Labradoodle/Goldendoodle Color Genetics

Doodle Color Genetics

DEFINITIONS

Locus - The location of a series of genes. Each gene series is
referred to as a ‘locus’.

Gene Series - A set of genes that controls a related set of traits.

Dominant - A "strong" gene which masks, or trumps, the
presence of other genes at it's own locus. A dominant gene
needs only one copy for it’s trait to be expressed. If paired
with a recessive gene, the dog is said to be ‘carrying’ the
recessive gene. ‘B’ is the designation for the dominant black
gene, ‘b’ is for the recessive chocolate gene. A Bb dog is black
carrying chocolate. Note that in this article, if only one gene, a
dominant one, is shown, the other gene is assumed but not
indicated, as it’s presence does not affect the phenotype. For
example, if a genotype is listed as Bdd, there IS another B
series gene present, either a ‘B’ or a ‘b’, but it is not written.
Another way of designating this would be to write it Bxbb.

Recessive - A "weaker", or hidden, gene which must be present
in double combination in order for it's effects to be shown. So
if ‘b’ is recessive chocolate, a dog must be ‘bb’ to have
chocolate coloring.

Carrying - The presence of a recessive gene paired with a
dominant gene. In this case the recessive gene can be passed
to progeny, but its effects cannot be seen in the dog carrying
it. So Bb is Black (B) carrying chocolate(b).

Phenotype - The visible appearance of a gene's effects -
example: "Bb" - phenotype is black. PHenotype is the PHysical
appearance of the dog.

Genotype - The genes carried, but not necessarily with visible
effects - example: "Bb" - genotype is black(B), carrying
chocolate(b). GEnotype is the GEnetic make-up of the dog.

The E Series

Dogs have two major types of pigment granules in their coats. The production of
the pigment granules is controlled by something called the Extension genes or the
Extension series. One type of pigment is red/yellow (pheomelanin), the other is
black/brown (Eumelanin). The black/brown type of pigment is dominant to the
yellow kind of pigment, so the designation for the black/brown pigment is E (for
Eumelanin). The gene for the recessive, yellow/red pigment, is e. If an E is present,
dark pigment granules will be produced, but if the genotype is ee, yellow/red pigment
granules will be produced. An E does not tell you if the dark pigment will be black or
brown, however. Another gene series (B Series), discussed below, controls the
SHAPE of the pigment granules, and, depending on the shape, the granules will look
black or brown. It’s important to realize that the E series genes contribute to COAT
color, not eye, skin or nose pigmentation. A dog has to have at least one E in order
to have any brown in the coat. ee is yellow/ red because the darker, Eumelanin
pigment, is completely prevented from forming. One important thing to remember
for later is that the dominant E allows expression of genes of another series, the A
series. The recessive ee overrides the A series and completely masks it. More on that
later!

Another variant of the E gene is Em,a melanistic mask where the muzzle is black. This
is often seen in Afghans and Great Danes, sometimes in poodles and there for in
Doodles. Em is dominant to E.

The B Series

The B gene, or B series, affects, coat, nose, skin and eye color. It affects the color by
changing the shape of the pigment granules produced by the Extension gene.   The
B version, which is dominant, will cause black pigmentation in the nose and cause the
Eumelanin in the coat, made by the extension, gene to look black. The b version,
which is recessive, causes the nose pigment to appear brown, and causes the
Eumelanin in the coat, made by the Extension gene, to look brown. As with all
dominant genes, only one has to be present for it to be expressed. That is, BB and
Bb will show as black, bb will be brown.

