Secret of Orange Cats Finally Revealed After 60-Year Search

Key Points:

• Researchers have identified that the distinctive orange fur of cats is caused by a 5 kilobase deletion in a non-protein-coding region of the Arhgap36 gene on the X chromosome, leading to increased expression of this gene in orange-furred skin cells.
• This genetic mutation explains the sex-linked inheritance pattern of orange fur, with males typically being fully orange and females exhibiting patchwork patterns like calico or tortoiseshell due to random X chromosome inactivation.
• The studies confirmed that the mutation affects pigment cells by suppressing dark eumelanin pigments and promoting reddish to yellow pheomelanin pigments, resulting in the characteristic orange coat color.
• Despite popular anecdotes about orange cats' intelligence, there is no scientific evidence linking the fur color mutation to cognitive or health issues; the gene's overexpression appears limited to pigment cells without broader developmental effects.
• Additionally, a separate global study noted a correlation between higher cat populations and increased reported happiness levels across 93 countries, though causation has not been established.