I'm confused... Paint genetics HELP PLEASE

crysann

I'm sure by now all my Paint questions are getting exhausting, but my momma always said I was like a bull dog, once I got a hold of something I kept going at it until i was sure I had shook all the life out of it LOL.
So, with that said, Help please.
What is the actual definition of Homozygous? I tried to research it myself I promise, but I got so confused I had less of an understanding than when I started.
So, the question is (by know y'all are aware that I have Cocoa Jet) her daddy was a homozygous Tobiano her mother an overo with a recessive QH gene (overo in her case being Dominate). Is Homozygous only for a certian TYPE of color or is it for any color.? The reason I ask is someone sent me an email in regards to her (have her listed on Dreamhorse) and they asked if her could be homozygous. I don't know, couldn't tell you, completely LOST.
So will someone explain to me like I'm a very SMALL child how that works, don't get too detailed really only interested in Cocoa Jet's case.
Poor me, when I was growing up I was sheltered i guess, my parents always bought the horse that I liked and if it had papers they got filed away somewhere, I doubt if I ever even saw them.
I'm so clueless on this paint stuff. We raised appies, but it was my ex-hsbands thing, all I did was ride, feed and fix owies. Everything else was his job LOL.
Anyway, thanx for the help in advance

doubleopi · Posted: Tue Apr 22, 2008 9:15 pm Post subject:

Most any color can be homozygous. For example to get a chestnut, it must be homozygous chestnut w/no black gene.
In regards to the tobiano thing. To be homozygous, both parents must pass on the tobiano gene. A horse will express tobiano with only one gene, but will only be homozygous if it inherited two (One from each parent). If the horse is homozygous for tobiano EVERY baby out of/by that horse will express the tobiano gene.
In your horse's case. Her dad was homozygous, which means she got a tobiano gene from him (Cause every baby of his will carry and express that gene) but she is NOT homozygous because her mom did not carry and express tobiano and therefore could not pass that on to the baby.
I hope that helps. I'm sure someone else can and will explain it another way, which is always good.

crysann · Posted: Wed Apr 23, 2008 4:33 am Post subject:

So, if she carries the dominate gene of tobiano from her dad and the dominate gene of overo from her mom, what would that be? obviously i will have to have her tested to know. but...

horsetrainer89 · Posted: Wed Apr 23, 2008 9:55 am Post subject:

Homozygous is when there is no recessive gene and both genes are identical.

Example:

ee AA gg toto apap spsp lplp RnRn (well this is never ending so I will stop right there)

In this example, this horse would be a red roan. As you can see, all of the different genes are identical, such as the ee are both lower case, the AA are capitalized, etc. Homozygous refers to any color and not just tobianos or paints in general. It can be in any horse. It just will help you get a better pin point of the progeny that it will produce and will help you determine what color your horse actually is.

horsetrainer89 · Posted: Wed Apr 23, 2008 10:05 am Post subject:

If your mare does have the Tobiano gene and only one tobiano gene then she will be Toto, but if she has two tobiano genes than she will be TOTO. If she has an overo gene, then she could be Oo or OO, unless she is lethal white, then she will be OLo or OLO, with the L actually being like a exponent on the o's, but my computer wont do that. What is her base color? If she is a red type of horse; such as chestnut, sorrel, etc. Then she could have eeAA, eeAa, eeaa, eeAa', eea'a, or eea'a'. If she is a black type horse; such as buckskin (which she isn't I know), black, etc then she could have the same a's but with one or two capitalized Es. She obviously doesn't have the extension black gene so I wont talk about that.

Right now her phenotype could be:

ee aa toto oo, with any of those capitalized, but since I am not sure on her color, I cannot go any farther than that.

horsetrainer89 · Posted: Wed Apr 23, 2008 10:07 am Post subject:

Oh but she cannot be OLOL because then she would be dead. OLo or OLO means that she is just a carrier. Oh and both parents don't have to pass the tobiano gene, only one of them does. Tobianos generally produce tobianos, but there are exceptions. The lethal white gene could also be marked OFr( Fr being an exponent and meaning frame overo (frame overo is the only way to get a lethal white)) and there will also be a plus sign under the Fr. There are several ways to mark genes, so if you see it one way, it could also be another way.

horsetrainer89 · Posted: Wed Apr 23, 2008 10:11 am Post subject:

Oh and if she was both an overo and a tobiano (TotoOo) than she would be considered a tovero.

doubleopi · Posted: Wed Apr 23, 2008 11:04 am Post subject:

If you go to APHA.com, and look under "The Breed" link, they have explanations of the 3 main patterns (Tobiano, Overo and Tovero). From the pictures you've posted of your mare, it looks like she only has Tobiano.

horsetrainer89 · Posted: Wed Apr 23, 2008 11:24 am Post subject:

Well we do know that she is obviously a tobiano, but the thing is she may be carrying the sabino (which is a type of overo) gene, which would make her a tovero. That is what we are still debating on, but without a doubt she is a tobiano, with a possible sabino gene or two.

crysann · Posted: Wed Apr 23, 2008 1:11 pm Post subject:

Ok guys, I think I understand this...
Her mother was an overo and her dad a homozygous tobiano, so she CAN'T be homozygous. If bred then she has a chance of throwing color if bred to a colored stallion then the chances are higher right?

horsetrainer89 · Posted: Wed Apr 23, 2008 1:21 pm Post subject:

No she cannot be homozygous unless the dam was as well as the sire, then she could possibly be homozygous. The chances are greater yes, but you can never be 100% certain that it will turn out how you want it. I am glad I helped you out.

crysann · Posted: Wed Apr 23, 2008 1:46 pm Post subject:

Thanx appreciate it. Y'all all have a great evening

horsetrainer89 · Posted: Wed Apr 23, 2008 2:32 pm Post subject:

Your very welcome. I am glad that I/we could help.

NZ Appaloosas · Posted: Wed Apr 23, 2008 4:04 pm Post subject:

horsetrainer89 · Posted: Wed Apr 23, 2008 4:48 pm Post subject: