Dominant white article in The Bloodhorse

[springboro]

http://www.bloodhorse.com/horse-racing/ ... or-pattern

[Jorge]

I deeply respect the knowledge and investigations of these devoted researchers, yet I not necessarily have agree on the existence of many mutations out there ---especially if their pedigrees (TBs) are carrying "certain" ancestors. I still remember the years when "connoisseurs" referred to the astronomical odds against the appearance of white Thoroughbreds but then, when the cases of Mont Blanc (1963), White Beauty and War Colors (also foaled in 1963 by Ky Colonel), an Australian case in 1966, Clarence Stewart in 1979, just to mention a few made these proponents go back to the drawing board.

Don't judge me wrong, I profess great respect to these scientists but
we don't have to adopt "sine qua non", along with their factual findings, their secondary explanations.

[Linda_d]

Dominant white cases are rare, as the gene for the white coat color is usually a recessive trait. When a horse has one dominant white gene, the result will be a pure white horse that lacks pigment in the skin from birth. Historically, two dominant white genes have proved lethal for foals, generally within 48 hours of birth.

I think this is an error. Two frame genes produce the lethal white syndrome. I don't believe two dominant white genes necessarily do.

[heradine]

@linda i agree with you. i'm curious, what say dalene knight or the other breeders of colored thoroughbreds to this article?

[Jorge]

It's curious that certain specialized topics are brought up a-la "impromptu"
without the benefice of first consulting top world scientific "connoisseurs" and top reknown coat color breeders who may correct, or at least provide their hands-on valuable outlook on what looks like substancial errors. Academic titles are important, yet consensus is also another important element.

[RiddleMeThis]

Dominant white cases are rare, as the gene for the white coat color is usually a recessive trait. When a horse has one dominant white gene, the result will be a pure white horse that lacks pigment in the skin from birth. Historically, two dominant white genes have proved lethal for foals, generally within 48 hours of birth.

I think this is an error. Two frame genes produce the lethal white syndrome. I don't believe two dominant white genes necessarily do.

The syndrome they are talking about is LWO. However, Dominant White appears to be homozygous EMBRYONIC lethal. Meaning that the embryo never makes it to birth.

[Pan Zareta]

Link to full text (free) of the actual report as published in 'Animal Genetics'. It includes a photo of the foal with his dam.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2052.2010.02135.x/pdf

The colt was found to have a deletion, "not previously documented in horses", in exon 3 of the KIT gene and a missense mutation in exon 14 that "has been found in multiple breeds". The sire (3 white pasterns) was heterozygous for the exon 14 mutation. The exon 3 deletion was not found in sire, dam, or an unrelated control. The exon 14 mutation "is not associated with a dominant white phenotype". The exon 3 mutation is an unknown, but the authors note that similar deletions in other KIT exons are linked to dominant white phenotypes.

[reedhill]

riddlemethis..............so are you saying that if two DW's are bred together, they could possibly produce either a homozygus DW foal or a lethal white foal that won't make it?

[RiddleMeThis]

riddlemethis..............so are you saying that if two DW's are bred together, they could possibly produce either a homozygus DW foal or a lethal white foal that won't make it?

Yes, but realize it's not the same as LWO the foal would never be born. Its possible the mare would even lose it before you would check her to confirm she was pregnant. If it was after that it would be just a slipped pregnancy. It's not like LWO at all except the homozygous part.

You would NOT get a white foal that would die in 48 hours like LWO.

[reedhill]

Oh No, I just read this junky article. So glad opinions are allowed here.
IMO, whoever wrote this article apparently does not like white TB's.
The whole article has been formed by using parts of the original MD's work that
discovered the KIT mutations, and has loosely written a very short article with
much missing data in it. A quick read by a "non TB color" owner would surely give them
the indication from this, that white TB's and anything that has chrome and related to them is
a geneticly week and undesirable animal. I personally would like a rebuttal
writen from a completely different standpoint than this author.


