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Kayosa — Equine Genetics Guide - Base Colors
Published: 2014-03-08 19:39:32 +0000 UTC; Views: 2347; Favourites: 60; Downloads: 0
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New Version! see it here: Equine Genetics Guide - Base Colors V2Part 1 - Base Colors Genes and alleles <- You are here
Part 2 Equine Genetics Guide - White Pattern Genes
Coming soon, Part 3, Equine Genetics Guide Pattern interaction examples(what does a real tobiano-sabino look like and why)
and later on, Part 4, Equine Genetics Guide Base Color Examples(four different sub-guides of black, bay, brown, chestnut)
FAQ
None added yet, question away. I can also prove the genetics supplied with more then one reference.
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Comments: 19
I wish there was some research paper or something on Mushroom. At best information is vague.
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Hopefully the Davis university is working on something.
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I have no clue about Genetics, so thanks for making these guides as I am hoping it will help me a lot.
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Your welcome. 
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For flaxen, because it's a recessive gene, it's expressed as ff, not FF. FF indicates dominance, ff indicates recessive.
Pearl is located on the cream locus and as such is an imcomplete recessive dependant on cream. It does not affect coat colour at all unless there are two pearl copies or if there is a pearl and cream present. Pearl used to be known as Apricot, it's now referred to as pearl on 'insert base colour here'. When it has a cream modifier, it is known as cream pearl on... etc.
Other than those few points, this is a very informative genetics sheet and I look forward to what other parts you come up with. ^^
I also happened to notice your LW convo, and there's actually two forms of lethal white that come from two different coat colours. I'm actually doing a paper on one of them. One is just Lethal white, the other is Lethal White Overo Syndrome. LWOS is connected with Overo, but not all horses with Overo carry the gene and foals die a few days after birth if dominant. The other is associated with the White gene, where if a foal has WW, it is basically absorbed by the mother before birth.
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Flaxen, as always, is under debate. There is a lack of proper information on flaxen, and the reason it is last because I didn't want to put it in at all. I will be changing it due to new information.
Lethal White Overo Syndrome is tied to Overo, and Homozygous(when you say dominant I think you mean homozygous) overo is usually fatal(overo is an incomplete dominant) like you said.
Dominant White has 20 different alleles now, so when you say WW, which one do you mean since not all homozygous White gene are fatal?
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With Homozygous overo(Which is what I meant by dominant, yes, sorry.) it depends. the LWO gene is not in fact Overo, but a different gene tied to overo which may or may not be present in the horse. A horse may be an Overo carrier, but not carry the LWO gene. From what I understand of the genetic testing that they do for APHA and the like(From what I've seen on horse testing sites as their disclaimer), they don't actually test for the actual Overo gene, but for this LWO gene, using Oo and nn for their testing results. So a horse could be overo, but not a carrier. Obviously, this is made more complex by the fact that Overo is being considered an incomplete dominant gene and has a variety of expression. (This site here for example. www.horsetesting.com/LWO.htm) The 'mutated' gene, or LWO, is actually caused by a missense mutation within the mutated overo gene itself and thus you can have overos who don't have this mutation.
With WW, I believe it's the most common form of the Dominant white that gives it's lethality in the homozygous form, but unfortunately with that one I haven't spent a lot of time looking into it. Overall, like overo, homozygous is considered taboo for breeding, for these reasons. xD
I apologise for sticking my nose in and throwing my opinions around when you don't even know me. Colour genetics are one of my passions and I'm always game for learning more and sharing what I learn with others. I hadn't known the correct genetics for Pangere or mushroom before I came across this, so thank you for sharing.
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Don't worry, Color genetics are also one of my passions, and I fell in love with genetics when learning dog genetics. Horse genetics are so much more interesting. Plus I love making theory with other enthusiasts.
What I think is happening is the term Overo is over used and may belong to more then one pattern gene. It is entirely possible that LWO is true overo, and other patterns that look the same are different genetics at play. They test for a LWO, which is responsible for the foals death. With the amount of white patterning genes floating around out there an overo horse that is LWO positive and the ones without that are called overo could have a different gene responsible for the patterns Since LWO does cause patterns like the almost pure white for homozygous foals.
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Within the APHA, it definitely is. The site defines overo as being sabino, overo and splash. However, Overo has been discovered to be a distinct gene, a dineucleotide mutation within a specific gene, and it's the LWO that is attached in this gene. So it's pretty much a mutation within a mutation that's hereditary. That's what my paper is being written on atm, along with Tobiano and splash genes that have been narrowed down. There's not a ton of information on it, but I've found one or two papers that talk about it briefly in their discussions.
Haha my next goal is learning dog genetics on the side, just for dA.xD
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This is really interesting, in your tobiano-sabino one are you going to talk about lethal white foals? I'm working with a breeder who refuses some mares if they carry a certain gene related to coat color that, when bred with her stallion, results in lethal white foals which never survive to adulthood.
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I will be covering a lethal white, but not extensively. I will probably provide a link to an informational page for people who want to know more.
From what I already know lethal white is related to Overo, is her stallion an Overo paint?
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Yeah the description of the whole genetic thing on her website goes like this:
"Millenium Miracle & Tristans Millenium both carry the "lethal white overo gene", which is also responsible for their beautiful coat patterns. When they are crossed with another carrier of the gene, there is a 25% chance they will produce a lethal white foal (Always ending in death). With Millenium Miracles color rate, as well as his large amount of frame patterned progeny, if you choose to take a gamble your odds getting a lethal white when breeding a frame carrying mare is about 75%. We do not reccomend you take the risk, testing to be sure of your mares frame overo status is cheap easy insurance.
It is important to know that this is NOT a disease or defect. It is a color gene that only produces color when in heterozgous form (one copy). Only if Sire and Dam both have the gene, and BOTH pass on the gene does it result in a Lethal White Foal. Due to frame overo having varying pattern expressions, a "solid" or a tovero can carry frame as well. We reccomend testing on all quarter horse mares, breeding stock paints along with regular registry. The frame pattern is also in thoroughbred lineage, and while less common can be a risk as well."
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Oooh, That is a Great description, do you have a link to her website for further reference? I have a collection of good resources.
Thank you so much for commenting, I love verifying sources and learning more.
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www.meriklewaters.com/lethalwh… here's the link, she also has a couple links in there for further reading on the subject from credible websites.
I have some questions you might be able to answer.
I have a purebred Morgan gelding, he's a red bay but sometimes expresses subtle dappling. I've heard that it's common in Morgans as a breed to have dappling in solid coat colors, do you think it's a genetic related or just the type of hair their breed has?
I also have a Tennessee Walker mare that is registered as a sorrel yet she has silver, black, blonde, and sorrel hairs in her mane. What's your opinion on that?
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I think dappling isn't strictly genetic, as I have a dun horse that has slight dappling. To me(I haven't studied dapples) I think dapples are either related the hair type and/or the likely hood of sun bleaching. My sisters horse is a sun bleached black horse that sometimes expresses dapples.
Tennessee walkers colors are rather interesting, and as much is known on horse colors more colors are being discovered all the time. My best guess is something else is going one here, as the Silver gene which usually causes that mane coloring only effects black. I suggest asking Lesli, who runs this epic horse color blog: equinetapestry.com/ you should take a few pictures of the whole horse and a close up of the mane hairs.
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