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Description
The ASIP gene has four different alleles that affect the pigmentation of coat colour in dogs. In dogs that do not carry the dominant black gene (ky/ky at the K Locus) and are not "e/e" for the E Locus, the agouti gene is allowed to express and determines the colour of the dog's coat. The four alleles work as a hierarchy, the most dominant allele that the dog has will always be expressed (assuming n/n for the K Locus). The most dominant allele is "ay", followed by "aw", then "at", then "a."
While the Agouti gene (A Locus) does determine the base coat colour in dogs that are ky/ky for Dominant Black, the colour of the dog can still be modified by other genes, such as the B Locus or D Locus. For example, a dog that is "b/b "for the B Locus will still have all areas that would be pigmented as black modified to a chocolate pigment. Thus a fawn dog that is also "b/b" will just show a chocolate nose, whereas a dog that is "at/at" will be chocolate and tan, rather than black and tan.
a Y Allele
The "ay" allele is the most dominant of all four alleles. The "ay" gene produces a coat colour that can range from a light fawn to darker red to a sable. This variation of colour is due to variance in expression of this gene. A dog (ky/ky for K Locus) that has 1 or 2 copies of the "ay" allele will always express the "ay" coat pattern. Thus, a dog that appears fawn or sable could be carrying any other of the three alleles, and would never express them. However, that does not mean they will always pass on a copy of the "ay" allele; a dog that is ay/aw, ay/at, or ay/a has a 50% chance of passing on the "ay" allele, and a 50% chance of passing on the other allele. A dog that has two copies of the "ay" allele will always pass on that "ay" allele, and as long as that dog is bred to another dog that is "n/n" for the K Locus, will always produce fawn/sable pups.
aw Allele
The "aw" allele produces a colour known as "wild sable", or sometimes called the "wild type" or in some breeds, "wild boar." With this colouration, the hairs switch pigmentation from black to reddish or fawn. This colour is sometimes seen in German Shepherds and other shepherd breeds. It is recessive only to the "ay" allele. If a dog is "n/n" for the "ay" allele, a dog with 1 or 2 copies of the "aw" allele will express this colouration. A dog that is n/n for "ay" that has 1 copy of the "aw" allele can carry either the "at" or "a" allele and not express it, though can pass either allele to any offspring.
at Allele
Both the "black-and-tan" and "tricolour" phenotypes are caused by the "at" allele. A tricolour dog is "black-and-tan", plus white, which is generally just an absence of colour, rather than being a different pigment the dog is making. For a dog to be a black and tan or tricolour, he must be "n/n" for the dominant black gene, and have either 2 copies of the "at" allele, or have 1 copy of the "at" allele and 1 copy of the "a" allele. This is because the "ay" and "aw" alleles are dominant over "at". A dog that is"at/at" will always pass on a copy of the "at" allele to any offspring. However, he must be bred with another dog that has at least 1 copy of the "at" allele to possibly produce any black and tan or tricolour pups.
a Allele
A dog that is solid black, but is also "ky/ky" for the K Locus, must have two copies  of the "a" allele. This is also the case for dogs that are bicolor, but are negative for K Locus. This is generally the cause of a solid black German Shepherd. The "a" allele is sometimes referred to as the recessive black gene. Because is the most recessive, for a dog to express this phenotype, he must have two copies of the "a" allele. A recessive black dog will always pass on the "a" allele to all offspring.
A
Locus Testing
Animal
Genetics currently offers testing for all four A-Locus alleles.
Cost
$40.00
US for the a single allele test (ex just aY Allele test).
$65.00 US any two allele tests (ex. aY and a Alleles).
$75.00 US combination rate for
all four tests (aY, aw, at, and a.)
Sample Collection
Collect
sample using buccal swabs provided by Animal Genetics. Ensure that
the dog has not eaten within a few hours of sample collection. Any
food particles can inhibit the test. Rub each of the swabs along
the inside of the dog's mouth for 10-15 seconds, and allow the swabs
to dry thoroughly. Label the provided envelope with the dog's name,
and place the swab inside it. Download and complete a submission
form for each sample and send along with payment to Animal Genetics
for testing.
Results
Results are given using
the following symbolic notation:
aY-Allele Results:
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aY/aY
|
The
dog carries two copies of the dominant aY allele. The dog will
always pass on the
"aY" allele to any potential offspring. |
|
n/aY
|
One
copy of the dominant aY allele is present. The dog can pass on either allele to
potential offspring. |
|
n/n
|
The dog does
not carry the aY allele, and will not have a fawn or sable coat
pattern. |
at-Allele Results:
|
at/at
|
The
dog carries two copies of the at allele. The dog will
always pass on a copy of the at allele to any offspring. |
|
n/at
|
The
dog carries one copy of the at allele. The dog will
can pass on a copy of the at allele to any offspring. |
|
n/n
|
The dog does
not carry the at allele, and will not have a tricolor or black-and-tan coat
pattern. |
a-Allele Results:
|
a/a
|
The
dog carries two copies of the recessive black allele. The dog
will always pass on a copy
of the allele to future offspring. |
|
n/a
|
Only
one copy of the recessive black allele is present. The dog will
not express the recessive black coat color, however, the dog
can still pass on a copy to any offspring. |
|
n/n
|
The
dog does not carry the recessive black allele. He will not express
the recessive black coat color, and cannot pass it on to any
offspring. |
Combination Results:
|
aY/aY
|
The
dog carries two copies of the dominant aY allele for fawn/sable coat color. |
|
aY/aw
|
The dog has one copy of the aY allele for fawn/sable coat color, and one copy of the aw allele for the wolf sable phenotype. The aY allele is dominant over the aw allele.
|
|
aY/at
|
The dog has one copy of the aY allele for fawn/sable coat color, and one copy of the at allele for the black-and-tan or tricolor phenotype. The aY allele is dominant over the at allele. |
aY/a |
The dog has one copy of the aY allele for fawn/sable coat color, and one copy of the a allele for the recessive black phenotype. The aY allele is dominant over the a allele. |
aw/aw |
The
dog carries two copies of the aw allele for wild sable coat color. |
aw/at |
The dog has one copy of the aw allele for wild sable coat color, and one copy of the at allele for the black-and-tan or tricolor phenotype. The aw allele is dominant over the at allele. |
aw/a |
The dog has one copy of the aw allele for wild sable coat color, and one copy of the a allele for the recessive black phenotype. The aw allele is dominant over the a allele. |
at/at |
The
dog carries two copies of the at allele for tricolor or black-and-tan coat color. |
at/a |
The dog has one copy of the at allele for tricolor or black-and-tan coat color, and one copy of the a allele for the recessive black phenotype. The at allele is dominant over the a allele. |
a/a |
The
dog carries two copies of the a allele for recessive black coat color. |
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