Spotting the Stripes: Genetic Mutation Gives Stripes to King Cheetahs

Rare stripes in some cheetahs found only in sub-Saharan Africa made scientists classify it as a different species. Now, the mystery has been solved. Mutation in a single gene is causing the stripes in the cheetah similar to the blotched pattern or stripes in feral cats.

Researchers from the Stanford University School of Medicine along with the National Cancer Institute and Hudson Alpha Institute for Biotechnology in Huntsville, Alabama, studied the feral cats in northern California in order to understand the biological secret behind the stripes in the cheetah.

While some tabby cats have stripes on their back, some tabbies do have stripes in irregular swirls. These tabbies were called as "blotched" and were not considered as common in the wild. Even the cheetahs with the blotched pattern were initially thought to belong to a separate species and were known as "king cheetahs."

When the research team compared the DNA samples of both the tabbies and the cheetahs, they found that both the felines share a mutated gene. The gene, which was initially unknown, was dubbed as Taqpep.

During their study, experts found that every tabby cat with a blotched pattern had both the copies of the gene mutated, while every striped cat had at least one unmutated version of the gene, according to the report in Science.

They noticed the same mutated gene was found in a family of king cheetahs. But they also found that the gene Taqpep did not have any control over the actual colors of the skin.

When the experts observed the feral cat skin after a seven week gestation period, they found that a blotched pattern had appeared following the growth of hair. Further observation and analysis of the cat skin showed that the level of genes did not change; instead they found that another gene known as Edn3 mRNA was active below the black hair. As the cat grows, the varying levels in the gene Edn3 bring in a pattern of either stripes or spots.

Similarly, researchers noticed that the gene Edn3 was responsible for the pattern in king cheetahs. While Taqpep establishes the patterns or spots during the initial stages of the feline's growth, it is then implemented by Edn3 as the embryo grows.

"This is very strong evidence that Edn3 is a critical regulator of black versus yellow hair in animals," Greg Barsh, emeritus professor of genetics and of pediatrics at Stanford, said in a news release.

"The researchers hypothesize that expression of Taqpep is required to establish a pattern of stripes or spots in early feline development that is then carried out by Edn3 as the hair grows," he said.

This would also explain why the number of spots or stripes doesn't change as the feline grows into adulthood.

Experts are further planning to study about the genes, in order to find out if they have resistance to any disease, as the genes belong to the family that produce the immune system and act as receptors to defend infections caused by viruses, the Science report said.