What Makes Cats Tick(ed)? Studying the DKK4 Gene

Our feline friends are known for a wide variety of colors and coat patterns, each uniquely captivating. The biological puzzle of a cat’s coat pattern from leopards to house cats has been on the minds of scholars and theorists alike for ages. What makes a tuxedo cat black and white? Why does my brown tabby have a white tail tip?

In 2021, a paper was published in Nature Communications, authored by a group of researchers from Stanford’s Department of Genetics that uncovered a gene that may be responsible for the assignment of coat patterns in cats. The gene has been named DKK4, shortened from “Dickkopf 4”.

The foundation of the team’s hypothesis stretches back to a paper published in the early 1950’s by Alan Turing titled, “The Chemical Basis of Morphogenesis”. In the paper, Turing describes a chemical process that both stimulates and inhibits gene activity. The researchers sought confirmation that this process could be the cause of whether feline coats were solid or exhibited stripes, blotches, or ticking. In this case, the DKK4 gene is the inhibitor, causing disruptions in the overall assignment of pigmentation (i.e., stripes).

A study of kitten embryos uncovered new data, where varying thickness in the top layer of the skin mimicked what we see in adult coat patterns. The DKK4 gene was present in the skin cells of embryos, meaning their coat patterns had been genetically established even before hair follicles had formed. The study showed varying amounts of DKK4 in the skin, causing alterations in the pattern. Mutations within the DKK4 gene further disrupt patterns and result in what’s known as “ticked” or “agouti hairs”, where the hair itself is banded with two or more pigments. Ticked fur is seen commonly in Abyssinian cats.

Coat patterns can be temporarily altered by environmental factors, too. Prior to birth, the pigmentation of a kitten’s coat is very sensitive to heat. If a mom cat experiences a fever due to illness or prolonged stress, it has the potential to affect the genetic process in the developing pigment of her kittens’ fur, aptly named fever coat.

Fever coat typically presents as silver, grey, or cream-colored coats, most prominent at the tips of the fur, darkening toward the root. Fever coat creates a visually striking coat but has no negative implications for the kitten’s overall health. While the coat pigment did not fully develop in the womb, their coat color is still written in their DNA and will present a little later in the kitten’s life.

The diversity in feline coat patterns is vast, and this research focused on a small number of them. The cats we share our homes and lives with still hold many mysteries waiting to be uncovered. What we do know is each cat’s personality is just as unique as their striking appearance.

References

Kaelin, C. B., McGowan, K. A., & Barsh, G. S. (2021, September 7). Developmental genetics of color pattern establishment in cats. Nature News. https://www.nature.com/articles/s41467-021-25348-2

Turing, A. (1952, August 14). The Chemical Basis of Morphogenesis. Biological Sciences. https://www.dna.caltech.edu/courses/cs191/paperscs191/turing.pdf