Hi all. I’ve come across a rather attractive APHA filly. Correct, no vices… with one downfall. She came up positive for the lethal white gene… I’m pleading ignorant on this…
Can anyone shed some light on it for me?
What are you planning to use her for? A riding horse? I am assuming you are not planning to breed her, but if that is your case then more research or a call into the APHA to understand the issues with carriers (which I guess she would be) would be in order. They are trying very hard to limit the passing of this mutation on for the benefit of the entire population and other breeds that cross in. Here’s an article I found – the first of many that came up on google.
http://www.apha.com/breed/lethalwhites03.html
And, I am adding this, since technically all Overos carry the gene, I am not sure what it meant by “she came up positive for the lethal white gene.” Is she solid white? I did read that are some false hoods regarding solid white paints so that would be an area to look into if so…
Q: Do all overos carry the lethal gene?
A: According to this theory, all overos would carry the lethal white gene, meaning it’s the overo gene itself, and if you get two copies of it, you get lethal white syndrome. We haven’t seen any evidence that there is an overo gene that doesn’t carry it. However, there may be other types of spotting, like sabino, that might not carry it because they might be different from overo.
Yeah, from what I gathered deffinatley not as a brood mare. Just for a riding/show horse.
Does it effect her everyday or just if she was to be bred?
Like I said, I know nothing about this.
[QUOTE=Bounceback;6268469]
Yeah, from what I gathered deffinatley not as a brood mare. Just for a riding/show horse.
Does it effect her everyday or just if she was to be bred?
Like I said, I know nothing about this.[/QUOTE]
No, she wouldn’t have any effects of the true “lethal whites” as they do not live past a day. There does not appear to be any ill effects based on her being a carrier of the gene. But I am still a bit confused as all Overos carry the gene (it is the gene for overo) so they are all carriers. Basically the research says in an overo to overo cross there is a 25% chance of a lethal white. However, those overos can be bred to a true solid or true tobiano with no risk for lethal white. (apparently the “true” is key as sometimes there is overo in there).
Unless there is some new research that has allowed them to identify certain Overos she’d be just like all the rest.
I’ll add that there is this myth out there so maybe this comes into play?
From APHA:
Myth #2—All Paint foals born white have lethal white syndrome.
While Paint foals that are born all white should be highly suspect of having lethal white syndrome, there are some white foals that are completely normal. While both might appear normal at birth, a lethal white foal will soon (usually within 24 hours) demonstrate several definite symptoms that indicate its condition.
The most characteristic trait of lethal white syndrome is a lack of gut activity, so a lethal white foal will probably fail to pass its meconium and will also begin to show signs of colic. Its condition will deteriorate quickly, with or without treatment.
Ok, well a little more research indicates that they have perhaps further identified the gene, she wouldn’t have any ill effects of being a carrier and there now is a way to eliminate the possibility of a lethal white foal…very interesting! Good luck!
From APHA:
At the whiter extreme, the frame overo pattern is responsible for lethal white foals. It is the pattern most closely associated with these foals.
Recent characterization of the gene involved in the lethal white foals has confirmed that the foals with two doses of the gene are white, and die soon after birth from gut innervation abnormalities. Horses with only one dose are frame overos, and survive.
This documentation is important for breeders of Paint Horses. With DNA tests now available for the frame gene (and the lethal white foals that can accompany it) it is possible to test breeding horses. Those with the gene can be mated to horses without it, resulting in about half frame and half nonspotted foals, but avoiding completely the production of lethal white foals.
She can be bred, just breed her to tobiano or an overo with minimal white. I was very active in the APHA for 15 years so know this lethal white gene well, and all overo’s ARE overos because they carry the gene. Your mare is fine, but be careful to breed to minimal white when breeding her, if you do breed her.
Diane Halpin: Facebook
Laurel Leaf Hanoverians: Facebook
[QUOTE=dianehalpin;6268503]
She can be bred, just breed her to tobiano or an overo with minimal white. I was very active in the APHA for 15 years so know this lethal white gene well, and all overo’s ARE overos because they carry the gene. Your mare is fine, but be careful to breed to minimal white when breeding her, if you do breed her.
Diane Halpin: Facebook
Laurel Leaf Hanoverians: Facebook[/QUOTE]
No you can breed her to an overo with worries - it just need to be N/N for LWO. It can still have splash or sabino. It is FRAME overo that is the problem. And yes - minimal white can still carry frame.
Yes, that’s true, bugsyskeeter! I stand corrected regarding the frame overo modeling.
To the OP - having the lethal white gene doesn’t affect your horse at all, except to allow her to have a frame overo pattern. All it means that is you need to be careful should you choose to breed her. Thats it!
Yes, please, if this mare is ever bred, you MUST make sure the stallion is N/N - tested.
Never, ever go by looks when it comes to Frame (what some people still call Overo, which drives me NUTS, because Frame is just 1 Overo pattern; Overo encompasses several patterns, not just Frame), unless it’s a stallion of a breed that does not carry Frame.
A completely solid horse can carry Frame. A horse who only looks Tobiano can carry Frame.
