Talk:White (horse)

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Material here was moved from the Gray (horse) article.

If anyone has a photo of a truly white horse--i.e. not a gray with a white hair coat--feel free to post here. One is needed.

Contents

[edit] Genetics of White Horses

Corrected the genetic expectations of white x colored in two spots, from 25% to 50%.

Statistically, a white horse (Ww) bred to a horse of another color will simply produce white offspring about 50% of the time,

* Color Stallion X White Mare (or vice versa): 50% of foals will be white, 50% will be colored

As shown by the Punnett square in the section, white (Ww) x colored (ww) gives you 50% (two squares) Ww (white) and 50% (two squares) ww (colored).

66.107.12.18 13:45, 31 August 2006 (UTC)



Since this is a question on genetics, I figured it probably belonged here. I apologise if that's not the case. ^_^ But I'm somewhat baffled - I've been researching colour genetics in horses for several years now, and the question of a W gene has come up multiple times, but never have I seen actual proof of such a gene existing - except the "proof" of one really old photo of a supposedly Dominant White horse, but which has nothing backing up this claim except that it is a pale horse with dark eyes and pink skin. I know this can occur due to the actions of other genes though, and I'm just curious since I noticed "However, there is also strong evidence that the "W" gene exists independent of any gene for spotting patterns, as confirmed by the mapping of the "W" WNT1 gene in 2004" in this article, but when I clicked the reference links I have only come up with speculation and "might be"s, and a search for information on the WNT1 gene itself led me to sites on cancer research, and a proposal to attempt to map the horse genome. This latter article I went through and it seems to be suggesting that the WNT1 is a genetic marker which may be linked to "white" horses, but I could not find a definite reference to the gene being proven or not. Though admittedly, technical reports are not my forte, so if someone who knows better points out my errors I'll be grateful and probably less confused. ^_^ That "mapping of the W gene" phrase in this article caught my eye and made me wonder if there'd been some sort of discovery that I somehow missed. If there's proof of a W gene I am extremely interested in locating it, as this whole white-horse issue is a question which has plagued me since before I even heard the word "genetics", and when I'm attempting to help others learn about colour genes I'd prefer not to have my facts all messed up. :") Thanks! 58.163.152.146 21:29, 11 September 2007 (UTC)Penniroyel

Basically, not all color genes have been specifically mapped--quite a few, actually (I don't think they've mapped the Gray gene, either, for example). And it is pretty fascinating. Both White and Sabino are real curiousities and they haven't figured out the whole puzzle, so if you do spot more studies beyond those listed in this article and in Equine coat color genetics, feel free to note them. But in short, from what seems to be out there, we unquestionably have more than a few horses with pink skin and blue eyes, and they alsotrue white (Ww) don't appear to occur unless at least one parent is white. The theory is that W is a dominant (in that one parent must have the gene for it to pass), Sabino is even weirder and may be a gene-complex, not a single gene. Of th sabino genes, they have mapped SB1, which in some cases causes a "maximum sabino" which is also an all-white horse with pink skin, and I can't recall if SB1 produces blue eyes and dark eyes both or not...SB1 is not a dominant, I don't think, but check the UC Davis site to verify what's the current status. Montanabw(talk) 19:07, 12 September 2007 (UTC)


