More canines are being tested for potential genetic diseases, experts say use caution
Lisa Marr wanted to know more about the 2-year-old Australian cattle dog she had adopted in Missouri. So like a growing number of dog owners, the Ohio college professor bought a kit to test his DNA.
In February, she took a saliva sample from Badge and mailed it to Embark Veterinary Inc., a Boston startup. A few weeks later, she learned that he is indeed a purebred. But Embark also sent her an e-mail containing what it said “could be alarming news.”
As part of the $140 test, Embark screened Badge for about 170 genetic conditions and found that he had two copies of a mutation linked to a form of progressive retinal atrophy, which causes blindness. Marr, a 55-year-old biology professor who lives outside of Columbus, felt better after an Ohio veterinary ophthalmologist and other cattle dog owners told her it could be years before Badge goes blind.
“I’m very happy I did it,” Marr said of the DNA test, adding that she now spends $50 a month on vitamins for Badge’s eyes. “If I didn’t do it and down the road he started losing vision, I would have been much more devastated.”
But such commercial DNA tests for potential inherited diseases in dogs are drawing fire from experts.
Several prominent veterinarians and scientists say the genetic screening that Embark and a competitor have performed on well over a million dogs too often provides misleading results that can upset owners and even lead to poor medical decisions.
Dr. Lisa Moses, a Harvard bioethicist and veterinarian at Angell Animal Medical Center in Boston, said that while some inherited diseases such as progressive retinal atrophy are caused by a single defective gene, most are caused by multiple mutations.
Other factors, including the environment, also play a role in triggering genetic diseases.
And little or no research has been done to predict how often mutations actually lead to illness, she said.
“There’s a giant gulf between having a genetic variant and having the disease,” Moses said. “For the vast majority of these problems, we have zero information about how likely it is that an individual dog is going to get sick if they have that genetic variant.”
Moses and two other prominent Massachusetts researchers were so concerned about mail-in dog DNA tests that they called for regulating them in a commentary published in July in the prestigious scientific journal Nature.
The authors cited the case of a dog owner who euthanized a 13-year-old pug after a commercial DNA test found the pet carried a mutation for a neurodegenerative disease — a mutation the authors said posed little, if any, risk.
Ryan Boyko, who founded Embark in 2015 with his brother Adam, an associate professor of biomedical sciences at Cornell University’s College of Veterinary Medicine, said each genetic defect that his company screens for “has been shown to be tightly linked to disease in at least one breed.”
“It’s true that the exact percentage of dogs with that mutation that get that disease isn’t known, but it is predictive,” Ryan Boyko said. Embark’s test results, he added, routinely include caveats such as “this mutation does not in any way guarantee” a dog will develop the disease.
Embark, a spinout company from Cornell’s veterinary school, appears to be thriving despite the criticism. The privately held startup, located near Chinatown, has raised more than $19 million in venture capital, including $10 million announced last month.
Embark’s investors include Anne Wojcicki, the CEO of 23andMe, which makes a commercial DNA testing kit for humans. That test has also stirred controversy, including questions about its ability to detect all varieties of mutations in a gene linked to breast cancer.
Last year, Embark made at least $10 million in sales from its kit, which has a $199 list price but sometimes sells at a discount, Boyko said. The company started 2018 with 16 employees, has 46 now, and expects to reach 75 by the end of the year.
Embark is one of several companies that market dog DNA tests. But it and Wisdom Panel of Washington state are the best-known brands that screen for both breed and potential genetic diseases. Wisdom Panel, whose product went on the market in 2007, screens for at least 150 genetic conditions and has been used on more than 1.2 million dogs, according to company officials.
Boyko said that about two-thirds of Embark’s customers buy the kits to learn about their dogs’ ancestry. The rest want to know about risks for hereditary disease.
“Most dog owners consider them a part of their family and have a deep emotional connection and yet know nothing about their background,” Boyko said. The test is also popular among breeders, he added.
Screening dogs for genetic diseases became possible after an international team led by researchers at the Broad Institute of MIT and Harvard completed the sequencing of the dog genome in 2005. Dogs have 78 chromosomes, while humans have 46.
Ryan and Adam Boyko have long been passionate about dogs.
Ryan, 35, who graduated from Harvard University with a bachelor’s degree in computer science and holds a master’s degree in epidemiology from Yale, took DNA samples from semi-wild “village dogs” on his honeymoon in Africa. Adam, 41, who has a doctorate in biology from Purdue University, also studied those dogs and how they evolved.
Several years ago, the brothers approached Cornell and licensed technology that became the basis of the Embark test. The company has collected hundreds of thousands of canine DNA samples. Once a customer mails Embark a dog’s saliva sample, it typically takes two to four weeks to get results.
Embark says the test can identify more than 250 breeds in a dog’s ancestry — even wolf, coyote, and dingo. The firm tests for genetic conditions that range from a blood platelet disorder to forms of glaucoma.
Loki Kriese, a 32-year-old computer-aided design technician from Victoria, British Columbia, used Embark’s DNA test on Bandit, a mixed-breed female puppy she adopted. Bandit tested negative for genetic problems, but her ancestry — German shepherd, Rottweiler, and several other breeds — prompted Kriese to put the dog through intensive training.
“Without the Embark DNA test, I could not have predicted Bandit’s transition from meek and mellow puppy to working powerhouse,” Kriese said in an e-mail to the Globe.
Samantha Hughes, 34, an IBM employee who lives in Boston, tested her mutt, Madden, and learned he is a blend of four breeds: Staffordshire terrier (44.5 percent), Siberian husky (31.1 percent), golden retriever (18.9 percent), and boxer (5.5 percent). She also found out that he has a genetic mutation that could make him dangerously sensitive to multiple drugs.
But several veterinary experts said there isn’t enough scientific data to support screening dogs for most genetic mutations and that the results often confuse owners.
Angela Hughes, a veterinary geneticist at Wisdom Panel (no relation to Samantha), disagreed. Scientists have gathered a lot more data on canine genetics, she said. Just last year, she co-wrote a study of 152 genetic disease variants in more than 100,000 mixed-breed and purebred dogs.
For his part, Ryan Boyko said the feedback he gets from customers proves DNA tests are valid. As an example, he said Embark has informed some customers that their dogs had a genetic propensity for blindness, just as Badge did.
More than once, the customers told Embark employees, yes, my dog went blind years ago, according to Boyko.
Embark’s test provides another layer of information, Boyko said. It doesn’t replace a visit to the doctor.
“No genetic test is a diagnostic tool,” he said. “You still have to take the dog to the veterinarian, where they’re going to look at the sum total of the animal.”