Genetic Makeup of Calico Cat Fur May Help To Save Human Lives

Persian calico cat
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Persian calico cat

The temperamental behavior of calico cats has been greatly maligned and misunderstood. These felines are thought to be feisty, stubborn, willful and even arrogant. Some folks in fact, refer to these beautiful cats wearing their striking coat color (albeit often affectionately) as having “cattitude”.

Since the calico pattern doesn’t represent a particular breed of cat, but rather only the cat’s color, the calico cat’s disposition is strictly influenced by its inherited genes and environment. Therefore the calico cat’s behavior largely depends on its pedigree, or how the kitty has been handled since birth.

The calico cat pattern is seen among others, in the Japanese Bobtail, the Persian, Rex, American Shorthair, British Shorthair, Maine Coons, Manx, Exotic Shorthair, and even the “hairless” Sphynx. Each of these breeds is known to have special behavioral characteristics, many of them which are especially appealing to certain cat lovers. However, breeders and guardians of calico and tortoiseshell kitties continue to maintain that the behavior of these cats differ from any other colors or breeds.

Because some coat colors in cats is linked to the X chromosome, the majority of calico cats are female. Occasionally a male kitten is born wearing this color pattern. A prevailing myth that continues to abound is that male calico cats are extremely valuable, but due to the genetics involved male calico cats are almost always sterile.

Although these stunningly beautiful kitties are certainly eye-candy for cat lovers, NBC News is reporting on some exciting and promising research about the genetic anomaly connected with gender in calico cats. This research may help scientists better understand DNA and calico cats may help researchers understand the so-called flipping the “off switch” in genes.

According to a team of researchers at the University of California, San Francisco, (SCSF) the unique orange-white-black coloring on these cats is caused by the inactivation or “silencing” of one of their two X chromosomes. The cells in female animals have two copies of the X chromosome which is inherited; one from the mother and one from the father.

Since scientists don’t fully understand exactly how a cell turns off a chromosome, they are trying to learn more about the way in which different types of genes can be “switched” on and off without impacting the underlying sequence of DNA.

According to Scitable,

“In cats, the fur pigmentation gene is X-linked and depending on which copy of the X chromosome each cell chooses to leave active, a black or orange coat color results. X inactivation only occurs in cells with multiple X chromosomes, which explains why almost all calico cats are female.”

In order to visualize the DNA, scientists used soft x-ray tomography and were able to identify one specific chromosome; the inactive X chromosome in female cells. This research may lead to greater understanding, diagnosis and treatment in humans of X-chromosome related diseases.

Explaining some of the research implications, Elizabeth Smith, a postdoctoral fellow in the Anatomy department at SCSF said,

“Uncovering how only one X chromosome is inactivated will help explain the whole process of ‘epigenetic control,’ meaning the way changes in gene activity can be inherited without changing the DNA code. It can help answer other questions, such as if, and how traits like obesity can be passed down through generations.”

While this seems to be promising news, since the study’s findings were presented at a medical meeting,until a peer-reviewed journal publishes its findings, the data and conclusions should only be considered preliminary.

So calico kitty guardians, please pay attention! There is no further need to complain about your cat shedding all over everything. Based on the vital information their precious fur may uncover, it’s possible that in the near future it will save the lives of many humans.

Share your thoughts about this news with a comment.


  • Photo credit: Flickr User: Archangeli
  • Sources: Scitable,
  • USNews
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Michael Broad

Hi, I'm a 74-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I love nature, cats and all animals. I am concerned about their welfare. If you want to read more click here.

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66 Responses

  1. Jo Singer says:

    I am absolutely blown away by these gorgeous kitties. Thanks everyone who shared your beautiful photos with us.

    They are all PURRRRRRRRRRRrrrfect!

  2. Amy says:

    Dot on the left is much braver than Freckles on the right. It took Freckles almost 4 months to trust my latest rescue “the southern belle” Bianca I adopted from Red Fern rescue in Tennessee. They are almost 5 and are still that size when the picture was taken in 2009.

  3. Amy says:

    Dot the Snot and Freckles

  4. Amy says:

    Hello, I am back and you all MAY have answered a question I have wondered about for about 5 years now. I do have a black calico,a brown calico. But the ones I wondered about were my mainly white cats with just spots of calico. They do have orange,brown and black areas on their bodies. From looking at the pictures posted I assume mine would be considered calico also. The only distinction is that both of the white ones have short coats compared my black calico and my brown calico. I assume that no matter the length of the coat makes no difference. Am I correct?

    • Amy says:

      Have no way of knowing how that picture showed up?????

    • That is correct, Amy. The calico coat comes in a wide range of varieties from a coat that is all mixed up with blurred boundaries between the colours to clearly defined blobs of colour, which you see on the Japanese bobtail cat. The famous three colour Japanese bobtail is the one favoured by the Japanese and you can see it here on this page. It is a calico cat. The coat length varies too, as you say, and you can also see dilute colours.

