How does this happen?

I figured this was as good a place as any to post this question!

How does a calico have one blue, one brown eye?



She's avaliable for adoption here. Of course, I know Jan's got a little calico cutie with blue eyes. But I've never actually seen one in person!

So, genetically, how does it work? I mean, a Siamese marked DSH, I could see blue eyes, but the calico has me befuddled!

Wow!
She sure is cute, if only she was closer....

She has a somewhat sad look though

Originally Posted by Arlyn

She has a somewhat sad look though

Click to expand...

She's been in foster care until Saturday. She's scared & wants to go back "home".

I owned a black/white with odd eyes - deep blue, so I'm guessing that one parent was a siamese as it was a very deep siamese blue color.

One parent had to have odd eyes, or blue eyes and the other one gold. Even if one parent was a odd-eye white - it was masking color under the white and very possible to get an odd-eye calico.

I know there is a persian breeder who specializes in odd-eye bicolors, calicos and brown tabby/whites! She has some amazing cats and all are accepted - shown and bred.

If I remember right, this litter was found abandoned @ 1 week of age. So, no parental history.

The white spotting gene can cause a blue eye - the gene supresses the production of pigment in both the skin/fur and the iris, so if the cells in the eye are pigment-suppressed the eye will be blue rather than the 'natural' colour, and this can result in one blue eye and one normal.

White spotting factor, aka Piebald white spotting or Leucism, does not supress the production of pigment in the skin (as albinism or the siamese genes do). Pigment cells are entirely absent from the affected area of skin. Early in the animal's embryonic development, pigment cell precursors form in a embryonic structure called the neural crest. White spotting factor prevents the normal migration of the pigment cells from the neural crest to their eventual location in the skin. This interruption can be anywhere from total (solid white cats), to very little (like Birmans). Because the way pigment cells migrate to the eyes is different than the way they migrate to the skin, piebald white spotting can have varying effects on the eyes (there are two layers of pigmented cells in the iris, arising from different embryonic structures), solid white cats can have normal eye color, while the Ojos Azules variant of the white spotting factor causes blue eyes in almost solid non-white cats. Normally, though, a cat will only show blue eyes if they have white in the area of the face around their eyes. Cats with the siamese sequence of genes have blue eyes for a different reason (supression of pigment production due to malformation of the enzyme tyrosinase). True albino cats (the true albino gene for cats is located in the same place as the gene that causes siamese coloration) have pink eyes, due to a complete lack of pigment.

I'm not sure I wholly understood all of what you said Catfur, but I *think* it makes sense!