Gene Behind Orange fur in Cats

Scientists have finally discovered the gene responsible for orange coat color seen in orange, calico and tortoiseshell cats. Two independent studies confirmed the gene responsible for the coloring is the ARHGAP36 gene located on the X chromosome. This confirms Geneticist Clarence Cook Little theory, he originally theorized the gene would be on the X chromosome in 1912. 

The gene being on the X chromosome explains why there are more male orange cats and why only female cats can be calico or tortoiseshell. The way it works is a deletion mutation near the ARHGAP36 gene increases RNA production creating the orange color. In calico and tortoiseshell cats the gene is subject to x-inactivation which is why only female cats or male cats with an extra X chromosome are the only ones with calico and tortoiseshell fur.

 https://www.science.org/content/article/gene-behind-orange-fur-cats-found-last

https://phys.org/news/2024-12-ginger-tortie-calico-mystery-gene.html