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the following link has the most informative and easy-to-understand explanation of equine color genetics that I have come across: http://www.equinecolor.com/color.html
I have revamped the page. It still needs work, and especially pictures inserted to make the concepts clearer. The curent version is based on http://dreamviewfarm.com/genetics.html. As author of that site, anyone wanting to take the time to copy the pics from there to here is welcome to.
I have recently been researching the genetics of horses, and have found this article to be one of the least accurate I have come across. Although much of it is correct, it still states many theories that have been disproven for as long as a decade in some cases. I am currently writing an article on current horse genetics, and will post it here once it is complete. In the meantime, anyone researching horse genetics is recommended looking elsewhere. Bill Killed The Unicorns 08:01, 16 September 2006 (UTC)
Noted earlier comment since removed by poster (See 'Accuracy of Article'), though it worth resurrecting for comment.
Suggest that it might be useful to explain what and how various theories are "outdated by 10 years" in the article and provide some links to current research so that those of us who care can take a look and see what kind of consensus can be reached. My point is merely that we float test balloons before diving in with wholesale edits of what clearly was an article that someone took a LOT of work to create.
I find the genetics of color quite interesting and a field that has changed beyond recognition since I took a class that discussed genetics during the 1980's. I am not surprised that even now there are still changes and debates going on...but I have also seen some head in the sand attitudes amongst people who dislike the revelations of modern genetics and attack the science itself. (Thinking here of the early days of HYPP being linked to Impressive as an example.)
I am not a geneticist, I am just a horse person with a penchant for wordsmithing and my (warning: bad pun coming) horse in this race is to try and separate what is POV from what is flat-out inaccurate (amazing how often people confuse the two). If I am convinced that something is the consensus of modern science, I am happy. If not, I like to see the various points of view presented so that people can look into the issue for themselves. (Like the eternal debate over on the wild horse article over whether equus ferus is or is not the same as equus caballus...sigh...everyone argues, no one cites to research. How can we laypeople decide if we can't review the research others have done? Arrgh!)
Personally, I have yet to see a good research citation on the question of dominant white (WW) as a lethal, as contrasted with Lethal White Syndrome (OO). At this point, it is my understanding that both exist, but I have also seen (though am not yet convinced) some arguments that there is no such thing as the W gene at all, that all "white" horses are so-called fully-expressed Pintos...curious to hear what folks think? Montanabw 00:17, 17 September 2006 (UTC)
Very little has actually been published on the subject of albinism in horses. One paper claims to have found the genetic marker that coincides with the White gene, but their evidence is doubtful, and the article has received no citations. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-0388.2004.00481.x?prevSearch=allfield%3A%28white+genetic+mapping+horse%29 (Sorry: restricted access to full article.) If anything, they seem to have mistaken the sabino gene for the White gene. My discusions with experts in the field suggest few, if any, see the White gene as a plausible theory.
Current genetics tells us that horses that appear white are generally not albino, but instead contain genes for localised albinism, such as the leopard complex, the sabino complex, or various others. In these cases the white markings are fully expressed, and it is almost impossible to find any pigmented coat on the horse. This is not, however, considered true albinism, such as that supposedly caused by the White gene. Additionally, when many dilition genes are present, it is not possible to detect the presence of any pigment, and the horse appear white. This is not considered to be a form of albinism.
Currently the White theory states that the white gene is a dominant trait, so that ww codes for non-white, Ww codes for a completely white horse, and WW codes for a completely white horse with a lethal genetic illness (Lethal White Syndrome) that causes it to die soon after birth. By this theory, both parents of a LWS foal must be completely white, yet this is almost never the case. Instead, both parents have only small patches of white, caused by the Overo gene. (In very rare cases the overo gene is not present, although the horse still has the gene that codes for LWS.) Now that a genetic test exists for Overo, it has been confirmed that all LWS foals are OvOv and appear completely white, and both their parents are usually Ovov.
Since genetics tests have proven that it is not the White gene acting to cause all the traits that we have previously associated with the white gene, then this seems to be sufficient proof to say that it doesn't exist.
In case you're interested, Animal Genetics, Inc, is one of the organisations that offers genetics testing for the overo gene. You can read more about it here: http://www.animalgenetics.us/LWO.htm Bill Killed The Unicorns
I have never come across a site, paper or expert in the field that has stated or implied that the so-called Lethal Albinism is not Lethal White Syndrome. Could you please state your sources. Thanks. Bill Killed The Unicorns 02:24, 12 October 2006 (UTC)
Your sources only state that homogenous W is lethal, they do not say that the condition is different to that of Lethal White Overo. This is nothing new, and by no means implies the two conditions are sepparate.
I am yet to see anything suggesting Lethal White Syndrome is linked to Sabino. My statement was merely saying that from what I read of the article, it seemed they had mistaken the effect of the sabino gene (as far as colour is concerned) for the effect of the W gene, and it is possible they had merely mapped the sabino gene, not the W gene.
As for the article I referred to, perhaps it is a little soon to be drawing conclusions about it. Although it is unusual for an article to go this long without citations, it does not necessarily mean that this is due to poor conclusions. I therefore retract my statement suggesting as such.
