Coat colour A locus / Agouti (ASIP-related) - Horse

What does this test examine?

This DNA test examines the equine A locus, focusing on the ASIP allele c.191_201del. This allele is commonly called the recessive a allele or non-agouti allele. The test is useful when base colour, the distinction between black and bay/brown, or carrier status for recessive black matters for breeding decisions.

What does Agouti mean?

The ASIP gene helps control where black pigment appears in the coat. A horse with at least one functional A allele usually restricts black pigment to the points, such as mane, tail, lower legs and ear rims, when the E locus allows black pigment. A horse with two a alleles can show black pigment across the body and can therefore have a black base coat. In chestnut horses, A-locus status may be genetically present without a visible effect because the E locus does not produce black pigment.

Practical value of this test

• A/A: no recessive a allele detected; the horse does not pass on this tested a allele.
• A/a: one copy of the a allele; the horse can pass the allele on without being recessive black.
• a/a: two copies of the a allele; this genotype enables a black base coat when the other colour genes support it.

The result helps breeders plan matings more precisely, identify hidden carriers and combine A-locus information with results for the E locus, cream, champagne, dun and pattern loci.