# Liver Pigment



## flatcoated (Feb 3, 2013)

Here's what I know of Flatcoat color genetics:

Liver is a recessive trait controlled by the TYRP1 Gene. The two alleles are dominant black (B) and recessive brown (b). Two copies of brown are needed to dilute black pigment to brown. For yellow dogs, the brown allele does not dilute the hair color, but will change the color of nose and foot pads from black to brown if two brown alleles are present.

Yellow is a recessive trait controlled by the MC1R gene. The two alleles are dominant black (E) and recessive yellow (e).

Genetic color profiles present in flatcoats are as follows:

BB EE - black, does not carry liver or yellow
Bb EE - black, carries liver
bb EE - liver, does not carry yellow
BB Ee - black, carries yellow
Bb Ee - black, carries yellow and liver
BB ee - yellow, does not carry liver
Bb ee - yellow, carries liver
bb Ee - liver, carries yellow
bb ee - liver pigmented yellow

Not sure precisely what this means for Goldens. The genetics are of course closely related, but I don't know exactly what influence other portions of the ancestral mix have had.


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## K9-Design (Jan 18, 2009)

Liver pigment of the haircoat, nose, paw pads and eye rims is controlled by the B locus. It is a recessive gene.
BB = homozygous dominant = black
Bb = heterozygous dominant = black
bb = homozygous recessive = liver

Goldens do NOT carry the recessive "b" allele. No purebred golden will ever have liver coloration. No crossbred offspring of a purebred golden retriever will ever have liver coloration.


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## flatcoated (Feb 3, 2013)

K9-Design said:


> Goldens do NOT carry the recessive "b" allele. No purebred golden will ever have liver coloration. No crossbred offspring of a purebred golden retriever will ever have liver coloration.



Interesting. Anney, do you know whether the b allele was intentionally bred out or if it never made it into the gene pool in the first place? If you can recommend any sources, I'm very curious.

For anyone who's interested in a dummies guide type overview to color genetics, www.doggenetics.co.uk is a very nice, accessibly presented resource.


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## K9-Design (Jan 18, 2009)

You can eliminate the recessive "b" allele in two generations of breeding, and you will never ever get it back unless you cross back with a liver dog or carrier. That is what happened with the golden. I'm sure the golden has ancestors that were liver or liver-factored but good old Lord Tweedmouth kept meticulous records of his breeding program from day one so we know exactly what went into the golden, and never have they had liver coloration. 

As you know, dogs recessive on E locus (ee) are yellow coated regardless of if their base color was black, liver or grey. Every golden is ee so of course even if goldens were bb we would never see it except for a brown nose & paw pads. This just simply isn't seen in purebred goldens. There are plenty out there with poor pigment that may look brown to pink, but typically their paw pads give them away as just having poor (black) nose pigment.

Goldens are one of the very few breeds that have extremely limited genetic color variance. They are all the same color genetically, and it's a recessive color so there's nothing "hiding" behind a dominant allele.


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## Claudia M (Aug 8, 2012)

flatcoated said:


> Here's what I know of Flatcoat color genetics:
> 
> Liver is a recessive trait controlled by the TYRP1 Gene. The two alleles are dominant black (B) and recessive brown (b). Two copies of brown are needed to dilute black pigment to brown. For yellow dogs, the brown allele does not dilute the hair color, but will change the color of nose and foot pads from black to brown if two brown alleles are present.
> 
> ...


Thanks! I am in process of getting Darcy's tests done!


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## flatcoated (Feb 3, 2013)

K9-Design said:


> You can eliminate the recessive "b" allele in two generations of breeding, and you will never ever get it back unless you cross back with a liver dog or carrier. That is what happened with the golden. I'm sure the golden has ancestors that were liver or liver-factored but good old Lord Tweedmouth kept meticulous records of his breeding program from day one so we know exactly what went into the golden, and never have they had liver coloration.



