Cat color code cracked: Gene behind orange hue unveiled
Two independent research teams have finally determined what causes cats to be orange. It turns out that a specific gene is responsible for the unique coloration of domestic cats, ending years of searching for the answer to the mystery of these ginger quadrupeds.
The teams discovered that a missing segment of DNA in the non-coding part of the cat's genome is what gives these animals their distinctive orange coloration. “It's been a genetic mystery, a conundrum,” said geneticist Greg Barsh from Stanford University in an interview with Science Alert.
What are the details of the Arhgap36 gene discovery?
Barsh and his colleagues found that skin cells of cats with orange fur express 13 times more RNA from a gene called Arhgap36 compared to those of non-orange cats. Instead of a mutation in the protein-coding section, researchers identified a deletion in the preceding sequence that affects gene expression.
"The 5 kilobase deletion was present in every orange cat the researchers examined out of a database of 188 cats," described the research team in their analysis. Their work is available online and awaiting review on bioRxiv.
Does orange fur equal male cat?
The gene mutation is located on the X chromosome, which explains the differences in coloration between male and female cats. Most orange cats are males, while females with orange fur often have patches of various colors. “Taken together, these observations provide strong genetic and genomic evidence that the 5 kb deletion causes sex-linked orange,” wrote Barsh and his team in their paper.
For thousands of years, people have wondered how a black and orange cat could parent kittens with a range of colors. Males from this pairing are usually orange or black, while females can have calico or tortoiseshell coloring. The research confirmed that the mutation responsible for orange fur is located on the X chromosome, leading to these differences in coloration between sexes.
Despite a reputation for being less intelligent, there is no scientific evidence linking orange fur color to intelligence. The Arhgap36 gene is known to cause developmental issues in other animals, but in orange cats, it is over-expressed only in pigment cells.
