The C Locus, technically referred to as the Color Locus. Rabbits have two kinds of pigment in their fur color: phaeomelanin, which causes red and orange shades, and eumelanin, which causes the black and brown shades. The C Locus determines how much color pigment is expressed on the hair shaft.
Ranging from all color (‘C’) to no color whatsoever (‘c’), this locus has the most variations, with five distinct genes. The C locus also has some incomplete dominance between some of the recessive gene mutations that can change the expression of the fur color. For most breeds, very few of the colors caused by the more recessive C variations are recognized, so most of these colors are very rare.
The ‘C’ or Full Color Gene
- Completely Dominant.
- Causes no change to the coat color, allowing the other genes to determine where color is placed.
- Colors that contain the Full Color gene include blue self, Harlequin, and chestnut agouti.
Chestnut Agouti (A_B_C_D_E_)
Blue Harlequin (A_B_C_dde(j)_)
Blue Non-Extension Steel (A_B_C_ddE(s)e)
The ‘c(chd)’ or Chinchilla Dark Gene
- Reduces the phaeomelanin (pigment that causes yellow, orange, and red) in the coat color.
- Recessive to ‘C’, incompletely dominant over ‘c(chl),’ and fully dominant to ‘c(h),’ and ‘c.’
- When paired with ‘c(chl),’ the ticking may be less distinct and murkier.
- Colors that contain the Chinchilla Dark gene include Lilac Chinchilla, Black Magpie, and Black Silver Tipped Steel.
Black Chinchilla (A_B_c(chd)_D_E_)
Blue Chinchilla (A_B_c(chd)_ddE_)
Lilac Chinchilla (A_bbc(chd)_ddE_)
The ‘c(chl)’ or Sable (Chinchilla Light) Gene
- c(chl) is incompletely dominant and homogenous and heterogenous pairings of this gene cause different results.
- When ‘c(chl)’ is homogeneous, it creates a dark, almost solid coloration, like a dulled self. This is referred to as seal.
- When ‘c(chl)’ is paired with ‘c’ or ‘c(h)’ it causes a shaded coloration, where the rabbit is darker at the points (the face, ears, belly, tail, and back) and lighter on the stomach.
- ‘c(chl)’ may also mess with the Chinchilla Dark gene, since it removes both phaeomelanin and some of the eumelanin (the pigment that causes brown and black). Usually the change is not drastic, but if you want to breed for either ‘c(chd)’ or ‘c(chl)’ it is important to use animal that ONLY have the gene you are breeding for. For example, a breeder is working on a chocolate chinchilla project, so the breeder avoids buying any animals with ‘c(chl)’ based colors in their pedigree.
Chocolate Magpie (A_bbc(chl)_ddE_)
Chocolate Sable (A_bbc(chl)_D_E_)
Unknown, possibly broken Smoke Pearl.
The ‘c(h)’ or Pointed (Himalayan) Gene
- The ‘c(h)’ genes removes phaeomelanin and most of the eumelanin on the fur shaft, except around the ears, tail, ears, and nose, causing the rabbit to look as if it has color painted on its ‘points.’
- Recessive to the Full Color, Chinchilla Dark, and Chinchilla Light. Dominant over ‘c.’
- Possible combinations on the genotype when it is expressed are c(h)c and c(h)c(h).
- Most often found in the California breed, and colors include black, chocolate, blue, and lilac pointed.
The ‘c’ or REW (Red Eyed White) Gene
- Removes all traces of phaeomelanin and eumelanin so that the coat is completely white. It also removes pigment from the eyes, making them red.
- Completely recessive to all the other C Locus gene variations, so the only possible combination is cc.
Quick shoutout to the Nature Trail for their explanation of the C Locus! I relied on it for this post to be sure I correctly explained the C Locus. Check out their explanation for further reading!