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e-mail: david-pedersen@uiowa.edu

Release: Immediate

UI researchers studying genetics of panic disorder

IOWA CITY, Iowa -- Researchers at the University of Iowa College of Medicine are interested in talking to families whose members experience panic disorder -- repeated, unprovoked bouts of anxiety or terror that occur for no apparent reason.

The researchers hope that by studying family members with this condition, they will move closer toward identifying the gene or group of genes responsible for panic disorder.

"When something frightens us, it's normal to feel panicky or anxious. But what makes panic disorder a disease is that people with this condition suffer panic attacks when there is no reason for them to be frightened," says Dr. Raymond Crowe, UI professor of psychiatry. "This is a disorder that often runs in families, which is why we are interested in its genetic origins."

Crowe recently received a three-year, $600,000 grant from the National Institute of Mental Health to continue genetic linkage studies of families with panic disorder, a project he and his colleagues have been working on for 10 years. So far, UI researchers have studied 20 families -- about 300 people -- who have three or more members with panic disorder.

Panic disorder is one of several types of anxiety disorders, along with certain phobias, obsessive-compulsive disorder and post-traumatic stress disorder. Physical symptoms -- chest pain, dizziness, shortness of breath and sweating -- can often accompany panic attacks. It affects as many as three percent of the population and affects women more than twice as often as men.

Agoraphobia, or the fear of leaving the safety of one's home and being out in public, can sometimes occur because of panic disorder, Crowe says. "We've talked to people who have become agoraphobic because they had a panic attack in a public place. The experience made them fearful of returning to these types of situations," he says.

Several medical and behavioral treatments are available for panic disorder. Various antidepressants have been effective for panic disorder, and support groups also seem to help people with agoraphobia. But as Crowe notes, researchers have yet to find the biological basis for anxiety disorders. This is where genetics studies come in.

Crowe and his colleagues conduct interviews and collect small blood samples from families who have three or more members with panic disorder. The interviews, which last about an hour and are done at the families' homes, collect information about each person's panic attacks and the conditions that cause them. The interviews help confirm which persons in a family have the condition and which do not.

DNA is then extracted from the blood samples in order to study each person's genetic makeup. Genome markers --similar to mile markers on a road or map -- enable researchers to identify similarities or differences in people's genetic sequencing. "We look for whether all of the people in a family with panic disorder share one of those markers," Crowe says. "We want to see if people with the disorder inherit the marker and also if people who don't have the disorder do not inherit it."

If they do, and this kind of sharing becomes apparent in family after family, it suggests the shared marker is close to a gene that predisposes individuals to the disorder. "We use the markers as tools to narrow it down. Then we will look for actual genes in that area and see if we can find a mutation in one of them that might be the cause," Crowe says.

By identifying the disorder-causing gene, researchers may gain clues as to what parts of the brain, or which chemical messengers to the brain, are affected. This may ultimately lead to better, targeted treatments. "We might find a deficiency in a chemical or perhaps that the chemical is present, but inactive," Crowe says. "The more people and families we are able to study, the more it helps. Families with four, five or six members with panic disorder are really valuable to us."

Families with three or more members experiencing panic disorder are invited to take part in the UI study. For more information, call (319) 353-4347.

6/26/97