What makes a calico cat?

Raphael Carter raphael at indirect.com
Sat Aug 6 13:39:43 EST 1994

In article <31pc3q$ira at search01.news.aol.com> inin at aol.com (Inin) writes:

>In article <bowersox.771542380 at taweret.Colorado.EDU>,
>bowersox at taweret.Colorado.EDU (Paul Bowersox) writes:

>i thought there was no such thing as a male calico cat

That's more or less true.  Red in cats is carried on the X chromosome.  A 
female cat that is homozygous for red, or a male cat that has the red gene on 
his (one) X chromosome, will be a red tabby.  A female cat that is 
heterozygous for red will be some variety of tortoiseshell; if she also 
carries the dominant gene for white, she will be a calico.  It takes two X 
chromosomes to make a calico, so the only calico "males" have abnormal 
karyotypes like XXY.  They're very rare, and most of the time they're 

Another consequence of the above is that there are are more male than 
female red tabbies, since the male only needs one red gene to become a 
red tabby while the female needs two.  

Interestingly, there's no such thing as a solid red cat, not really; the red 
gene overrides the "solid" gene.  Cats that appear to be solid red always 
have a very subtle, blurred tabby pattern which you can see on close 

== Raphael Carter | raphael at indirect.com | pre-operative Minnesotan ==
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