# Genetics, the beginnings



## Silver Moon (Sep 4, 2013)

So I've just spent the afternoon trying to understand and get my head around mouse varieties, colours, codes and genetics.

Luckily ( I think), I'm quite interested in all this, so I guess that's a good start.

I am however a little confused about one thing.If we take chocolate for example ( a/a b/b ), I understand the a/a comes from black, but what about the b/b? I haven't found a colour / code of just b/b to breed and get a/a b/b?

I know it also depends on what hets everyone carries, but we will forget about that at the moment :lol:

Am I anywhere near understanding this or have I got it all wrong? :?:

Jake


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## Fantasia Mousery (Jul 16, 2011)

a/a b/b is chocolate, yes. So... the b-gene is a gene that dilutes the original colour of the mouse, which means chocolate is a b-diluted black. Don't know if that helps?


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## Silver Moon (Sep 4, 2013)

Thanks for that.

So anything carrying the b/b gene has the chance to be bred to a black to create a chocolate? e.g. Cinnamon?


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## Fantasia Mousery (Jul 16, 2011)

Yes and no. A Cinnamon is the Agouti equivalent of a Chocolate. Cinnamon is A/* (meaning, unless you know the background, you don't know whether it is A/A or A/a) b/b.

In order for a Cinnamon x Black pairing to give Chocolate, the Black will have to be B/b, thus carrying Chocolate. But the Cinnamon will also have to be A/a. Let's say we make a pairing with a Black that does carry Chocolate, and a Cinnamon being A/a. We will get:

50% A/a
50% a/a
and
50% B/b
50% b/b
Together, these will be Agouti (A/a B/b), Cinnamon (A/a b/b), Black (a/a B/b), and Chocolate (a/a b/b).

The tricky part will be if the Cinnamon is A/A and the Black is B/B. You can get Chocolate, yes, but not from the first pairing. It will require some breeding back to parents and sibling pairings. If you want me to explain that further, just ask.


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## Silver Moon (Sep 4, 2013)

I think I kind of understand that a bit better :lol:

But if you are willing to go into genetics in more detail, please don't let me stop you


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## Fantasia Mousery (Jul 16, 2011)

I'm always willing to, but it's easier for me with more or less specific questions. 

Let's say you have a Cinnamon that is A/A (this is most common if the mouse is from a breeder who doesn't use blacks, but you never know for sure), and a Black that is B/B (unless there's Blue somewhere behind it, it won't be B/b - however, in theory it could be endless generations back).
So we have an A/A b/b Cinnamon, and an a/a B/B Black. The outcome will be 100% Agouti - we call them Litter A. All of them will be A/a B/b. That means all of them carry Black and b.
But pairing a buck and doe from Litter A will give the outcome in my previous post.
However... If we take one from Litter A and pair it with the Cinnamon parent - this will be Litter B, we will get 50% Agouti (A/A B/b and A/a B/b), and 50% Cinnamon (A/A b/b and A/a b/b).
If we instead take one from Litter A and pair it with the Black parent - this will be Litter C, we will get Black (a/a B/b), Agouti (A/a B/b), Cinnamon (A/a b/b), and Chocolate (a/a b/b) - 25% of each.

If we take a Chocolate from Litter C and breed back again to the Black parent, we will be completely free of the Agouti gene, which means no more Agouti and Cinnamon. 
If the same Chocolate is bred to its Black sibling, we will get 75% Chocolate and 25% Black, instead of 50% of each.

Keep in mind everything is theoretical. In reality, the outcome is almost never 50% one and 50% the other.
Right now I have a litter where I should be getting Himalaya, Siamese, Colourpoint Beige and Beige. I got 1 Himalaya and 3 CPB/Beige (they're only a week old, and they won't be getting points until 5-6 weeks). I didn't cull.


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## Silver Moon (Sep 4, 2013)

Thanks very much for that post 

I find it really interesting ( the whole genetics side of things ), and will hopefully help me when I come to planning my breedings, but this doesn't really matter as we don't know what hets they carry so could come out with anything lol


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## Fantasia Mousery (Jul 16, 2011)

An interest in genetics definitely helps learning them.  I think it's very interesting as well.
Even though you don't know what your mice carry, you can still figure out what should come out of a pairing. If you need help again, don't hesitate to ask.


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## Silver Moon (Sep 4, 2013)

Fantasia Mousery said:


> An interest in genetics definitely helps learning them.  I think it's very interesting as well.
> Even though you don't know what your mice carry, you can still figure out what should come out of a pairing. If you need help again, don't hesitate to ask.


Surely what they carry depends on any visible outcomes, so anything would only be a very rough guess?

If we take two of my mice,

Blue belted longhair boy ( lgh/lgh a/a b/b, ( or a/a ln/ln ( unsure if dilute or leaden ) ) bt/bt

Chocolate piebald normal coat female ( a/a b/b, s/s )

Any ideas?

There should be some chocolate, but will they all be chocolate and just carrying blue if the male is dilute?

And a 50/50 split long hair / normal? ( not quite sure how coat genetics work in terms of dominance etc


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## Fantasia Mousery (Jul 16, 2011)

Your longhaired mice are most like go/go and not lgh or ln.
Also, you write it in alhpabetical order, so it's a/a bt/bt d/d for your buck, and a/a b/b s/s for your doe (which you wrote correctly). The d is what dilutes a Black into Blue.

From that pairing, you will only get Black (a/a B/b D/d). If your doe carres d, or your buck carries b, you will also get Blue or Chocolate. Now, even more interestingly: if your doe carries d and your buck carries b, you will get 100% Lilac.  Lilac is genetically Blue Chocolate (a/a b/b d/d).

As for the markings, all will be Self, but they will also all carry Belted and Piebald.
The same goes for coat. All will be SH, but will all carry LH.

When you look at gene codes, capital letters are dominant, and they are written first (example: A/a, never a/A). That goes for everything, whether it's colour, coat, marking, you name it.

EDIT: To answer your question, yes. It's possible that they carry something else in common, but there's no way to know what unless it shows up in the litter. That would be from other genes completely, as all their above mentioned genes are recessive, so nothing is hidden there.


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## Silver Moon (Sep 4, 2013)

Haha now I'm lost.

so all blues are a/a d/d ?

I thinks there's still loads for me to learn before I even have a fraction of the knowledge I want to have before breeding :lol:


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## Fantasia Mousery (Jul 16, 2011)

Yes. Just like Chocolate is a b-diluted Black, Blue is a d-diluted Black. And Lilac is a b- and d-diluted Black.

Actually, you might find it easier to learn genetics while you breed.  Some people just understand it better when they can see the outcomes of litters. If something pops up in a litter that was unexpected, it's sometimes easier to figure out that way around.


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## Silver Moon (Sep 4, 2013)

Thanks 

Think we will just have a "play" at breeding and see what we end up with :lol:


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