Albinism - what is known

Straight quotes from an equine geneticist:

Well, albinism can be caused by a lot of different mutations in a lot of different genes. It's not just one mutation that isn't found in horses that everybody else has. Actually, MATP (the cream gene) is an albinism gene, so in a technical sense, palominos, buckskins, cremellos, perlinos, etc. are all forms of albinism in horses. But if you mean white coats and pink eyes, the classic form of albinism, we have never seen that occur in horses. It doesn't mean it couldn't pop up one day, but so far a mutation causing that phenotype hasn't occurred.

someone then asked her this question
Quote:
If cream is a form of albino then why the difference between single and double dilutes? Is that just the way that this form of albinism in horses works? Are there any other species of animal with this same sort of albinism?

Answer:
More like that's the way the mutation works. Different mutations affect the same gene differently. This one is just an incomplete dominant, so you get a "dosage effect." Here are a couple of reference sites for you...here is one for the gene itself:

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=606202

And here is one that discusses how mutations in this gene can cause albinism:

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=606574


From another:
Really, you have the generic definition of the word, followed by the scientific definition of the word in humans, followed by the scientific definition in other animals, etc. It's no wonder people get confused.
In humans, the key symptom of albinism is a defect in vision - not coloring. So in fact an albino person may have perfectly normal coloring, at least to the naked eye, contrary to the actual (general) definition of the term. Humans have eyes unlike all other mammals and our vision is superior to any but the diurnal birds. But the retina has an outer pigment layer which is required for normal visual processing.
The impetus behind trying to strike the term "albino" from the lexicon probably had as much to do with social stigma as anything. There is a lot of prejudice attached to it.

Pink eyes occur in smaller mammals because the eye is shallow enough for the blood vessels at the back of the retina to be seen. I'm not sure the effect can truly occur in horses. I know people with albinism fight very hard against that stereotype.


I asked if cremellos, etc had sight impairment:

To be honest, how horses see is still not fully understood - but there is no evidence I know of that points to any impairment. They seem to perform just as well as any other horse.




This message was edited Jan 31, 2009 8:40 AM