New test developed to fight gene doping in horses

Researchers at the University of Pennsylvania School of Veterinary Medicine have developed a test that can detect the presence of a potential gene-doping agent in the joint fluid and blood of a horse, the researchers announced on Thursday, a finding that represents the first step in combating what may be an emerging threat in performance athletics.

The researchers, who were led by Dr. Mary Robinson, an assistant professor of veterinary pharmacology at the university, developed a polymerase chain reaction (PCR) test to detect a specific gene therapy agent that had been injected into the joint of a horse. The test was able to detect the agent in the joint’s synovial fluid for up to 84 days and detect the agent in the horse’s blood for 28 days, Robinson said in an interview.

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Gene doping – or its medically valid twin, gene therapy – refers to the use of DNA or RNA material to trigger long-lasting or even permanent changes to protein development in cells. Although the concept of using gene-doping agents to improve the performance of humans and equines has been theorized for decades, researchers in both human and equine athletics have yet to produce evidence that the agents are currently in use.

However, based on their potential to radically transform the regulation of performance-enhancing substances and the challenges in detecting their use for doping purposes, researchers like those at the University of Pennsylvania have been attempting to develop tests that can provide evidence that the drugs were used to artificially create an edge in performance athletics.

“This is a great result in terms of providing a proof of principle,” said Dr. Rick Arthur, the equine medical director of the California Horse Racing Board and a member of a gene-doping subcommittee established by international racing regulators in 2016. “Anything like this helps us to be prepared for what could be a critical time in the future.”

The University of Pennsylvania researchers said that the PCR test was the first of its kind.

“For the first time, we have demonstrated that a PCR test performed on a blood sample can detect the local administration of a gene therapy into the joint of a horse,” Robinson said. However, Robinson cautioned that the test was designed to detect only a “specific gene therapy,” and further research will be needed to expand testing capabilities so that any number of theoretical gene-doping agents could be detected.

“We’re working on that right now,” Robinson said. “That’s in progress as we speak.”

Dr. Mary Scollay, the executive director of the Racing Medication and Testing Consortium, praised the researchers for their results but also cautioned that tests will need to be designed to detect the use of multiple agents in timeframes well past 28 days. Gene-doping agents can theoretically have lifetime impacts on an athlete due to their potential ability to permanently alter gene function.

“We’re talking about altering DNA on a going-forward basis, something that will impact a horse for the rest of its life,” Scollay said.

Although the gene therapy agent in the research project was able to be detected nearly three months after injection in the horse’s synovial fluid, racing regulators in the U.S. are accustomed to using blood samples to test for illegal substances, and drawing synovial fluid from horses’ joints would be logistically difficult, in addition to being incredibly expensive. Robinson said that it is unclear yet whether they can extend the detection rates for the agents in blood.

“It’s hard to say,” she said. “It depends on how much of the product hangs around.”

Although no known gene-doping agents are thought to exist, Arthur pointed to the rapid progress in developing vaccines for the coronavirus as providing a cautionary note for performance-athletics regulators. Most of the vaccines that have been developed relied on scientific principles at least tangentially related to gene therapies.

“The technology has been moving very, very quickly,” Arthur said. “It’s not beyond the realm of possibility that someone could develop a gene-doping agent very quickly.”