      • Amy says:

        Micheal the picture of the Japanese bob tail is exactly what I am talking about. I do have pictures somewhere and I will try to find them. Although they are sisters their marking are quite different. Thank you for finding a picture that shows pretty much what I was talking about.

  5. Iniki says:

    This is hopeful. I have to say that we have calicos and torties here. Some are mellow and some are dominant. All of them are very intelligent and learn easily. This is a very interesting article. Thanks Jo.

  6. Sharon says:

    I have had the good luck to be the guardian of a lovely calico girl; who someone dumped in the street a number of years ago. Let me see if I have a digital image of her. She passed away after battling lymphoma bravely. I am now the guardian of a “tortilicously delicious” tortie girl (my ‘pet’term for her).

    I don’t know how well this will show up, but this was Stormy:

  7. Vicki Jasch says:

    Law Honey! I do not know a thing about this subject, but I love Calico cats’s colors.

  8. Elizabeth Ann Scarborough says:

    Good blog, Jo. As long as they can do research on the kitties that benefits the humans and doesn’t hurt the kitties, I’m all for it.

  9. valerie (surrey) says:

    Going back to the temperamental behaviour of calico cats, it describes my Tiggy who passed away last year exactly. She was feisty,stubborn and wilful.but also very loving and caring and I miss her a lot what a character she was. could be coincidence but who knows. Felt I had to comment on this and I read all the input very interesting.

    calico cat

  10. Harvey Harrison says:

    I don’t see the picture of Turkanna that i posted, so here it is again.

  11. marc says:

    In the latin languages Calicos are just known as ‘3 colour’ cats.

  12. Harvey Harrison says:

    I think it needs to be made clear that calico usually means red and black with white, or tortoise-shell and white. The origin of the word is Calicut a city in India where a white cloth with a coloured pattern was woven, but also can refer to a plain white cloth. A pure tortoise shell without white is quite rare but my female Mongolia is one of them. Diluted forms also appear such as blue and cream with white such as my Turkanna. The “calico” colouring can even be expressed in a Van pattern as with Turkanna.

  13. Ruth aka Kattaddorra says:

    A very interesting article but like Michael I don’t understand genetics of the cat’s fur so I can’t really make a sensible comment.
    But I do hate it when people stereotype cats, or people come to that, torties(calicos) don’t have any more catitude than other coloured cats, redheaded people aren’t all hot tempered, all blondes aren’t dumb.
    But I suppose if it’s helpful research and doesn’t harm the cats in any way it’s OK.

    • Exactly my feelings as well.

      • Caroline says:

        And exactly mine as well. You can’t read my mind, and you certainly can’t make sense of my rhetoric nor soused sarcasm when it doesn’t make any sense. (Always, the vodka. Hopefully, I won’t make the mistake of reaching for it the next time that I just need to talk to a friend.)

  14. Caroline says:

    I will leave it up to you Michael and your co-writer…

  15. Caroline says:

    I think that we truly need to approach this patchy subject matter in a different way; something more akin to a “true” CFA breed…


    • Caroline says:

      were you being sarcastic, Jo? I won’t even ask if you were being facetious. Obviously, there is no ego involved here. Thank goodness, no cats were harmed in the writing of this article.

      • Caroline says:

        I don’t care who you rescue, himmie, norwegian, hairless, nor siamese. Just write an article that is well-researched, if anything. Something worthwhile, to the species. please. regardless of pedigree. 😉 Or is that what PoC is about? Focusing on the breed? or focusing on education?

        • The website focuses on all aspects of the cat while focusing on cat welfare and respect for the cat. The site provides information, as you know, about wild cat species, domestic cats, stray cats and feral cats. I don’t have to explain that to you 😉

  16. Caroline says:

    Jo, WHY didn’t you start with your premise in the first paragraph, instead of what you chose? If you would like me to help you, I can. [Don’t ask Michael to pick it up for you.]


  17. Caroline says:

    Jo, [sigh] yes they can be temperamental, but so is the inanimate tempura, when frying…

  18. It is nice to see that the humble domestic cat can help people in unforeseen ways. I’ll presume that any research that concerns the calico cat in this instance, in no way harms the cat.

    The genetics of the cat coat is highly complicated. I have read about it quite a lot and never quite understood it although I have a reasonable grasp of it. One difficulty is that even the experts do not know everything there is to know about the genetics of the cat coat types. It is work in progress. An expert on cat genetics by the way is Sarah Hartwell. She loves genetics and understands the subject instinctively. I’m the opposite. I find it baffling! It’s like trying to figure out what happens on a computer hard drive. You can’t see it, you can only imagine it.

