- This topic has 29 replies, 1 voice, and was last updated 14 years, 4 months ago by .
-
Posts
-
Hmmmm maybe this one ~ a Foreign White group 1.
http://cat-chitchat.pictures-of-cats.org/2008/09/albino-siamese-cat.htmlI found this. its just informational
http://www.springerlink.com/content/k6354u4323n32047/This one is kinda neat… scroll down to the cats
http://www.lifeinthefastlane.ca/35-ghosts-of-nature-albino-animals-of-the-wild/weird-scienceGot the reference to the European Albino from here:
http://www.messybeast.com/whitecat.htm
‘The “European Albino” bred in Belgium is a European shorthair type white cat with ruby-red eyes which have pale translucent blue irises.’I don’t have any particular reason for wanting pics, I just ran into the reference to this cat and was very frustrated that of the entire internet, only one sentence exists about it!
Messybeast also talks a lot about the new albino Siamese “breed”, but this is not the same cat as the European Albino.
I really don’t like the cat in the photo Phoenix posted.
And the “Albino Siamese” – that’s not a real albino, seeing as how it has blue eyes, is it?From messybeast:
“True albinism causes pinkish eyes, but some albinos or partial albinos have pale blue eyes. There are too few albino cats studied to draw firm conclusions, but this mutation is not necessarily linked with deafness.”So albino cats can have light blue eyes, and apparently its only dominant white (non-albino) that has a sure link to deafness.
Further on regarding albino Siamese cats, it says:
“Feline geneticist Don Shaw, writing in Cats Magazine, September 1972 to February 1973, looked into the so-called Albino Siamese and wrote that not all so called Albino Siamese were true genetic albinos and that many are blue-eyed whites of Siamese type (what we now call Foreign Whites). However, some Albino Siamese had pinkish-blue eyes rather than the clear blue of other blue-eyed white breeds. His research found that early registrations of “Albino Siamese” mentioned “Chinese Whites” – reportedly cats of Asian origin with Malay type and apparently blue-eyed whites having the piebald (white spotting) gene. Unlike other albino animals, the cat’s eye structure always gave bluish tone, even to the pink or ruby eyes normally associated with albino animals; this made true albinism in cats difficult to detect.”Interesting. Thanks, Pam. (Didn’t see your post before mine or I could have read it myself. Sorry. 😳 )
If you’re willing to pay for the article, I believe this is a scientific paper documenting the origin of the “European Albino” breed:
http://www.springerlink.com/content/k6354u4323n32047/
It may or may not have pictures. It sounds like the original parents to the breed are highly inbred, but that the white was fairly easily transferred to a Siamese background.Oh, by the way, the link of deafness to blue eyes and albinism is usually via a single biochemical pathway. A single gene mutation can screw up that pathway and cause all kinds of changes. I always thought it was interesting that one of the genes, MITF, caused different phenotypes depending on where in the gene the mutation is. For example, if the mutation is small and in one area, mice get a single white spot on their head (I have always wondered if those people with that single lock of white hair had the same type of mutation). If the mutation is larger and in a similar area, larger areas lose pigmentation, including inside the ear. Functional melanocytes are required for normal hearing (weird, huh?) And if a mutation is in another area of the gene, it messes up osteoclasts, cells responsible for breaking down bone (a normal process required for skeletal turnover–your skeleton now is a whole new skeleton than the one you had 5 years ago). When the osteoclasts are messed up, you get bones so dense that sometimes there’s no room for bone marrow. And the effect that mutation of this gene is known for is smaller than normal eye size (micropthalmia).
If you’re interested in the research behind all of this, here’s the OMIM database entry for MITF.
http://www.ncbi.nlm.nih.gov/omim/156845GD, Any idea if the melanocytes that cause deafness when absent is the same reason the OLWS affects the bowls in foals when homozygous?
Phoenix wrote:GD, Any idea if the melanocytes that cause deafness when absent is the same reason the OLWS affects the bowls in foals when homozygous?
They’re related, it seems, but not the same. The gene that causes OLWS is called endothelin 3. It’s required to allow melanocytes to migrate. That’s why they’re pale–the melanocytes never managed to make it to their final destination (skin, hair, etc.). But endothelin is also important for the migration of other cells, and that’s why the bowels don’t work–the cells required to move to the proper place to make the intestines work never managed to make it to their mark.
*edited to add that the cells missing in the bowels of OWLS foals are nerve cells that control the bowels.ghostndragon wrote:Phoenix wrote:GD, Any idea if the melanocytes that cause deafness when absent is the same reason the OLWS affects the bowls in foals when homozygous?
They’re related, it seems, but not the same. The gene that causes OLWS is called endothelin 3. It’s required to allow melanocytes to migrate. That’s why they’re pale–the melanocytes never managed to make it to their final destination (skin, hair, etc.). But endothelin is also important for the migration of other cells, and that’s why the bowels don’t work–the cells required to move to the proper place to make the intestines work never managed to make it to their mark.
