Horse Genome Project releases scientific standards for genetic testing

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The scientists behind the Horse Genome Project first began meeting in 1995 to develop genetic tools to benefit the equine community. The project's latest meeting, Sept. 12-15, 2018, in Pavia, Italy, was followed by a release of genetic testing standards to reaffirm the scientists' commitment to rigorous validation when translating discoveries into clinical practice.

The guidelines are a response, in part, to a rise in some commercially released genetic tests that lack published peer-reviewed results and data.

"Translation by commercial companies without sound scientific evidence is not a practice that we support. The guidelines are really a position statement by the research community to say, while we think it is valuable for scientific discovery to be translated into practice, owners and veterinarians should use caution and assure themselves that what they are purchasing is backed by published and sound scientific data," said Dr. Molly E. McCue, professor in the Department of Veterinary Population Medicine and interim associate dean for research at the University of Minnesota College of Veterinary Medicine.

Extracted DNA being dropped into test tube
After DNA extraction from blood or hair roots of horses, laboratories use molecular genetic techniques such as polymerase chain reaction assays, restriction fragment length polymorphism analyses, and sequencing to determine whether the variants of interest are present in each animal being tested. (Photo by L. Brian Stauffer/University of Illinois)

The Horse Genome Project is a long-standing group of international scientists that is currently focused on the functional annotation of the horse genome—the scientists want to know what each piece of the genome does.

Companies are more likely to sequence a horse's genome now because of a decrease in price. Sequencing the first horse genome was a $7 million project, but now sequencing costs about $1,000 per horse, said Dr. McCue, who is one of the more than 100 scientists involved in the project.

Valid genes

Dr. Finno posing with a horse
Dr. Carrie Finno, one of the members of the Horse Genome Project, says that with some of the newer genetic tests in horses, veterinarians need to provide more education that, even with a positive genetic test, the horse isn't guaranteed to get the disease. (Photo by Dr. Marybeth Whitcomb)

The guidelines from the Horse Genome Project likely won't stop some companies from selling genetic tests that haven't undergone rigorous scientific testing, but they will make people in the veterinary world more aware.

"Veterinarians need to understand that their clients are getting their information about genetic testing from places other than their (office). They are getting it from Facebook, from Twitter, and from Dr. Google. And so, it behooves us as a profession to make sure we understand the difference between responsible testing and testing that hasn't been validated so that we can inform our clients and make sure they are making the right choices," said Dr. Annette Marie McCoy, assistant professor of equine surgery at the University of Illinois College of Veterinary Medicine and member of the project.

Historically, genetic tests for horses were primarily available through a university genetic laboratory, but as private companies have started to sell and market genetic tests for horses, the need to solidify standards has increased for the community.

"At a university, we tend to be more focused on the research and discovery, so our genetic testing labs offer a service for people, but they are not focused on profit, as opposed to private commercial testing companies were they have stakeholders to answer to. So, there are some questions that are arising with some of the companies that are out there in terms of the scientific validity of some of the tests they are selling and marketing to people," Dr. McCoy said.

She continued: "There is a need for testing in a centralized location because of economies of scale, if nothing else, and you can argue whether that needs to be under a university or whether you can do it as a private company. I think you can do it as a private company. There is nothing wrong with making money off of providing a service. There just needs to be transparency, in terms of what exactly you're testing for."

The need for client education is strong, test results can be confusing, and some companies lack the proper genetic counselors to explain the results. So, the responsibility falls on geneticists to provide that education.

Horse Genome Project workshop participants, 1995
The Horse Genome Project's first workshop in 1995 in Lexington, Kentucky (Photo by Dr. Doug Antczak/Cornell University)
Horse Genome Project workshop participants, 2018
The Horse Genome Project met in September 2018 in Pavia, Italy, to discuss and draft a statement on the application of genomics in the equine industry. (Photo by Marco Santagostino/University of Pavia)

"I always try to talk to owners about services like 23andMe. If you submitted a sample for that panel and you found you had increased susceptibility to a certain disease, it does not mean you are guaranteed to have that disease, it just means you are at a higher genetic risk. It is the same thing in animals," said Dr. Carrie Finno, associate professor of veterinary genetics at the University of California-Davis School of Veterinary Medicine. "I think historically it has been if the horse tests DNA-positive, it has the disease. With some of the newer genetic tests in horses, we need to provide more education that, even with a positive genetic test, the horse isn't guaranteed to get the disease. There may be environmental risk factors and other genetic factors that play a role in disease manifestation."

A lack of genetic testing standards isn't just an equine problem.

"I've talked about getting the small animal group involved. It is the same issue in companion animal, ie dog and cat, genetics. There are these tests that come out, validation may be lacking, and there is often no associated client education," Dr. Finno said. "It is not just horses, it is a widespread, veterinary problem. ... I think the next step is for all of the scientists that work on animal genetic diseases to come together and talk about how we validate a test, how we provide education to owners and veterinarians, and how we make ourselves available for counseling on what those test results mean."

Futuristic care

Genetic testing isn't likely to go anywhere. The potential behind continuing genetic research and finding the right genetic tests for certain diseases could be endlessly beneficial to the overall health of animals.

"When we discover the basis of a genetic disease, we can diagnose it more easily, and we can also understand what is disrupted," Dr. McCue said. "If we understand what is going wrong with normal biology, then we can look at treatments that may be helpful for those animals—be it a particular drug target or changing the way those animals, like horses, are housed or managed. In short, understanding the underlying genetic mutation can help us understand disease pathology and lead to better treatment."

Genetic testing is the future of more personalized medicine, Dr. Finno said.

"There is going to be a day where you send in a DNA sample of your animal, and we can provide you with a report, similar to 23andMe for humans, that shows diseases, the best diet and exercise plan based on their genetic profile, and what they are genetically suited for as far as discipline. That is where we are going, but we all have to embrace the technology in the meantime. Once you know where it is coming from and you know the scientists behind it are validating and publishing their results, you can trust those tests," Dr. Finno said.

Scientific guidelines from the Horse Genome Project

  • Scientific discovery should be reproducible and subject to the peer-review process.
  • Scientific research projects must conform to best practice in relation to owners' consent for use of samples and research ethics.
  • Industry stakeholders must be provided with the opportunities for education so that scientific developments are best communicated for translation into practice that will have the greatest potential to benefit the horse.
  • Clear differentiation must be made between scientific developments, commercial opportunity, and opinion.
  • Some genetic tests may be diagnostic for the presence or absence of a trait; others may be used as a screening and selection tool for prediction of potential to develop a trait.
  • The integration of genetic information with traditional breeding approaches will be important for the sustainability of a healthy horse population for the future.

Read the "Consensus Statement on the Translation and Application of Genomics in the Equine Industries."

Related JAVMA content:

And coming around the track, looking promising ... The horse genome map (July 1, 2002)

Further research on horse genome receives funding (Feb. 15, 2015)

Unlocking the genetic secrets of your dog (March 15, 2017)

New database provides guidance on genetic testing in dogs (July 1, 2018)