Genetic Mystery Solved: 5kb Deletion Causes Orange Cat Fur
After 60 years of research, scientists have identified the specific genetic cause for orange cat fur. Two independent teams discovered that a 5 kilobase deletion in the non-coding region of the Arhgap36 gene on the X chromosome leads to overexpression of this gene in melanocytes. This overexpression shifts pigment production from dark eumelanin to reddish pheomelanin. The X-linked nature of the mutation explains why most orange cats are male, while females often display calico or tortoiseshell patterns due to random X-chromosome inactivation.