Cause of Calico Cat Coloration


Cocalico

Calico coloration only happens in female cats because the genes that control color are in the X gene and the two X genes battle it out in the cat as it develops. Here’s a video that explains the concept:

When a female embryo is four days old it consists of just 100 cells. At this point the x-chromosome from Mom and the one from Dad are both active. But in order for proper development to occur, one of the x chromosomes must be switched off. Through a tiny molecular battle within each cell, one of the x-chromosomes wins and remains active while the loser is deactivated. This is done by wrapping the DNA tighter around proteins, modifying histone tails, and DNA methylation – molecular markers to indicate this