Question of the Day, and Answers

…..Cats in formation!

Minlit asked a question about white cats and how they come about.  The problem is that there isn’t just one answer, there are four different causes to an all white cat.

The first is White Spotting. Spotting itself isn’t rare, but being 100 percent spotted is.  A white cat from this cause can have any color eyes. If the eyes are blue, there is a chance that the cat will be deaf.

The second cause is “Dominant White”. This gene will block all color in the hair, and can also result in blue eyes. A blue-eyed cat from this cause can be deaf as well.

The third cause is the True Albino. This is extremely rare, and results in a pink-eyed cat.

The fourth cause is another variant of Albino that results in a pale blue-eyed white cat.

There is one interesting feature of white cats – often as kittens they have marks on the head showing what color they are ‘under the white’. This is handy for breeders who would otherwise not know if a white cat was orange or black genetically.

…..Trouble brewing?

littlemiao has been working on the Quizlet!

 Okay… So, an orange girl-kitten and a tortie kitten would indicate that there must be two fathers, because if there is one orange girl kitten, it means it had to be O/O, but a tortie/calico can only occur with O/o, so that would mean there must be one O-dominant father and one little-o father.  Is that right?

And does that mean that different coat lengths in the same litter don’t indicate two fathers?

First off – Great job littlemiao!

Your reasoning is spot on and you have almost all of it, but the two girls must be all black and all orange rather than tortie and orange.  In the case you give the orange female does require that both the mother and father contribute an Orange gene. But for the tortie kitten the father could contribute his orange gene again and mom could contribute a non-orange ‘o’  gene if she was herself a tortie cat. The only way to make sure that some other father is involved is to have an all black female kitten – an o/o combination. Since the first kitten was proved to have an Orange dad, the second kitten’s non-Orange dad must be a different cat altogether.

The Orange locus is doubly special in that you can see both genes expressed in a female kitten all the time (due to X inactivation) and you know that the Dad must have had a Y gene that could not be passed to a female kitten. So there are only three genes from both parents that *could* be passed to a girl kitten, so it is logically possible to have an impossible mix with just two kittens.

So trying the same idea with the long hair gene, you have two problems. The first problem is that short hair is dominant. So there is no visible difference between a cat with one gene (L/l) or two (L/L).  True dominance thus hides some of the information about the kitten you need to define the parental genes.

So a shorthair kitten tells you only that at least one parent had a shorthair gene, and so was short-haired.  A longhair kitten tells you that both parents had a longhair gene, but it doesn’t tell you what they looked like. They could be longhairs (l/l) or shorthairs (L/l).  You would need more information to be able to prove anything.

In fact, Julius’ mom was a shorthair and produced a longhair kitten. So we know she was a L/l.  We also know Julius’ dad had a l gene, but not if he had two, or one. If you look at the entire litter you can use probability to compute the odds of each parent gene option, but you can’t know for sure.

The final problem with the longhair gene is that both parents have two genes to contribute to any kitten. So you need more than two kittens even in theory to prove a third parent’s involvement, or you need more information about the parents. For a trivial example, a single shorthair kitten requires a second father if you know both parents were themselves longhairs – ignoring a spontaneous mutation.

All good things must come to an end!

About Oldcat

Engineer with Cats
This entry was posted in Calpurnia, Cats, Genetics, Gustavus Adolphus, Julius Caesar. Bookmark the permalink.

14 Responses to Question of the Day, and Answers

  1. Anne D says:

    I love these posts!! Trying to figure a way to save them together in a folder.
    Now a question about white cats. Mine is all white with one black dot on her pink nose. She has yellow eyes. So is that the white spotting pattern or white dominant pattern with a black freckle? I have noticed freckles like this on orange cats too. Any genetic significance???


    • Oldcat says:

      Well, you could create a folder of shortcuts to all the post in your browser.

      Failing that, most browsers have a ‘save page as file’ option on a menu that could be used to save a copy of a page on your disk.

      The way to prove a difference between dominant white and ‘Level 10 Spotting’ would be to find even a single black hair, which would prove it isn’t DW. I don’t know for sure, but a rogue spot could be a freckle and acquired after birth, or like a birthmark and be possibly genetically related. But I have not heard that DW can’t have black marks, just not black hair.