And in reference to a statement you made a while ago regarding the editing of the article: "My point is merely that we float test balloons before diving in with wholesale edits of what clearly was an article that someone took a LOT of work to create." I can understand how you can feel some sort of attachment to an article you put a lot of effort into, but I do not see this as an excuse to leave inaccurate data available to the public purely for sentimental reasons. In the equine genetics inductry, new discoveries are being made all the time, so naturally, new information will have to be added to update the article, and disproven theories will have to be removed. It should also be noted that my purpose to update this article does not include revamping the entire thing, merely stating the different theories, be they true, false, or disputed, and discussing why they have such a status. You will not lose much of your work, unless it is merely repeating something that I will say in a more concise manner. I will be happy to discuss with you any ideas for improving the layout and content of this article.Bill Killed The Unicorns 13:14, 26 October 2006 (UTC)
I think you misunderstood what I said. From what I can tell, it seems the researchers have mistaken Maximum Sabino horses for Albino horses (based solely on the fact that they are all completely white). It has long been accepted that these two genes are sepparate from each other, and I don't dispute that. However, I find it interesting that in reference to the horses they studied, they state:
"It seems, that the action of the dominant white allele is not always fully penetrant, resulting occasionally in spotted look alike offspring. These horses resemble a coat colour pattern known as sabino spotting."
"All of these white born horses transmitted the white or almost white phenotype in a dominant manner to their progeny." (Note: most Maximum Sabino horses are almost completely white.)
"Among solid coat colours, dominant white (W) segregates in this light draft horse population, going back to a founder mare ('Cigale') born in 1957. According to the studbook entries, the parents of the white-born founder mare were both of solid pigmented bay coat colour, with only negligible white markings." (Note: a single sabino gene results in white markings on the face and/or legs, and could quite likely be overlooked, resulting in the horse being recorded as solid.)
"All horses were classified into two categories as either solid coloured or dominant white; the latter including also 'sabino-like spotted phenotypes'. Thus, in this study, all horses observed with the sabino-like colour pattern were treated as incomplete dominant whites." (Since the Sabino gene has already been mapped, it is clearly not Dominant White, yet in this study it seems it has been treated as such.)
"White horses carry mostly tiny residual pigmented patches and have sometimes even 'spotted', sabino look alike, offspring (Fig. 2). These 'spotted' look alike horses may again have entirely white progeny." (This is consistant with the Sabino gene inheritance.)
"Microsatellite ASB23 was not fully informative in the pedigree, as some dominant white horses (W/w) were found homozygous for one of the marker alleles." (Note: Homogenous Sabino causes Maximum Sabino.)
"In addition, a focus should be given to an accurate description of phenotype nomenclature, i.e. to the question of whether dominant white is in fact an exhaustive expression of the sabino colour pattern or the sabino phenotype the result of incomplete penetrance of dominant white?"
All of these statements can easily be explained with reference to sabino gene(s), not W. In their conclusion, the researchers all but state this (see last quote) when discussing possible future research.
Their examinations of pedigrees and offspring of the tested horses suggests evidence of Sabino patterns, but their data is mentioned vaguely, so I cannot give a definite yay or nay on this theory. The lethal nature of the genes they mapped were not studied. It was assumed all horses tested were W/w. Their evidence suggests otherwise (see the second-to-last quote), which suggests that either W/W is not lethal, or that they were not looking at W genes. Unless the horses can be shown to NOT have a non-albino condition that causes the horse to appear completely white, it cannot be concluded that the gene they mapped is actually W. You might be interested to note that the W gene the researchers refer to is consistantly given the name 'Dominant White'.
Also, I am still working on the equine genetics article I am writing. It is nothing more than a summary of all known theories in this area, so it should be appropriate for Wikipedia. It is not finished yet, because I still have to summarise the pattern genes, and the most recent discoveries and conclusions (those that have come out since I started writing it), but it should be finished soon. I will add it to the wikipedia entry once I am done, including all my sources and references. It should be noted, however, that many of them are not online. Be patient and I will get this up soon.Bill Killed The Unicorns 08:50, 27 October 2006 (UTC)
Cite my sources? I already did! If you're going to respond to a comment here, please read the WHOLE thing. I don't like to repeat myself. The paper is the same one I was referring to at the beginning of this section (White genes). I even provided the link. Unfortuanately, only the abstract is available to the general public. The quotes I mentioned were taken from the body of the article. As for the point I was trying to make - I was trying to emphasize the poor quality research these people had undertaken, more specifically the number of possibly incorrect assumptions they had made, such as a horse that appeared sabino actually being albino. Bill Killed The Unicorns 05:09, 30 October 2006 (UTC)
Again with the misquotes! "As for "it seems the researchers have mistaken Maximum Sabino horses for Albino horses" I only want to note that there is NO SUCH THING as an "albino" horse" What I was trying to say is that it seems the researchers see a Maximum Sabino horse, and think its an Albino horse. These researchers are not only trying to prove the albino gene exists, but also map it. You also seem to be unfamiliar with the whole White theory: WW=lethal albino, Ww=albino (carrier of lethal gene), ww=non-albino. According to Sponenberg or Bowling. By this theory an albino should be able to exist. In practice I've never seen conclusive evidence of the gene existing, but thats beside the point. Also, you keep stating that Lethal Albino and LWS are two different things, yet you never quote an expert saying as such! You might also be interested to know that not all albinos have red eyes, regardless of animal species. In many cases the eyes are blue. Other possibilities might exist. Typically, though, albinos have white hair/fur/etc, and pink skin (if applicable). A horse with the sabino gene tends to have pink skin, blue eyes (very rarely brown), and white hair on at least part of its body. So its not so unusual to think that a Maximum Sabino might be mistaken for an albino. (Technically speaking, Sabino, along with the other pattern genes, is a type of localised albinism, but not THE albinism that is supposedly caused by the W gene.)
