Yorkshire Terrier coat color thread.

[pstinard]

Originally Posted by MyGirlSasha

well whatever causes it, I think its beautiful

[Mike1975]

Hi everyone.
I was wondering whether you have information concerning the "silver gene" located at V locus.
Can this gene also be found in Yorkies?

If not, whats the genetic cause of the difference between dark steel blue and light steel blue for example.
Can this be caused by the incomplete dominance of the Graying gene?
Meaning that :
GG dog is a light steel blue
Gg dog is a dark steel blue and
gg dog is black

Thanks
Mike

[pstinard]

Originally Posted by Mike1975

Hi everyone.
I was wondering whether you have information concerning the "silver gene" located at V locus.
Can this gene also be found in Yorkies?

If not, whats the genetic cause of the difference between dark steel blue and light steel blue for example.
Can this be caused by the incomplete dominance of the Graying gene?
Meaning that :
GG dog is a light steel blue
Gg dog is a dark steel blue and
gg dog is black

Thanks
Mike

Hi Mike,

I wrote to a canine coat color genetics researcher last summer, and she was interested in taking a closer look at the G (dominant greying) locus. She thought it could be a genetic variation of the same gene that causes Merle patterning. It's obviously not the same mutation as Merle, because the color patterning is different and Merle is homozygous lethal, but it could still be a variation in the same gene. I sent her a cheek swab DNA sample from my dear Bella, and she was going to have a student sequence Bella's Merle gene to see if they could find anything, but she never got back to me--I'll follow up with her tomorrow.

So the dominant greying gene in Yorkies is still somewhat of a mystery, but your hypothesis makes sense. My understanding is that GG is silvery blue, Gg is darker blue, and gg is black.

From reading up on the "V" locus you mentioned, it sounds exactly the same as the G locus. I'm pretty sure it's another name for the same gene. Here is a link to an article about the "V" locus:

http://www.havanesecolors.com/ggv.html

[Mike1975]

Thank you Phil for your reply!

This site for havanese and some other sites for poodles, were the reason I asked about the V gene (silvering gene).

Havanese and poodles also carry the Graying gene but its effects is somehow different than in yorkies, considering that both breeds have double coats instead of the singe coat found in our breed. Also they carry different alleles in other locii, so the final result is completely different.

In this quiz answer Quiz # 2 answer it says :

"TIERRA started life as a Black and Tan puppy with extensive markings in a pale golden colour. She appears to carry the Saddle Tan variation which has faded her coat from the front to the shoulder leaving her head and front light coloured and her back and rear dark coloured. The chinchilla gene is very prominent and started work early to lighten her tan to creamy white. The silvering and greying genes played a large part in her colour change as well. The silvering gene has lightened her black to pewter and the graying gene has liberally interspersed it with silvery white hairs."

In a poodle site Color Genes in the Poodle I came across this :

"Most authorities describe a dominant allele (G) for graying; non-gray would be gg. Some also consider it to be the gene for silver, in which case it would have to be a partial dominant. Willis (1989), however, says that silvers are dilute grays (ddG_; he does not indicate whether ddGG and ddGg would be the same). Searle (1968) says simply that "this dominant gene apparently leads to a progressive graying in coat-color throughout life and seems to be present in poodles."

My own study of standard poodle pedigrees is consistent with the interpretation that gray and silver are separate genes. To avoid confusion, let's call the silver gene V . This gene shows incomplete dominance. In other words, if a poodle that is VV would be black, Vv would be a dark blue-gray and vv would be silver. Both blues and silvers are born black. Silvers "clear" during the first year. This involves the gradual loss of pigmentation from about 90% of the inner coat (hairs become transparent or white, depending on thickness), but a substantial percentage of the outer, guard hairs retain some color."

It seems that havanese and poodles carry both genes (G and V) and their combination alters the final phenotypic result.

To add a little more confusion, Joan Gordon claims :

The next gene you need is the one that assures the age at which the blue skin will retreat from the head allowing only the gold to grow and a gene to tell your black puppy that it is time to kick in the color pattern in each hair for the blue. Connected to this is the gene that tells the dilution factor to stop at a specific color and to maintain it at that color.

