Pet Genomics: Value and Limits
How informative are genomic tests for your pets?
This is the story of a dog called Petunia. Nature shared Petunia’s story in July to start a conversation about how we use genomics when it comes to our animal companions. The article begins:
“Last year, a 13-year-old dog, let’s call her Petunia, started having trouble walking and controlling her bladder and bowels. Distressed, her owners bought a US$65 genetic test through a direct-to-consumer (DTC) company. It suggested that the pug carried a mutation that is linked to a neurodegenerative condition similar to the human disease amyotrophic lateral sclerosis (ALS, or motor neurone disease).”
Petunia’s owners put her to sleep based on the prognosis, believing that she would suffer, become paralyzed and die.
But limited public data suggests only 1 in 100 dogs with the detected genetic mutation actually develop the rare disease that Petunia’s owners feared. The dog’s condition could have been caused by other less-serious spinal disorders.
Genomic testing can provide useful health information, even for pets, but how do we put it in its proper context?
Limited data means limited value
The most important part of understanding the value of pet genomics is having a full grasp on what we still don’t know. The Nature article points out that many dog genetic tests are based on “candidate genes.”
That’s not the same as knowing for sure that a gene — or a specific mutation within that gene — causes a given disease. It just means that the gene has been identified for further investigation. One examination of human genomics found that fewer than 2% of candidate-gene studies yielded confirmation in later research.
So far, the same rigor that scientists have been asked to apply to humans hasn’t carried over to veterinary medicine. Pet genomics companies can market tests for use based solely on small candidate-gene studies, many of which never become public. Because of that, data can point to misleading conclusions or be flat-out wrong.
The article in Nature advocates for a myriad of changes to the pet genomics industry, including setting guidelines for handling and presenting information to sharing data used to justify findings.
Everything in its right place
None of this is to say you can’t find value in genetic testing for pets. You just need context to appreciate what it is you’re actually looking at in the results.
Much of the industry surrounding the pet genome focuses on subjects like ancestry. These tests can be useful for breeding, but they can also be a fun way to learn more about your pet.
Even the medical genetics tests can offer insight, as long as you understand what you’re getting from these companies. You need to read your results carefully and remember that a claimed genetic predisposition (or a claim that the pet is not genetically predisposed) is far from definitive at this point. Treat it as one data point in determining a course of treatment and consult with your veterinarian to develop your broader plan.
Researchers work hard to reveal the secrets of the genome, both in humans and animals. Direct-to-consumer genetics tests, for people and pets alike, make understanding the state of that research all the more important, so that you can understand what the test results actually mean when they show up on your doorstep.