I'm not sure where you're getting your information on sabino, but you're way out. For the sabino 1 locus, at least, one sabino gene results in sabino markings on the face, legs and occasionally belly, while two genes results in fully expressed sabino, ie: Maximum Sabino, where most or all of the horse is white. A second sabino gene is theorised to exist, but I don't know how it is supposed to act. I think the Sabino 1 gene has a genetics test for it now, so the sabino theory stated here has been conclusively proven.
As for Maximum Tobianos (ToTo?) these don't exist simply because the Tobiano gene acts in a different way to the known Sabino gene. Maximum Tovero can exist, but this is several different genes, eg: Spl, Sa, To, all acting at once to create a white or near-white horse.
I hate to say it, but your knowledge of the actions of the pattern genes seems to be pretty poor. Next time, instead of questioning my knowledge on the subject, look it up, either here or elsewhere, to find out what the generally accepted or plausible theory(s) are, THEN come discuss it with me if you feel it necessary. I'm sorry, but I really see no point in debating such easily accessible, proven information.
"and I really question if a group of researchers are so stupid as to confuse albinos and maximum sabinos! I really doubt it." Is it really that hard to imagine? Maximum sabinos and 'albinos' both have all-white hair, pale eyes, and pink skin. In the case of the former some small amounts of spotting can occur, but not always. The quotes I mentioned above have been taken from the article by these researchers, and they clearly state that any horse that appeared sabino was recorded as albino.
Evidence exists to say that there is at least two genes that cause sabino spotting (currently named sabino 1 and sabino 2). I do not dispute such a claim. I've got an email somewhere from one of the current genetics experts that goes into this in detail. I'll try to find it. Also, I might have been mistaken when I stated that homogenous sabino 1 caused maximum sabino. I was quoting from the theory that came about before knowledge of sabino 2. All that is really clear, from what I know, is that more sabino genes are needed for maximum sabino, than for 'normal' sabino. Bill Killed The Unicorns 04:06, 2 November 2006 (UTC)
I'm saying there is no conclusive evidence to suggest that the White gene even exists. I don't know what causes the effect that is described as albino, but I certainly think sabino is a good possibility, although not necessarily the only one.
I know you stated earlier something about test breeding, but it should be noted that this sort of proof does not confirm the existance of White, only suggest it exists. Something similar occurred regarding Lethal Roan. Not long after the Lethal Roan theory came about, test breeding was undertaken, with the conclusion being that several healthy homogenous roans were seen. It is now thought that roan might be polygenic, in which case previous test breeding would be inconclusive, and it is now though Lethal Roan might be a possibility. Bill Killed The Unicorns 12:05, 3 November 2006 (UTC)
Try looking at the evidence FOR white genes. Especially some of the first evidence by (I think) Sponenberg that made him suggest the White gene in the first place. Its very shakey. (In case you can't find it, he basically states that a lot of horses appear completely white, and names the gene that causes this as dominant W -the first mention of W, I might add- then also notices that a lot of foals that are born completely white end up dying due to a colon defect, and makes the assumption that the gene that causes the foals to be white is the same one that causes the other white horses to be white. -Interpret this how you will-) The problem with many of the methods that look at the White gene is that they identify the presence of albinism solely on the colour of the horse. As i've mentioned, phenotypically, albino and maximum sabino are often identicle. According to theory they are genotypically different, but that remains to be proven. As for the differences between LWS and lethal albino, you keep stating that the symptoms are different, yet never do you state a source for it (despite my repeated requests for it), and never have I so much as heard of an expert implying this. For the last time, PLEASE STATE YOUR SOURCES!!! User:Bill Killed The Unicorns 11:46, 6 November 2006 (UTC)
I DID read what you wrote. Perhaps you missed my reply. I'll state it again to save you the trouble of looking for it: those sources only state the theory of the white genes. Not once do they say the symptoms of it are different to those of LWS. In fact, they don't even detail what the symptoms are. I'm not even sure you've read your own sources. They have almost no relavance to what you are stating.
You also say that there is no such thing as an albino horse. Although this is pretty much what I've been trying to say all along, it suggests that you are not familiar with the White theory. On the same sites you list above, it says that a single (dominant) white gene results in an "albino" horse (yes, they do use that terminology), while two of them is lethal. Now lets leave the dispute about teminology out of this, and just stick to the subject of the argument.
Finally, you state that sabino has neither lethal albino or LWS. I agree with you on this point, but I think you misunderstood what I said earlier. I was trying to say that Sabino horses are sometimes identified as albino based only on their phenotype (what they look like). Other factors are not looked at to determine if they have LWS or lethal albino or nothing, so there is nothing to suggest that the horse is not albino. If other factors WERE looked at, then it would be clear whether or not the solid white horse in question was sabino or albino or something else.
