Scientists solve the mystery of orange cats

Garfield, Puss in Boots, Toulouse from Disney's "The Aristocats": cultural icons, perhaps; oranges, without a doubt.

Now, scientists on two continents have solved the mystery of the DNA that gives our furry friends, particularly males, their remarkable color.

Scientists hope that solving the puzzle may also help shed light on whether orange cats are at greater risk for certain health problems.

For decades, scientists have observed that cats with completely reddish coloration are much more likely to be male. This coincides with the fact that the gene is located on the X chromosome. Chromosomes are larger sections of DNA, and male cats, like other mammals, have one X and one Y chromosome , which contain different numbers of genes.

Since this is a gene found only on the X chromosome, which in this case controls pigment production, a missing DNA fragment is enough for a cat to become completely red-haired.

In comparison, female cats have two X chromosomes, so DNA would need to be lost on both chromosomes to increase production of lighter pigments to the same extent, meaning mixed coloration is more likely.

"These reddish and black shapes are due to the fact that, early in development, one X chromosome in each cell is randomly exchanged," explains Professor Hiroyuki Sasaki, a geneticist at Kyushu University.

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"As cells divide, areas with different active coat color genes are created, resulting in distinctive patches."

They discovered that red-haired or orange-haired cats are missing a section of their genetic code, meaning the cells responsible for their fur, eyes, and skin tone produce lighter colors. The breakthrough has delighted not only scientists but also the thousands of cat lovers who originally funded the research.

It has been known for decades that genetics gives orange tabby cats their distinctive hue, but until now, scientists have been unable to pinpoint the exact location in the genetic code.

Two teams of scientists from Kyushu University in Japan and Stanford University in the US revealed the mystery in simultaneous articles published Thursday.

What the teams discovered was that in the melanocytes—the cells responsible for giving cats their fur, hair follicles, and eye color—of these animals, the ARHGAP36 gene is much more active.

Genes are made up of fragments of DNA that give instructions to a cat's cells , like those of other living things, on how to function.

By comparing the DNA of dozens of cats with and without orange fur, they found that those with reddish coloration had a section of DNA code missing in this ARHGAP36 gene.

Without this DNA, ARHGAP36 activity increases. Scientists believe the gene instructs these melanocytes to produce a lighter pigment.