Firstly what I would like to do before going into all the genotype codes, what to put to what and what not to put to what I think it is important that you acquaint yourself with the fundamentals of genetics. The individual genes, the functions they perform and the associated genes they work well with and rabbits they can be found in. Once you have understood how the genes work you should be able to understand the sometimes complex world of genetics, and hopefully make it a lot simpler and less scary.

There are three pattern groups and ONLY three. These are Agouti Pattern, Tan Pattern and Self Pattern. From these three patterns all colours of rabbit are formed. Markings of rabbits, such as Dutch, Butterflies, Hotots and Silvers etc are just colours with marking genes and are NOT patterns in their own right. With this in mind, the below table will show you how all these genes work with each other and hopefully help you understand why you see what you see in the rabbit colours that you have.
Gene Name Description Examples
A Agouti Pattern - Banded Hair A rabbit with this gene in its genotype has banding. Fawn or white at its eye circles, triangle at nape of neck, feet, legs, and inside of ears. The belly colour on this rabbit is white. Agouti,Opal,
Lynx, Cinnamon,
Chinchilla, Squirrel and Wiltshire
at Tan Pattern This gene removes the banding of the agouti pattern but leaves the nape, inside ears, nose fork and eye circles, ticking and belly as above. The tan pattern colour points can appear in tan, fawn, or white. Marten Smoke, Marten Sable, Fox, Otter & Tan. Also unstandardised colours such as Sooty Otters and Marten Seal Points etc
a Self Pattern - Non Agouti or Tan This gene removes the banding fully from the hair shaft producing a solid coloured rabbit. Black, Blue, Chocolate, Lilac
Also many other colours such as sooty, sealpoint etc. Explanation later though

It is always a good thing to remember that genes come in pairs. Most colours are created by a combination of FIVE pairs of genes. Each pair is created from one gene passed on from the father and one gene from the mother. There are instances, as in the REW, where only one pair of genes is needed, although the rest are hidden underneath.

From the above table you can see the three pattern groups in order from top to bottom. This is called the order of dominance. It is important to remember this when calculating genotypes. Any pattern can carry the patterns on the row below, but not those above. As you can see from the table, Agouti is at the top so can therefore carry the Tan pattern or the Self pattern. The Self rabbit being at the bottom can carry no other pattern at all (except REW's and BEW's, but we'll take a look at that later).

The Agouti and Tan patterns only need the first half of their pair to creat the pattern. It does not matter what the second gene is. The Self pattern is ALWAYS two recessive a's together. There is no space in the pair to carry another pattern gene.

The 'A' series governs the pattern of the coat.  The B, C, D and E govern the colour.  These are the genes that can change Black to Blue/Chocolate, Agouti to Opal/Orange and Sable to Smoke, Sealpoint to Bluepoint and so on.  With some colours only one pair of genes needs to be changed, with others more. NB. There are two genes in the 'E' series, i.e: Harlequin and Steel that have other effects on the coat.  The Harlequin gives a brindled coat and the Steel will turn a white Agouti belly black etc.
Gene Name Description Examples
B Black If combined with Agouti (A_) this gene produces the black band.  If combined with the Tan Pattern (at_) it produces the base colour of your rabbit
In self (solids) (aa), produces solid black colour.		  
b Chocolate If combined with Agouti (A_), this gene produces a brown band instead of black. If combined with the Tan Patten
(at_) it prduces the base colour of your rabbit
In self (solids) (aa), produces solid chocolate colour.		  
C Full Colour Development Allows all 4 dark and all 3 yellow pigments to be present. Completely dominant.  
cchd Dark Chinchillation Allows all 4 dark and only 1 of the 3 yellow pigments to be present. Area becomes white or pearl. Completely dominant over the following c genes below. Chinchilla, Squirrel & Wiltshire also Fox when expressed with (at )  When expressed with Self (aa) and non extension -also Iron Grey
cchl Light Chinchillation
(Shading gene)		 Allows 2 of the 4 dark and none of the 3 yellow pigments to be present. This lightens the colour to sepia brown. Causes shading effects. Incompletely dominant over the following c genes below. Shading is fine-tuned with the colour intensifier genes. Sable, Smoke & Sealpoint and other dilute versions of above, also marten when expressed with (at )
ch Himalayan Causes dark extremities (points), which include the ears, nose, feet, and tail. Produces red eyes with other ch or c. Incompletely dominant over c. Himalayan, Californian
c Albino (REW) This is what we call an epistatic gene and it blocks the expression of all other colour genes, producing a white rabbit with red eyes. Also known as masking White (red eyes)
D Dense Coat Colour Produces the full colour shade. Causes the eye to be brown.  
d Diluted Coat Colour Changes black to blue, chocolate to lilac, agouti to opal, orange to fawn, Sable to smoke, sealpoint to bluepoint etc, Causes eye to be grey-blue.  
Es Steel This is a modifier gene and the most dominant of the E series.  It covers the middle band with dark pigment. Darkens the agoutis eye circles, triangle at nape of neck, feet, legs, inside of ears and belly. Leaving behind coloured tips to the guard hair.  
E Full Extension of dark pigment Working with the C series genes it allows the complete and full expression of the dark brown pigment.  
ej Japanese This gene works with the Agouti pattern gene and causes the black and yellow colours to be arranged in individual areas instead of individual hairs in a mosaic like pattern. Harlequin, Magpie (with cchd) Rhinelander (with Enen) and Tri Dutch (with Dudu)
e Non-extension of the dark pigment Working with the C gene series (and the rufus modifiers), this gene removes all or most of the dark pigment, leaving yellow or white. Orange, Fawn, Sooty, Sealpoint, Frostie, Beige

Written by Phil Batey