E and B Series Interactions

Let’s stop here and see how the E gene and the B gene can interact. If the dog is ee,
there IS no dark Eumelanin, the only pigment the coat produces is the yellow/red
Pheomelanin pigment, therefore the dog’s coat will be in the yellow/red spectrum. If
the dog then has 2 recessive B series genes, bb, the shape of the pigment granules
causes the dog to have a rose, liver or brown nose. So an bbee dog would be
yellow/apricot/red coat with a rose/liver/brown nose. If the B gene is present, the
nose will be black. It doesn’t matter if it is Bb or BB, the nose will usually be black.
An BBee, or an Bbee dog is yellow/red with a black nose, although occasionally a
Bbee dog will have a nose that is lighter. If that dog has an E gene, the dark, instead
of yellow pigment will be produced in the coat.   So BbEe, BBEE, BBEe, and BbEE
would all be black dogs with black noses.   However, if the dog is bb, the granule
SHAPE will make it appear brown instead of black. So an bbEe or bbEE dog has a
chocolate coat with a brown nose.

Beyond E and B

The genetics discussed up to this point is the genetics familiar to most, as it explains in
its entirety the genetics of coat color in Labradors, and all these genes can be
determined in readily available lab tests. In other words, people can send in a cheek
swab and find out if their dogs carry these genes. However, once poodles enter the
picture, the coat genetics complicate considerably, and not all the genes can be
tested for by commonly available means.

The A Series

There is a gene series called A, for Agouti, that controls where in the hair shaft
pigment is produced. The 3 versions of this are Ay, which can cause a red color with
black hair tips, commonly called a sable at, which causes phantoms, and a, recessive
black.

If a dog is ee however, the A series is short-circuited, and it will not be expressed at
all! In addition, it appears as though very interesting things happen in crosses
between Poodles and Goldens due to genes at the A locus. Every Golden has genes
at the A locus, but their expression in masked by the ee genotype which doesn't
allow any dark pigment to be produced. So for Goldens, the content of that entire A
series is an unknown, only to be revealed when crossed and unmasked! Breeding a
Golden to a Poodle with the at phantom gene often results in phantom
Goldendoodles, meaning that Golden had a masked at gene. Sometimes a litter with
unexpected black puppies can result from a Poodle with one a gene and a Golden
with a masked a gene.

The K Series

Another gene series important in poodles is the K series (coming from the word
blacK). The K is a dominant dark color over the whole coat, and overrides almost all
other genes. Notice that I said K causes dark colors. Whether that dark color is black
or chocolate depends on the B series. A dominant B gene will produce black in a K
dog, but the same K will produce brown in a bb dog. A second variation in the K
series is k, causing a recessive, non- dark coloration. When a dog is kk, it is like a clear
window, it allows other colors and patterns, those in the A series, to show through. K
is like opaque glass, nothing shows but dark, covering up the A series.   A final
variation in the K series is kbr, a recessive gene causing brindle coloration. K is
dominant to kbr, which in turn is dominant to k. The important thing to realize about
this series is that dominant K trumps AMOST everything at every other locus. The
dog WILL be dark at birth with this gene, with two exceptions. The first was
mentioned earlier, if the dog is ee, and the only pigment it CAN produce is yellow/red,
then it will be yellow/red!

The S Series

This Series is responsible for the pattern of color called Parti, and is caused by a
variation called sp. This gene is recessive to the dominant allele, S, which causes solid
coloration. The sp/sp genotype causes patches of dark color on a white
background. Which dark color is expressed depends on the other genes present.
An ExBxspsp dog would have patches of black, while an Exbbspsp dog would have
patches of chocolate.

The Dilution Gene

The one other thing that can alter the expression of the K gene is the presence of a
recessive dilution gene. The dominant D gives full color, the recessive version is d,
and causes colors to become diluted if 2 copies are present. So a Kdd dog, black at
birth, will ‘dilute’ to blue, a chocolate,bbdd, will dilute to beige or cafe.

Putting It Together

So the E, B, K and A loci act together like this:

If the B-locus is B, the coat and nose will be black UNLESS the dog is ee.

If the B-locus is bb, the nose and coat will be brown UNLESS the dog is ee.

