In most cases, one cell line will dominate the other, with only small populations of the second DNA within the body. Tetragametic chimerism occurs when early embryos fuse together to create a single organism. Klinefelter syndrome is a genetic condition in which the male is born with an extra copy of the X chromosome, making him XXY. The most common causes of chimerism are Klinefelter syndrome and tetragametic chimerism. One of which is turned off, in a process known as X inactivation, the result is random patterns of orange and black or cream and blue, if she is dilute. That is because each cell contains two X chromosomes. The female (XX) has two X chromosomes, if she inherits one copy of the orange gene and one copy of non-orange (usually black) she will display both colours. As the male (XY) only has one X chromosome he will either be orange or cream (if dilute) or non-orange. The orange and cream gene is carried on the X chromosome. Related: Rare cat colours Dilute male calico cats Obb SDE/ShutterstockĬalico occurs almost exclusively in female cats, only 1 – 3,000 male cats are tortoiseshell or calico. Two dilute cats can only ever produce dilute offspring. Cats can have a dense coat colour (black or red), and carry one copy of the dilute gene, and if the other parent also carries a copy of the gene (regardless of whether he or she has a dense coat colour), then there is a 1 in 4 chance the offspring will be calico. Dilute calico is accepted in the following breeds:Īs the dilution gene is recessive, the cat must inherit a copy from each parent in order for the trait to develop. It certainly is more difficult to find a random-bred or purebred dilute calico than other coat colours and patterns. The dilute calico coat colour and pattern is considerably less common than other coat colours and patterns but is not rare. Dilute calicos can be found across many breeds of cats as well as random-bred domestics (moggies). The dilute calico is a coat pattern and colour and not a breed. Kittens who inherit two copies of the white spotting gene will have more areas of white than kittens who only inherit one copy. The W S gene is pleiotropic (a gene that has different effects), and exhibits complete penetrance for the absence of coat pigmentation by disrupting replication and migration of melanocytes into the hair, and incomplete penetrance for hereditary deafness and iris colour. In addition to the blue and cream, the dilute calico also has areas of white, predominantly on the underside, caused by the dominant white spotting gene ( W S). The dilution gene is recessive, therefore the cat must inherit two copies (one from each parent) for dilution to occur.
Black becomes grey and orange (red) becomes cream or brown becomes lilac and orange becomes cream. The result is clumps of melanin of varying sizes along the hair shaft and areas which lack pigment, producing the illusion of a lighter coat colour. Production of melanin is normal in the dilute cat, however, the pigment granules are enlarged and deposited unevenly in the hair. Melanosomes synthesise, store and transport melanin out of the cell via the dendrites to neighbouring keratinocytes (keratin producing cells). Menalocytes are specialised cells that contain organelles known as melanosomes. Melanophilin is essential for the even distribution, transport, and translocation of melanin (pigment granules). This gene provides instructions for making melanophilin, a carrier protein found in pigment-producing melanocytes. The muted grey and cream is caused by a single base deletion 1 bp in the melanophilin (MLPH) gene. Also known as a muted calico, a dilute calico cat is a domestic cat with a tri-colour coat comprised of grey (blue) and cream along with areas of white.
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