For more rat genetics, see the
AFRMA Rat Genetics book,
specific articles listed with the various standards descriptions,
and the articles on the Info Pages: Breeding – Colors/Genetics –
Rat Genetics, part 1,
Rat Genetics, part 2,
Rat Genetics, part 3.
See also the Rat Biology article
Why do some rats have white blazes and megacolon?
See the AFRMA Rat Color Standards book and the Standards pages for photos.
Go to Fancy Rat Genes, Alphabetical Name Listing for a complete list.
See also Fancy Rat Genes, Genetic Code Listing for breakdowns by genetic code.
|Albino||cc (covers up the actual color/marking so can be either an agouti-based or black-based color; a.k.a. P.E. White)|
|Banded||? (from Hooded stock)|
|Bareback||hh or hhe or hHms or hhi?|
|Berkshire||Hh or hhe or hihi or hihn|
|Capped-Stripe||hreh; Hrehre (lethal)?|
|Collared||? (usually from Dalmatian breedings) or Heh? or Hehi?|
|Down Under||hdu? (dominant)|
|English Irish||Hh, or Hhi if no Hooded produced in 2 Irish breedings|
|Essex||Hro++ or Hro++H (color fading gene; has Berkshire markings but breeds as a Self)|
|Hooded||hh or hml|
(Hm=Hooded Modifier; hms or hml—short or long)
|Irish||Hh, or Hhi if no Hooded produced in 2 Irish breedings|
|Roan (Husky)||? (recessive; roan gene lightens color with each moult till rat is nearly white; always in Berkshire or Berkshire Blaze markings)|
|Roan: Striped||? (recessive; a.k.a. Banded Husky)|
|Snowflake||? (small white spots belly and sides; a.k.a. |
stippeltjesin the Netherlands which means dots)
|Variegated||? (2 Var. never produce Self or Hooded)|
|White: black-eyed||hehe or any h|
(marked selected for no spots; in either agouti-based or black-based color)
Note: could also be slsl (Spotting Lethal); these suffer from aganglionic megacolon associated with white coat color, usually BEW but occasionally have small spot on head and hips and die usually within first week to 35 days after birth
|White: pink-eyed||cc (albino; covers up the actual color/marking so can be either an agouti-based or black-based color) Note: extremely diluted P.E. Self colors or a P.E. Marked with all markings bred off can look like a P.E. White|
Note: Many rat colors/varieties have not been studied by geneticists so codes are given by fancy rat genetics experts or are unknown
Note: Capital letter=dominant genes unless otherwise noted; lower case letter=recessive genes
“–” means that either the dominant or recessive allele could occupy that space without affecting the outcome
* = g or Me or Dal code by Nichole Royer
** = Cscs Fyfy code by Ann Storey, N.F.R.S.
+ = ce or ci code by Nichole Royer
++ = Hro code by Sheila Sowter, N.F.R.S.
# = cm or cs code by Nicole Housel
? = genetics unknown