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

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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.


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

Pleiotropy: University of Richmond