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True Roan in Gypsy's?

JNFerrigno April 03, 2011 April 03, 2011

Forums

I've searched and searched, and haven't found what I feel are true roan vanners. What I find I feel is sabino roaning. Any one know of any to exist?

rabbitsfizz Mon, 04/04/2011 - 03:16

Well, it exists in Welsh Cobs, so I would assume it exists in Gypsy Cobs- it may just be there is/was prejudice against it- I do not know of any Gypsy prejudice against Roan, but you never know!

Maigray Mon, 04/04/2011 - 07:13

Yes. Vines Gypsy Horses had a classic roan colt up for sale a couple of months ago. I remember because I wanted to save him for the galleries, but never got around to it.

JNFerrigno Mon, 04/04/2011 - 21:37

I'd love to be able to see the photos. But they have so much white on them, that roan might be covered by something else. I was asking because an artist friend of mine wants to know if she created a roan gypsy vanner if it would be considered pure.

Monsterpony Mon, 04/04/2011 - 22:51

I would bet it isn't that common as Gypsys are so often tobiano and I would bet a significant portion are homozygous for it. They can't be homozygous for tobiano and have classic roan given that they are both KIT mutations.

Daylene Alford Tue, 04/05/2011 - 15:49

Theoretically it could happen but they would essentially both be on the same gene and therefore the roan would have to be linked to one or other of the tobiano. Since they would be so close together, the chances of them becoming linked are minuscule (without a spontaneous mutation).

Threnody Tue, 04/05/2011 - 17:25

I agree with admin. I do think it is more of a case roan being inherited alone and non-obscured is a rare thing in a breed with so many white patterns to begin with. And since roan in the breed is likely linked to tobi and other KIT patterns it's rarer to see it by itself unaccompanied.

As far as homozygous tobi existing with other KIT mutations, I think it depends on which KIT mutations are inherited to make a non-viable embryo. Kind of like how some KIT mutations can viably exist in homozygous form (like roan, tobiano and SB1), while others have been proven not to (Like the W4 dominant white mutation). Certain combos can prevent a foal from forming, but we don't know exactly all combinations that are viable and which are not.

Monsterpony Tue, 04/05/2011 - 20:21

It is not possible for a horse to have more than two KIT mutations. Tobiano is slightly possible as it is not technically a KIT mutation so much as a regulator of KIT existing just next to the KIT locus. There would have to be a crossover event right at that tiny space in the DNA between the tobi and KIT for a homozygous tobiano to exist with a KIT mutation. It is not possible to have more than two KIT mutations (excluding the above tobiano example) in a horse. That would be the same thing as having a cremello pearl (CcrCcrCprl).

RiddleMeThis Tue, 04/05/2011 - 20:55

[quote=Monsterpony]It is not possible for a horse to have more than two KIT mutations. Tobiano is slightly possible as it is not technically a KIT mutation so much as a regulator of KIT existing just next to the KIT locus. There would have to be a crossover event right at that tiny space in the DNA between the tobi and KIT for a homozygous tobiano to exist with a KIT mutation. It is not possible to have more than two KIT mutations (excluding the above tobiano example) in a horse. That would be the same thing as having a cremello pearl (CcrCcrCprl).[/quote]
We discussed this a while back with Horsegen, and I believe from what I am remembering about that conversation is that it IS possible to have a cremello pearl, just highly highly highly unlikely due to location.

And as for the homozygous tobi to exist with a KIT mutation, no crossover would technically have to occur. You could just have a new KIT mutation.

Threnody Wed, 04/06/2011 - 08:52

Thanks RMT! That's really neat that its theoretically possible but highly unlikely that a multiple cream pearl of any combo could happen.

I'm trying to understand more of what was posted about homozygous tobiano. So the homozygous tobiano rabicano posted above could have occurred from crossover if rabicano is indeed a KIT mutation?

And in the scenario of a theoretical homozygous roan with SB1, this would have a similar result as the theoretical double cream pearl? Being genetically possible but exceedingly unlikely?

Sorry for the 20 questions but I'm also wondering how to do the punnet squares for a combination of these patterns now.

RiddleMeThis Wed, 04/06/2011 - 18:26

[quote=Threnody]Thanks RMT! That's really neat that its theoretically possible but highly unlikely that a multiple cream pearl of any combo could happen.[/quote] You're welcome.

[quote] So the homozygous tobiano rabicano posted above could have occurred from crossover if rabicano is indeed a KIT mutation?[/quote] Yes. Either a crossover, or a new mutation of either tobiano, or rabicano, with rabicano most likely being more likely.

[quote]And in the scenario of a theoretical homozygous roan with SB1, this would have a similar result as the theoretical double cream pearl? Being genetically possible but exceedingly unlikely?[/quote] Yes. Assuming rabicano is also a KIT mutation, it would work that same way as that as well.

[quote]Sorry for the 20 questions but I'm also wondering how to do the punnet squares for a combination of these patterns now.[/quote]Treat them like you would A+ A At and a. You can only have any combination of two. Does that make more sense or would you like a bit more??

RiddleMeThis Thu, 04/07/2011 - 13:34

Found the thread and I've quoted the relevant posts from horsegen
[quote]Roan and Tobiano are two mutations in the same gene--KIT (we think...technically, roan hasn't been identified, but mapping data puts it squarely in KIT). Cream and pearl are two separate mutations in the same gene--MATP. There's no real difference between the two scenarios, except that roan and tobiano are (most likely) a little farther apart than cream and pearl, so we would expect crossover between them more often than the MATP mutations. However, in both scenarios, they are very close, and crossovers will be extremely rare. Probably less than 1%.[/quote]

[quote][quote]Quote:
So theoretically you could have a horse that was homozygous for cream with pearl added?[/quote]Theoretically, yes. A horse could have cream and pearl on one chromosome, and just cream on the other. Theoretically, a horse could also be homozygous cream and homozygous pearl. The incidence of either of these occurrences is extremely unlikely due to the small chance of the crossovers necessary in the population to make it happen, but is possible.[/quote]