Maximum expression overo gene?

[Doffy]

I am looking at purchasing a small yearling colt that has tested positive to be a carrier for the frame overo gene. He is solid white and he is listed as a maximum expression of the overo gen. Could someone please explain this to me. Does this mean that he has a higher chance of siring overo foals?

 

[MiLo Minis]

I am looking at purchasing a small yearling colt that has tested positive to be a carrier for the frame overo gene. He is solid white and he is listed as a maximum expression of the overo gen. Could someone please explain this to me. Does this mean that he has a higher chance of siring overo foals?

I am just working on getting all this together in my head but I will give it a shot.

If he tested positive for LWO then he must have some colour somewhere on him - possibly in his ears, few tail hairs maybe but somewhere or else he would have died shortly after birth. IF he is ALL white he is a maximum sabino but you say he tested positive. Yes he would stand a very good chance of siring overo foals.

Wait for more people with more knowledge - they will come!

 

[Songcatcher]

It sounds as though this colt has another "overo" gene besides Frame. The addition of Splashed or Sabino (especially if homozygous for one of them) could contribute to the colt being solid white. If that is the case, he would stand a better chance of throwing color due to the additional Pinto genes. He cannot be homozygous for the Frame gene (LWO) as that would be lethal.

Edited: He could be maximum expression Splash or Sabino and also carry the Frame gene, just as a horse can be homozygous for Black and also carry the Agouti gene or Silver gene.

 

[Robin_C]

My LWO-positive mare is white as the driven snow, and yes she is also a double-dilute, but she is really, really white -- not creamy (she is a lab-tested smoky cream). Not a colored hair on her body. Both parents exhibited sabino, so I'm assuming she is maximum sabino in addition to her two cream genes and of course her frame overo gene. The most frequent use I've seen of the term "maximum expression" generally refers to the sabino gene which is totally separate from the frame gene, though many people consider sabino an overo gene (while others do not).

Rest assured though that when an all-white horse is born to two overo parents, there are understandably some tense hours ahead for the owners following the birth. I am looking forward to breeding this mare for the first time but will make sure that the stallion is a non-LWO carrier and preferably solid so I can get some of her underlying color back. Underneath all that white is a black frame overo!

Robin C

 

[JennyB]

Dolly hi,

I am not sure if a max. white overo will sire more overo foals or not. I have heard that this is true<?>

: I know that Lisa Davis of LTD Mini's has quite a record with her overo stallions and they are not max. white overo's, although I think she has had some max. whites. You may want to ask her.

My stallion was born white with sorrel on the top of his head, ears and a little down his back, and blue eyes. His sire, Van-Lo's Ace's Shiloh Supreme was also(what I call) a max. white with dark eyes. His dam was a small sorrel mare with a huge star-her sire was a sabino stallion. My stallion tested positive for LWO and I have always called him a max. white sabino overo. Whether that is right or wrong, am not sure

:

He has had 8 foals so far.

One a solid red roan, star, strip and faint snip, NO blue eyes--dam was a red roan sabino

two a solid black with a few white hairs on forehead, NO blue eyes--dam was a solid black-bay

three a solid blue roan, star, faint snip, NO blue eyes--dam was a solid silver dapple

four a max. white, tiny top hat and a little chest shield, Blue eyes--dam was a black pinto

five a white and black tovero pinto, Blue eyes--dam was a silver dapple pinto

six a solid sorrel, blaze face, Blue eyes, four stockings--dam was a solid bay

seven a solid black-bay, star, NO blue eyes--dam was a minimal black-bay pinto

Here is a not so good summer picture of him when the sun bleaches his dark to white

Here he is in the winter when you can see his marks better

I call him a max. white because he is mostly white, but not all white.

None of his foals have been tested for the LWO gene, but he has sired only the one out of seven so far. Maybe he is NOT a max. white, but since he tested postive for the LWO gene, I assumed he was an overo even though what color he has does NOT competely cross his whole back. He also does not have a dark leg and has two black pot marks on his under lip-one on each side.

The foal in my avatar was the seventh foal-this years colt who is for sale by the way :aktion033:

My take,

Jenny

 

[rabbitsfizz]

Overo is a blanket term including three patterns, which, for some reason, have become lumped together under one heading.

Sabino.

Splash

Frame.

These three patterns are no more linked to one another than they are linked to Tobiano, but do look similar so it is probable that people found it easier to lump then together than to attempt to identify.

