A genetic mutation in horses that would typically halt protein production has become a molecular asset. Researchers at Johns Hopkins University and Vanderbilt University have identified a rare instance of genetic recoding that enhances oxygen metabolism and energy production in horses, donkeys, and zebras.

The findings, published in Science, provide insight into the genetic foundation of exceptional equine athletic ability, and hint at an entirely new way of dealing with stop codons.

Few mammals match horses in aerobic performance. Muscle tissue in thoroughbreds consumes oxygen at rates exceeding 360 liters per minute. Oxygen uptake per unit of body mass is more than twice that of elite human athletes. While many genes involved in muscle structure and locomotion have been studied, the genetic basis for this level of metabolic output has remained unclear.