Frame is ONLY an issue in the homozygous form, and it kills foals - you’ll never find an adult O/O 
This is a little off topic but the first foal birth I ever saw in person was a lethal white. The girl who was watching the barn (where I used to train horses) that weekend starting freaking out when the foal emerged. Running around and crying “it’s a lethal white!” I was like, what in the world?!? The mare didn’t even attempt to acknowledge the foal which I thought was quite amazing that she instinctually knew it wouldn’t survive. The mare had had other foals in the past and was always a good mom. It was very sad and I hope I never see that again.
Overo means: Anything not Tobiano (to the Paint world). This includes Sabino, Splash, Rabicano, etc. Frame Overos all carry the lethal white gene. One gene for this is not a problem (it’s like having a black foal with one chestnut parent, they carry one chestnut gene). It is only relevant if you intend to breed the filly, and then it’s only important in narrowing down choices to stallions that do not carry LWO. There is nothing wrong with carriers of LWO, except you have to be more careful when breeding (but that applies to many things in many breeds, from Belgians to Arabians). It’s not like HYPP which can have symptoms in hetrozygous (N/H) and Homozygous (H/H) forms, but more like SCID or Herda, which are only issues in Homozygous forms.
It means she is herterozygous (1 copy) of the gene. As a riding horse it means nothing. As a breeding mare it means you have to be darn sure she is ONLY bred to a stallion that is tested negative. A foal homozygous for LW will die of intestinal dysfunction shortly after birth. It is most commonly found in Paint and QH breeds but there are a few odd TBs that carry it as well…so just breeding to a non stock horse diminishes the odds of a LW foal bu is not risk free without testing. There is some debate is all or MOST frame overos are postive for LW…but it is a moot point. You already know the filly is a carrier.
[QUOTE=dianehalpin;6268503]
She can be bred, just breed her to tobiano or an overo with minimal white. I was very active in the APHA for 15 years so know this lethal white gene well, and all overo’s ARE overos because they carry the gene. Your mare is fine, but be careful to breed to minimal white when breeding her, if you do breed her.
Diane Halpin: Facebook
Laurel Leaf Hanoverians: Facebook[/QUOTE]
tobianos can still be carriers as most Paints are so interbred among coat patterns…just because it looks Tobi is may still be an LW carrier. And not ALL overo patterns are LW either…just frame. Minimal white or even no white does not mean it is not a carrier either. Plenty of solid QHs are carriers.
[QUOTE=About Time;6268802]
This is a little off topic but the first foal birth I ever saw in person was a lethal white. The girl who was watching the barn (where I used to train horses) that weekend starting freaking out when the foal emerged. Running around and crying “it’s a lethal white!” I was like, what in the world?!? The mare didn’t even attempt to acknowledge the foal which I thought was quite amazing that she instinctually knew it wouldn’t survive. The mare had had other foals in the past and was always a good mom. It was very sad and I hope I never see that again.[/QUOTE]
while a horrible thing to happen if the foal IS O/O for LW…just be aware that not all solid white horses are LW> they can be homozygous sabino or dominant white as well. LW (homozygous/deadly form) can be 100% avoided by DNA testing the parents. Our stallion was DNA tested negative. A mare bred to him by an ourside mare owner had a DNA tested mare that was negative…and she still freaked out when the all white foal was born/called me in a panic.I asked if he nursed and pooped…she said yes…and I said then he is fine! We have had 4 all whites here (3 from the same family)
If you read the link in the 2nd post…NOT all overos carry the lethal white gene!!
[QUOTE=crosscreeksh;6270347]
If you read the link in the 2nd post…NOT all overos carry the lethal white gene!![/QUOTE]
See post #5 that’s what it says.
[QUOTE=crosscreeksh;6270347]
If you read the link in the 2nd post…NOT all overos carry the lethal white gene!![/QUOTE]
This is EXACTLY why it just makes me NUTS to hear “overo” used in the context it’s too often used, which is to mean “frame” - “oh, don’t breed 2 overos together, you could get a lethal foal! :eek:”
:no:
Overo is not-Tobiano. Frame is ONE of the Overo patterns - there are others: splash, sabino, and technically dominant white.
Frame = lethal white gene; lethal white gene = frame.
N/O is FINE. Absolutely no ill effects from it, and sometimes you get really, really cool patterns :yes:
O/O is a lethal foal 
Overos can have 1 or all of those patterns. You must never assume they do or don’t have Frame just by looking at them: only know for certain based on being tested.
[QUOTE=JB;6270569]
This is EXACTLY why it just makes me NUTS to hear “overo” used in the context it’s too often used, which is to mean “frame” - “oh, don’t breed 2 overos together, you could get a lethal foal! :eek:”
:no:
Overo is not-Tobiano. Frame is ONE of the Overo patterns - there are others: splash, sabino, and technically dominant white.
Frame = lethal white gene; lethal white gene = frame.
N/O is FINE. Absolutely no ill effects from it, and sometimes you get really, really cool patterns :yes:
O/O is a lethal foal
Overos can have 1 or all of those patterns. You must never assume they do or don’t have Frame just by looking at them: only know for certain based on being tested.[/QUOTE]
And to expand upon the amazingly wonderful post above… You CANNOT assume that a tobiano doesn’t carry overo. Most do. Not all carry frame however, but some do. (Many are called “toveros”). There are horses out there that carry Tobiano, frame, splash and sabino. So even if you don’t “think” the horse carries frame, if you do breed her, test. It’s not expensive… and it’s the only way to be sure.
