X chromosome

Researchers suspected that the mutation causing the condition was somewhere on the X chromosome, because females, which have two X chromosomes, are less affected.

This tallies with the fact that the gene is carried on the X chromosome.

The abnormal IP gene is located on the X chromosome.

Using skin samples collected from variously colored cats, the researchers homed in on a mutation on the X chromosome that increases the amount of a protein called Arhgap36 only in pigment-producing cells called melanocytes.

Multicolored cats from such a cross are almost always female, suggesting the gene variant that makes fur orange or black is located on the X chromosome.