As for stating my sources, if I have them on hand I do try to post a link to them. Unfortunately, a lot of my sources are not found on the internet, eg: email/verbal conversations, so backing it up with physical evidence is not always possible, unless you want names and addresses so you can research it and contact the people yourself. Some sources aren't in English either, which is clearly a problem. Another problem is the great quantity of sources. Sifting through them all to find out which ones I'm quoting is not always practical. Especially when I am quoting from a conversation - i've simply talked to too many people to know who said what. Once I post all my data on here I'll include ALL sources though, so you've welcome to sift through it all then, and critically analyse the validity of them. Bill Killed The Unicorns 12:26, 6 November 2006 (UTC)
Let's keep it civil shall we? There's no need for sarcasm.
My reason for stating that W does not exist comes from real sources, not things I've made up, or attempted to directly research myself. A while ago I posted on a forum the article I wrote, that I've previously mentioned. It can be found here: http://hababeri.com/erworld/index.php?topic=6002.0 This particular version of my article is incomplete and a bit old, and my knowledge of horse genetics has since improved, plus new discoveries have been made, resulting in the accuracy of some sections being a little less than perfect, but most of it should be reasonable. More importantly, it also includes all the sources I used, and a glossary of terms. Anything I have said can be backed up by the sources listed here. Some are people, not sites, so you won't necessarily be able to find them all on the internet, but you might be able to find an email address if you wish to contact them. My article does not go into a lot of detail on the White gene theories, but my sources will, if you care to look them up.
And for future reference, in animals in general, 'true albinism' does not necessarily result in pink eyes. Animals can still be correctly classed as albino without having pink/red eyes. Just google 'albinism' if you don't believe me. Bill Killed The Unicorns 03:46, 14 November 2006 (UTC)
Upon further investigation, it seems that although the White gene has not been completely disproven, there does not exist any evidence to suggest it does exist, as confirmed by an expert I interviewed. In order for there to be a suggestion that it exists, there must be found a horse that appears to be completely white over it's entire body, and has been genetically tested and found to be negative for all known genes that could possibly cause this, including pattern genes (eg: Sabino) and dilution genes (eg: cream). As yet, no such horse has been found, and until it is, the White gene will remain an increasingly unlikely theory. Bill Killed The Unicorns 16:33, 17 April 2007
I'm afraid I don't understand your reasoning for removing the statement "Unproven Theory" from the section for the white gene. There is no genetic test for this gene, and there is debate about it's existance among prominant scientists, therefore it is a theory. Flaxen and Dominant Black are stated to be unproven theories, yet there is certainly less debate about flaxen than white. There are some conflicting views of the pangare gene, yet that is not stated to be an "Unproven Theory". The same goes for Sooty, yet once again there is no statement saying "Unproven Theory". This article seems to lack a bit of consistency. My suggestion for this article is to define what "Unproven Theory" means, and add a statement saying whether each gene is proven or not. Eg: Unproven Theory = no genetic test available, debate among scientists about it's existance. Plausible Theory = no genetic test available, no known debate among scientists about it's existance. Proven Theory = genetic test available, proven beyond all reasonable doubt. I see the pearl gene information hasn't been added in yet either. Considering how long thats been out I'm surprised. Additionally, I think there should be a bit of consistancy with the gene symbols used. I realise different scientists use different symbols, but I think we should pick one set of symbols and stick to it. Using the same symbols as those used by the UC Davis Veterinary Genetics Lab should be a start, since they do genetic testing. I'm not familiar with the symbols used in this article for the cream gene. I haven't seen any scientists using them before. I'll leave it up to you whether or not you want to add in these corrections or not. Bill Killed The Unicorns
I never said it didn't exist, just that it wasn't completely proven. And by the definitions stated above Grey would actually be classed as a plausible theory: It is generally accepted that it does exist, although a genetic test for it does not yet exist. Even if 'most' of the debate about White is among breeders, not geneticists, as you claim, there is still some debate among scientists, so therefore it is an unproven theoory. Just because you have found one group of scientists saying they think White exists doesn't mean they all think that. I have talked to at least one expert who has doubts about the white gene, even if they haven't (yet) published a paper saying as such. Bill Killed The Unicorns
j.1439-0388.2004.00481.x. Accessed September 6, 2006 at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-0388.2004.00481.x?journalCode=jbg —The preceding unsigned comment was added by Montanabw (talk • contribs) 01:58, 26 April 2007 (UTC).
Perhaps you should refresh your memory of the above discussion on White Genes. There is already stated more than enough evidence to show that there is debate in the scietific world about White, regardless of which side you take. I will not repeat myself. If you feel it is in the best interests of Wikipedia's readers to ignor my suggestions and remove my corrections when you have already stated you don't actually know anything about horse genetics, but are just here to edit the syntax, then so be it. I will make no further contributions to this article. It is no skin off my nose if an inaccurate article remains as is. Frankly, your over-protectiveness of an article you haven't even written, or even know anything about, is astounding. Bill Killed The Unicorns
Again with the misquotes! I have never said I know more than any expert in the field, nor do I presume to think that I do. What I AM saying, is that I have not disregarded sources just because they contradict what other sources say, which is something you have clearly done with this article. This appears to be the main reason for the gross amount of inaccuracies in this article. I may not be an expert in the field, but I at least state all theories, rather than disregarding some just because I don't like them, which is more than I can say for you. You do not have the knowledge or authority to decide which theories belong in this article and which theories don't, but due to your agressiveness you are limiting what can be written here, and I feel that goes against the whole purpose of Wikipedia. Bill Killed The Unicorns
For future reference, the "term paper" you saw was the incomplete first draft of a project I had barely started. I posted it solely to give you an idea of what sort of stuff I might be adding to the article, not to prove any particular point. Additionally, I have already stated that the White gene has not been disproven, since this would require something along the lines of genetic testing for all pattern genes, which clearly has not been achieved yet. All I've been trying to say is that it has been neither proven nor disproven, and therefore this article should state this. A quick search of Google Scholar, or any major article database, should show this.