If in 150 years no Golden has ever manifested liver coloration in pads and nose, that's rock solid evidence that what you say about the non-presence of the b-allele in Goldens is true, so I'm not contesting your core assertion that there is no liver in the Golden gene pool. But even with Lord Tweedmouth's exemplary record-keeping, there has to have been at least a small element of dumb luck if he succeeded in keeping the b-allele entirely out of the Golden gene pool. In a pre-genetic-testing era, recessive traits cannot be selectively eliminated in only two generations since they can hide for so many more before ever manifesting. The ease of fixing a recessive trait and the difficulty of eliminating one that has entered the gene pool in the first place is exactly why it is easy to ensure that all Goldens are ee, while it is difficult or impossible to entirely eliminate yellow coloration from flatcoats. Today color testing makes it is entirely possible to ensure that no two carriers are ever bred, but the gene itself, while uncommon, is stubbornly persistent.

Oddly enough, have recently noticed that yellow carriers are proportionately over-represented in a small pool of flatcoats that I consider to have had outstanding qualities and breed type while also exhibiting superior health and longevity. This is not to suggest that I think FCR breeders should ever breed for yellow, but now that we can easily identify the gene through testing, I do think something significant might be lost if the Ee phenotype was selectively eliminated for good.


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## mylissyk (Feb 25, 2007)

K9-Design said:


> Liver pigment of the haircoat, nose, paw pads and eye rims is controlled by the B locus. It is a recessive gene.
> BB = homozygous dominant = black
> Bb = heterozygous dominant = black
> bb = homozygous recessive = liver
> ...


No crossbred offspring of a purebred Golden will have liver coloration? Then how do we get Golden's with liver pigment?


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## Selli-Belle (Jan 28, 2009)

Thanks for the info. I saw a decent looking Golden who had a liver nose and eye rims. I did not look at his paws ;-)


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## Courtneexo (5 mo ago)

K9-Design said:


> You can eliminate the recessive "b" allele in two generations of breeding, and you will never ever get it back unless you cross back with a liver dog or carrier. That is what happened with the golden. I'm sure the golden has ancestors that were liver or liver-factored but good old Lord Tweedmouth kept meticulous records of his breeding program from day one so we know exactly what went into the golden, and never have they had liver coloration.
> 
> As you know, dogs recessive on E locus (ee) are yellow coated regardless of if their base color was black, liver or grey. Every golden is ee so of course even if goldens were bb we would never see it except for a brown nose & paw pads. This just simply isn't seen in purebred goldens. There are plenty out there with poor pigment that may look brown to pink, but typically their paw pads give them away as just having poor (black) nose pigment.
> 
> Goldens are one of the very few breeds that have extremely limited genetic color variance. They are all the same color genetically, and it's a recessive color so there's nothing "hiding" behind a dominant allele.





K9-Design said:


> You can eliminate the recessive "b" allele in two generations of breeding, and you will never ever get it back unless you cross back with a liver dog or carrier. That is what happened with the golden. I'm sure the golden has ancestors that were liver or liver-factored but good old Lord Tweedmouth kept meticulous records of his breeding program from day one so we know exactly what went into the golden, and never have they had liver coloration.
> 
> As you know, dogs recessive on E locus (ee) are yellow coated regardless of if their base color was black, liver or grey. Every golden is ee so of course even if goldens were bb we would never see it except for a brown nose & paw pads. This just simply isn't seen in purebred goldens. There are plenty out there with poor pigment that may look brown to pink, but typically their paw pads give them away as just having poor (black) nose pigment.
> 
> Goldens are one of the very few breeds that have extremely limited genetic color variance. They are all the same color genetically, and it's a recessive color so there's nothing "hiding" behind a dominant allele.


i have a golden that im trying to figure out haha both his parents have the jet black nose lip and paw and had a litter of 8 pups and mine was the only pup with all brown features including paw and its not lack of pigment the paws are 100%brown along with his eye rims lips and nose.i was told both parents are purebred but they are not registered so no way of me knowing without dna


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