It is important to know if a patterned horse has LWO and IMO any foals sired by a LWO carrier should be tested at birth- they do not have to be visual frames in order to carry LWO and the test is cheap enough.

Only Splash is though to carry deafness- and that is still an unproven area. Luckily work is being done on it at present.

Maximum expressions of any pattern do not have to have any colour on them anywhere, even at birth, and I am sure that these horses are what has given rise to the myth of "White" horses.

When you mix the patterns, however they do tend to get wilder, so it is more than probable that your colt has present Sabino, at least. He could of course also have Splash and Tobiano- wouldn't that be fun??

Since it is likely he has other patterns present it is also therefore likely that he will throw these other patterns.

He cannot be H/Z for LWO therefore he has no more chance of throwing Frame than does a less wild marked Frame.

He could be H/Z for Splash, but as yet there is not test for this, or foe Sabino - there is a test for H/Z Tobiano but the tests I would have done, if I were you, would be for base colour- this is the most unusual one as, as has been demonstrated, even though he is visually white, he might actually be genetically Black!!!

As to expression of pattern, it is MO that Max expression, unless H/Z for a pattern, would not sire more colour than a "normal " expressed animals.

Now, what you have to do is look at him carefully and say to yourself "Would I buy this horse if he were Sorrel??"

If the answer is "YES" then go ahead and buy him, and keep us posted on the results!!

:

 

[Becky]

Does this mean that he has a higher chance of siring overo foals?

It's very likely that the colt carries more than one pattern. In my opinion, this gives him a greater chance of siring patterned foals for you. My stallion, Harts Tip Top Flash, pictured in my avatar, sires approx 80 percent patterned foals even out of solid mares. He is a combination of tobiano, splashed white and possibly sabino. Flash is solid white except for the tiny red medicine hat on top of his head. My other two current breeding stallions also likely carry more than one pattern as they both have a blue eye along with tobiano for Captain and sabino for Incognito.

 

[kaykay]

the gelding in my avatar was purchased from lisa and is a maximum expression overo. NO color on him whatsoever. I have been told by Lisa and other breeders they DO throw a much higher percentage of color as a lot of them can be carrying every pinto gene. I dont believe lisa ever tested Cheif as hes a gelding so it woudlnt really matter LOL

 

[Dona]

the gelding in my avatar was purchased from lisa and is a maximum expression overo. NO color on him whatsoever. I have been told by Lisa and other breeders they DO throw a much higher percentage of color as a lot of them can be carrying every pinto gene. I dont believe lisa ever tested Cheif as hes a gelding so it woudlnt really matter LOL

ANY horse who carries multiple pinto genes has a much higher rate of throwing pinto babies. Toveros, for instance, have a high rate of pinto babies, as there are multiple pinto genes involved.

Doesn't necessarily mean a MAX white will tho. MAX Whites are sometimes simply SABINO (from a mating of two sabino parents) So don't be fooled thinking ALL Max Whites will have a higher percentage of throwing colored foals. But, yes, many MAX whites can carry splash & frame as well...which would greatly increase the percentages of that horse throwing a "pinto". That "pinto" may be a frame, sabino, splash, or a combination of the three. OR...a Tovero (if Tobiano is added to the mix)

:

Many horses that are wildly marked carry multiple pinto genes too, and are capable of a high percentage of pinto foals.

 

[rabbitsfizz]

I assumed from the original question that we were being asked if a Max Expression white would sire more Frame foals than a "normal" pattern Frame.

The answer to that is obviously No.

Also obviously, as has been said by others, the more patterns present, the more possibility of one or maybe more patterns expressing.

No more than the average for each pattern though.

You may get pattern, it will not necessarily be Frame, and will depend on what other patterns are present.

You need to ask exactly WHAT is behind this colt- if you have a pedigree fro him it would be a start- we could help more then.

 

[kaykay]

well for sure you need to test to see what patterns are present. the poster knows the horse is carrying frame as hes already been tested. If he was mine i would have him tested for Tobiano too to see how many pinto genes hes carrying. Also if the poster knows what the sire and dam are carrying would be a big help. Lisa has an all white stallion for sale right now that so far has produced 100 percent colored foals. This is just MY personal experience but I have found thru the years that breeders with all white overo horses rarely sell them because they do produce such a high number of colored foals. The exception would be a max sabino.