For decades, orange cats have charmed their way into homes and hearts. But their vibrant fur color has been a genetic mystery, puzzling researchers for 60 years.
Now, scientists have uncovered the secrets behind this distinct feature, revealing the genetic factors that give these cats their unique hue, according to Ziare.
The research, carried out by two independent teams, focused on a gene called Arhgap36. Researchers found that orange cats produce significantly higher amounts of RNA from this gene compared to non-orange cats.
What’s surprising is that the mutation isn’t in the protein-coding region of the gene but in a sequence just before it. This missing segment, about 5 kilobases long, influences how the gene is expressed, leading to the development of orange fur.
The discovery stems from an analysis of 188 cats, including 145 orange cats, six calicos, and 37 non-orange cats. The genetic deletion was present in every orange cat studied.
These findings confirm that the gene responsible for orange fur is located on the X chromosome, shedding light on why male orange cats are more common.
Why Orange Cats Are Often Male
The connection to the X chromosome explains the gender disparity, that is known to be found among orange cats.
Male cats have only one X chromosome, so if it carries the mutation, they will be orange.
Female cats, with two X chromosomes, experience a phenomenon called X-inactivation.
This leads to patterns like calico or tortoiseshell, where orange fur is mixed with black or white patches. In rare cases, when both X chromosomes carry the mutation, female cats can also be entirely orange.
A second study by Kyushu University supported these findings, showing that increased activity of Arhgap36 suppresses other pigmentation genes.
This shifts pigment production from darker shades to red or yellow.
These breakthroughs not only explain the genetics of orange fur but also the patterns seen in calico cats. The additional mutation causing white patches in calicos disrupts pigment cell development during early growth.
