Splashed White Gene Testing Information

[Joanne]

I was refered to one of the researchers at UC Davis VGL yesterday regarding one of the negative tests results on one of my horses. The horse Cross Country Blue Moon phenotypically looks to be a tobiano splashed white combination. He was tested homozygous for tobiano, but negative for splashed white 1,2,and 3. She agreed that he looked to be carrying the splashed white gene and he has been tagged for further study.

The highlights of the conversation are as follows:

1.) It is helpful for you to include a photo with the test request. This is done from your computer where it says "Optional Picture". You click on Manage Picture and choose a photo which shows your horse's color the best. A side view, like what you would use for registering a horse, is great. They do look at these photos.

2.) Once they run more tests they will know if the lethal form is found in other breeds, such as the miniature horse. The more miniatures that are tested the better.

3.) Phenotypically, the lethal forms SW-2 and SW-3, do not look different from the SW-1.

4.) They are seeing a few (2-3 so far) horses that appear (phenotypically) to be Splashed White, yet are testing negative. They still feel there may be more Splashed White genes that have yet to be mapped. These horses are being tagged for future testing. If you feel that one of your horses may fall into this category, you can send in additional photos and the testing number to them for their review. It is helpful if you can document that you have tested the horse for other color genes and what those results were.

5.) Unfortunatly the test form does not ask if the horse has blue eyes, or brown eyes, or a mixture, so it is not yet know if there are brown-eyed splashed whites yet. These horses, if they exist, may be a combination of pinto patterns.

6.) Miniature horses seem to express their color patterns differently than full size horses. A concept that I found interesting.

I hope this is of help to those of you considering testing. I am anxious to see all of your results and hope you post them as they come in. We have sent in a second group for testing and should have results in a week.

Those of you that are interested in testing your horses, here is the link:

UCD Vet Genetics Lab

 

[rabbitsfizz]

I think they have a LOT more work to do.

Why on earth are they not asking for pictures as part of the study?

Why are they not asking if the horse has blue eyes or whatever?

I know it's a step in the right direction to have any test at all, but I would not be testing my horses (in fact I am not) until I know if it is as pointless as Sab1.

If it looks as if it is Splash, and your gut tells you it is Splash,and it is neg for LWO, the chances are it is Splash!

 

[Joanne]

I am fine to be part of the research, in fact I welcome it. I realize genes are variable and if catches 95% of splashed white or sabino pinto I am fine with that.

The only way for the researchers to learn is to support them and send in the samples. If you wait on the sideline you are not part of the solution.

It is up to the people submitting the samples to attach a good photo. They will not refuse to run it if no photo is attached. For those that were part of the original research they were required to submit a photo as well as pedigree information. That is optional now. I have chosen to submit both photos and pedigree information.

I have been part of these tests as they have become available over the last 17 years. Tobiano, Frame, Sabino, and now Splashed white. Along the way the red factor etc tests. I hope to be around for many more of these findings.

I personally find it to be exhilarating to be part of the process. And very happy if my horses fall out of the criteria and it helps them find something new.

 

[rubyviewminis]

Thank you so much for your information Joanne.

 

[Lizzie]

How would pedigree information help, Joanne? I can see it might help, if the horses in the pedigree had been tested and colour/pattern confirmed, but so many pedigrees in the breed, give the incorrect colour.

Lizzie

 

[bevann]

I am no longer breeding, but I always like learning about anything new in genetic research regarding horses.I find it fascinating that many of the color finds also pertain,in many cases -in some way, to other species.I am grateful that people are willing to take the time to send in samples for research.Without samples there will be no progress.Thanks,Joanne, for sharing with us.I have learned so much from this Forum and the sharing of others.Guess I will always be a student.I love learning new things even though I don't always understand some of it especially when it gets very technical.Please keep sharing and sending in samples.

 

[REO]

Quote: lethal forms SW-2 and SW-3

LETHAL??? There is lethal SPLASH? I never heard of that until your post. Can you post info about that please Joanne?