Thanks for the reply, and I completely agree, genes are fascinating, and the sabino pattern is one of my favourites. Maximum sabino is usually my first thought when I see horses that are being claimed as dominant white, since extreme sabino is closer to true white than a creme or champagne/creme dilution due to the lack of pigment rather than the pigment simply being diluted. Also, sabino sometimes makes the eyes blue and sometimes doesn't, depending on the location of the depigmented areas, and thus could explain the dark eyes. And yes, the UC Davis site did mention the pattern as being a gene-complex rather than a single gene, as not all horses with sabino patterning tested positive for SB1. They also mentioned that SB1 was a dominant gene, but that a homozygous SB1 horse is at least 90% white (much like the "cat tracks" that can often be found on a homozygous tobiano, perhaps?), and I have seen at least a few cases of extreme sabinos being close enough to completely white that the only pigment left is a few tiny spots of dark skin that are only visible when the horse is wet, and in some cases dark eyes (depending on the spotting location and extent). Splash White seems to be more commonly associated with blue eyes than sabino, as far as I can recall, though both do often cause blue eyes - but it may have been just that Splash can have a tendency to make the blue eyes paler than other spotting genes, as some Splash horses have eyes which look almost silver rather than blue. And as I have not heard of a W horse having silver-ish eyes, and the fact that dark eyes seem to be preferred, it sounds as if Splash is not the gene responsible. However, the UC Davis site still hasn't really answered any of my questions about the W gene because it states that the eyes of a Dominant White are sometimes dark, sometimes blue (a trait also attributable to spotting patterns) and that these horses are sometimes referred to as albino, which is technically a misnomer as true albino shows a lack of pigmentation in the eyes as well, resulting in red or pink eyes from the blood vessels showing in the unpigmented iris. It also suggested that homozygous W is lethal, which made me curious as it suggested a possible link to the Overo Lethal White Syndrome and thus made me wonder if it was maybe connected, perhaps some kind of overo which causes one huge white spot over the whole horse - this could also explain the different eye colours, and the fact that I have seen some supposedly W horses being listed as having tiny spots of coloured skin. This site (http://omia.angis.org.au/retrieve.shtml?pid=2710) also seemed to have some information on the gene, and although some of the more technical aspects had me a little confused, it seemed to me as if there was a possibility it could be referring to Dominant White as being an all-over white spot, though I could be wrong on this as I am uncertain as to the exact way the true albino gene blocks colour in other animals - the reference to the specific way the gene blocks out the pigment in a set pattern (from the "top" of the horse to the belly) made me wonder, due to the way the documented spotting patterns have specific ways of forming the white patches which can help to identify the genes causing the spots (eg frame not crossing the topline, often having a white face but coloured legs, etc, as compared to tobiano crossing the topline and usually having socks or stockings but normal facial colouring, and more rounded spots than an overo, and the lacy edges of sabino spots or the crisp, blocky edges of the Splash spots - that sort of thing). Though of course, this is speculation as I am not a professional geneticist and have not been able to verify this with someone who is. Gah, I'm rambling. Sorry. Just been trying to figure this gene out for way too long and still have no real clue about whether or not it even exists - though from what I can see I'm leaning toward it possibly being a form of overo if it does exist. Thanks again, hopefully some day someone will figure out what this elusive colour is all about. :) 58.163.153.183 14:22, 4 October 2007 (UTC) Penniroyel

If you haven't checked all the references and links in the article, please feel free to do so, also there is a long-ranging and quite heated discussion of this at [{Equine coat color genetics]] too. (I spent way too much time arguing with a college kid) There is a lethal white syndrome article too. Bottom line, in layman's terms, appears to be as follows:

