September 24, 2007

Research Links Human, Canine

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For years, Cornell veterinarian and animal behaviorist Dr. Katherine Houpt has been investigating the genetic roots of aggression in dogs at the Veterinary College’s Animal Behavior Clinic. However, her research, propelled by recent technological developments and a new DNA bank on campus, could potentially shed light on human behavior as well.
Houpt and her resident Dr. Julia Albright are currently collecting blood samples from canines diagnosed as aggressive, processing it at the DNA bank and then shipping it off to the Ostrander lab at the National Institutes of Health in Washington, D.C. The data is then brought back to Ithaca, where the Cornell biostatistics department analyzes it.
“The basic goal is to find the gene or genes that may be responsible for aggression in several spaniel breeds of dogs,” Albright said.
Achieving this goal has, until recently, been a laborious process. Prior to the development of genome-wide scanning technology, Houpt and Albright, as well as others in the field, had to sift through the data individually. According to Dr. Nicholas Dodman, program director of the Animal Behavior Department of Clinical Sciences at Tufts University’s Cummings School of Veterinary Medicine, this sifting process was like “looking for terrorists, house to house.”
“Now that we can look at the whole all at once, we can see which areas the affected genes reside in,” said Dodman, who is conducting research on Obsessive Compulsive Disorder in dogs, cats and horses.
After locating the genes specific to aggression in dogs, Houpt and Albright hope to assist breeders in screening for these flaws. Such screening would reduce the number of dog attacks, which account for dozens of deaths and hundreds of injuries per year in the US, according to Albright.
But it’s not just canine aggression that Houpt and Albright are after. Identifying the aggressive genes in dogs will help enable further research on other diseases linked with aggression in other species.
“Future studies may analyze the genes associated with other types of aggression in many breeds, and even in humans,” Albright said.
The question then arises: Can human aggression truly be traced to our genetic makeup alone? According to Albright, some people do not believe that human behavior, such as aggression, has a genetic component. Dr. Frederick Goodwin, research professor of psychiatry at The George Washington University, said he thinks that making inferences about human behavior from animal DNA is not a simple process.
“For many of the basic emotion states of humans, there are animal models. But that doesn’t mean the animal model is a carbon copy of them,” said Goodwin, who has done extensive work on bipolar disorder in humans. Still, he conceded, “you can learn something valuable from [animals].”
In humans as well as animals, there are outside variables that could incite aggression and skew test results. Biologists and psychiatrists alike agree that circumstances alter behavioral conditions. But for animal behaviorists such as Houpt, Albright and Dodman, finding the “cleanest models” is absolutely essential, and doing so can help reduce flaws in the data brought on by differences in environment. Dogs are ideal candidates for behavioral research, as they can be inbred in closed populations of tight-knit genetic groups. Testing on a human population would be fraught with difficulty, Dodman said.
“You would need very large samples, and there’s the contamination factor,” he explained.
No one knows this better than Goodwin, who works with people. He added that, in animal studies, researchers can get much closer to the actual tissue than they can ethically in humans. Thus, researchers are forced to draw indirect inferences when studying human subjects.
The difficulty of studying human behavior leads many scientists to believe that animal research is the most expedient means of finding problematic genes.
“The animal people are probably going to get to the OCD gene before the massive human effort. Nothing’s easy, but we think our way might be a little quicker,” Dodman said.
Dodman predicts the gene for OCD in dogs will be found within the next three months. This optimism is shared by Houpt and Albright, whose inquiry into aggression parallels the study of OCD. Six months ago, however, none of them would have had such high hopes; around February, the Broad Institute at Harvard and The Massachusetts Institute of Technology released a chip that would catalyze the search for problematic genes, improving upon previous technology developed at NIH.
“The genome-wide scanning technology is fairly new, but very exciting,” Albright said.
According to Dodman, “the time is right” for investigating animal aggression, and he is “not surprised” that Houpt is going in that direction. As far as future studies into human behavior go, Goodwin said he believes that “the field of psychiatry is going to recognize that the study of human behavior and genetics belong in the same laboratory.”