White Cats, Star Trek and Deafness

Several weeks ago, some of our blogger friends made comments about blue eyes that had us reaching back to last summer. We located an article we wrote on blue-eyed cats, gave it an update, and posted it last Monday.

As a result, we got some great questions from you. Things like "is my cat an albino?" "what about odd-eyed cats?" and "people expected my white cat to be deaf but he isn't!"

Special thanks to the Kitties Blue at the Cat on My Head, to our Auntie Bernadette at the Creative Cat and Auntie Connie at Tails from the Foster Kittens (who, by the way, is visiting us right now - aren't you jealous?) for their input.

You guys had such cool comments that we decided to go find our Star Trek post from last year and update it!

 ***

Before we go all sci-fi on you and pull out our Doctor Who references, bear with us as we do some science (we'll make it painless. Uh, we hope....)

#1: There are 8 different 
      genes that determine what 
      a cat’s fur will look like. 

Some of them are more basic, while others are what you’d call modifiers. An example of a foundational gene would be the Black Gene. Allie has this gene.

Huh? The girl’s clearly grey, not black. True.

But we’re not dealing with the black color, we’re dealing with the Black Gene – and it has 6 different settings. Take a look at the table below.

A cat with an active black gene fits into one of these categories.  They’re either set on high beam or low beam (full density or dilute), but their coloring can also come in one of 3 different concentrations.

I mentioned modifiers. Some of these 8 genes don't determine the color of your cat. They change or overwrite that color. For example, the boys have the albino gene, which modifies coat color by turning the color off at certain temperatures.

If you want to read more in depth about the 8 different types of genes, click here to read our post from last summer on it. 

#2: The White Gene 
       isn't a color gene. 
       It's a masking gene. 

If a cat has this gene turned on, then the gene’s basically overwriting any color gene your cat has! This gene has three basic settings: low, medium and super-charged.

If the setting’s on low, it’s called a Gloving Gene. Like you’ve probably guessed from its name, it “puts gloves” on a cat - those cool white paw markings you see in some Ragdolls, Himalayans, and of course the Snowshoe cat.

If the setting’s on medium, that’s known as the Spotting Gene. That’s what can give a cat that classic tuxedo look with a white blaze along the nose, and that elegant white bib down the chest.

Genetically "white"? No.
Golden eyes = Spotting gene.
Photo: Incanus Japan

The “S” – or Spotting – Gene is responsible for all other styles of black-and-white coat patterns, too. And the amount of white spotting can vary from just a teensy bit here and there to full-on white.

In fact, often times a cat we think of as a white cat really isn’t. At least, not genetically speaking.

If there’s even one colored hair anywhere on a kitty’s body, then the cat doesn't have the White Masking gene – just a really active Spotting gene instead.

This kitty basically has one big white spot all over his body.

Enough already. Bring on the Tardis. Warp speed please!

Alrighty then! How's this?

Because the White Masking gene is responsible for masking all color everywhere, that means pigment is masked or blocked in the eyes as well. Interestingly enough, this phenomenon causes white cats who have this "W" gene to be deaf.

But not all blue-eyed white cats are deaf, you say. Most are, but not all. Correct!
For those white cats that are not deaf, there is a different gene at play - the Spotting gene we mentioned earlier. So, what makes a white cat with the "W" gene deaf?

Star Trek.

Um. Come again?

Star Trek: the reason white cats are deaf 

Okay, well, maybe we're stretching the truth just a teensy bit.

Here's what's going on:

There is a spiral-shaped cavity in the inner ear called the cochlea.

This is where sound waves are converted to electrical signals and sent to the brain for processing.

In order for those electrical signals to be transmitted upstream to the brain, ion balance needs to be maintained.

(Sounds like some kind of warp drive, doesn't it? 
Like I said, Star Trek. I rest my case. ;-)

We have no idea what ion balance is, and if you figure it out please let us know,
because we're weird like that and love to get our geek on.

Bottom line here is, the thing responsible for maintaining this mysterious ion balance is a thin layer of pigment called melanin that coats the inside of the cochlea.

Blue eyes, by Blue Ridge Kitties

Can you see where we're going with this?

If the White Masking gene blocks the production of all pigment in a cat's body...then that melanin isn't going to be there.

No melanin means no ion balance.

No ion balance means no sound transmission.

No sound transmission means complete deafness.

So there you have it: Star Trek - the reason white cats are deaf.
That's our story and we're stickin' to it!

Odd-eyed Lily by Jason Farmer

But what about odd-eyed cats?  There are occasions where the Spotting gene does invade the cochlea and prevent the melanin layer from developing. But this is fairly uncommon.

In fact, 60-70% of all odd-eyed cats hear just fine, thank you.  Any apparent deafness must be attributed to the fact that the cat is, well, ignoring you.

