# Mutation or a malformation?



## jocysbs (Jun 23, 2013)

Hello, I would like to know if one ear is smaller than the other is a mutation or a malformation? :? :?


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## OrangeTyrant (Jan 17, 2014)

It could be either.

The only real way to find out is if it's heritable (mutation) or you do genetic testing, although, it's not really a desirable trait you'd want to breed again to find out.


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## Rhasputin (Feb 21, 2010)

It could, be either! There is theoretically a gene known as 'gremlin' which causes one ear to be lower like a dumbo rat, and one ear to be normal. There is some demand for gremlin mice (though nobody can fill the demand because nobody breeds it!) so if you do test breed, i'm sure the mice can find good homes if it passes down.


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## Lottiz (Feb 8, 2010)

What if both ears are like the gremlin ear. Is it a dumbo mice then? Or is the gremlin gene connecting with other genes so they can be sick/blind/deaf?


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## madmouse (May 19, 2012)

Lottiz: if both ears are incredibly low-set, and this happened in a sudden random genetic mutation (instead of slowly being selected for over time), you would likely classify that as dumbo. Many people call mice "gremlin" when they have one regular ear and one low-set ear, but there are likely more than one cause of such ears, some may be genetic and some random deformity. There is a specific gene called "gremlin" in the lab, but it is associated with skeletal limb deformities and less-than-normal number of toes so that I think many of the pet gremlin mice that pop up are not the lab gene called gremlin. Gremlin mice I've seen usually have ears the same size, just set at different points on their heads. I have also seen mice with two different size ears (which I think is what the OP is talking about), I personally wouldn't call that gremlin- but yeah, Rhasputin's right, no one knows what causes different size ears as no one tries to breed for it.


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