Color & Texture by Joan Gordon

Many stunning yorkies have maintained their TRUE (not enhanced) deep dark blue color to the age of 5 and sometimes later. On the contrary there are specimens that cant hold color up to 2 years of age. The blue dillutes and dilutes to a silver color and finally we come up with an almost white dog. Most of these dogs have routs of a darker color, but as the hair grows the dilution factor is so strong that can't hold correct color. Additionally these dogs have super silk quality, and amazing texture.
Somehow dilution factor of the Graying gene or the V gene or maybe both of them are connected to texture.
Moreover it seems to be a connection between gold and blue - in other words phaeomelanin and eumelanin.

To quote again Joan Gordon from http://dandugmore.netfirms.com/color.html:

"Since a Yorkie is actually a brown dog with a blue saddle- just as an Airdale and many other breeds are. They only way you can lighten or darken your dogs color (I do mean the blue as well) is to plan your breeding on the color of the gold. The blue color and the gold compliment each other. Light gold equals light blue - rich gold color equals dark blue. Bred this way they can pass it to the next generation. Lots of you do this without knowing it. Gold is the first thing anyone checks on their newborn puppies"

My -short- experience with the breed, confirms Joan Gordon.
Light gold = light blue and rich gold = dark blue.

BUT on the other hand there is another cause of silver color, and that is lack of pigmentation in general. This can easily be seen if we check the skin under the blue, which should be pink instead of blue, or a very very light blue, meaning that there is not enough eumelanin.

It is also very interesting that both colors are connected through the patterns of each other - controlled by A locus. The allele responsible for their tan pattern is [As] (saddle tan) according to Malcolm Willis. Tan on the forelegs extends up to the elbow and on the hindlegs it extends from the foot to just below the stifle. As you have mentioned in a previous post, the tan is not coming up quite as far on the body as in other saddle tan breeds.

Under the blue coat, the skin has a bluish tint and under the tan coat the skin is pinkish in color. If the pink skin invades the blue skin or vise versa, we will get an unclear gold and an incorrect blue.

So how can we explain all these genetically?

As for the hypothesis concerning the incomplete dominance of Graying Gene, it can be probably explained through Red Legged yorkies.
I hypothesize that a Red Legged is a [gg] dog. When bred together they of course reproduce themselves (recessive homozygous) , but when bred with a [GG] dog they can produce a [Gg] dog.

Thanks again
Mike

[pstinard]

Originally Posted by Mike1975

Thank you Phil for your reply!

This site for havanese and some other sites for poodles, were the reason I asked about the V gene (silvering gene).

Havanese and poodles also carry the Graying gene but its effects is somehow different than in yorkies, considering that both breeds have double coats instead of the singe coat found in our breed. Also they carry different alleles in other locii, so the final result is completely different.

In this quiz answer Quiz # 2 answer it says :



In a poodle site Color Genes in the Poodle I came across this :



It seems that havanese and poodles carry both genes (G and V) and their combination alters the final phenotypic result.

To add a little more confusion, Joan Gordon claims :


Color & Texture by Joan Gordon

Many stunning yorkies have maintained their TRUE (not enhanced) deep dark blue color to the age of 5 and sometimes later. On the contrary there are specimens that cant hold color up to 2 years of age. The blue dillutes and dilutes to a silver color and finally we come up with an almost white dog. Most of these dogs have routs of a darker color, but as the hair grows the dilution factor is so strong that can't hold correct color. Additionally these dogs have super silk quality, and amazing texture.
Somehow dilution factor of the Graying gene or the V gene or maybe both of them are connected to texture.
Moreover it seems to be a connection between gold and blue - in other words phaeomelanin and eumelanin.

To quote again Joan Gordon from http://dandugmore.netfirms.com/color.html:



My -short- experience with the breed, confirms Joan Gordon.
Light gold = light blue and rich gold = dark blue.

BUT on the other hand there is another cause of silver color, and that is lack of pigmentation in general. This can easily be seen if we check the skin under the blue, which should be pink instead of blue, or a very very light blue, meaning that there is not enough eumelanin.

