![]() ![]() These can express tortoiseshell and dilute tortoiseshell coloring. In very rare cases, male cats are born with two X chromosomes and a Y chromosome (XXY), a condition called Klinefelter syndrome in humans. They’ve only got X chromosome, so only one instruction for coat color – ruling out tortoiseshell patterning. Most male cats have the XY combination of sex chromosomes. This is almost always, but not 100% true. You may have heard that only female cats can have a tortoiseshell coat color. Can you get a male dilute tortoiseshell cat? ![]() However there is one kind of dilute tortie that is truly unique: males. There is even some evidence that suggests people prefer lighter colored cats like dilute tortoiseshells, and that selective breeding may increase the prevalence of the pattern. From the classic domestic shorthair to fancier breeds like the Persian or the Scottish Fold, dilute torties sport their unique colors in all shapes and sizes. In fact, you might know several! Since the tortoiseshell coloring can appear in many cat breeds, there are more dilute tortoiseshell cats out there than you might think from the genetic odds alone. This makes dilute tortoiseshell cats pretty special. Of these female tortoiseshell cats, they also need to carry two recessive genes for dilution. That is, they must be female, ruling out half of the feline population. To have a tortoiseshell pattern, cats need two X chromosomes. On the one hand, from a statistical perspective the odds are still against dilute torties. With all of this talk about sex-linked pigmentation and recessive genes, you’re probably wondering if dilute tortoise cats are rare. ![]() This mutation is recessive, which means a tortie cat needs to inherit it from both of her parents for it to show in her coat. And the hairs that grow from them take on take on a characteristic washed-out, or dilute, appearance. When it’s mutated, it doesn’t work properly, so those cells can’t produce as much pigment. The MLPH gene plays an important role in the pigment producing cells which give our cats’ coats their color. The answer lies in a specific mutation of a gene called the melanophilin gene, commonly abbreviated to the MLPH gene. Once diluted, black pigment turns to blue, and red pigment turns to cream, rather like adding white paint to black or red paint. The pastel colors that make dilute torties so appealing are actually just diluted versions of black and red pigmentation. And ta da – a tortoiseshell pattern emerges! Adding the “dilute” to dilute tortie – more genetics!Ĭolor dilution of the tortoiseshell pattern is also influenced by genetics. So some skin cells retain the instruction for orange fur, and others keep the instruction for black fur. This process is known as lyonization and which X chromosome deactivates is completely random in each cell. Now it gets amazing – during an unborn kitten’s earliest development, one X chromosome in every single cell deactivates. In tortoiseshell cats, these instructions don’t match – they’ve got one gene for orange fur, and one gene for black fur. Female cats have two X chromosomes, and therefore receive two sets of instructions (genes) for coat color. The X chromosome is a sex chromosome, but it also contains lots of other information, including instructions about coat coloring. Dilute tortoiseshell cat genetics – what do sex chromosomes have to do with coat color? Female cats have two X sex chromosomes male cats have one X sex chromosome, and one Y chromosome. One pair – the sex chromosomes – decide your cat’s gender. This can get a little confusing, but the results are worth the struggle!Īll of a cats physical characteristics are determined by their genes, which are arranged in 19 pairs. How does this happen?īefore we get into the reasons for dilution, it helps to understand the genetics behind the standard tortoiseshell coloring. Standard torties have a mix of orange and black fur, either finely interspersed (a brindle tortie), in big splodges (a patchwork tortie), or somewhere in between (just a tortoiseshell tortie!) Dilute tortie cats have a tortoiseshell coat pattern with one remarkable difference: instead of the striking, dark mix of orange and black, dilute tortoiseshell cats have a muted, almost blue and yellow color. Tortoiseshell cats attract attention wherever they go. In the world of cat fanciers, some coat colors elicit more curiosity than others. Tortie is short for “tortoiseshell”, a popular coat pattern seen on many cat breeds. ![]()
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