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Discussion Starter #1 (Edited)
I ordered an AKC research pedigree for the one 'mystery dog' in my Elly's 3 generation pedigree. Acc. to the AKC research pedigree, the mystery great granddam, registered as a sable, descended of two parents registered as white. Actually all dogs in the 5 gen research pedigree were registered as white.

Now I know that white is a recessive masking gene in the GSD and that two white GSDs will produce white puppies although they all carry color on a different locus.

Lisa suggested to me that there can be bleed through of color in whites, and Elly's 'sable' ancestor might have been registered incorrectly. A light bulb went on. What resurfaced in my mind then was the information given to me by a person familiar with the 'Rin Tin Tin' breeding program. Rin Tin Tin IV (the one in the 50s movies) showed a very light colored saddle, favored as it worked well for the black and white movies of the time. Lee Duncan himself is to have crossed whites in with the black/tans to get this dilute color. And the contemporary Rin Tin Tin kennel that line bred on Rin Tin Tin IV is said to do the same to maintain the color of Rin Tin Tin IV.

An incorrect registration can happen easily as 'sable' isn't a precise term in terms of genetics. A sable dog with tri-banded hair is an agouti in the language of genetics. I've heard the light colored saddles referred to as sable several times, too, and I can see how that happens. A light colored saddle can appear sable but doesn't have the tri-band hair of the agouti.

Does anyone know of bleed through 'sables' with known ancestry? The genetics of this may not be understood yet, but maybe more color genetics savvy members can comment on what is known about the genetics of this color?

I have to decide whether I will include this research pedigree in a genomic diversity analysis or whether I should dismiss it as incorrect, leaving a hole in Elly's otherwise multi-gen pedigree. Thank you for your input!

Rin Tin Tin IV: http://www.pedigreedatabase.com/german_shepherd_dog/dog.html?id=488850-rin-tin-tin-iv
 

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If white GSDs are producing by the combo of the recessive black and recessive red masking genes (As I believe Samoyeds are) Then I do not believe bleed through it plausible. Because the recessive black gene stops any red from being produced in the coat, and the recessive red stops any black from being produced in the coat, hence a white dog. There needs to be two copies of these recessive genes in order for them to work.
Dog Coat Colour Genetics
Dog Coat Colour Genetics

The super light base red coats are not produced by "bleed through" of other genes. The intensity of the red coat is affected by the I locus. Info here:
Dog Coat Colour Genetics

Here's info on "Sable" in GSDs, aka Wolf Grey/Agouti. My only other suggestion would be to maybe try and contact the person who runs this site and see if they may be able to shed more light?
Dog Coat Colour Genetics
 

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Discussion Starter #3
Thank you for your response! In GSDs it is a recessive gene for white (not for black) that expresses white color. This locus of this gene is called MC1R and the recessive allele for white on this locus is called e. The letter stands for 'extension'. The hypothetical I gene ('i' for intensity) that is discussed in the source that you quote might be an explanation for what is called 'bleed through' by breeders, and it could be responsible for the silver/light tan shades of very light colored 'sable' GSDs (that are not agouti sable). So far, it has been thought to regulate reddish/tan colors, not silver shades. This I could be a single locus or the interaction of different loci, we don't know yet. TY for posting the link to the 'doggenetics' site, it's one of the pages that I consulted as well, very informative.
Now I know that white is a recessive masking gene in the GSD and that two white GSDs will produce white puppies although they all carry color on a different locus.
The most detailed source that I found on on coat color in WGSDs is this page: White Shepherd Genetics Project - Coat Color Quote:
"When an e allele at MC1R is inherited from each parent, the e/e genotype offspring can have only phaeomelanin (yellow/red) based coat colors of yellow, tan, light brown, red/rust or cream."

Rephrasing my question to be more precise: How much color can a GSD who is known to carry e/e express?
 

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Discussion Starter #5
Yes, Magwart, thank you. The coat color of the dog in your photo is likely true bleed through. But I am also still exploring!

Would one think of such a color as 'sable"?

It could perhaps also be a dog with a bit more pigment, but still very light or 'diluted'. Pics are of Rin Tin Tin dogs from the contemporary Rin Tin Tin kennel, posted with url. Rin Tin Tin b/c it's a line where colored and white dogs have been crossed many times to get a very light color. This light pale color is sometimes called 'sable' but it is not 'agouti sable'.

This color is also often considered 'poor pigmentation' b/c the standard calls for strong pigmentation. I don't consider it 'poor' b/c the dog is fully functional, the pale color doesn't come with any side effects. But that's just a side note :)


http://www.pages.drexel.edu/~jh939/Class/Images/Rin-Tin-Tin-4-Full-Size.jpg
http://www.pages.drexel.edu/~jh939/Class/Images/Rin-Tin-Tin-5-Full-Size.jpg
 

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Discussion Starter #6
Rin Tin Tin XII and Rin Tin Tin's Quella Hollywood Dogs
(again dogs from this kennel only chosen to see the color pattern)
 

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