This is my sister Sara getting slapped in the face by our late kitty Tiger.
I just finished up a genetics class this quarter and cat coat colors were brought up a lot as examples, and me being cat crazy-of course I found this interesting.
I grew up with a dilute calico cat named Tiger. You can read a little bit about Tiger on my sister’s blog here.
So here is how you genetically get a dilute calico cat:
Mammals have two sex chromosomes, XX for females and XY for males. You get one chromosome from each parent. So, if a female gets an X chromosome from mom that is carrying the orange gene, and an X chromosome from dad that is carrying the black gene, we have the beginnings of a calico cat.
Next: In females, one of the X chromosomes is inactivated. So, in a calico (this applies to torties too) where you see orange, the X chromosome carrying the black gene was inactivated in that particular spot and all the cells surrounding descended from the cell with the inactivated black X chromosome. The same happens in reverse to get black spots.
You may ask: where does the white come from then? Well that is another gene, that is not linked to the sex-chromosomes (called autosomal). The gene is called pie-bald spotting. It can happen in humans-you’ll see patches of skin lacking pigment in random places around the body. So, a tortoiseshell cat does not have the pie-bald spotting gene and a calico does.
Next: Why is Tiger gray and light orange? The answer is yet another gene-solid or dilute. Tiger has the gene that codes for a dilute coat color.
That explains the basic genetics of how a calico cat comes about. Male calico cats are possible but are very rare. In order to have a male calico the cat must still have two X chromosomes. So he could be an XXY or an XX that includes SRY (maleness gene-in rare instances it can cross-over from the Y chromosome to an X and pass it on to offspring).
So there you have it-an introduction to cat coat genetics.