It is also very interesting that both colors are connected through the patterns of each other - controlled by A locus. The allele responsible for their tan pattern is [As] (saddle tan) according to Malcolm Willis. Tan on the forelegs extends up to the elbow and on the hindlegs it extends from the foot to just below the stifle. As you have mentioned in a previous post, the tan is not coming up quite as far on the body as in other saddle tan breeds.

Under the blue coat, the skin has a bluish tint and under the tan coat the skin is pinkish in color. If the pink skin invades the blue skin or vise versa, we will get an unclear gold and an incorrect blue.

So how can we explain all these genetically?

As for the hypothesis concerning the incomplete dominance of Graying Gene, it can be probably explained through Red Legged yorkies.
I hypothesize that a Red Legged is a [gg] dog. When bred together they of course reproduce themselves (recessive homozygous) , but when bred with a [GG] dog they can produce a [Gg] dog.

Thanks again
Mike

It sounds like the jury is still out on whether the V (Silver) and G (Greying) loci are the same. From the definition on the poodle website (Color Genes in the Poodle), it seems that Yorkies, or at least my Bella, has what the poodle people would consider a Siver gene rather than a Grey gene. I base this conclusion on the fact that as Bella turned silver, the tips of the hairs were black, and silver grew in from the base. (The poodle site implies that Silver is gradual, whereas Grey is all or nothing: "The graying gene leads to a gradual accumulation of white hairs in both the inner and outer coat.... In silver dogs, as in blues, the transition from black to white for each hair is gradual, but occurs at an earlier age.") It looks like Joan Gordon agrees with this analysis, and also relates color to hair texture. Now whether or not this is a real distinction, I have to take their word for it. There is very little information about progressive greying and silvering in the canine coat color scholarly literature. Everything seems anecdotal at this point.

I agree with you about redleg Yorkies being gg--that's something I was thinking about before you brought it up.

I'll keep you posted if I hear anything back about Bella's DNA analysis, or if I spot a new research article.

[Mike1975]

Thanks I appreciate your time!

Achieving dark steel blue through graying gene only, is a bit confusing based on the information we have until now.
Its like racing against time before hair completely dilutes. There must be some kind of maintenance at a specific hue - preferable dark hue. The key word is "maintenance", otherwise color will keep diluting until silver or worse white is achieved. And unfortunately that's the case in too many yorkies - excellent species in soundness and conformation.

But that is not what's happening to yorkies that hold their color much longer. Interestingly the signs that a dog will keep color are apparent on phaeomelanin - like thumbprints for example.

So maybe we are dealing with 2 different genes, or a mutation of some kind - like you 've mentioned.

Looking forward for news concerning Bella's DNA and new researches. Its always a pleasure to read new findings!

Mike

[lilbumbleybees]

This is a fascinating thread! Man, I have missed this forum!

[Marhcarter]

I found a suprisingly informative article in Wikipedia about the genetic basis of coat color & pattern with a fairly simple explanation of each locus. They didn't have the V-locus, though, which is how I came across the article to begin with; searching for information on V-locus.
http://en.wikipedia.org/wiki/Coat_(dog)

[tricia208]

What great questions and information!

Joan Gordon is a good source of information. Her last known address was
1651 West Ridgewood, Glennview, IL 60025. I know that she loves to share her knowledge and experience with Yorkies lovers. I don't have a phone number or email for her. At her age she may not email. Feel free to write her.

I just looked and there is a letter from Joan Gordon posted on a website:
Joan Gordon - Quality Traditional and Parti Yorkshire Terriers
It was difficult to read the address but it appears to be the same as listed above.

[Mike1975]

Recently I read Ann Seranne's book "The Joy of breeding your own show dog" where she writes about the "recessive “blue” silky coat".

Are we dealing with recessive here?
Because if we did, it would be easier for breeders to lock this trait in their lines.

Instead, breeding together 2 dark blue silky coats, the resulting pups are not always dark blue!
And this is easily explainable if we consider only the Graying Gene effect.
According to our knowledge for Graying Gene "anecdotal" principles, a dark steel blue dog must be Gg in G locus.
This simply means that the elusive DARK STEEL BLUE is a result of heterozygosity.