What do SW-2 & SW-3 DO to make them lethal?

 

[Joanne]

Since there are no live homozygous splashed white SW-2 and SW-3, the therory is that they die before birth and are absorbed or aborted.

So far SW-2 and SW-3 have only been identified in paints and quarter horse breeds and only very rarely.

The UC Davis Splashed White test checks for alll three for the same $25.00 fee and reports all the results on all three.

Again, the lethal forms have not been identified in miniature horses at this time.

Lizzie they are only asking for sire and dam info. How it helps is easy for me to see. I have several horse generations on my ranch. In fact with the first ten samples results we have determined that a former herdsire is a carrier of Splashed White -1. We have his grand son and great grand son here and they are also Splashed White carriers,

 

[REO]

I thought that SW-2 and SW-3 were types of Splash.

I didn't know that SW-2 and SW-3 automaticly equalled homozygous Splash. And are lethal.

I'm confused. Am I misunderstanding the way you have your posts worded? Not just this last one, but all of the ones I've read. (Me confused? It could happen!

)

3.) Phenotypically, the lethal forms SW-2 and SW-3, do not look different from the SW-1.

It is *sounding* to me (by your wording) that SW-2 and SW-3 are homozygous and are lethal forms.

OR are you meaning to say that IF SW-2 and SW-3 are DOUBLED and homozygous, that THEN they are then lethal?

Thanks Jonanne! I'm trying to get this right in my lil ol pea brain!

HELP me Joanne!!!!

 

[Becky]

Robin, I believe what is inferred, is that SW-2 and SW-3 are lethal when in homozygous form.

The patterns are the same as SW-1 in heterozygous form. At least this is my understanding.

 

[REO]

Thanks Becky!! I wasn't quite sure of the meaning the way it was written.

I guess I would have understood it better if it had said it the way I've re-written it below

3.) Phenotypically, the homozygous, and therefore lethal forms of SW-2 and SW-3, do not look different from the SW-1

Sorry I'm a bit slow!!

OK, I understand now!

Thanks to all that bring new info and share it with all of us to learn from!

 

[Joanne]

Becky is correct.

There are three Splashed White markers identified at this time; SW-1, SW-2 and SW-3.

SW-1 is not lethal when doubled and is by FAR the most common type.

In SW-1's homozygous form it creates this type pattern on a horse, providing there are no other pinto genes combined. This is one of our horses and trhe only one that tested homozygous so far and carries no other pinto genes.

Splashed white SW-2 and SW-3, are lethal when doubled, as Becky correctly stated. So far they have only been found in Paints and Quarter horses and only in a rare group of certain pedigrees. Hence the value of knowing the pedigree Lizzie.

Just to be clear Robin, the homozygous form of the SW-2 and SW-3 are lethal and die before birth, so there are no living lethal homozygous SW-2 or SW-3 horses. The carriers are only in heterozygous form (having one copy of the gene), and yes, phenotypically those horses with a single gene look like heterozygous SW-1. Without testing you would not know a carrier from a non carrier of the lethal gene.

So far, miniature horses have not been identified with having a lethal form of Splashed White.

For those interested in testing their horses, here is the link to the UC Davis website: UC Davis order form

 

[Lewella]

Joanne did the person you talked to by any chance say which lines in AQHA and APHA had SW2 and SW3?

 

[Joanne]

Joanne did the person you talked to by any chance say which lines in AQHA and APHA had SW2 and SW3?

Lewella, I did not ask and I suspect they would not tell the public. This is researchers information that they would not want to release for fear that breeders and owners would not want that information to get out. It may come out in the Paint Horse Journal in the future, but I would think they would be worried about horse sales. We will just have to see how the paint and quarter horse industry handles it.

One of the other things they mentioned was that miniatures seem to have a different way of expressing their color patterns on horses than full size horses. A comment I thought was very interesting. I think I will go back and add this to the original post.