Shocking, I know.

Oh by the way, our Maxwell’s deafness isn’t caused by that. He’s got plenty of melanin in his ears!

His blue eyes are caused by the albino gene, and while that does turn off pigment in select areas of the coat and eyes, it leaves the melanin in the ears untouched.  If you’d like to find out what caused Maxie’s deafness, you can read about it in 2011’s Less Adoptable series post on deaf cats here.

One last comment and we're done - honest! White cats are not albino cats. There are albinos, but they have the Albino Gene (the basic one, not the temperature-sensitive one) and feature pink pigmented eyes.

And...wait for it... true albino cats are not deaf.  Go figure.

***

We sincerely apologize for our Mommy. She is SUCH a geek.




_______________
Sources:

Pleiotropy: University of Richmond
Basic Genetics as Revealed by Cats (U of California at Berkeley)
Hartwell, Sarah. White Cats, Eye Colours and Deafness, Messybeast.com. Retrieved February 2007.

Click these links to read last year's posts for more info on why a Siamese's coat is pointed (and called a temperature-sensitive albino) ...
or the genetics of coat coloring and what causes the striking look of a tuxedo kitty!




 
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Giveaway is open until 12/31.

White cats, Star Trek, and deafness

We've fallen into the habit of using Monday's posts to talk about health, medical and safety issues - and even interesting science topics. Lately, we've been looking into the genetics of cat coloring.

You can read about why a Siamese is pointed...
What causes the striking look of a tuxedo kitty...
Even why some cats have blue eyes!

Today is a continuation of the topic from three weeks ago: White Cats

***

A truly solid white cat has the White Masking, or "W" gene to thank for its striking coat.  But that's not all a kitty gets from that "W" gene.

photo: Wikimedia Commons

Because that gene is responsible for masking all color everywhere, that means pigment is masked or blocked in the eyes as well.

If you read our post in July about what happens when pigment is blocked in the eye, then you won't be surprised to hear that these "W" kitties have gorgeous blue eyes.

(If you'd like to read a bit more on the science behind why this takes place, click here .)

Interestingly enough, this phenomenon causes white cats who have this "W" gene to be deaf.

But not all blue-eyed white cats are deaf, you say. Most are, but not all. 

Correct!  

For those white cats that are not deaf, there is a different gene at play - the Spotting gene. You can read all about the difference between a White Masking gene and a Spotting gene in the post on Monday, August 6.

So, what makes a white cat with the "W" gene deaf?  Star Trek.
Um. Come again?


Star Trek: the reason
white cats are deaf

Okay, well, maybe we're stretching the truth a little bit. Here's what's going on:

There is a spiral-shaped cavity in the inner ear called the cochlea. This is where sound waves are converted to electrical signals and sent to the brain for processing. In order for those electrical signals to be transmitted upstream to the brain, ion balance needs to be maintained.

(Sounds like some kind of warp drive, doesn't it? Like I said, Star Trek. I rest my case. ;-)

odd-eyed cats are often deaf in only one ear

We have no idea what ion balance is, and if you figure it out please let us know, because we're weird like that and love to get our geek on.

Bottom line here is, the thing responsible for maintaining this mysterious ion balance is a thin layer of pigment called melanin that coats the inside of the cochlea.

Can you see where we're going with this?

If the White Masking gene blocks the production of all pigment in a cat's body...then that melanin isn't going to be there.

No melanin means no ion balance. No ion balance means no sound transmission. No sound transmission means complete deafness.




Oh by the way, our Maxwell’s deafness isn’t caused by that. He’s got plenty of melanin in his ears!  His blue eyes are caused by the albino gene, and while that does turn off pigment in select areas of the coat and eyes, it leaves the melanin in the ears untouched.

(If you’d like to find out what caused Maxie’s deafness, you can read about it in last year’s Less Adoptable series post on deaf cats here.)

So there you have it: Star Trek - the reason white cats are deaf.

We sincerely apologize for our Mommy. She is SUCH a geek.


_______________
sources:
Washington State University Animal Sciences' paper on melanin and ion balance

Pleiotropy: University of Richmond

Monday Medical: What's in a coat color?

Well, after the earth-shattering discovery that da boyz are albinos, Allie demanded equal time.

After all, she figured, if the Brats had cool, special genetic traits, then someone as stylishly adorable as her own grey-and-white self must have some, too. Right?

Far be it from us to disagree with the Little Princess in the household! Truth is, Allie does have a few specially modified genes of her own.

There are eight different genes that determine what a cat’s fur will look like. Some of them are more basic, while others are what you’d call modifiers – they change or overwrite the more foundational genes.

(That’s what the albino gene does with the boys – it modifies their coat color by turning the color off at certain temperatures.)  While Allie doesn’t have an active albino gene, she does have a different modifier. It’s responsible for the tuxedo white pattern in her coat.

