# Question about pinto genetics



## JCnGrace (Apr 28, 2013)

How many different patterns can a horse inherit? For instance, I've heard some described as having frame, splash, & sabino for example. Can't they only carry 2 pattern genes? Can 1 gene produce more than 1 pattern? 

I have a gelding homozygous for tobiano, dna tested and while he was still a stallion he sired 4 spotted foals out of solid mares, but I would guess based on what I've learned here that he has more patterns than just tobi, but if that's the case how could he be homozygous?

Pics so you can see what I'm talking about.

Thunder





Sorry I can't find a good picture of his left side on the computer. One of these days I gotta learn how to scan:? There'll be another one you can see a little better on his foal pictures.



Some of his offspring:
Cloud





TJ





Flash-full brother to TJ


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## Chiilaa (Aug 12, 2010)

I think it is important to go back to basics here. You are right in that genes come in pairs, and you can only have two in each pair. Genes are found in pairs on a locus (plural loci). So each LOCUS has a pair of genes. Many of the white pattern genes are found at different loci, which means that they inherit separately to each other. A few share a loci, but they are the exception rather than the rule - eg Tobiano and Dominant White are both on the same loci.


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## Tryst (Feb 8, 2012)

^^^^ this

Tobiano, splash, frame, sabino, black, cream, agouti, etc are each on their own loci. Each parent will pass a gene from each loci, so a horse can carry multiple patterns, and could, in theory, be homozygous for all of them.


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## JCnGrace (Apr 28, 2013)

Thanks! Your explanations unfogged my brain a little. The color/pattern genes were just starting to be isolated back when we were raising paints and once we stopped I became lazy about keeping up with the info as it became available.


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## Tryst (Feb 8, 2012)

Just a minor edit on what I wrote . I said that a horse could be homozygous for all of those genes listed, but homozygous frame is lethal... So all the rest of them at least


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## JCnGrace (Apr 28, 2013)

I actually knew that one Tryst.  It's amazing how fast the science of genetics is progressing. Now I just have to get brown vs. bay down. Can you see enough of the mare with the black/white filly to tell? I have no clear pictures of her on my computer unfortunately. When bred to a sorrel stallion she has produced a bay and a black. Her pedigree so you can see some of the colors in her background. It doesn't have her dam's color on allbreed but she was black according to APHA's pedigree.

Skip The Tin Paint

Far left in her summer coat...again not a good picture in order to see her entire body.


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## NdAppy (Apr 8, 2009)

The mare with the filly cloud is a BAB (bad *** brown).


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## JCnGrace (Apr 28, 2013)

Thanks NdAppy! So...genetically speaking a brown would pass along black just like a bay would?

And just a coincidental fact, that mare was bred and born in your state of North Dakota.LOL


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## NdAppy (Apr 8, 2009)

Brown, bay and wild bay are all modifications of the agouti gene. 

That's cool!


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## sunandbeach (Oct 20, 2013)

those painted horses are beautiful....they always remind me of horses from the old cowboy and indian movies.....and the Indians always seemed to ride the more beautiful painted horses....and the cowboys had the solid colored horses


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## Dustbunny (Oct 22, 2012)

^^^Except for Little Joe Cartwright, who rode pintos. : )


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## JCnGrace (Apr 28, 2013)

Thank you Sunandbeach.


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## Chiilaa (Aug 12, 2010)

Tryst said:


> ^^^^ this
> 
> Tobiano, splash, frame, sabino, black, cream, agouti, etc are each on their own loci. Each parent will pass a gene from each loci, so a horse can carry multiple patterns, and could, in theory, be homozygous for all of them.


Just touching on this. Tobiano and the only currently testable sabino are located on the same locus, so they cannot be homozygous for one and carry genes of the other. Also on this locus is roan and all of the currently testable dominant whites. I imagine the other forms of sabino and dominant white that aren't currently testable would be here too, and I would not be surprised if it turns out rabicano is too.


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## NdAppy (Apr 8, 2009)

True roan is also on the same locus as tibia of as well. A horse that is to animal and roan is automatically heterozygous for both patterns.


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## Chiilaa (Aug 12, 2010)

NdAppy said:


> True roan is also on the same locus as tibia of as well. A horse that is to animal and roan is automatically heterozygous for both patterns.


I love your autocorrect so much :twisted::twisted::twisted:


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## NdAppy (Apr 8, 2009)

*facepalm* That's what I get for trying to post from my iPad. 

It should say - 
True roan is also on the same locus as tobiano as well. A horse that is tobiano and roan is automatically heterozygous for both patterns.

*sigh* Remind me just to read from my iPad and not post anymore. :rofl:


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## DraftyAiresMum (Jun 1, 2011)

To the OP regarding passing on the black gene...

All horses are one of two base colors: red (ee) and black (EE or Ee). Then there are modifiers on top of that. In the case of your mare, she carries the brown form of the agouti gene (AtAt or Atat). There's also the bay form of the agouti gene (AA or Aa) and the wild bay form of the agouti gene (not sure the genetic designation for that one). So, your mare, being brown, would have to be EEAtAt, EEAtat, EeAtAt, or EeAtat. In order to produce a bay foal (if the foal was truly bay and not brown), the sire would have to carry bay agouti (AA or Aa). However, since agouti restricts the expression of black to the hard points of the horse and being a red-based horse, the sire wouldn't have any black to restrict, his agouti status would only be known through testing. 

NdAppy and Chiila, that brings a related question to mind. Can a horse carry more than one form of agouti? For example, if the OP's mare is homozygous for brown could she be heterozygous for regular bay as well. Or are they mutually exclusive? I think I know the answer, but I'm still curious.
_Posted via Mobile Device_


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## NdAppy (Apr 8, 2009)

A horse can be AA, AAt, AtAt, AtA+, AA+, A+A+, (A+ is wild bay, not testable) but cannot be homozygous for one form and still carry another


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## DraftyAiresMum (Jun 1, 2011)

Ah, ok! That makes sense. Thanks, NdAppy!
_Posted via Mobile Device_


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## JCnGrace (Apr 28, 2013)

Thanks Drafty. Those agouti designations always confused the heck out of me back when I was doing research because I could never find a good source that put it in laymen's terms. 

Nd, Drafty asked about being homozygous for brown, but can a horse be heterozygous for brown and heterozygous for bay (is this the AAt agouti?) and which color would be dominant? 

I want to thank everyone for their input on this thread. It's fascinating and I'm even starting to get some of it through my thick skull. Keep up the discussions!


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## NdAppy (Apr 8, 2009)

Yes a horse can be heterozygous for both and it would show as AAt. Normal bay is dominant over brown.


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## mysticdragon72 (Nov 1, 2010)

Just as a side note here, and this is based solely on the photos of your stallion but it looks like he also carries the Splash gene as well as being homozygous for Tobiano... the way the white markings on the under side of his jaw is one trademark for Splash.


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## JCnGrace (Apr 28, 2013)

Thanks MysticDragon, I was wondering that as well.


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