Density of Color

Some cats have vibrant, deeply colored coats. These come in the colors black, chocolate, cinnamon, and sex-linked red.

Cats with these coats have at least one copy of the "dense" gene (D), which is dominant and ensures that each hair is packed tightly with numerous pigment globules to give the richest color.

Other cats have lighter, "dilute" coats in blue, lilac, fawn, and sex-linked cream.

These cats have two copies of the dilute gene (d), which is recessive and results in clumping and scatterering of the pigment globules in each hair: the effect is to create a paler shade of any of the dense colors.

Some breeders think that there is also a "dilute modifier" gene, provisionally called Dm, which modifies action of the dilute gene, d, but is located at a different site on the chromosome, and so is able to "interact" with d.

If a cat carries both the dd dilute trait and the Dm modifier gene it will have a "modified" color: blue and lilac modify to different shades of caramel, and cream modifies to apricot.

Other cat breeders dispute this, and claim that these colors are just bad blues, lilacs, or creams.