One mutation, the Anophthalmic White mutation can produce two different types of white pattern - White Bellied and Roan. The Anophthalmic White mutation occurred in the USA in 1958.
With cream based colours (such as Black Eyed Cream, Red Eyed Cream, Sable, Chocolate (Sable), Copper, Mink, Blue Mink, etc) the Anophthalmic White gene produces a Roan where the coat has both white and coloured hairs intermingled. Many Roan hamsters have colouring on the head but lack a good amount of colouring on the body. For showing the hamster is required to have a marbled appearance of colour over the back.
With non-cream based colours (such as Golden, Cinnamon, Yellow, Dark Grey, Black, Silver Grey, etc) the Anophthalmic White gene products a White Bellied version of that colour and the normal ivory belly is turned to pure white or has a very large patch of white on it. Sometimes the hamster can also have a small sprinkling of white hairs on the back somewhere.
The Anophthalmic White gene can produce eyeless white hamsters when the offspring inherit two Anophthalmic White genes. Therefore Roans or White Bellied hamsters (from the Anophthalmic White gene) should not be mated together or to each other as 25% of the litter will inherit two Anophthalmic White genes and be eyeless whites.
The Anophthalmic White gene should not be confused with the Banded or Dominant Spot genes where these genes also changes the belly colour to white as part of their pattern.
Of course it is possible to combine the Anophthalmic White gene with the Dominant Spot or Banded genes and so some Dominant Spot or Banded Hamsters could also be Anophthalmic White and eyeless whites would then be produced if these were mated to any other hamster which containing the Anophthalmic White gene.
Roans and White Bellied Hamsters (from the Anophthalmic White gene) tend to have a ruby glow in the centre of the eye and this is most often seen by shining a torch into the hamster's eye. However, this glow can be extremely difficult to see on red eyed colours.