![]() I like to think of the X chromosome as having four sections (or arms), and the shorter and smaller Y only has three. If she also inherits the white spotting gene which is responsible for the white coat colour, she will be black, red and have areas of white. If however, the female kitten inherits both the O and the o (usually black) gene, then because she has two X chromosomes (instead of an X and a Y like the male), both black and red will show making a tortoiseshell cat. If the X chromosome carries the o (non-orange) gene, then the male will be another colour, usually black. This is the same for colour blindness in human males too.Īs the male cat only has one X chromosome, if it carries the O gene (which remember, is dominant), then he will be an orange/red male. Because females have two chromosomes, the good one prevents her from developing the condition, however as the male-only has one X chromosome, he will develop hemophilia. Interestingly, the faulty gene for hemophilia, a blood clotting disorder, is also sex-linked and found on the X chromosome. Male – XY (X from the mother, Y from the father).Female – XX (X from the mother, X from the father).Each cat will inherit an X from its mother and an X or Y from the father. The mother’s eggs only carry an X chromosome, but the male sperm can carry either an X or a Y chromosome. The O gene is dominant (all dominant genes are abbreviated in UPPER CASE, all recessive are lower case). The red (actually known as orange and abbreviated to O) gene is only carried on the X chromosome, which makes it sex-linked. To understand why calicos are so rare in male cats, we need a basic understanding of genetics. Only 1/3,000 calico or tortoiseshell cats are male. Learn more in our article: Calico cat colors Male calico cats The chart below shows the effects of the dilution and the dilute modifier genes on the coat colours. Some cats carrying the dilution gene display clumping and an uneven distribution of the pigment granules in the hair shaft, producing a dilution of the coat colors which changes black to grey (blue), chocolate to lilac, and orange to cream. The colour density gene, or dilute modifier gene, caramelises the coat colour of dilute cats who carry the gene. Just like dilution genes can cause coat colors to change from black to gray, it can also cause changes from chocolate to lilac and and orange to cream. The gray and cream coloration of a calico cat is due to the dilution of the black and orange genes. This concept can be applied to all calicos with dilute coloration. The amount of pigment determines if coloration will be dense or dilute. The colour density gene controls the amount of pigment in each hair. Both chocolate and cinnamon are recessive to black (B) and therefore will only show if the cat inherits two copies of the gene. One produces chocolate (b), and the other produces cinnamon (b l ). Scientists at the Veterinary Genetics Lab at The University of California at Davis discovered two mutations. Cinnamon with red (orange) and white calico catsĬinnamon is a warm brown and is produced by a second recessive allele of B, denoted with the symbol (b l ). Brown and red calico Brown with red and white Calico cat (DepositPhotos) 3. Brown with red (orange) and white calico catsīrown with red and white patches is second of the two most common calico cat colorations. Black and red calico cat Black calico cat 2. This concept can be applied to all color patterns of calico cats. Male calico Patch#Similarly, a red patch of fur is created when the X chromosome carrying the gene for black fur is inactivated. A black patch of fur is created when the X chromosome carrying the gene for red fur is inactivated. Black with red (orange) and white calico catsīlack with red and white patches is one of the two most common calico cat colorations. Calico cat coat colorsĭue to the genetics behind the calico coloration, no two calico cats have the same patterns - including twins. This means a bi-color or calico cat is genetically a colored cat, but the S gene has switched off the color in certain areas. The gene responsible is known as piebald or spotting gene (abbreviated to S) and is dominant, as signified by the uppercase S. Why not white? Because a cat with a colored and white coat (calico or bi-color) has a gene that switches off color in some parts. There are four base (solid) colors in cats: Related: What’s the difference between a calico and a tortie cat How does the calico coat pattern occur? Calico cat peeking through tree trunks (DepositPhotos) Calicos are not a cat breed, the word calico refers to the coat colour only, and occurs in both random-bred and some purebred cats. A calico is a domestic cat with a coat pattern that consists of a white base (25-70%) with patches of red and black, red and grey or red and brown. ![]()
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