The domestic cat's original coat color was probably greyish-brown with darker tabby stripes, a color that provides excellent camouflage in a variety of environments. All other coat colors and patterns are the result of genetic mutations; for example, solid coat colors such as black and blue are the result of a gene that suppresses tabby stripes; an orange coat is the result of a gene that transforms black pigment to orange; and a solid white coat is the result of a gene that completely suppresses all formation of pigment.
Two pigments, black and orange, form the basis for all coat colors in the modern domestic cat. These pigments may be combined with each other or with white (the absence of pigment). A single gene, the O (Orange) gene, determines whether a cat's coat contains black or orange pigment. The O gene can be thought of as a switch that is either on (orange) or off (black). The gene is located on the X chromosome, so its inheritance is sex-linked.
"Cat," Microsoft® Encarta® Online Encyclopedia 2003
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