      There is definitely some pigment in your cat, since there is some in the yellow eyes to keep them from being blue or pink, and some pigment in the ears to keep her from being deaf.

      To be all white using dominant white you need only have a single W gene. To be all white using White Spotting you probably need two S genes, then your polygenes have to be uncommonly high as well. Even though S is probably commoner than W out there, if I had to bet I’d go with Dominant White.


  2. Lurkertype says:

    The longhair/shorthair discussion reminds me of two of the Miao Brothers: Professor Tashi, the shorthair, and his littermate, the late and much-missed Prince Tantra, the longhair. They had one Siamese parent (short) and one Himalayan (long). Almost equally handsome boys. (I say almost b/c Tantra was resplendent)

    Of course, when you have a cowkitty dad and a tortie mom, you get the lovely effects of the Kibbles who live with littlemiao’s brother (see earlier posts if you’re new to this!).


    • Oldcat says:

      That’s an odd pairing because usually breeders want to keep the Siamese body shape and mixing with a Persian cat would risk having something that looks like an inbetweener. There are longhaired offshoots of Siamese out there – Balinese if pointed, Oriental Longhair if not.


      • Lurkertype says:

        Maybe it wasn’t a Himmie. But they weren’t deliberately bred, I don’t think. littlem obviously knows more.


      • littlemiao says:

        I wish I knew more. My mother *said* they were part Himmie, but they have such a classic Siamese nose. The very first Miao Kitty (from before I was born) was a true Himmie with the Persian face. He looked like Mani (dark seal point?) except with a smooshed nose. So I don’t know if Tweets was part-Himmie or 100% long-haired Siamese.


  3. Lurkertype says:

    Oh, and I’m sad Cal didn’t get to be half on half off in the above photo.


    • Oldcat says:

      Well, she is on the edge of the other carpet…but the real ‘half on’ is that her back half is on top of a advertising magazine I got in the mail a while back.


  4. littlemiao says:

    Another question: Is whisker color controlled by the same genes as coat color?

    I have noticed a lot about whiskers. Chun’s (lynx-point Siamese) are different colors on the same shaft, like agouti hairs. My brother’s kitten kibbles have white whiskers with the occasional black whisker tossed in. Heqat, a tuxkit, has white antennae on one side and black on the other, so it looks like he is missing an eyebrow. Ronjon, a pale orange kitty from the first litter, has a few dark whiskers mixed in with his orangish whiskers. Sprocket’s appear to all be white, even though he is b&w. Kemi, black, has had a white whisker or two grow in in the past couple years.


    • Oldcat says:

      I did a little research when you asked it last time and the answer seems to be yes they follow the coat color. But they say that the size and thickness of the average whisker means that the color often doesn’t ‘take’ and the whisker remains white,

      For what it is worth, the black whiskers on Julie seem to be thinner than the others.

      There wasn’t a lot on ear hair color. Looking at my cats, it seems like the hair inside the ear itself is white, while that growing from the head can be colored normally.


      • littlemiao says:

        Ooops, I totally forgot I had already asked. I’ve been kind of disorganized since my vacation. 🙂 I will have to examine whisker thickness now. So according to this theory, thinner whiskers would be more likely to take on the non-white color?

        Ear hair on the Miao Brothers also looks lighter than the rest of their coat. Kemi, black with his dramatic white tufts, is the best example.


      • Lurkertype says:

        Ah! That explains why I seem to always have white cat whiskers no matter what color fur the whiskers grow out of! I’ve always wondered that.

        My tortie has mostly white whiskers, but some of them are black, and they are always thinner and shorter than the white ones. Her ear hair is black, though, and it’s also very fine.

        Tuxie has all-white whiskers, from his eyebrows to his snout, to his “curb feelers” — the carpal hairs on the back of his legs.

        But like Kibble Ronjon, all the orange kitties I’ve known always have a few black whiskers mixed in with the white ones. How does that happen? I’m going to have to look at orange girl whiskers to see if it’s an O/o O/O thing.


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