Whites and Bicolors

White is dominant over all other color genes, wether as all-over white (W), or as the white spotting gene (S) that gives us the bicolors.
 
White hair, unlike all other hairs, contains no color-producing pigment at all.
Behind its snow white exterior, the white cat is genetically colored, and it passes on this color potential to its offspring.

White cats carry the dominant W gene, which masks the expression of all other color genes. Often, a hint of a cat's underlying color breaks through in a "kitten cap" in the hair on the head of newborn kittens. As the kitten grows, the cap disappears to leave pure white.

Deafness is sometimes associated with the W and S genes, although it is more common in white cats with blue eyes than in those with yellow or orange eyes. These white cats are different from albino white cats that have no pigment in their pink eyes: albino white is uncommon.

Bicolored cats are white-coated with patches of color - tortie-and-whites are variously classified as bicolor or tricolor - and come in two types. The standard bicolor has a pigmented saddle over its back, with the white principally concentrated on the underparts and legs.

The Van pattern, originally associated solely with the Turkish Van, but now also seen in other longhair and shorthair cats, consists of predominant white with solid or tortoiseshell patches restricted to the head and tail. One theory is that these cats carry two copies of the white spotting gene S, giving them a superabundance of white.