If you insist on adding your own bias to this article, and removing any attempts to correct this, then I no longer consider this worth my time. You may have your article all to yourself. Bill Killed The Unicorns
Some exciting discoveries within the past month... Two new genetics test are now available. One is for the silver dapple gene, but the other is for a rare, newly discovered gene known as Pearl (aka Barlink). This gene seems to act in a very complex manner, depending on the presence of the creme gene or homogenous chestnut. I'll try to get my hands on the official article... Bill Killed The Unicorns 13:14, 26 October 2006 (UTC)
The generally accepted theory is that Brindle is as a result of chimerism. This is not a new theory, although it is possible their evidence for it might be. Still, I'd appreciate it if you could post a link for this article. It does sound fascinating. Bill Killed The Unicorns 08:55, 27 October 2006 (UTC)
Just because the two main experts in the field have not come across this before does not mean that it is a new theory. When I was researching brindle in horses, I came across plenty of sites that stated it was chimerism, although admittedly I don't know how much proof they had for it. These people may have prooven that brindle is chimeric, but the theory for it is not recent. Off the top of my head, I can't quote any sources, but if you look it up on google, it should be fairly simple to find. Its actually quite common, as these things go. Bill Killed The Unicorns 02:13, 30 October 2006 (UTC)
Just for interest, there is a rare pattern known as white brindle. This appears to be the same as brindle, but with white stripes, rather than black. The current theory states that this is as a result of chimerism with the roan gene. Just a curiosity - i don't know how accurate this theory is, or what evidence it has. Bill Killed The Unicorns 04:06, 2 November 2006 (UTC)
The best article I have seen on the white gene issue is Overton, Rebecca. "By a Hair" Paint Horse Journal March 2004. It explains LWS and how that test works, it mentions W as a gene that really does exist and says that WW foals are actually reabsorbed as embryos, it discusses the way the LWS gene cannot be determined by coat pattern, as it can be masked by many colors, it has even cropped up in the offspring of solid-colored horses. This one may be the most useful in practical terms. Now, can we end this discussion? It's getting redundant. User:Montanabw
There are inconsistencies in the abbreviations used. I do not know which is correct, but this is confusing to a newbie like me. I hope someone who knows what is right will get them consistent.
Formulas table uses C and CC often; I did not find a C in the Alleles table. (??C for chestnut??) Formulas also uses Ccr and CCr, which may be a combination of the unknown C and Cream. Alleles table did not seem to combine the abbreviations that way.
Alleles table mostly uses lower-case for second letter, as in Cr and Rn. However, TO is also used.
Formulas table uses RN for roan, not Rn. Uses TO for tobiano, which is consistent with Alleles table. but confusing. Signupslls 13:42, 19 October 2007 (UTC)
Updated the Cream Dilution Gene Allele table with industry standard abbreviations. If accepted, will update rest of table. —Preceding unsigned comment added by ChuckBiggs2 (talk • contribs) 02:46, 24 March 2008 (UTC)
The known, not proposed, genes to date with all the mind-numbing information...(more coming, interrupted)
COAT COLOR...
Locus: Extension (E)
Gene/protein: Melanocortin-1-receptor (MC1R)
Mutation: C901T (basepair format) single nucleotide polymorphism
Notation: Wildtype = E, C901T polymorphism = e
Phenotypes
Locus: Agouti (A)
Gene/protein: Agouti Signalling Protein (ASIP)
Mutations: 11 basepair deletion in Exon 2 (Positions 2174-2184); another as yet undescribed in peer reviewed journal
Notation: Wildtype = A, ADEx2 = a; unpublished = At
Phenotypes:
Locus: Dun (D)
Gene/protein: unknown (I believe "they" know where it is...but not tellin!)
Mutations: unknown
Notation: Wildtype = D, non-dun = d
Phenotypes:
Locus: Cream (C)
Gene/protein: Solute carrier family 45, member 2 (SLC45A2) aka Membrane associated transporter (MATP)
Mutations: N153D single nucleotide polymorphism, exon 2
Notation: Wildtype = C, N153D = CCr
Locus: Champagne (Ch)
Gene/protein: Solute Carrier 36 family A1 (SLC36A1)
Mutations: C188G single nucleotide polymorphism
Notation: Wildtype = ch, C188G = CH
Phenotypes:
Locus: Silver (Z)
Gene/protein: Silver homolog (SILV) or Premelanosomal protein 17 (PMEL17)
Mutations: Arg618Cys single nucleotide polymorphism
Notation: Wildtype = z, Arg618Cys = Z
Phenotypes:
Locus: Pearl (Prl)
Gene/protein: Unknown (no paper)
Mutations: unknown
Notation: Wildtype = prl, unknown mutation = PRL
Phenotypes:
COAT PATTERN...
