page title icon Cat Coat: White Cats and White Spotting

by Linda Mathews Last Updated August 3, 2021

Incredible but true! From a scientific point of view, a white cat coat does not exist. Three genes determine the base color of a cat’s coat: the black color gene, the orange color gene, and the color saturation gene. Where does all the variety of colors come from?

All possible combinations of these genes create only eight cat colors:

  • Black;
  • Blue (gray);
  • Dark brown (chestnut or chocolate);
  • Lilac (lavender);
  • Light brown (cinnamon);
  • Beige (yellowish-brown);
  • Red;
  • Cream.

These eight primary colors can mix and form different colors and fur patterns:  tabby, spotted, tortoiseshell, chinchilla.

However, where does white come from?

Special genes are responsible for the white coat color. These are color intensity and albinism genes. They suppress the natural color of the coat.

So, for example, a color suppression gene masks the color and pattern of the coat fully or partly. The albinism gene affects the color of certain areas of the body and eyes. It can only be in one of five states (alleles):

  • Solid color “C” – the albinism gene is absent.
  • Albino “c” – means a congenital absence of melanin pigment. These cats have white fur and pink eyes.
  • Blue-eyed albino “ca” – the albinism gene almost completely suppresses all colors of not only the coat but also the eyes. In these cats, the eyes are colorless, however, due to the refraction of light, they appear blue.
  • Burmese “cb” – leads to mild albinism.
  • Siamese “cs” – leads to moderate albinism like in Siamese cats.

In this article, we will look at the science behind white and spotted cats, the different coat colors of cats, and give information on the relationship between genes that block the main coat color and deafness. Keep reading!

The White Spotting Genetics and Scale

Cats acquire a two-tone pattern due to the piebald gene, which is responsible for the presence, size, and shape of white spots in the main coat pattern. The gene exists in four alleles: spotless “s”, spotted “S”, partially spotted “Sp”, and Burmese “Sb”. White spotting variation is measured on a scale from 1 to 10, with 10 being the highest amount of white. This scale contains several levels: low, medium, and high.

White Spotting Scale

Low-grade: less than 40% of the cat coat is white

Medium-grade: 40-60% of the coat is white

High-grade: more than 60% of the cat coat is white

White Spotted & White

It is known that the phenotypes of white and white spotting are associated with the W locus of the KIT gene. This locus has three possible states (alleles): W, ws, w. Below we will take a closer look at each allele.

The “W” allele means completely white and is dominant to other alleles or other color genes (the “W” allele eliminates the effect of any color gene). 

“ws” is the main white spot allele. This allele is codominant with the “w” allele for cats without spotting at all. This means that both alleles are fully manifesting their effect.

If a cat is W/W, this denotes that the cat will be completely white, and other color genes will be blocked. If a cat has ws/ws, this signifies that more than half of the cat’s body will be white. If a cat has ws/w, this means that it will have white spots on its coat, covering a small area of the body. However, the “ws” allele is not alone in causing white spots, as science still does not know the genes that also cause white spots.

Cats with N/W (N stands for non-white) will be white and will have some degree of hearing impairment; cats with N/ws will have white spotting.

 Mitted

Mitted means that the white color of the cat reaches the ankles in the front (resembles mittens) and reaches the thighs in the back (resembles knee socks). 

The locus is responsible for the presence of white spots, it is recessive and is located in the KIT gene. This gene is found in cat breeds such as Ragdoll and Maine Coon.

If a cat is g/g (homozygous for the gloved allele), then it will be mitted. If a cat is g/N (N means the allele is non-gloved), it will not be mitted. On top of that, some scientists have argued that other genes can cause gloved markings. This fact still requires additional study.

White Color and Deafness

Scientific research distinguishes between deafness in white cats and deafness in white cats with blue eyes. There is no specific gene responsible exclusively for deafness in cats. The gene responsible for deafness in white cats is autosomal dominant and is denoted by the letter “W” (white gene). This gene is responsible for the white coat color, blue eye color, and deafness.

According to Cornell University veterinarian James Flanders, “About 80 percent of white cats with two blue eyes will start to show signs of deafness when they are about four days old as the result of cochlear degeneration.”

However, although the “W” gene has full penetrance (the frequency of manifestation of an allele of a particular gene) for white coats (all cats with this gene are completely white), it has incomplete penetrance for blue eyes and deafness. Deafness can be unilateral (affects only one ear) or bilateral (affects both ears).

Thus, despite the association of deafness with white coats and blue eyes, not all white cats or white cats with blue eyes are deaf. The mechanism of deafness is still unclear, and scientists associate it with interactions with other genes and environmental factors.

Bottom Line

Hence, if you’ve decided to buy this magical white furball, this information on white cats, cats with white spotting, and genetics behind it will be helpful.

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