The E Series
The E genes are the last of the five main color genes in a rabbit's genotype. They control how far the darker pigment extends up the hair shaft. The E series is made up of five genes: E(d), E(s), E, e(j), and e.
The Dominant Black Gene (E{d}):
Both the most dominant and rarest gene of this category, the dominant black gene fully colors a rabbit's fur. In other words, the darker pigment extends all the way up the hair shaft AND completely covers all colors. When this gene is possessed, an otherwise Chestnut rabbit appears to be a solid black, and an opal appears to be a blue. Though interesting, this gene is very rare, and very few presumed selfs are actually dominant black carriers.
The Steel Gene (E{s}):
The steel gene, like the c(chl) gene, isn't fully dominant over the three other E genes. A true steel rabbit has a self coat with hairs tipped in either silver or gold, depending on the C gene. In other words, the darker pigment goes all the way up to the tip of the hair shaft, which is a different color. Though true steels are agoutis, the E(s) gene covers up the white markings. Agouti rabbits with the E genes E(s)E(s) or E(s)e, as well as self rabbits with these sets of E genes may appear to be blacks, but will carry the steel gene recessively.
The Full Extension Gene (E):
The full Extension gene is the most common E gene, as well as the original gene expressed by domestic rabbits' wild counterparts. It correctly expresses the darker pigment all the way up through the tip of the hair and does not cover other colors. It is almost fully dominant over e(j) and e, but an agouti rabbit carrying e(j) may have a vague harlequin pattern on its sides, known as harlequinized colors.
The Harlequin Gene (e{j}):
The harlequin gene creates a striped pattern. This is because the gene distributes the darker pigment and the lighter pigment on separate hairs. When a rabbit has two of these genes, they have a harlequin pattern no matter what the A genes are. However, when a harlequin rabbit carries the e gene, they must have the agouti gene to have the striped pattern. Otherwise, the coloring will more closely resemble a tortoise shell rabbit.
The Non-extension Gene (e):
The non-extension gene is the most recessive of all the E genes. It produces lighter and often yellow tinted colors such as orange and black tort. The darker pigment barely extends up the hair shaft and is quickly replaced by another color. The result is that the e gene can cause a rabbit's coat to appear shaded, despite there not being a c(chl) gene. This is because the darker color at the base of the fur is the only color showing at the rabbit's points. In those places, the fur is not long enough to show the other colors that appear on longer hair shafts.
That covers the basics of the E gene! Though it may seem a little complicated at first, rabbit genetics are really pretty simple. If you have any questions, feel free to email me at bunnyjeans101@gmail.com