  • No one has totally figured out overo coloration, except for the Lethal White gene, which is somehow linked to overo, but many overo horses do not have the lethal recessive, so the color pattern alone is not the trigger for it. Overo also apears to have some recessive characteristics, as exhibited by the "cropout" Quarter horses who are solid for generations, then pop out an overo foal.
  • Tobiano is a dominant. And apparently dominant over overo. You cannot have a Tobiano unless one parent is also Tobiano (though some horses can be pretty minimally Tobiano, another probable source of "cropout" Quarter Horses). However, Tobianos (and solids) have thrown lethal white foals, but so far in every case of this, the tobianos (and the solids) have overo ancestors. So whatever is going on with lethal white, there is an overo connection, but they haven't figured it out completely.
  • Sabino is NOT overo, though the Paint horse folks group the two together (they did so before modern genetic studies). Sabino in general does not appear to be a true dominant, or else we'd see more of it, as we do with Tobiano, which is. Sabino has no connection to lethal white. Sabino appears to come from more than one gene. And yes, some Sabinos with SB1 are pure white or nearly so-- the "maximum" Sabinos. There do not appear to be "maximum" Tobianos at all, nor any living "maximum" Overos. (The so-called "living lethals" are all probably maximum sabinos) SB1 to date has been found in breeds like the Tennessee Walker and the Mustang, but not in other sabinos like the Arabian and the Clydesdale -- so SB 1 cannot be the only Sabino gene. There are a very few true white Arabians, apparently fewer than 11 in the world. I don't think anyone has DNA tested them for SB1, and all the ones I know of (two or three) have dark eyes.
  • Dominant white, the "W" gene that some people think doesn't exist, appears to be a different kettle of fish. However, the Mau study in 2004 suggests that the gene is real, and earlier studies confirmed that it exists. All "White" (as opposed to Sabino) horses have at least one white parent, thus the W gene, whatever else it is, behaves like a dominant. WW foals are never even born, they die or are reabsorbed in the womb. Lethal white foals (OO) are born alive, but have no colon and will die within a week.

So anyway, the weight of current research suggests that there are Sabino, overo, tobiano and white genes. Hope this helps. Montanabw(talk) 17:30, 4 October 2007 (UTC)

[edit] Very Rare

Totally agree that they are extremely rare. My grandfather always told me, there are very few white horses. Culnacreann 17:58, 2 October 2006 (UTC)

I think the popularity in the USA for various unusual colors makes them a bit more common in the USA than Europe, but they are still pretty rare here. Be interesting to see how the "is there really a W gene" issue shakes out--one school of thought says all "white" horses are actually maximally-expressed sabinos. I can't say I agree, but fascinating concept--pintos of various sorts more popular in the USA than in Europe, I think. Important either way for white horse coloring to be in a separate article from the Gray horse one, especially given the way people get all mystical about white coloring in any animal... :-) Montanabw 19:02, 2 October 2006 (UTC)

[edit] Fair use rationale for Image:Lone Ranger and Silver (3).jpg

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BetacommandBot (talk) 00:45, 14 February 2008 (UTC)

Added rationale to article and image page. Hope this does the trick. Montanabw(talk) 20:25, 15 February 2008 (UTC)

[edit] popular culture

Moved here from the White Horse (disambiguation) talkpage. Is it worth creating a "WH in culture" section?

  • A white horse is depicted as the loyal mount of Prince Charming in fairy tale literature
  • In Christian tradition, a white horse is ridden by one of the Four Horsemen of the Apocalypse
  • The white wind-blown caps of sea waves are often described as white horses, for example in the Beaufort scale windforce 5 is described as "Moderate waves, many white horses".
  • The heraldic signs of both Kent and the House of Hanover contain a white horse
  • Referenced in Blind Lemon Jefferson's song See That My Grave Is Kept Clean recorded in 1928. The precursor to references by both Bob Dylan in his version of the song of the same name and also Beck's. "I got two white horses following me, Waiting on my burying ground."
  • Referenced in Beck's song Farewell Ride. "Two white horses in a line, carrying me to my burying ground."
  • Referenced in Jeff Buckley's song Mojo Pin. "I'm blind and tortured, the white horses flow."
  • Tori Amos makes references to White Horses in two songs. The first one is on "Winter": ""All the white horses are still in bed/All the white horses have gone ahead" and the second one, in the song Horses. "The record (Boys For Pele) begins with the white horses from Winter coming back to take me on this journey and we ride and go find the demons..." -- Tori; Making Music, Jan 1996

BrainyBabe (talk) 19:17, 16 April 2008 (UTC)

