“Lassie, come home!”
But first, Clemson genetics researcher Leigh Anne Clark, would like to get a cheek swab to study your genes.
Anyone who has had a 5-pound Yorkie or 90-pound Lab nudge her hand, requesting a scratch under the chin or a rub of the ears, or a rescue mutt who’s been more faithful than friends or family, would be pleased knowing geneticists like Clark are working tirelessly to understand the underpinnings of diseases that affect dogs.
Clark has a simple explanation for her team’s work: “We like dogs.”
Over the past decade and a half, Clark, with her colleagues and students, has discovered genes in collies like Lassie and Shetland sheepdogs (aka shelties) that explain a variety of traits in the two breeds. In February 2017 the scientific journal, PLoS Genetics, published the results of her most recent research: the identification of two new genes associated with a painful and disfiguring disorder called dermatomyositis.
There are ramifications for humans, too, in Clark’s research. Pigment disorders affecting dogs and humans are often accompanied by hearing and vision difficulties. Understanding the genetic underpinnings of pigmentation in dogs could help scientists understand diseases in humans such as vitiligo. Dermatomyositis, an autoimmune disorder, affects collies and shelties almost exclusively, making them the only animal model for the human form of the disease.
Juvenile dermatomyositis occurs in several thousand children a year in the United States, creating a skin rash and inflammation that weakens muscles and makes joints sore. In adults, dermatomyositis strikes between ages 40 and 60. In addition to a rash and progressively weakening muscles, adults with the disease have a higher risk of cancer, lung disease and heart disease.
Studying human dermatomyositis is difficult; studying the disease in dogs is much simpler. There’s a lot of genetic diversity among people, which is healthy for the long-term resilience of the human race, but confusing when trying to pin down genes associated with a specific disease. In humans, the disease presents differently from person to person, and there’s a lack of biological data to study. With collies and shelties, the genetic pool is much smaller, making it easier to isolate genes specifically associated with the disease.
Clark became a fan of the TV show “Lassie” when she was a little girl growing up in Austin, Texas. “I thought that was the greatest dog,” she says. Who could argue? Well, Clark’s mother did. After years of Leigh Anne’s begging for a collie, her mother finally acquiesced — sort of. The family adopted a Shetland sheepdog, which looks like a miniature collie.
But that one sheltie wasn’t enough for Clark. She continued to go back to the breeder where she’d gotten the sheltie to visit new puppies.
“During one visit, the breeder asked if I’d like to help on the weekends,” Clark says. “Basically, he needed another set of hands to help with the puppies. I eagerly said yes!”
Being around the breeding practice introduced her to genetics. At Texas A&M (where, coincidentally, the mascot is a collie named Reveille), Clark worked with Keith Murphy, who served as her doctoral adviser and her boss during her postdoctoral fellowship. Murphy would later become chair of the department of genetics at Clemson and recruit Clark to the Clemson faculty.
Clark was fascinated by the work of a veterinary dermatologist on the faculty, Christine Rees, who was leading a clinical trial of improved therapies for dogs with dermatomyositis.
“Every month, this group of affected collies and shelties would come in, and she would try these new therapies,” Clark says. “We got together and decided this was a good opportunity to understand the genetics of the disease. If we can understand the genetics of the disease, then rather than treating the disease we could eliminate it altogether.”