So breeding together with another Gg dog, the resulting pups will have 50% chances to be Gg, 25% to be GG (silvery color) and 25% to be gg (black).

To add (again ) more confusion

Quoted from Yorky Club Magazine - United by passion for Yorkies.

I could not resisted to ask the breeders if there is any evidence that breeding a light blue Yorkie to a dark one or a light gold to a dark gold will produce the correct color. Mind you, this theory has been going on for years. Logically, it makes sense; genetically, it does not.
It is a crazy idea mixing a black dog with a silver one. It is like mixing paint, it does not work.” Affirms Mrs. Gordon. **
We might breed a light dog if the dog is exceptional in other ways and it’s color pattern was where it should be and if the dog did not have a running gold and if the dog still was darker on the end of the tail. If the texture is correct a dog with a very intense gold (nearly red) will darken both colors but of the offspring or this breeding will have to be bred to correct texture or you will be right back where you started with a mixed bag of colors.”

Roberta agrees “They do not mix together or dilute one another.” And then, she observes “unfortunately, with our litters being as small as they are, there is not enough pups to really show your percentage of each color. There is not enough puppies to draw the correct conclusion.”

**
Let assume that a black bitch is gg, and a silver dog is GG.
Bred together, ALL the resultant puppies will be Gg...

Hmmm

[pstinard]

Originally Posted by Mike1975

Recently I read Ann Seranne's book "The Joy of breeding your own show dog" where she writes about the "recessive “blue” silky coat".

Are we dealing with recessive here?
Because if we did, it would be easier for breeders to lock this trait in their lines.

Instead, breeding together 2 dark blue silky coats, the resulting pups are not always dark blue!
And this is easily explainable if we consider only the Graying Gene effect.
According to our knowledge for Graying Gene "anecdotal" principles, a dark steel blue dog must be Gg in G locus.
This simply means that the elusive DARK STEEL BLUE is a result of heterozygosity.

So breeding together with another Gg dog, the resulting pups will have 50% chances to be Gg, 25% to be GG (silvery color) and 25% to be gg (black).

To add (again ) more confusion

Quoted from Yorky Club Magazine - United by passion for Yorkies.



**
Let assume that a black bitch is gg, and a silver dog is GG.
Bred together, ALL the resultant puppies will be Gg...

Hmmm

Part of the problem could be with terms. What one person might consider "blue" might not be what someone else considers "blue." And there is a recessive "blue" allele at the D locus that results in the "blue born." I agree with the conclusion of the person you quoted, "There [are] not enough puppies to draw the correct conclusion." What is really needed to figure this all out is a database of standardized photos (taken under the same lighting conditions, dogs of the same age, etc.) of dogs and their parents, taken at various stages in their development. An experienced canine coat color geneticist needs to look over all of these data and perform a meta-study. Unless the same pair is bred over and over again, litters are too small to draw any more than anecdotal information, and that seems to be all we've got. The G locus is barely in the scientific literature at all, and the V (Silver) locus, which may or may not be the same as the G locus, has even less information in the literature.

[Christinee]

I have no idea what all that means. LOL Charlie is silver. I have a friend who calls him silver instead of Charlie. The other day someone told me he looked purple. LOL Is he a yorkie? haha

[pstinard]

Originally Posted by Christinee

I have no idea what all that means. LOL Charlie is silver. I have a friend who calls him silver instead of Charlie. The other day someone told me he looked purple. LOL Is he a yorkie? haha

If it's any consolation, Bella is silver too. "Blue" is just a name for a desirable shade of greyish/black. Here's a link to a picture:

http://www.22dog.com/images2/Yorkshire-Terrier.jpg

[Mike1975]

Is this silver?

[pstinard]

Originally Posted by Mike1975

Is this silver?

This looks more like the highly desirable classic "blue" to me. The lighter highlights in that photo are more of what I consider silver. I suspect that the dog in your photo is heterozygous Gg. My Bella is lighter than that, and I suspect that she is GG.