OH GOD NOOOOOOOO! See WP:DISAMBIGUATION. Sorry to overreach These damn "popular culture" things can grow to eat the whole article. This is precisely what disambiguation pages are for! And wikipedia discourages 'lists' in articles when possible. People can link to this article in their respective articles if they want to, but not the other way around. Montanabw(talk) 23:16, 17 April 2008 (UTC)
None of these are named white horses. I will reinstate the use of the term for certain waves on the dab. The passing references in songs etc. are trivial, but someone or ones thought them worth the time to add, which is why I haven't deleted, but moved here. It would be good to have an article about Knight on a white horse, the proverbial rescuer. The heraldry example already exists at dab more precisely. BrainyBabe (talk) 06:13, 18 April 2008 (UTC)
No, it isn't the naming problem. It's the "popular culture/trivia" problem. Wikipedia in general frowns on lists and excessive trivia sections in articles, and while occasionally a trivia section is interesting if it can be limited to just a few quirky tidbits that are humorous or interesting, for "white horse" such a list can grow beyond belief until we have every song, movie, TV show, anime cartoon and god knows what -- at most, there is an argument to be made for a "white horse in myth" section that summarizes some of the major beliefs from antiquity, but that would be, IMHO, all we'd want. A trivia section would eat this article, I fear. Best to not even start one! Montanabw(talk) 03:36, 19 April 2008 (UTC)

[edit] Recommendations

There are many ways to skin a cat. All roads lead to Rome. "White" is a weird word. In summary, the "W" gene is not exclusively related to color, nor is it an on-off switch for true pink-skinned (unpigmented) white horses. The "W" gene goes by the names KIT, Mast Cell Growth Factor Receptor (MGFR), and Stem Cell Factor Receptor (SCFR). There are many known mutations on equine KIT:

  • Single nucleotide polymorphism in exon 4; heterozygotes are nearly all-white.
  • SNP in exon 12; heterozygotes are nearly all-white.
  • SNP in exon 13; heterozygotes are nearly all-white.
  • SNP in exon 15; heterozygotes are nearly all-white.
  • SNP in intron 16; homozygotes are nearly all-white.
  • Chromosomal inversion downstream from the gene itself causes KIT to be flipped; expression varies from mostly solid to mostly white but most are about 50/50.

W/KIT has more than 90 known allelic variations in mice; more will doubtless be found in horses.

What I am trying to communicate is that the use of "W" and "w" is not true to the nature of dominant white in any animal, including horses. Instead, I propose that this article focus on the phenotypes of dominant white. If the focus is on the phenotype (pigment-less skin and white hair), then the genetic causes (which are numerous) will describe themselves: KIT is frequently involved because it is in necessary to normal migration of melanocytes in development.

Also, what I didn't include in this post was to identify "Sabino-1" and "Tobiano" in the list of known allelic variations of KIT. Countercanter (talk) 16:06, 9 June 2008 (UTC)

Interesting. We (i/you/we, whatever) just have to keep it in understandable English and figure out how to avoid WP:NOR (which can be frustrating when one has a synthesis in their own head but can't find the publications to support it, even though the conclusion is obvious!). I guess we are sort of on the same track, in that we should have a section for the non-scientists on why white horses are white (as popularly understood - pink skin, not grays) and then a separate section on the genetic that cause these things?
So what about "dominant lethal white" - the thing that there are no true albinos and that WW is fatal (and NOT the same as LWS?)
Third, places like UCD make a big deal out of sabino-white (or "maximum Sabino", i.e. the SB-1 horses) being something that is NOT "dominant white" (because Sabinos do not produce lethal white foals unless they carry frame or W in addition to SB-1??) So of the genes you list up there, which are which?
Fourth, I have never confirmed Tobiano producing an all-white horse OR a cropout, though I have heard informal claims to both. And tobiano is dominant -- so whazzup wit' dat?
All in all, what we have here is a science in such flux. Wanna bet by this time next year we have to rewrite the whole thing again? Montanabw(talk) 01:20, 11 June 2008 (UTC)