agouti with white undercoat

It's unlikely this is something you can recreate by breeding animals outside of this line. There's no way this is just a combination of existing genes.

You should try breeding one of the "white based" boys to a completely unrelated doe...that will tell you if it is dominant or recessive.

This is fascinating!

Thapsus! You made it! How wonderful to have you here!

Do you just have this expressing in agouti? I think it'd be interesting to out-cross not only to test it's dominance, but also to see what colors it works with.

The link shared earlier about white underfur, the gene that this may or may not be, stated that it was nearly invisible in non-agouti (I assume they meant black) mice. It would be incredibly interesting to see what it does to yellow, black, or chocolate mice, however, as that'll give you a better idea of how it works.

Oh man...a black "smoke" mouse (smoke is what a white undercoat is called in some other species like rats and cats) would be soooooooooooo awesome!!

I've had x-brindles with white undercoats...but I believe its an effect of Mo^br itself

These guys are wicked cool.
I'm not as fond of agouti as the self but I'd
probably scale my blues way back to get a line like that.

I mean..wow. just wow.

SarahC on Fancy Mouse Breeders, has sent me this message

"The agouti mouse with the white undercoat.I get those,they come out of pearls.I get them in black and blue.I guess with the right breeding you could produce some decent pearls,the longer fur maked the pearling more dramatic."

Interresting....... thanks for sharing Casey!

Roland says in an email, "I have not seen mice with this undercoat before. Perhaps it is a new mutation? Would be interesting to see offspring without long hair and offspring from crossing back to normal agouti and F2 from F1 x F1."

I think this is pretty amazing! I would LOVE a LH black with a white undercoat. Simply gorgeous.

So, next generation has been born. Sire of the litter is cinnamon white based and mother is white based agouti. Parents are from those two litter I have shown in this topic.

Pups are now almost 3 weeks old and white under fur have just become visible.


So it is heritable at least. Next pups from white based dad and carrier mom will be 3 weeks old in 4 days. Then we will see if it is dominant or recessive.

WOW those are so neat looking!! Love it!

Thanks for keeping us up to date and posting that pic! Wow!

Glad I logged on, so glad it's hereditary!

So in that litter above that both parents are white based, 5/8 pups are white based.

I have two litters where dad is white based and mom could/should be a carrier -> no white based pups.

Weird. Not a normal recessive.

Next both parents white based litter is now 3 weeks old, so white underfur should become visible in few days.

Very interesting!!! This is such a neat experiment. I wonder if you got the 5/8 ratio because they need a copy of some other modifier to create that white...very strange.

Not getting any in two litters doesn't mean it doesn't inherit normally. It is possible that it's just poor luck. :/

Puzzling, indeed! I'm sure with continued breeding an inheritance pattern will emerge.

Hi! I'm still here and so are white based mice.









Still don't know how it inherits. Probably not dominant. Probably recessive that needs more than one gene or perhaps need some gene not to be present, I don't. How ever: pups from both white based parent can all be white based, but they also might not be. I did two litters with same parents both white based. In first litter there was one white based pup out of 5 (didn't cull any). In second litter all pups were white based. I've had litters where both parents are white based -> no white based pups. I've had litters where parents are not white based (but from white based line) -> white based pups.

I so far have only agouti and cinnamon white based. But I now have lilac, black and chocolate carriers(?) born. Hopefully I will eventually find out if they can be any color or if it needs ticking to show.

ack I Love them so much!!

I really love watching this as it develops. They are really neat looking.

New version? A hidden "fox"?

Black long haired boy


But when you blow






So only the belly is white underneath. The short hairs too, but it was too difficult to catch on film (because I was taking photos, and holding the mouse at the same time).

Could this be just some fault in color, or could it really be same gene doing it. I have two of these boys. And also black mice from the same parents but without underwhite belly fur. There are also "normal" white based agouti siblings.

Also this could be chocolate's version (at least with good imagination)

Thapsus, I have read about a white undercoat gene in the AFRMA Mouse Genetics book. One exists, but only so far in labs. I think you've got it!

[edit] Here's what it says on page 152 of _Mouse Genetics_, 6th edition, 2012 from AFRMA:

uw, Underwhite (15; Slc45a2^uw: solute carrier family 45, member 2, underwhite; homozygotes light beige color on the dorsal side and much lighter on the ventrum; heterozygotes are dark brown; eyes very light at birth but darken with age)

There is also:
wuf, White Underfur (unknown; white underfur)

Thank you for posting that Ann! I find that fascinating. Sorry if this is a silly question, but do they know what chromosome or loci it's on? Or just that it is recessive.