Changing the face (and LOOK!) of TB's in the years to come!

[soft hearted]

And yes there are a handful of "supposed" True Roans, however they are 1. not in the US and there are at most ten of them, and its debatable whether it IS true roan or just something mimicking true roan. They have not been identified by genotype because the roan mutation has no been found yet.

Agree on the rabicano with Showmethemoolah.

Completely DISagree with the statement on roans. There IS a test (ask the QH people) for roan. There was a scare for a while that a double dose of "roan" would be lethal, so there were supposed to be no homozygous roans. When the test was developed, a few found they DID have homozygous stallions that were a) alive and b) fertile
It may be a very small, incidental number now - but at some fairly near foreseeable future point, they'll be much like the Cr. gene. More and more common until someone finally manages to get a homozygous that then makes sure there are many crops worth popping out.

[RiddleMeThis]

Completely DISagree with the statement on roans. There IS a test (ask the QH people) for roan. There was a scare for a while that a double dose of "roan" would be lethal, so there were supposed to be no homozygous roans. When the test was developed, a few found they DID have homozygous stallions that were a) alive and b) fertile
It may be a very small, incidental number now - but at some fairly near foreseeable future point, they'll be much like the Cr. gene. More and more common until someone finally manages to get a homozygous that then makes sure there are many crops worth popping out.

According to researchers at UC Davis and University of Kentucky (and now Cornel) they have NOT found the mutation, and there is NO test for it yet. Now if you have proof (like someone actually offering a test for it) that they apparently don't have I would love to see/hear it as I know MANY people who would love to test their horses for roan.

[xfactor fan]

According to something that I heard about 3rd hand--so take it for exactly what that is worth--

The "True Roan" is lethal in the double dose. However, there may very well be two versions of the gene floating around, the regular one, and one where there is a slight inversion of the gene that cause roan. Not a huge number of these around. So lets call them Roan 1 and Roan 2.

Roan 1 x Roan 1 = early embryo death
Roan 2 x Roan 2 = unknown, but likely early embryo death

Roan 1 x Roan 2 = foal that is "true breeding roan"

Exactly what is going on with the Catch a Bird roans is unknown. They seem to be a new mutation that causes the roan pattern, and it may be the exact same mutation as the standard roan, or a new variation of the gene that expresses as a roan phenotype.

The Dominant White study showed that essential the same phenotype --maximum white horses--showed up in several populations, but was slight different in each case indicating a new mutation for each population.

[TrueColours]

Exactly what is going on with the Catch a Bird roans is unknown. They seem to be a new mutation that causes the roan pattern, and it may be the exact same mutation as the standard roan, or a new variation of the gene that expresses as a roan phenotype.

Its too bad that he isnt still around to do some testing on. I wonder if they kept some hair from him when he passed away?

I wonder too if his propensity for throwing what appear to be true, actual roans is linked to his chimerism and that gene not coming through in any of his foals but the roan gene did???

And I also wonder if his chimerism and/or roan characteristics had anything to do with the fact that he appeared to be sterile except for those few foals that he had early on?

[Jorge]

As per the traditional "roan" phenotype seen in various Catch A Bird's descendants, apparently there is no question that all of these sported darker head, darker points, and mixed white hairs, with no whitening-out with age. In synthesis, they all betrayed the well-known visual characteristics of a genuine "roan" ("R" gene) equine. Whether they were truly carrying the "roan" ("R" gene) that's another story since I am not aware is DNA tests were performed. But for me, if the aforementioned visual characteristics are present, (let's say, like hearing a "quack" from a duck) then the case must be labeled as "roan". I have been following these cases with much interest.

As per the appaloosa-like phenotyped horse named "sendmethemoolah", there are 4 characteristics that define an appaloosa, neither of which are present here. In synthesis, he cannot be labeled as an appaloosa TB.

Wrapping up this angle, if we are going to use genotypical descriptions to establish a list of coat color nomenclatures we must examine the opinion of the experts, such as Dr. Sponenberg's books. Will examine this angle soon.

[RiddleMeThis]

As per the traditional "roan" phenotype seen in various Catch A Bird's descendants, apparently there is no question that all of these sported darker head, darker points, and mixed white hairs, with no whitening-out with age. In synthesis, they all betrayed the well-known visual characteristics of a genuine "roan" ("R" gene) equine. Whether they were truly carrying the "roan" ("R" gene) that's another story since I am not aware is DNA tests were performed. But for me, if the aforementioned visual characteristics are present, (let's say, like hearing a "quack" from a duck) then the case must be labeled as "roan". I have been following these cases with much interest.

