Scientists Finally Know Why Ginger Cats Are Orange: Genetic Mysteries Unlocked

Part of the beauty of cats is their amazing range of coat colors and patterns. Visit your local cat rescue, and you’re likely to see everything from black and white tuxedo cats to lilac colorpoint, calico, and tortoiseshell. But the orange color, commonly called ginger, has been somewhat of a mystery in the world of cat genetics. Why are orange cats so incredibly orange, and why are they predominantly male?

The Suspect: ARHGAP36

Scientists may finally have answers for us. According to two different papers published simultaneously in May, ginger cats are missing a particular section of genetic information that controls the color of their fur, eyes, and skin.

The cells that give your cat their particular coloring are called melanocytes. The melanocytes contain a set of genes, made up of DNA, that instruct the body’s cells on how to function and produce melanin. The new discovery is that in these cells, a gene called ARHGAP36 is much more active.

Why does the blandly-named ARHGAP36 gene matter? When they compared the genes of cats of all colors, the scientists noticed that in ginger cats, a section of the genetic code in ARHGAP36 was missing. That section of code appeared to suppress the gene’s expression, resulting in the many coat colors we know and love. Without that code, the gene was fully active, resulting in the distinctive orange coloring.

Why Are They Mostly Male?

If you know a ginger cat, chances are good that he’s male. Scientists have been investigating this phenomenon for decades, and the prevailing theory is that it’s because this gene is carried on the X chromosome.

In case your biology is a little rusty, here’s how it works. Sex-linked traits, meaning traits that are more common in either males or females, are controlled by genes located on the sex chromosomes X and Y. Female cats (and humans) have two X chromosomes, while males have XY chromosomes. That means that a recessive gene on a male X chromosome will always be expressed, whereas a female would need to carry two copies for it to be expressed.

What does that mean for our orange kitties? One missing gene on an X chromosome in a male could be enough to turn him entirely orange. A female would have to be missing the gene on both X chromosomes to be fully orange, making it much less likely.

For more on this fascinating phenomenon, check out my colleague Dr. Karyn's detailed genetic breakdown.

A Little Background

According to the BBC, the project started as a passion project for a retired geneticist and cat-lover named Professor Hiroyuki Sasaki. He crowd-funded the research using donations from thousands of cat lovers all around the world, eventually raising 10.6 million yen (over $73,000 USD).

What’s next for these intrepid researchers? If you have any intriguing ideas from watching your cats, let us know! We can get the GoFundMe started now…

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