Ginger cats are very much part of the collective imagination, whether through Garfield or Azrael in the Smurfs. But the scientific community has long been at a loss to explain the genetic mutation responsible for their orange colour. Now, two independent research teams believe they have solved the mystery.
In most mammals, including humans, ginger hair results from mutations in a protein called Mc1r. This protein instructs melanocytes to produce either dark or light pigment with red-yellow highlights. When it is less active, these skin pigment cells are limited to producing a light pigment with a red-yellow hue, giving rise to red hair.
In cats, however, the gene coding for the Mc1r protein does not appear to be the cause of ginger hair, as the majority of ginger cats do not have Mc1r mutations. “It’s been a genetic mystery, a conundrum,” says Professor Greg Barsh, a geneticist at Stanford University, speaking to Science magazine.
Prof Barsh and colleagues sought to understand the genetic mechanisms that produce ginger hair in cats by taking skin samples from eight cat foetuses – four ginger and four non-ginger – from spay/neuter clinics. By analysing the RNA produced by melanocytes, the researchers identified the genes activated in these cells. They found that the melanocytes of the ginger cats produced 13 times more RNA from a specific gene, Arhgap36, located on the X chromosome. This discovery could explain the origin of the orange colour, as the researchers suggest in a paper, published on the bioRxiv pre-publication platform.
However, on closer examination of the Arhgap36 gene, the researchers found that it had no mutations that could account for the orange colour of some cats. They did, however, identify an anomaly in a DNA sequence located just upstream of this gene, likely to influence skin or hair pigmentation.
These results were corroborated by Professor Hiroyuki Sasaki’s team at Kyushu University, who also demonstrated the role of the Arhgap36 gene in the orange coloration of certain cats’ coats. Although this is a major discovery, further research is required to further our knowledge of these fascinating felines. – AFP Relaxnews