    As for “calico cat behaviour”, I’ve always thought that this is Internet hype. There was and probably still is quite a lot of chatter about the character of the calico cat but it means that the colour and pattern of a cat’s for is linked to his or her character and I find that hard to believe.

    That said, people say that redheaded people have a certain character. Clearly people like to link hair colour with character. I think the way people linked redheaded people with a fiery character has spilled over to the calico cat and they have made a similar deduction, which I’m sure is incorrect.

    • Caroline says:

      Jo said: That said, people say that redheaded people have a certain character. Clearly people like to link hair colour with character.

      Wow. who wrote your dissertation?

      • I wrote that not Jo! It is common knowledge 😉

        • Caroline says:

          lol. Please refresh my memory…Who “discovered” and “colonized” the New World? You? and the Spaniards? Well, guess what. My people were here long before that. And long before you claimed “your” Charles Dickens, long before John Muir, followed Michael Pollan. so please, don’t pretend that you do not have problems in your nation, that need to be dealt with where animal abuse and welfare is concerned.

          Not to say that I have never expected anything less than your help. Just stop criticizing and start doing something constructive about it on this website. Michael, you were saying something, and I think that it needs to be reiterated. You are willing to come over here to the U.S. and shoot footage? of whom? I will do all that I can, as I’m sure all of your fellow stateside PoC’ers are willing and ready, at your service… 🙂

          • The only people I criticise and who deserve it are the veterinarians to declaw cats and I want to interview them and find out what goes on inside their craniums! I try to avoid being judgemental. But it is impossible to avoid being judgemental in respect of veterinarians who declaw cats.

            • Caroline says:

              I am very sorry for that silly tirade, Michael. Actually, it would be such a relief to me if you contact Dr. Rebecca Arnold, “Dr. Becky” as most of us know her here. All-Feline Hospital, here in Lincoln, NE, is her practice. I would so love to do anything I can to facilitate this. just let me know, okay?

              • Caroline says:

                I have been so conflicted, as you know, about continuing with our Veterinarian-Client relationship, e’en though it has lasted some 20+ years. If there is anything I can do to help facilitate this, please let me know?

              • Caroline, sorry but I appear to have forgotten but why did you want me to contact Dr Rebecca Arnold?

                • Caroline says:

                  In my where you came to the States to conduct interviews with the seemingly most caring vets who still perform a de-claw “or two” once a month or so. It must have been my brain, overloaded with stress, and delusional images set in. 😉

          • Ruth aka Kattaddorra says:

            Michael is right, we can’t possibly avoid being judgemental of vets who declaw cats, they know it’s cruel, but day after day they smugly amputate healthy toe ends just because it’s legal there to do so.
            It’s the worst form of animal abuse ever because it’s done by people who are supposed to help animals, not maim them.
            We have never pretended we don’t have animal abuse here in the UK but the difference is that our abusers are ignorant cruel people but they are not butchers masquerading as vets.

            • Caroline says:

              I know this, Ruth. I understand, I feel very strongly about zero tolerance for declawing. A true ailurophile certainly would have expected the U.S. to have ended this decades ago. I see animal cruelty everywhere, we all do, but you are right. This is something that should have been on the books long ago. No excuse for it. I feel as you, and hopefully all of us here on PoC, you know that I do. No excuses for our vet.

            • Caroline says:

              Ruth, you know that I agree with the brutality and cruelty. When my veterinarian of many years, who has done so much to help the feral colonies and strays in our little town, what am I supposed to do? Tell my cats, sorry, you no longer have a doctor/surgeon. I have to take them somewhere, and she is the only DVM I’ve ever fully trusted w/my felines. I have to approach cautiously with inundating her my contempt for her abominable practice of even doing ONE declaw per month. Does that make sense? Tell me how best to approach it–if you were me, what would you be doing as a human who needs to take the best care of her cat that she possibly can, but has no place to go within 290 km? I think that you know how much I want to keep repeating in as many ways that I can how unethical she is to be still performing declaws in her practice. I DO NOT care if she is down to four per month “on average.” It doesn’t make any sense to me to email me to say this!

              • Caroline says:

                Let me rephrase that, if Michael does not do it for me: I can hardly stand to image the brutality and cruelty to those trusting kittens and cats. You amaze me, Ruth. Your perseverance, your strength that never fades. I truly admire you, and you know that we all do here. Tell me again, what would do, if you were in my shoes? I need to hear it.

