There are a few different markings in rats. The main three are self, hooded and Berkshire, with the others being variations of these.
Self – HH
The rat is one colour, with no white markings at all. Most self rats in this country have white toes.
Berkshire – Hh
The rat has a white tummy and chest. The Berkshire marking can range from one tiny spot of white on the belly to the whole belly and chest.
This is a variation on the Berkshire gene, where the entire belly and chest are white, with splashes of white up the sides of the rat between the front and hind legs.
This is a variation of the Berkshire gene, where the chest has a triangular shaped white marking.
Hooded – hh
The rat has a white base, coloured head and neck with a stripe going down from the hood to the tail. This stripe is often broken, irregular or spotty.
This is a variation on the hooded gene where there is no stripe down the back, leaving the back completely white.
This is a variation on the hooded gene where the coloured part of the hood only extends to the back of the head, the rest of the body remains white.
Same as for Capped (see above), except the coloured cap is split with a white face marking.
This is believed to be a white marking modifier gene and is very unpredictable. Breeding two blazes together can still result in none of the offspring showing the trait. This makes perfect wedge blazed rats very hard to reproduce.
This is another variation of face marking and is more common than the wedge blazed marking. Lightning blazes range in size and shape but generally a rat is referred to as lightning blazed if it has a long thin stripe of white on its face.
Another variation of face marking is the head spot. These can range in size from only a few white hairs to a large splodge, usually positioned on the forehead. This is the most common type of face marking.
Downunder – Du
This marking can occur on both hooded and berkshire rats and shows as a stripe or splodges of colour on the white belly. Although the marking is not visible on a self rat as there is no white on the belly to show the marking, it is still inherited the same way. It is a dominant gene.
Black Eyed White – nn
The BEW gene is co-dominant. It is similar to the albino gene in that it masks the true colour of the coat. This gene is believed to cause an extreme overmarking of white which results in the white marking covering the entire rat. Heterozygotes often have face markings that range from head-spots to lightning blazes with chin straps, and variegation in berkshire heterozygotes. Often the coat and ears of a black eyed white are mismarked with smudges of colour, and much less frequently, larger splodges of colour.