1. When a horse has one dominant white gene, the result will be a pure white horse that lacks pigment in the skin from birth.

2. Historically, two dominant white genes have proved lethal for foals, generally within 48 hours of birth.

1. is not true.
2. is going to be found out that it is not true amoung the THOROUGHBRED breed, yes, maybe other breeds,
and there is a breeder out there that is going to prove this in the next 1-3 years. (not RHF)

Jorge, I agree with you 100% and I suspect Dalene is laughing at this article right now.

[Pan Zareta]

1. When a horse has one dominant white gene, the result will be a pure white horse that lacks pigment in the skin from birth.

2. Historically, two dominant white genes have proved lethal for foals, generally within 48 hours of birth.

The article ("De novo mutation of KIT") makes neither of those statements, directly or by implication. The remarks therein re. the KIT mutations, including those that cause dominant white, appear to be completely consistent with previously published, peer-reviewed, reports with which I'm sure the more discerning members of this forum are familiar. It would be most appreciated if one of them would let me know whether the mutation on exon 14 has been documented previously in the TB.

[Linda_d]

1. When a horse has one dominant white gene, the result will be a pure white horse that lacks pigment in the skin from birth.

2. Historically, two dominant white genes have proved lethal for foals, generally within 48 hours of birth.

The article ("De novo mutation of KIT") makes neither of those statements, directly or by implication. The remarks therein re. the KIT mutations, including those that cause dominant white, appear to be completely consistent with previously published, peer-reviewed, reports with which I'm sure the more discerning members of this forum are familiar. It would be most appreciated if one of them would let me know whether the mutation on exon 14 has been documented previously in the TB.

I think RHF was referring to the Bloodhorse article, not the original article. I have to agree somewhat if that's the case. At the least, the BH article author isn't particularly knowledgeable about color genetics as he doesn't realize there's a difference between DW and frame overo because the result he's described as being homozygous DW is really LWO.

Aren't there more than 1 variety of DW, so wouldn't that mean that 2 different DW variations would act as DW1DW2 rather than DWDW?

[reedhill]

Yes, I was definately referring to the BH article.

The author is making statements based on bits of information she has heard or read, thus telling the world that gets the BH magazine, that they have potential relationship to serious health problems or death

Researchers recently discovered a new genetic mutation in a Thoroughbred foal that was born with large portions of nonpigmented skin. Whether or not another horse with the the same rare mutation will be born is unknown, but the discovery has fueled researchers' pursuit of knowledge about coat color-related genetics and their potential relationship to serious health problems or death.

What could possibly be more horrible and untrue!
Plus the author makes no mention and gives no credit to the:

Tosso Leeb, University of Bern, Switzerland ~ for his kindness and willingness to share information and answer questions, as well as for his hard work on the KIT gene studies.

http://www.duncentralstation.com/PDF/KI ... Castle.pdf
The Nancy Castle article that is true and does give multiple references and credit. Now this would be great to see printed in the BH as a correct and factual rerbuttal

[Pan Zareta]

Thanks Linda-d, and my apologies, reedhill. I did think you were referring to the article in Animal Gen. I'd read it, but not the piece in BH until just now. You're right about it. At the very least BH ought to print correction of the factual error.

[Desert Oasis Sporthorses]

I think RHF was referring to the Bloodhorse article, not the original article. I have to agree somewhat if that's the case. At the least, the BH article author isn't particularly knowledgeable about color genetics as he doesn't realize there's a difference between DW and frame overo because the result he's described as being homozygous DW is really LWO.

Aren't there more than 1 variety of DW, so wouldn't that mean that 2 different DW variations would act as DW1DW2 rather than DWDW?[/quote]

I think I have an e-mail somewhere regarding two dominant whites and the location of the KIT and whether or not it is embryonic lethal. I have to go back through my e-mails. I am getting older and more senile by the day, but I seem to recall I have something or have read something. I will find it and post what I have.