Locus: Leopard (Lp)
Gene/protein: Transient receptor potential cation channel, subfamily M, member 1 (TRPM1)
Mutations: unknown
Notation: Wildtype = lp, unknown mutation/leopard complex = LP
Phenotypes:
Locus: Gray (G)
Gene/protein: Syntaxin 17 (STX17)
Mutations: 4.6kb duplication in intron 6; cis-acting regulatory mutation
Notation: Wildtype = g, cis-acting regulatory mutation = G
Phenotypes:
Locus: Frame Overo (O)
Gene/protein: EDNRB
Mutation: Ile118Lys
Notation: Wildtype = N, Ile118Lys = O
Phenotypes:
Locus: Sabino 1 (SB1)
Gene/protein: KIT
Mutation: KI16+1037A or r.2350_2472del or c.2350-13T>A or g.166003T>A, resulting in exon skipping
Notation: Wildtype = sb1, KI16+1037A polymorphism = SB1
Phenotypes:
Locus: Roan (RN)
Gene/protein: KIT
Mutation: Unknown
Notation: Wildtype = rn, unknown polymorphim = RN
Phenotypes:
Locus: Tobiano (TO)
Gene/protein: KIT
Mutation: Downstream chromosomal inversion
Notation: Wildtype = to, chromosomal inversion = TO
Phenotypes:
Locus: White 1 (W1)
Gene/protein: KIT
Mutation: c.2151C.G or g.164267C>G or p.Tyr717X, nonsense mutation from SNP in exon 15
Notation: Wildtype = W+, p.Tyr717X = W1
Phenotypes:
Locus: White 2 (W2)
Gene/protein: KIT
Mutation: c.1960G>A or g.160670G>A or p.Gly654Arg, missense mutation from SNP in exon 17
Notation: Wildtype = W+, p.Gly654Arg = W2
Phenotypes:
Locus: White 3 (W3)
Gene/protein: KIT
Mutation: c.706A>T or g.131675A>T or p.Lys236X, nonsense mutation from SNP in exon 4
Notation: Wildtype = W+, p.Gly654Arg = W2
Phenotypes:
Locus: White 4 (W4)
Gene/protein: KIT
Mutation: c.1805C>T or g.160429C>T or p.Ala602Val, missense mutation in Exon 12
Notation: Wildtype = W+, p.Ala602Val = W4
Phenotypes:
Locus: White 5 (W5)
Gene/protein: KIT
Mutation: c.2193delG or g.164309delG or p.Thr732GlnfsX9, Deletion in Exon 15 produces frameshift, premature stop codon
Notation: Wildtype = W+, p.Thr732GlnfsX9 = W5
Phenotypes:
Locus: White 6 (W6)
Gene/protein: KIT
Mutation: c.856G>A or g.136456G>A or p.Gly286Arg, missense mutation in Exon 5
Notation: Wildtype = W+, p.Gly286Arg = W6
Phenotypes:
Locus: White 7 (W7)
Gene/protein: KIT
Mutation: c.338-1G>C or g.130210G>C or r.spl?, Splice site mutation at 3' of Intron 2, alters reading of Exon 2-21
Notation: Wildtype = W+, r.spl = W7
Phenotypes:
Locus: White 8 (W8)
Gene/protein: KIT
Mutation: c.2222-1G>A or g.164835G>A or r.spl?, Splice site mutation at 5' of Intron 15, alters reading of exon 15-21
Notation: Wildtype = W+, r.spl = W8
Phenotypes:
Locus: White 9 (W9)
Gene/protein: KIT
Mutation: c.1789G>A or g.160413G>A or p.Gly597Arg, missense mutation at Exon 12
Notation: Wildtype = W+, p.Gly597Arg = W9
Phenotypes:
Locus: White 10 (W10)
Gene/protein: KIT
Mutation: c.1126_1129delGAAC or g.143284_143287delGAAC or p.Glu376PhefsX3, frameshift mutation at Exon 7
Notation: Wildtype = W+, p.Glu376PhefsX3 = W10
Phenotypes:
Locus: White 11 (W11)
Gene/protein: KIT
Mutation: c.2684+1G>A or g.169780G>A or r.spl?, Splice site mutation at 5' of intron 20
Notation: Wildtype = W+, r.spl = W11
Phenotypes:
Countercanter (talk) 00:51, 27 May 2009 (UTC)
Plopping them here for now. Countercanter (talk) 02:05, 26 May 2009 (UTC)
|-
|F
|F
f
|Flaxen: Effects visible on red or chestnut colors only.
FF or Ff: Red points on ee horses.
ff: Flaxen points on ee horses. Proposed theory, allele not located.[citation needed]
|-
|P
|P
p
|Pangare (Mealy): Lightening of hairs in limited regions. The effects of this allele appear in areas of "soft" skin, including the muzzle, behind the elbows, in the flanks, on the buttock, above or around the eyes, and along the belly.
PP or Pp: Mealy or Pangare dilution of pigment.
pp: no mealy looking lightening of pigment. Proposed theory, allele not yet located
|-
|Rb
|Rb
rb
|Rabicano: Partial roaning with ‘coon’ tail markings. Thought to be a dominant gene by Sponenberg.
