s genotype at E, K, and B Locus among others.
Reading Your Results
A. (CLEAR/NORMAL):
These dogs have two copies of the normal gene and the effect of A Locus on their coat color can be determined by testing at the A-AW, A-AT, and A-A loci. They will also not pass this mutation to any of their offspring.
B. (CARRIER/AFFECTED):
These dogs have one copy of the normal gene and one copy of the mutation associated with sable/fawn coat color. They will exhibit a sable/fawn coat color and the effects of A Locus on offspring coat color can be determined by testing at the A-AW, A-AT, and A-A loci. They will, if bred, pass the mutation to 50% of their offspring, on average.
C. (AT RISK/AFFECTED):
These dogs have two copies of the mutation and will develop a sable/fawn coat color due to the A-AY mutation and will pass this mutation to 100% of their offspring. However, this dog’s coat color is also dependent on the E, K, and B Locus genes.
Additional Details
Inheritances
Complex order of dominance with other A Locus mutations (AY > AW > AT > A) and also depends on results for E, K, and B Locus mutations.
Affected gene
ASIP
Chromosome
Ch. 24
Mutation
C.244G>T and 248G>A
Publication:
Berryere, T.G., Kerns, J.A., Barsh, G.S. et al. Association of an Agouti allele with fawn or sable coat color in domestic dogs. Mamm Genome 16, 262–272 (2005). [PubMed: 15965787]
