What makes a calico cat?

Steve Kilpatrick ST402658 at BROWNVM.BROWN.EDU
Mon Jun 13 21:19:57 EST 1994

>From: purves at jarthur.cs.hmc.edu (Bill Purves)
>Date: 13 Jun 1994 23:41:40 GMT
>>PS -- You might even comment on how a male calico cat might come about, if
>>you want to enlighten me on that score as well!
>A male calico cat doesn't come about... the male is hemizygous for this
>locus and will express only the color determined by the allele it
>carries on its single X chromosome.

Ah, but an XXY male (resulting from fusion of a Y gamete from the male
parent and an XX gamete, indicating nondisjunction of the X during
meiosis, from the female parent) will exhibit X-inactivation, and will
be a calico if heterozygous for the X-linked coat color locus.
Accordingly, calico males are very rare.

Steve Kilpatrick
Dept. of Ecology and Evolutionary Biology
Brown University
Providence, RI 02912

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