Piebald patches seen in black and white cats and some horses are formed in the womb. But what causes them? A new study suggests an answer.

Researchers at the Universities of Bath and Edinburgh in the United Kingdom set out to learn how pigment cells behave in mice and found that they move and multiply randomly during early development rather than follow instructions.

The study was published Jan. 6 in Nature Communications.

The study’s findings contradict the existing theory that piebald patterns form on animals' coats because pigment cells move too slowly to reach all parts of the embryo before it is fully formed. In fact, there is no complicated cell-to-cell communication to send the cells in a particular direction.

"Piebald patterns can be caused by a faulty version of a gene called ‘kit,’” said Christian A. Yates, PhD, a mathematical biologist from the University of Bath and one of the study’s researchers.

“What we have found is counter intuitive. Previously it was thought that the defective kit gene slowed cells down but instead we've shown that it actually reduces the rate at which they multiply.

“There are too few pigment cells to populate the whole of the skin and so the animal gets a white belly. In addition to kit, there are many other genes that can create piebald patterns. The mathematical model can explain piebald patterns regardless of the genes involved.''

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