Horses have undergone a genetic mutation previously observed only in viruses 🐎

Horses possess a rare genetic peculiarity. This adaptation partly explains their exceptional endurance without compromising their cellular health.


A team of researchers has identified a mutation in the KEAP1 gene in horses, which enhances their energy production while protecting their cells from oxidative stress. This discovery, published in Science, sheds light on a unique evolutionary trick, similar to a mechanism previously observed only in viruses. Horses thus rewrite genetic rules to optimize their performance.

Horses can consume more than double the oxygen of the most elite human athletes. This ability relies on high mitochondrial density in their muscles but also generates significant amounts of free radicals. The KEAP1 gene mutation allows them to maintain a delicate balance between energy and protection against cellular damage.

The study compared the KEAP1 gene in 196 mammalian species, revealing an adaptation specific to equids. Unlike what usually occurs, a premature stop codon is recoded into a functional amino acid, thereby improving the gene's efficiency. This genetic modification is a first among vertebrates.

This mutation reduces the repression of the NRF2 protein, essential for combating oxidative stress. It simultaneously increases mitochondrial respiration and ATP production, giving horses a unique energetic advantage. This controlled activation of NRF2 does not appear to have harmful effects.

The implications of this discovery extend beyond equine biology. Understanding how horses manage oxidative stress could inform research on human diseases such as cancer or COPD. This study opens new perspectives on genetic adaptation and its potential applications in medicine.

How can a stop codon become functional?

A stop codon is normally a signal that tells the cell to halt protein production. In horses, this signal is recoded into an amino acid, cysteine, allowing the KEAP1 gene to continue functioning. This mechanism demonstrates how a mutation can redirect a genetic function toward an evolutionary advantage.

This recoding is made possible by specific modifications in messenger RNA, which translates genetic information into proteins. Horses have thus developed a unique way of exploiting their DNA to enhance their physical performance.

This adaptation highlights the plasticity of the genetic code and its ability to evolve to meet specific needs. It also provides an example of how seemingly negative mutations can be repurposed for beneficial outcomes.