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X-Chromosome Causes Calico Coloring In Cats

A group of researchers at the University of California San Francisco has found a way to visualize the genetic process that gives calico cats their unique coats. For decades, scientists have known that calicos' splashes of color are caused by the random shutdown of a cat's X-chromosome in individual cells -- which explains not just the patchy coat, but also why calicos are almost always female. The X-chromosome that gets randomly turned off is responsible for determining sex, but also contains the gene that determines a cat's fur color. Before, scientists couldn't see which genes became inactive in the process that produces the calico coat -- but now, they can.

Using two different types of radiological scanning, researchers can now produce three-dimensional images of cat cells, which allow them to see which X-chromosomes are turned on and which are turned off. This process will not only help scientists understand mysterious feline phenomena like the calico coat better, but could also be the key to understanding a variety of X-linked genetic diseases in both cats and humans.

Chromosome scan image via E.A. Smith/UCSF View.