RbRb or Rbrb: Rabicano markings.
rbrb: No rabicano traits.
|-
|Spl
|Spl
spl
|Splash, Splashed White - A type of pinto horse coloring recorded in the overo family, but possibly related to other genes. Resembles reverse tobiano with white moving from the bottom of the horse towards the top. The horse's head will look as if dunked in bucket of white paint. Commonly has blue eyes.
SplSpl or Splspl: Splashed markings. Splash is not associated with frame overo lethal white syndrome.
splspl: No splashed markings.
Alternate theory:
Incomplete dominant. SplSpl:classic Splash markings.Splspl:socks, face markings, may be small in the "normal" marking range or into the pinto range with or without blue eyes. splspl causes no white at all.
|-
|Sty
|Sty
sty
|Sooty
StySty or Stysty: The Sooty effect is of black hairs mixed into a body coat or any other color, may create dark bays or "brown" horses and liver chestnut. Is most visible on Buckskin or Palomino.
stysty: No black mixed into coat. Proposed theory, allele not yet located.
|-
|E+ also noted as Ed.
|E+
e+
|Fading and non-fading black: proposed theory, allele yet to be located, does not appear to occur on the same locus as the E and e alleles.[citation needed]
E+E+or E+e+: Dominant black, non-fading horse. One theory, unproven and highly unlikely, is that E+ is dominant over agouti.
e+e+: no effect.
For future reference, the diff on the theoretical colors that was tossed from the main article; http://en.wikipedia.org/w/index.php?title=Equine_coat_color_genetics&diff=292343431&oldid=286149520
I know that there is a contingent amongst the Haflinger crowd that is big on proving that there is a flaxen gene, and the Friesian folks as well as some other color breeders are bound and determined to prove there is a non-fading black. Just FYI. Montanabw(talk) 06:22, 26 May 2009 (UTC)
...let's make it a TABLE.
Phenotype | Potential Genotype | ||||||
---|---|---|---|---|---|---|---|
Extension | Agouti | Dun | Champagne | Silver | Cream | Pearl | |
Bay | E/- | A/- | d/d | ch/ch | z/z | cr/cr | prl/prl |
Bay dun | E/- | A/- | D/- | ch/ch | z/z | cr/cr | prl/prl |
Amber champagne | E/- | A/- | d/d | CH/- | z/z | cr/cr | prl/prl |
Silver bay | E/- | A/- | d/d | ch/ch | Z/- | cr/cr | prl/prl |
Buckskin | E/- | A/- | d/d | ch/ch | z/z | CR/cr | prl/prl |
Perlino | E/- | A/- | d/d | ch/ch | z/z | CR/CR | prl/prl |
Bay pearl | E/- | A/- | d/d | ch/ch | z/z | cr/cr | PRL/prl |
Bay double pearl | E/- | A/- | d/d | ch/ch | z/z | cr/cr | PRL/PRL |
Amber dun | E/- | A/- | D/- | CH/- | z/z | cr/cr | prl/prl |
Silver bay dun | E/- | A/- | D/- | ch/ch | Z/- | cr/cr | prl/prl |
Buckskin dun | E/- | A/- | D/- | ch/ch | z/z | CR/cr | prl/prl |
Perlino dun | E/- | A/- | D/- | ch/ch | z/z | CR/CR | prl/prl |
Bay dun pearl? | E/- | A/- | D/- | ch/ch | z/z | cr/cr | PRL/prl |
Bay dun double pearl? | E/- | A/- | D/- | ch/ch | z/z | cr/cr | PRL/PRL |
Amber silver | E/- | A/- | d/d | CH/- | Z/- | cr/cr | prl/prl |
Amber cream | E/- | A/- | d/d | CH/- | z/z | CR/cr | prl/prl |
Double cream champagne | E/- | A/- | d/d | CH/- | z/z | CR/CR | prl/prl |
Amber pearl | E/- | A/- | d/d | CH/- | z/z | cr/cr | PRL/prl |
Amber double pearl | E/- | A/- | d/d | CH/- | z/z | cr/cr | PRL/PRL |
Buckskin silver | E/- | A/- | d/d | ch/ch | Z/- | CR/cr | prl/prl |
Perlino silver | E/- | A/- | d/d | ch/ch | Z/- | CR/CR | prl/prl |
Silver bay pearl | E/- | A/- | d/d | ch/ch | Z/- | cr/cr | PRL/prl |
Silver bay double pearl | E/- | A/- | d/d | ch/ch | Z/- | cr/cr | PRL/PRL |
Buckskin pearl | E/- | A/- | d/d | ch/ch | z/z | CR/cr | PRL/prl |
Buckskin double pearl | E/- | A/- | d/d | ch/ch | z/z | CR/cr | PRL/PRL |
Perlino pearl | E/- | A/- | d/d | ch/ch | z/z | CR/CR | PRL/prl |
Perlino double pearl | E/- | A/- | d/d | ch/ch | z/z | CR/CR | PRL/PRL |
Amber dun silver | E/- | A/- | D/- | CH/- | Z/- | cr/cr | prl/prl |
Amber buckskin dun | E/- | A/- | D/- | CH/- | z/z | CR/cr | prl/prl |
Amber perlino dun | E/- | A/- | D/- | CH/- | z/z | CR/CR | prl/prl |
Amber dun pearl | E/- | A/- | D/- | CH/- | z/z | cr/cr | PRL/prl |
Amber dun double pearl | E/- | A/- | D/- | CH/- | z/z | cr/cr | PRL/PRL |
dun + silver + cream = Silver buckskin dun
dun + silver + 2cream = Silver perlino dun
dun + silver + prl = Silver bay dun pearl
dun + silver + 2prl = Silver bay dun double pearl
dun + cream + prl = Buckskin dun pearl
dun + 2cream + prl = Perlino dun pearl
dun + cream + 2prl = Buckskin dun double pearl
dun + 2cream + 2prl = Perlino dun double pearl
champagne + silver + cream = Amber silver cream
champagne + silver + 2cream = Silver perlino champagne
champagne + silver + prl = Amber silver pearl
champagne + silver + 2prl = Amber silver double pearl
champagne + cream + prl = Amber cream pearl