*edited to add that the cells missing in the bowels of OWLS foals are nerve cells that control the bowels.Hmmm. So I wonder why dominate white or splash white foals aren’t affected. Wouldn’t they be lacking pigment as well? I think splash is linked to the deafness in horses… Or was that the OLW gene? I can’t remember.
Phoenix wrote:ghostndragon wrote:Phoenix wrote:GD, Any idea if the melanocytes that cause deafness when absent is the same reason the OLWS affects the bowls in foals when homozygous?
They’re related, it seems, but not the same. The gene that causes OLWS is called endothelin 3. It’s required to allow melanocytes to migrate. That’s why they’re pale–the melanocytes never managed to make it to their final destination (skin, hair, etc.). But endothelin is also important for the migration of other cells, and that’s why the bowels don’t work–the cells required to move to the proper place to make the intestines work never managed to make it to their mark.
*edited to add that the cells missing in the bowels of OWLS foals are nerve cells that control the bowels.Hmmm. So I wonder why dominate white or splash white foals aren’t affected. Wouldn’t they be lacking pigment as well? I think splash is linked to the deafness in horses… Or was that the OLW gene? I can’t remember.
If I remember right from what I read, dominant white horses have pigmented eyes, so it would seem that the melanocytes are functional. I don’t think it’s clear what causes dominant white. But the mechanism must be different from just having non-functional or absent melanocytes. It might have to do with the pigment itself rather than the cells that make it. If white splash is linked to deafness, it could be that depending on where the white is, there is a lack of melanocytes or a lack of functional melanocytes. I do remember reading that some OLWS foals are found to be deaf as well. I would imagine that those foals that have no coloration whatsoever are more likely to be deaf than those that show some coloration.
It’s not uncommon in other species to just have regions of non-functional melanocytes. Odd-eyed white cats often have deafness on the side of the blue eye. Same with dogs. Dalmation breeders like to have pups with black ears because white ears (that is no melanin/melanocytes near the ears) is linked to deafness. And odd-eyed people with white forelocks are often deaf (Waardenburg Syndrome). In addition, people with a certain type of Waardenburg syndrome (type 4) appear to have symptoms similar, though less severe than, OLWS (probably because are guts are simpler than horses’ guts) and is caused by mutation in the same gene. http://atlasgeneticsoncology.org/Kprones/WaardenburgID10089.html
I’ll do some more research later on dominant white and white splash later. I’m curious.
Yeah, the deafness mostly happens when the ears are white. Though some horses with white ears (inside and out) can hear so would suspect it’s coming from whatever makes dominate white different from OLWS.
Any hypothesis on albinoism in horses? Seems if albino cats can have blue eyes… Horses may as well… Have no clue if there’s been testing but current trends seem to stay with no albino horses theory.
There’s arguments for and against.
Since blue eyed cats can be albino, I’m curious if the same could hold true with horses.
Because their eyes are so big, maybe they can’t/won’t be pink.I don’t know what to say about albinism in horses. I did a little reading from online sources. The argument against albino horses seems to be “albino requires a recessive gene and so a gene from each parent has to be inherited for a horse to be truly albino” or “albino in horses is lethal” or “albino must have pink eyes.” I don’t buy any of these. It might be true that there are no true albinos, but I doubt it. Albino is merely the lack of melanin. Of course an animal can appear to be albino if melanocytes–the cells that produce most of the melanin–are unable to migrate. LWS, which some horse people seem to think is albino, is not albino because the gene does not affect the production of melanin but actually the migration of melanocytes.
Brown eyes would indicate for sure that the animal is NOT albino. Blue eyes MIGHT indicate that the animal is albino. If, in fact, the gene(s) responsible for the white hair, pink skin, and blue eyes causes a defect in melanin production, then, yes, the animal is albino. I don’t k know enough about horse eye color to tell you whether a blue eye has no melanin. But it’s very possible that there are truly albino, blue-eyed (or grey eyed–some pictures show either a pale, pale blue or almost grey eyes) horses are out there. It’s not clear to me whether dominant white is really an albino gene, and it’s not clear whether ALL dominant white mutations are homozygous lethal. At least in some cases, it is. But the gene associated with dominant white is called KIT. It’s a VERY important gene that can affect cell development and migration. Different mutations could have different levels of severity. It’s possible that mutations in KIT might result in albinism if there are no melanocytes rather than a failure of the melanocytes to migrate. Regardless, at least some dominant white horses have brown eyes, so are not albinos. Those with blue eyes might be.
I did not do any research on whether horses exist with a mutation in TYR. TYR is required for the production of melanin, so if there are horses that exist with a mutation in TYR, it’s likely they’re true albinos, regardless of their eye color.
- You must be logged in to reply to this topic.
