Overview
- A Stanford-led team used modern genomic tools on DNA from orange and non-orange cats, including samples from spay and neuter clinics, to pinpoint the causal region.
- They linked the trait to a tiny deletion near Arhgap36 on the X chromosome that switches the gene on in pigment cells.
- The misexpression blocks a late step in melanin synthesis, producing bright orange fur rather than dark tones.
- The X-linked inheritance accounts for the male skew in ginger cats, with females needing two copies or else showing tortoiseshell or calico mosaics.
- No expression differences were found in non-skin tissues, and the mechanism is a rare regulatory rerouting with evidence of centuries-long presence in domestic cats.