Scientists have finally solved the 100-year-old mystery of why some cats are orange

Time of India

16-05-2025

usually have all eyes on them. Not only because of their silly and chaotic behaviour, but also because of their fur, which is uniquely orange in colour, and the reason for it was an enigma to scientists till now.
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Now, scientists have finally solved the century-old mystery of why some cats are orange in colour.
Yes, in two studies published on Thursday, scientists have pointed out the gene that causes the orange cat fur. While one
was led by Stanford University's School of Medicine in the United States, the other
was led by researchers in Japan.
The American study
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'Over the past hundred years or so, it was recognised that orange cats kind of fall outside of the genetic rules for how coat colour in mammals is determined,' said Christopher Kaeline, geneticist at Stanford University's School of Medicine and author of the study.
Thus, the investigation into the coat colour of these felines addressed questions about animal evolution and how gene regulation is encoded in the genome.
While past studies had pointed to the orange mutation being caused by the X chromosome, by analysing sequencing data, the American scientists mapped the mutation to a DNA deletion near a gene called Arhgap36.
The researchers found that cats with the orange mutation expressed higher levels of RNA from the
, specifically in the pigment cells.
The protein produced by this gene limits a step in the middle of the biological pathway behind the coat colour.
In male cats that typically have one chromosome, the orange mutation signals more Arhgap36 protein in pigment cells and activation of a pathway to produce reddish yellow colour. Those that lack the mutation and Arhgap36 pigment cells have the colour black or brown. In females, the coat colour is more complicated as they have two X chromosomes.
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A process known as X-chromosome inactivation turns off one X chromosome in each cell, resulting in a mixed tortoiseshell or calico pattern.
The Japanese study
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Similar to the American team, the Japanese researchers also identified Arhgap36 as the reason for the orange coat colour. They also confirmed that the gene experiences chemical modifications that suggest it undergoes X-chromosome inactivation.
'The orange gene was a long-standing mystery for scientists,' said study author Hiroyuki Sasaki, a geneticist at Kyushu University's Medical Institute of Bioregulation and Institute for Advanced Study, by email.
'It is a great joy for me to have finally cracked it with my colleagues.'
Is the orange mutation responsible for ginger cats being goofy?
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It could be right? The orange mutation could be the cause that these ginger cats are way more trouble-causing than other cats, but according to the American team of scientists, it's not so. Potentially, it could be that their friendly demeanour was a by-product of them being typically males, but it could also be caused due to some other genes, as per Leslie Lyons, a feline geneticist at the University of Missouri College of Veterinary Medicine.