Rat Genetics Colors

Please first read the Basics of rat genetics before touching upon this!

Color Genetics are for the most part quite simple, at least for the basics.

There are two base colors for rats.

Agouti - this is the wild type standard for rats. The color is a dark brown and ticked with black guard hairs. Agouti is Dominant and represented with A/- The /- means it could be either AA as homo Agouti or Aa as hetro Agouti meaning it is an Agouti rat carrying black.

Black - this is recessive and represented by aa

All rats have the base color of either Agouti or Black.

They are both on the same locus and technically Agouti would be the standard, wild type coat and the recessive "black" gene just causes the hair to be a solid color. The dominant A causes the branding of the hairs, while the recessive a causes the solid colors. Because of this, technically all Agouti based rats can not be called Self but instead Unmarked.

So if you read the other page on genetic basics you learned about Dominant and Recessive genes. So if you bred an Agouti rat to a Black rat what would the babies be?

Agouti is Dominant. You can tell because it is represented by the uppercase A. While Black is Recessive, the lowercase a.

It will depend on if the Agouti parent is homo or hetro.

All of the other colors are just dilutes from those two base colors.

It is a simple concept, think of it like mixing different paint colors together. If you take a can of red paint and add white you begin to dilute that base of red and it turns different shades of pink! So depending on which genes are being expressed on that base, it will give you whatever different color.

Loci-

There are many different loci responsible for coat color.

A- Agouti Locus

Agouti and Black

B- Brown Locus

Chocolate

C- Albino Locus

Albino, Himalayan, Siamese, Marten, Tonkinese

D- Dilute Locus

Russian Blue

G- Gray Locus

Blue

M- Mink Locus

Me- Merle Locus

P- Pink eyed Locus

Pe- Pearl Locus

R- Red eyed Locus

Source for more info on the Loci- AFRMA

Written out Genotypes

Remember each locus has two alleles.

So as we discussed before, if a rat has Aa on their Agouti Locus - this would mean the rat was Agouti carrying Black.

But this is because Agouti is Dominant.

For a recessive color lets say Blue, it would need two copies. Recessive is lower case. So... gg = a blue rat. Gg = carrying blue but not expressed.

If a rat was aa gg it would mean it was a Black based Blue rat

If a rat was AA gg it would be an Agouti-Blue rat.

We generally wouldn't write out the entire line of Genotype but it can be helpful to show what a rat is carrying.

We split up the colors as Agouti vs Black because as I said Agouti has branding of the hairs, where as Black causes solid colors. So each color will have a different expression of color depending on if it is Black or Agouti.

These are US colors. It is somewhat different for UK

Agouti Based Colors

Agouti Homo- A/A

Agouti carrying Black - A/a

Agouti unsure if homo or hetro - A/-

Eye Dilutes

Red Eye Dilute r/r
RED - A/- r/r = Fawn
A/- R/r = Agouti carrying Red

Pink Eye Dilute p/p

PED = A/- p/p = Amber
A/- P/p = Agouti carrying Pink

Mink - m/m

A/- m/m = Cinnamon
A/- M/m = Agouti carrying Mink
A/- m/m R/r = Havana Agouti (mink carrying RED)

Russian Blue - d/d

A/- d/d = Russian Blue Agouti
A/- D/d = Agouti carrying Russian Blue

Blue - g/g

A/- g/g = Blue Agouti
A/- G/g = Agouti carrying Blue

Chocolate - b/b

A/- b/b = Agouti Chocolate
A/- B/b = Agouti carrying Chocolate

American Cinnamon am/am

A/- am/am = American Cinnamon
A/- Am/am = Agouti carrying American Cinnamon

Black Based Colors

Black Homo - aa

Eye Dilutes

Red Eye Dilute r/r
RED - a/a r/r = Beige

Pink Eye Dilute p/p

PED - a/a p/p = Champagne

Mink - m/m

aa mm = Mink
aa Mm = Black carrying Mink
aa mm Rr = Havana

Russian Blue - d/d

a/a d/d = Russian Blue
a/a D/d = Black carrying Russian Blue

Blue - g/g

a/a g/g = Blue
a/a G/g = Black carrying Blue

Chocolate - b/b

a/a b/b = Chocolate
a/a B/b = Black carrying Chocolate

Lilac/American Mink - am/am

a/a am/am = Lilac/American Mink
a/a AM/am = Black carrying Lilac/American Mink

The C Locus

A/- c/c = Albino
A/- c/ch = Agouti Himalayan
A/- ch/ch = Agouti Point Siamese

Marten

A/- c/cm = Silver Agouti Hetro non-Pointed
A/- cm/cm = Silver Agouti Homo non-Pointed
A/- cm/ch = Silver Agouti Pointed

Black Eyed Gene

A/- c/c Be = Ivory
A/- c/ch Be = Black Eyed Agouti Point Himalayan
A/- ch/ch Be = Black Eyed Agouti Point Siamese
A/- c/cm Be = Agouti Black Eyed Marten
A/- cm/cm Be = Agouti Black Eyed Marten
A/- cm/ch Be = Agouti Black Eyed Pointed Marten

Wheaten Burmese

A/- c/c Bu/bu
A/- c/ch Bu/bu
A/- ch/ch Bu/bu

Wheaten Sable Burmese

A/- c/c Bu/Bu
A/- c/ch Bu/Bu
A/- ch/ch Bu/Bu

Tonkinese (Siamese Sable)

A/- ct

The C Locus

a/a c/c = Albino
a/a- c/ch = Himalayan
a/a ch/ch = Seal Point Siamese

Marten

a/a c/cm = Marten Hetro non-Pointed
a/a cm/cm = Marten Homo non-Pointed
a/a cm/ch = Marten Pointed

Black Eyed Gene

a/a c/c Be = Ivory
a/a c/ch Be = Black Eyed Point Himalayan
a/a ch/ch Be = Black Eyed Seal Point Siamese
a/a c/cm Be = Black Eyed Marten
a/a cm/cm Be = Black Eyed Marten
a/a cm/ch Be = Black Eyed Pointed Marten

Burmese

a/a c/c Bu/bu
a/a c/ch Bu/bu
a/a ch/ch Bu/bu

Sable Burmese

a/a c/c Bu/Bu
a/a c/ch Bu/Bu
a/a ch/ch Bu/Bu

Tonkinese (Siamese Sable)

a/a ct

Multiple Dilutes

Pearl Pepe

Pe/Pe = Lethal
A/- m/m Pe/pe = Cinnamon Pearl
a/a m/m Pe/pe = Pearl

A/- d/d g/g = Agouti Silver Blue
a/a d/d g/g = Silver Blue
A/- g/g m/m = Platinum Agouti
a/a g/g/ m/m = Platinum

* Not a full list, more coming soon!