I thought it would be interesting to point something out (that I had wondered about during the discussion, but just now was able to check.)

The True Roan gene in horses as been narrowed down to a location. It is in the KIT gene (along with Tobiano, SB1, and Dominant White at least.)

What is interesting about that is that KIT is in a linkage group with extension, the gene that causes a horse to be either red or black based. What that means is MOST of the time KIT and Extension will pass TOGETHER.

Let me bring out an example to make this a bit more understandable.

Take for example this (stallion is Ee TOto) His E and TO are linked and his e and to are linked.

The black bar is black based horses and the red bar is red based horses.
The solid parts are solid horses.
The striped parts are tobiano horses
The checkered parts are "overo"


(Roughly)
He has six horses that are red tobianos and one horse who is a bay solid.
You then have 103 horses who are black based tobianos.
And 56 red solids.



Roan and extension should have the same linkage because roan is also in KIT. However when we look at Slip Catch it does not (though its possible that her one foal is a "cross over" so to say, its unlikely.)

Slip Catch is a supposed bay roan who is heterozygous for this roan gene. If it was the same roan as the original it should connect to either her E or her e.

However she then goes to produce a bay roan and a red roan by the same chestnut stallion. This means that she had to have passed BOTH E and Roan and e and Roan.

While it is possible that one is a linkage cross over I found this bit interesting. I will be doing a little more research tonight and see if I can find anything with the information I have, or can find.


Color do you happen to know where those photos were taken? Or by who? Or when? Or any information that might get me more information on this family of roans?

[angrovestud]

Riddle me this
That is so interesting we have a black tobiano heterozygous, he is EeTt and we mated him to our mare who is EeTtA and they have thrown 3 Homozygous TT foals we have been told by the geneticist that this is possibly happening because of the family connection between the two horses, as the DNA shape is a better fit when they are related I found that very exciting, as we now can specifically adjust our breeding programme to breed for TT Homozygous. if this Linkage is involved that makes even more sense beause the odd of this happening were 1 in 64
Thankyou.

[xfactor fan]

Re: Catch a Bird, there's some info in the Janet Gower equine color genetics book. If memory serves, all his roans were out of chestnut mares. So some account was taken of the color connection between roan and base coat.

Good catch on the base coat color/roan linkage on Slip Catch. However has anyone verified that the stallion is chestnut, and that the foals are indeed bay and chestnut? Could there be a wild bay in the mix somewhere? Sort to the horse genetic version of the old saying "If your mother tells you she loves you, first make sure it is your mother."

[RiddleMeThis]

Good catch on the base coat color/roan linkage on Slip Catch. However has anyone verified that the stallion is chestnut, and that the foals are indeed bay and chestnut? Could there be a wild bay in the mix somewhere? Sort to the horse genetic version of the old saying "If your mother tells you she loves you, first make sure it is your mother."

Well the foals DEFINITELY look bay and chestnut (albeit roan.)

The sire is Bletchicano. He is listed as chestnut, and is supposedly by and out of two chestnuts.

Also out of all his progeny listed on pedigreequery ALL are listed as chestnuts except the two roans.

I suppose they COULD be wild bay, but even the few wild bay TBs Ive seen that have minimal points, they were still listed as "Bay."

[xfactor fan]

Interesting.

Either there was a cross over, or the Australian TB Roan lives somewhere other than the KIT complex.

[xfactor fan]

There's another possibility.

Classic roan lives on Chromosome 3 along with sabino, Dom. White, and the Extension (base color) locus.

Appy roan or LP, seems to live on Chromosome 1. Perhaps the Australian Roan is more related to the Appy mutation than the Classic Roan mutation?

[RiddleMeThis]

Appy roan or LP, seems to live on Chromosome 1. Perhaps the Australian Roan is more related to the Appy mutation than the Classic Roan mutation?

I think it could possibly be in that location, but IMO it acts and looks different than LP so it would have to be a different mutation rather than the LP mutation again, if that makes sense.

[xfactor fan]

It is pretty clear that this is a brand new mutation. But the location of the appy roan mutation on chromosome 1, indicates that not all the "mess with white" genes live on chromosome 3 and the KIT complex.

I'd be stunned to find that it was the exact same mutation as the appy one.

[RiddleMeThis]

But the location of the appy roan mutation on chromosome 1, indicates that not all the "mess with white" genes live on chromosome 3 and the KIT complex.

Its not just Appy roan. Frame/LWO is not on chromosome 3 and neither is splash white.

[xfactor fan]

Do you know which chromosomes they live on?

I'm trying to put together a list of color markers for chromosomes. KIT and the merry band of whites are a great marker for movement of chromosome 3, and so on.