Genes Involved in Albinism, Dominant White, and White Spotting
- The "C" gene codes for the enzyme tyrosinase, the first step in pigment production. Its recessive alleles determine whether a cat is a complete albino (pink-eyed) or a temperature sensitive albino. The temperature sensitive albino genotypes are cbcb Burmese (sepia), cscs Siamese (pointed), and cbcs Tonkinese (mink). The cscs gene can turn a cat's eyes blue due to a reduced number of melanocytes, affecting pigmentation of the eyes. If a cat has the dominant C allele, then the cat is non-albino and full pigment production occurs.
- The white masking gene, W/w. The "W" gene prevents the normal replication and migration of pigment-producing cells during embryologic development. As a result, WW and Ww cats have a greatly reduced number of melanocytes and appear white, no matter what other color genes it may carry. Only a cat that is homozygous recessive (ww) will express normal pigmentation.Thus, W is epistatic to the other coat pigmentation genes. Some cats with the W allele of this gene are deaf and/or have depigmentation of the iris of one or both eyes, resulting in blue eye color. White cats are also more likely to get skin cancer.
- The white spotting or piebald spotting gene, S/s, has variable expression, so that an SS cat often has more extensive white patching than an Ss cat. It is this gene that creates the familiar white blaze across the face, a white bib, tuxedo pattern, or dappled paws. A hypothetical Sb allele ("gloving gene") may cause the mittens in Birman and Snowshoe breeds. Some researchers believe that there are separate white spotting genes for distinct forms of white pattern, such as the white locket that some cats have on their neck or bellies.
Read more about this topic: Cat Coat Genetics
Famous quotes containing the words genes, involved, dominant and/or white:
“Whether you want it or not,
your genes have a political past,
your skin a political tone.
your eyes a political color.
...
you walk with political steps
on political ground.”
—Wislawa Szymborska (b. 1923)
“Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.”
—Paul Tillich (1886–1965)
“The dominant and most deep-dyed trait of the journalist is his timorousness. Where the novelist fearlessly plunges into the water of self-exposure, the journalist stands trembling on the shore in his beach robe.... The journalist confines himself to the clean, gentlemanly work of exposing the griefs and shames of others.”
—Janet Malcolm (b. 1934)
“It is worth the while to detect new faculties in man,—he is so much the more divine; and anything that fairly excites our admiration expands us. The Indian, who can find his way so wonderfully in the woods, possesses an intelligence which the white man does not,—and it increases my own capacity, as well as faith, to observe it. I rejoice to find that intelligence flows in other channels than I knew. It redeems for me portions of what seemed brutish before.”
—Henry David Thoreau (1817–1862)