Tufts University Researcher Looks for Genetic Roots of Troubled Behaviors
Thanks to Boston.com for this interesting article on potential scientific breakthroughs.
Genetic link eyed in dogs' troubled ways
By Judy Foreman | September 3, 2007
All summer, Dr. Nicholas Dodman, head of the animal behavior clinic at the Cummings School of Veterinary Medicine at Tufts University, has been in doggie heaven.
Using brand new genetic "chip" technology developed by researchers at the Broad Institute of Harvard and MIT, where the entire dog genome was sequenced a couple of years ago, Dodman is finally poised to do the experiments he's been waiting years to do, exploring the genetics of complex psychiatric problems in dogs.
First, he'll compare the DNA he has collected from Doberman pinschers who suck fanatically on their own flanks with DNA from normal Dobermans to see precisely where the genes for this compulsive disorder lie. Then, he will do the same DNA comparisons of normal bull terriers and abnormal ones with another compulsive behavior, endless tail chasing. Dodman and other scientists also hope to use the latest techniques to find the genetic roots of rage in Springer spaniels, which in theory might help explain some human aggression.
"This is absolutely revolutionary," Dodman said last week.
Until the new MIT chip technology came along, the Tufts team was looking gene by gene to try to unravel the genetic origin of compulsive behavior in dogs. Now, they can search for multiple genes at once, knowledge that should also shed light on aggression and obsessive-compulsive disorders, or OCD, in people.
"It's like the difference between searching house by house for insurgents in Iraq and looking at the whole of Baghdad at once," he said.
These diseases can be easier to study in dogs than humans.
"The genetics of obsessive-compulsive disorder and other mental illnesses are likely to be very complex - and very difficult to study in humans," said Dr. Francis Collins, director of the National Human Genome Research Institute at the National Institutes of Health. "With their selective breeding and well-characterized behaviors, purebred dogs may provide a powerful system for untangling the genetic roots of these disorders." purebred dogs may provide a powerful system for untangling the genetic roots of these disorders."
Incessant tail chasing, for instance, is very breed-specific in dogs, said Alice Moon-Fanelli, a Tufts behavioral geneticist who works with Dodman. When people bring their pets in for excessive tail chasing, "nine times out of 10, it's a bull terrier or a German shepherd."
But not all researchers think studying dogs for insights into human behavior is a good idea. For OCD, for instance, human subjects make more sense, according to Dr. Michael Jenike, a professor of psychiatry at Harvard Medical School, because the testing is easy - just a blood test - and people can describe what they're thinking, which a dog obviously cannot. Jenike thinks his current research, searching for genetic markers in people with the disorder, will yield better scientific results about a disease that affects 6 million Americans and is characterized by intrusive, repetitive thoughts and ritualistic behaviors like excessive hand-washing.
Linking research on animal aggression with human behavior used to be controversial, but people nowadays are generally more accepting of the idea that genetics can influence human behavior, said Dr. Frederick Goodwin a psychiatrist and director of a center of neuroscience, medical progress and society at George Washington University Medical Center. The genetics of human aggression are still unclear, although it's obvious that "having been hit by your dad makes aggressiveness even worse," he said.
In dogs, though breeders hate to hear it, 27 percent of Springer spaniels bite people - usually their owners - said Cornell University veterinarian and animal behaviorist Katherine Houpt. Houpt and other dog geneticists are working to unravel the roots of this aggression.
Researchers in her lab found lower levels of two key neurotransmitters - serotonin and dopamine - in the more aggressive dogs. This fits, Houpt noted, with some human data linking low serotonin levels to an increased risk of suicide, which many researchers consider a form of self-aggression.
Houpt's lab has collected DNA samples from both aggressive and non-aggressive dogs and is now working with Elaine Ostrander, chief of the comparative genetics branch at the National Human Genome Research Institute (part of the National Institutes of Health) to look for "candidate" genes that may underlie aggression.