A brief, simplistic article on rabbit color genetics I wrote back in 2010

Genetics 101
Lisa Rodenfels

OK, its time for a brief rabbit color genetics lesson:
There are 5 gene pairs we are most interested in right now. A, B, C, D, & E.

The first is “A”. A is agouti, ‘a’ is solid or self. Agouti is
dominant to self. So an agouti rabbit can be AA or Aa. Self is
recessive, so it can only be ‘aa’. Watch how the gene pairs change
colors for you.
A-B-C-D-E- is a chestnut agouti, the same as a wild rabbit. It has
banded hair shaft, with grey at the skin, a tan band, and black hair
tips.
aa-B-C-D-E- is a black rabbit. The only thing that changed is that
this rabbit has 2 copies of the recessive “a”.

B is black, ‘b’ is chocolate.
A-B-C-D-E- is chestnut agouti , A-bb-C-D-E- is a chocolate agouti.
aabbC-D-E- is a chocolate rabbit. Notice chocolate has 2 copies of
the recessive a and b genes.
So you should know that you could never breed two chocolates together
and get any agoutis, or any blacks, since they don’t have those genes.

I am going to skip “C” until later, since it has more variables. Right
now, just know this gene pair creates the REW, pointed white (himi)
sable (shaded) and chinchilla rabbits. REW is the most recessive gene
in this set.

D is dense color, “d” is dilute color. Black and brown are dense, blue
and lilac are dilute colors.
aa-B-C -D-E is black, to make it a blue, you need two copies of the
dilute gene, or aa-B-C-dd-E-. Chocolate is aa-bb-C-D-E. A lilac is
aa-bb-C-dd-E-
You could never breed to lilacs together and get agouti, black, or even
chocolate or blue, since they do not have those genes.

E is extended color. ‘e’ is non-extended. This gene effects how the B
or b gene is expressed on the wool of the angora. It easy to see on a
tort. Notice how on a black rabbit, the black is all over or extended
all over the body. Then look at a tort. The points have black color
pigment in them, but it the body does not – only the tan/orange
pigment. That is what non-extended means.
Look at the genetic codes.
A-B-C-D-E is chestnut agouti. To make Fawn, its A-B-C-D-ee. The
non-extended gene takes the black out of the hair shaft – just leaving
the smut on the face, feet and tail of the rabbit.
aa-B-C-D-ee is a tort. The only thing different from a black is just
the non-extended genes.
aa-bb-C-D-ee is a chocolate tort. A lilac tort would be similar, just
with the ‘dd’ instead.

OH, the REW. The ‘C’ gene is for another post. For now, just keep in mind, REW only masks the rabbit’s
color. Remember, A-B-C-D-E is a chestnut agouti? Well to get a REW,
just change the C to a cc. This works both ways – in an REW, change
the “cc” to “Cc” and the colors the rabbit carries will show up.