                • Ruth aka Kattaddorra says:

                  Caroline stop torturing yourself over this vet, it’s making you ill! You have no choice but to use her for your cats, in your position I’d do the same because we have to put our own cats health and welfare first.
                  You’ve tried to make her see that all the good she does for some cats is wiped out by the fact that she cripples other cats, even 4 cats a month is 48 a year and she’s dooming those cats to live a disabled life,she ignores the fact that each and every cat deserves to keep their claws.
                  If I was you I’d say no more about declawing to her, keep on educating as much as you can, tell everyone you meet the truth about how cruel declawing is, they will tell people they meet, as word spreads YOU will be saving countless cats claws.
                  One day it will be banned and your vet will HAVE to stop, so like Michael says …don’t beat yourself up about it, you’ve done your best with her.
                  You are grieving for your dear little Lucky so be kind to yourself, take care of yourself, we need YOU to help us fight declawing xx

              • Caroline, if you have to use a veterinarian who is engaged in cat declawing because there are no other choices in your area then that is the way it is and nobody can blame you for using this vet. Don’t beat yourself up about it.

              • Jo Singer says:

                I had the same situation, Caroline- actually.

                The feline-only practitioner that cared for Mousie Tongue (my sealpoint Siamsese with megacolon) declawed and stood firm in her convictions, even though I tried very hard to knock some sense into her head. She claimed that declawing preserved homes. I tried to dispell this myth until I was blue in the face- to no avail. Talked about declawed cats being surrendered to shelters due to “bad” behavior- etc. She wouldn’t buy it.

                But she was the BEST feline practitioner in probably the entire state of Florida. She cured Dr. Hush Puppy’s impacted, infected anal glands- other vets would have removed them- but she preserved them. She had magical hands and was brilliant. So what was I to do but to continue taking my kitties to her. No one else could do what she did for them.

                She was very set in her ways, and I am sorry that her practice continues to declaw. I have a vet now that won’t declaw. She educates any person requesting the surgery and they change their minds. Her staff also educates folks inquiring about it. I gave her one of Jennifer Conrad’s DVDs for a Christmas present, and she has been showing it and discussing it in staff meetings. I am thrilled!

                No need to beat yourself up about it. Sometime we need to use vets who declaw. She saved Sir Hubble’s eye- she was the only one that even attempted to to this. So what can I say?

                Wish that all vets would stop- one day perhaps they will GET it- and understand how cruel and unneccessary it is. That’s why our work here and in the real world is so crucial.

            • Caroline says:

              Ruth, I am backtracking here through the comments. Shrimpster’s overnight, which I never expected–I waited at my hospital until they finally came up to me and said, like they so often do, “He has to spend the night. We’ve had too many emergencies in the last few hours.” That was not supposed to have been. I did not even get to say, “Hey Shrimp, I’ll see you first thing in the morning, xxx.”
              I just want to say that I do not believe for a second that Dr. Becky would “smugly” amputate. I do not know why her conscience does not take control and say, “Enough is enough!”
              I’m hoping that this morning, when I show up and wait, and I finally get to talk to her face to face, just like twenty some years ago when her practice was in the back office of a pathetic pet store at East Park Plaza, I can ask her, “why are you feeding the egos of those stupid humans who will not face their own demons? Because you won’t face yours?” I hope that I remember to ask her this, when I pick up my Shrimp to bring him back home. I do have a sealed envelope containing a note, asking if I could interview her in the near future on her reasons for performing de-claws, even if it be “only” four per month. She does so, so much good! How could she still justify this?

    • Caroline says:

      Well, could you please make a distinction between the terms “pedigree” and not so ‘purrfect’ degree? 😉 Here is my pic:

      X-Linked Genetics in the Calico Cat

      Calico is a coat color found in cats, which is caused by a SEX-LINKED, CODOMINANT allele.

      B = Black
      R = oRange
      BR = calico

      The following genotypes are possible;

      Female cats can be black XBXB, orange XRXR, or calico XBXR
      Male cats can be black XBY or orange XRY

      Show each of the crosses below and include the phenotypic ratios of the offspring.

      1. A black male crossed with an orange female

      2. An orange male crossed with a calico female

      3. A black male crossed with a black female

      4. An orange male crossed with an orange female

      5. A black male crossed with a calico female

      **If you are a cat breeder, what type of parents should you choose to have the MOST number of calico kittens?

      Sarah Hartwell probably has more experience in all of this, than any of us put together. Thanks, Michael.

      • Caroline says:

        Michael, is any of us “purr”fect? I am so tired of seeing the cat cat’s purr maligned on PoC, using it as an egotistical “nomenclature.”

        • No idea what you mean, Cal. Please explain yourself. The only thing I’m a line on this website is veterinarians who declaw cat and they deserve every bit of it and more.

          • Caroline says:

            I am willing and ready to do whatever I can to help in this endeavor. I just need your guidance. As well as Ruth’s. Let me know how I can best proceed, especially where my long-term veterinarian is concerned, because at this point I no longer know what is most constructive. I want to help as much as I can, to change our veterinarians delusional pattern of thinking. TIA, Cal

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