If the E-locus is ee, the coat is yellow/red; This makes things easy. It does not matter
what other genes are present! What is not so easy is figuring out what genes there
are at the K locus and A locus, because you can’t see any evidence of them!

If the E-locus is EE or Ee and at the K-locus is a K allele present, the coat is dark;
If the E-locus is EE or Ee and at the K-locus either kbrkbr or kbrk is present the
coat is brindle;

If the E-locus is EE or Ee and the K-locus is kk, the A-locus determines the coat color
(Ay or at or a). So all dogs with tan points (at) are kk. Similarly, all dogs whose red
color is caused by AyAy are also kk. These AyAy dogs do not have the black tips
because their ee genotype prevents the production of that dark pigment.

So the question arises for red dogs, are they ee or AyAy? Sometimes that is difficult
to assess. But some researchers (see Sue Ann Bowling's article) suspect that ee
dogs are a ‘clear’ red, with no black anywhere, and that AyAy red dogs often have
black whiskers, and are born with coats that are dark and lighten. Those red poodles
that fade to apricot are probably AyAy, unless they are eedd! (That is, red, but
diluted).The AyAy genotype can be a fooler, if one has assumed that all apricot dogs
are 'ee'. One would expect two apricot dogs to have only apricot pups. But if one
of those dogs is apricot due to AyAy then black and chocolate pups can occur in the
litter. That is what happened here:

Delight, the parti poodle seen to the right, could easily be mistaken for an apricot and
white (Bxee) poodle. If that were true and he was bred to an F1 Labradoodle
(Bbee) all puppies would be expected to be cream. But this is the litter that resulted:

Delight is a sable, not an apricot, and his genotype ofAyAyBbEe produced black and
chocolate pups when bred to a Bbee F1 Labradoodle.

It can be pretty overwhelming to look at a string of letters in a genotype and decide
which to think about first. It’s even harder to LOOK at a dog and decide what it's
possible genotypes might be! So let’s try prioritizing the gene series. The first thing I
would look at is the E series. If it is ee the dog is yellow/red. Conversely, a yellow/red
dog is most likely ee (although you should review the part on the ay series, as that is
possible!). But if there is an E in the genotype, the dog is geneticallysome color other
than yellow/red, even if the appearance is yellow/red.

Next I would look at the B series. If it is bb the dog will be in the chocolate spectrum,
unless you already determined it was yellow/red (ee) in which case only its nose will
be brown. So if the dog has an E and a B, you know it is making black pigment in
both it’s coat and nose areas, but if it is E and bb, that pigment is chocolate instead.

Next in line would be to look at the K series.....where in the coat the color appears.
The K would mean it is solid dark all over. kbrkbr or kbrk would mean the color is in
stripes (brindle). kk is that clear window looking at the A locus.....meaning the color is
determined by the A locus. This is where Ay (red) would be evident, or at (phantom
or black and tan points), or a, recessive black. All dogs displaying at, Ay or a genes
phenotypically are also k/k. Notice that a dog could carry either the a, Ay or at, but
if it was a K, those traits are impossible to see, as they are covered up by the solid
dark K gene.

Regarding the Golden Retriever Genotype

Golden Retrievers are commonly assumed to be genotype eeBB. I spent quite a bit
of time trying to track down an Goldens with brown or liver noses (meaning they
were eebb) and found only one instance. My feeling is that if there were very many
Bb Goldens out there, we would see Goldens with liver noses more often. So I have
concluded that the vast majority are BB. Because they are ee, the genotype at the
A series is masked, but pf course present. The possible variants are the same as for
all others, at,Ay and a, but it is impossible to know which of these are present until
the dog is crossed and they are expressed.

Thanks to Sue Ann Bowling and Sheila M. Schmutz for their great articles on dog
color genetics, I learned whatever I understand of dog color genetics from them!

eeBb pup, next to eebb pup

Sable pup with Em,
melanistic mask

Kona is bbEe