champagne + 2cream + prl = Perlino pearl champagne
champagne + cream + 2prl = Amber cream double pearl
champagne + 2cream + 2prl = Perlino double pearl champagne
silver + cream + prl = Buckskin silver pearl
silver + 2cream + prl = Perlino silver pearl
silver + cream + 2prl = Buckskin silver double pearl
silver + 2cream + 2prl = Perlino silver double pearl
dun + silver + champagne + cream = Amber silver cream dun
dun + silver + champagne + 2cream = Silver perlino dun champagne
dun + silver + champagne + pearl = Amber dun silver pearl
dun + silver + champagne + 2pearl = Amber dun silver double pearl
dun + silver + champagne + cream + pearl = Amber silver buckskin dun pearl
dun + silver + champagne + 2cream + pearl = Silver perlino dun pearl champagne
dun + silver + champagne + cream + 2pearl = Amber silver buckskin dun double pearl
dun + silver + champagne + 2cream + 2pearl = Silver perlino dun double pearl champagne
How awful, no?
There are ten options: black, chestnut, bay, dun, silver, champagne, heterozygous cream, homozygous cream, heterozygous pearl, and homozygous pearl. That is to say, the table that included all the potential coat COLORS in horses from KNOWN genes would be 10! Which, according to Google, equals 3,628,800. Since silver doesn't affect chestnut, it's rather fewer than that, but still... Countercanter (talk) 22:00, 26 May 2009 (UTC)
Surprise! Countercanter (talk) 13:57, 27 May 2009 (UTC)
Okay. I can appreciate why you wrote the intro the way you did. There is a difference between "We chose this arbitrary starting point because it would be easier to synthesize this way" and "The fundamental genetic default color of all domesticated horses is "red"." In reality, the DEFAULT (that is a simple term for "wildtype") coat color is bay dun with pangare. It seems logical to me, from the presence of grullo bred-back primitive horses, that the first event that may have altered the wildtype might have been "The Breaking of Agouti." Let me rephrase. BAY is the default. Uniform black is the result of the BREAKING of Agouti. Our friends researching early domesticated horse coat colors seem to feel that "The Breaking of Extension" was one of, if not the, earliest events, too. Let me rephrase again. NON-RED is the default. Chestnut is the result of the BREAKING of Extension. I think that as the data on Dun becomes more clear, we will hear more about it, but DUN is the default state and NON-DUN is the mutation. There is precious little molecular research out there on it. Aside: The one paper I read seemed to be drawing connections between "Dun" in horses and "Dilute" in dogs, cats, and mice. Can you imagine that there is a protein whose job it is to stick to a melanin granule and drag it to a good spot in the hair? These fibers are called melanophilin, and I believe they are similar to the fibers that grab the chromosomes and drag them apart in cell division, but I am just guessing. Anyways, this review seemed to suggest that Dun and Dilute were related. I use the Horsey Genome Scan to look for the Melanophilin (MLPH) gene and it's on chromosome 6, not 8...but then I'm not sure I had an entirely good grasp of the features. It also seems like such an obvious choice, and clearly researchers have been scratching their heads over candidate genes.
The important thing I wanted to communicate is this: I think that the "base color" approach is the most digestible way to understand horse coat color genetics. However, that introduction needs to say that: we chose this method of explanation because it's easier to understand, and it has no significance beyond that. Countercanter (talk) 12:38, 28 May 2009 (UTC)
Hmm. I understand why dun and cream are under the "dilution" heading, however, I kinda feel that dun does not belong under that heading. Dun is the wildtype, and to be categorized the same way as cream makes it look like it's a dominant mutation. Countercanter (talk) 12:41, 13 June 2009 (UTC)
I saw that on some of the genes it did mention the wildtype (E+/E+ etc.) but it looks like the agouti wildtype allele is missing (A+). Is there a reason for that? Also would it be redundant to add what the wildtypes are for each gene (cream, champagne, etc)? Correct me if I'm wrong. Tiny Trot (talk) 23:56, 27 January 2013 (UTC)
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"Horse sperm do [not] carry the color genes" and whatever follows from that, such as [the foal's color depending on the mother's genes]. It would be comparable to the human egg not carrying sex determination genes so that birth of a boy or girl depends on which human sperm fertilizes the egg. 100.15.127.199 (talk) 02:02, 17 January 2022 (UTC)
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