And it’s not only Allie. Some of our other friends in the blogosphere have the very same genetics.

What is it in a cat’s genetic makeup that turns a moggie like Katie Isabella, Austin, or Glogirly’s Katie into a tuxedo kitty?

We’ll start at the beginning.





The first stop in the flowchart of cat coloring is the following question: does your cat have black, orange, or white in its fur?

If you said orange, then we’re going to refer you to JaneA’s excellent article on orange tabbies at paws and effect. This article will tackle the other two colors.

So…question #1: is there any black in your cat’s coat? For Katie Isabella, Austin and Glogirly's Katie…the answer is YES! That means they have that black gene turned on full blast.

Is there black in Allie’s coat? (trick question) Yep!

Huh? The girl’s clearly grey, not black.

True. But we’re not dealing with the black color, we’re dealing with the Black Gene – and it has 6 different settings.

Take a look at the table below.  A cat with an active black gene fits into one of these categories.

They’re either set on high beam or low beam (full concentration or dilute), but their coloring can also come in one of 3 different concentrations.

[If any of you are artists out there, consider the dilution to be like the saturation level and the concentration to be like a luminance level. ]

Austin and the Katies are all kitties with the black gene set on high beam. Allie’s is low beam – a diluted black.  When you dilute black, what do you get? A gorgeous grey!

Okay, now that we’ve cleared Step 1 (aka The Black Gene) let’s go on to the next step. That's our first modifier gene, the Albino Gene.

If you’ve read our past posts on temperature-sensitive albinism, then you’ll know that this gene modifies coat color by turning the color off above a certain temperature.

Maxie the Albino ;-)

So...let's see...

Anyone on our short list an albino?
For Katie, Katie, Allie & Austin... nope, no albinos!

Okay then. Albino Gene set in the OFF position. We can move on to the next gene.


Next step, the Tabby Gene.  This gene modifies the black gene by introducing areas of the coat where the color is turned down - or off - in a certain pattern (that’s stripes, not plaid – sorry, style mavens).

Any of you guys have stripes in your coats? Let’s see: doesn’t look as if Austin or the Katies do.

How about Allie? Yup!  If you look very carefully at her tail, you’ll see Little Miss Stoned has some banding there. So the Tabby gene’s turned on. (But just on the tail!)

(When Allie gets into the nip, she really gets into it...!)

 Moving on…

The next stop is the White Gene. Technically this isn’t a color gene, it’s a masking gene. If a cat has this gene turned on, then the gene’s basically overwriting every single previous step we’ve gone through!

This gene has three basic settings: low, medium and super-charged.

If the White Gene’s turned all the way up to supercharged – well, then, you’re an all white cat. The supercharged setting is called the White Masking Gene and it’s designated as the “W” allele.

The gloving gene "gloves" the paw

If the setting’s on low, it’s called a Gloving Gene.

Like you’ve probably guessed from its name, it “puts gloves” on a cat, like our kitty model in the picture to the left.

Hey, that’s what’s going on with those cool snowshoe kitties!







If the setting’s on medium, that’s known as the Spotting Gene. And that’s what gives a cat that classic tuxedo look with a white blaze along the nose. And that classic white bib down the chest, too.

Of course we can’t leave out those dapper white “spats” on the paws, either!

Tuxies come in lots of flavors: black tuxedos, grey tuxedos, orange tabby tuxedos, and and grey tabby tuxedos, to name a few.

The White Spotting Gene can even be combined with the Albino Gene. Take a look at this gorgeous girl:
Geddy is a former Waif at Wayside Waifs where I volunteer (Allie's Alma Mater). You can see she has the albino gene – she's a pretty chocolate point Siamese girl – but overlaying that is the spotting gene, and this masks all color.

 So Geddy's a Siamese Tuxie! Cool, huh?

And as you can see in our three tuxedo models from the blogosphere, that tuxedo spotting pattern can vary from coat to coat, too!

The “S” – or Spotting – Gene is also responsible for all other styles of black-and-white coat patterns, and the amount of white spotting can vary from just a teensy bit here and there to almost full-on white.

In fact, often times a cat we think of as a white cat really isn’t. At least, not genetically speaking. If there’s even one colored hair anywhere on a kitty’s body, then the cat doesn't have the White Masking gene – just a really active Spotting gene instead.

Oh, and we can’t forget our sassy calicos, torties and torbies! You’ll find the spotting gene turned on in the calicos - and occasionally in the torties and torbies - as well. But these sassy cats' coats, often called Mother Nature's idea of abstract art, are topics for another post!

____________

Source:  

Basic Genetics as Revealed by Cats, Integrative Biology, College of Letters and Science, University of California, Berkeley

copyright © 2012, A Tonk's Tail