Pinging BlackOak

[Sarah32306]

I'll keep answering your questions, insofar as my own knowledge extends... as long as you remember that I could be wrong.

Eye colors in horses is not my strong suit. I know that blue eyes can be linked to certain horse coat colors (like the cream gene), I THINK they are also in some cases linked to certain paint genes (overo comes to mind), but such things aren't yet a part of HWO. Right now, on HWO, we only have one separately standing eye-color gene. This is tiger eye. Named as such (in the real world) for it's similarity to a real tiger's eye color. They've also been called goat eyes, for the same reason.
Tiger eye genes in horses, is directly related to the champagne gene and in real life is generally ONLY associated with the Paso horses.
The tiger eye gene is likely best described as an incomplete recessive. What this means is that when paired with certain other genes, it can express. In this case, on HWO, that singular 'other gene' is champagne. Only when paired with the champagne gene, can a SINGLE tiger eye express itself. Like paving the way for the gene to be seen. Otherwise, this gene remains hidden unless TWO copies are carried. Also, a single tiger eye gene, when expressed, will look differently then two genes (in this case, this is working a bit like the cream gene). The tiger eye gene is green-hued always, either as a hazel or gray-green or bright, brilliant emerald green or a stormy-green. The hazel hue is generally seen as a single gene, while the brighter, more brilliant greens are found only when two tiger eye genes are together.
That's about as far as I know eye colors in horses. Of course, I'm not getting into the diseases and illnesses of eyes, that's a 25-book-set encyclopedia style answer there!

So, depending on who you talk to, it is generally believed that albino-ism simply cannot exist in horses. I am not one of them. As the definition of albino is the inability or failure of a gene to produce color, in my belief, albino-ism in horses IS a possibility, but because of the very nature of it (a failing gene) and our general breeding practices, such a horse is simply 'discouraged' to exist. There have been some cases in the real world of 'possible' albino horses, most of them proven to be simply white or types of light-based colors. But there have been others that show all the signs of being albino, but because of certain circumstances, were not genetically tested. So, just because it hasn't yet been proven to exist, doesn't mean it CAN'T exist.
In other animals, albino-ism generally and most often happens as a deficient mutation as a fetus. The genes, for whatever reason, simply lack the ability to produce color, therefore we are offered a 'full-body' albino. However, we have successfully bred animals to be only partially albino, as in the case of the new zealands... also looking up himalayan lilacs bring up a few.
Albino-sim is marked most often by red-eyes and pale skin with white hair or fur. Generally speaking, albino is carried throughout a lifetime (but there are cases of it popping up and disappearing, depending on the gene's controlling it, they'll switch on and off randomly, the 'off' position is the failure of color production).

Okay! Thanks so much! I don't have any more questions at the moment, but your answers will really help me get started on my paper!

[Sarah32306]

Wikipedia's telling me that true albinism (complete absence of any pigment, resulting in pink skin, pink eyes, and sight and hearing problems) has never been documented in horses--the gene mutation that causes albinism in other mammals has not been found in horses.

In horses, white is gonna be caused by (according to wiki)

1. Extreme dilution--pearl or cream gene
2. Max sabino
3. Max LP
4. Dominant white (on the KIT gene)(I don't think this exists in HWO)
5. Lethal white overo (homozygous O/O--overo doesn't exist in HWO, so we don't have to worry about lethal white)

I'm pretty sure that all 'white' horses on HWO are either extreme dilutes, or max tobiano (which never quite happens IRL)

Thanks Uppercase Hazel!

[BlackOak2]

One must also remember that genes are not alike in all animals.
If a gene controlling blue eye color is found in one spot on one animal, this does not necessarily mean it'll be found in the same spot on a completely different animal. This is just ONE of the reasons, we cannot make a 'mutant' hybrid of... oh, lets say a monkey and a horse.
So saying that the mutated gene that is found in any other animal is not found in horse's is really saying that the mutated gene and it's position is not found in horse's at the same point. The genes that control horse colors in some instances are different in horses than it is in other animals. So it lends to the understanding that the mutation that controls albino-ism could also be different in horses. Mark I said 'could' and not 'are'.

[Sarah32306]

One must also remember that genes are not alike in all animals.
If a gene controlling blue eye color is found in one spot on one animal, this does not necessarily mean it'll be found in the same spot on a completely different animal. This is just ONE of the reasons, we cannot make a 'mutant' hybrid of... oh, lets say a monkey and a horse.
So saying that the mutated gene that is found in any other animal is not found in horse's is really saying that the mutated gene and it's position is not found in horse's at the same point. The genes that control horse colors in some instances are different in horses than it is in other animals. So it lends to the understanding that the mutation that controls albino-ism could also be different in horses. Mark I said 'could' and not 'are'.

Okay! Thanks!