Health News

Genetic Mutation Linked to Both Irritable Bowel Syndrome and Panic Disorder

Nov. 22, 1999 (Cleveland) -- Irritable bowel syndrome is the most common gastrointestinal disorder found in women, but little is known about what causes the often-incapacitating condition. Now a team of researchers is suggesting that a genetic mutation already linked to panic disorder -- also found more often in women -- may provide clues to understanding both conditions.

Catherine L. Woodman, MD, tells WebMD that a mutation of the cholecystokinin (CCK) gene is found in about one-third of patients with panic disorder. "Of course, another two-thirds of patients with this diagnosis don't have the mutation, so this isn't the whole story," she says. Nonetheless Woodman, an assistant professor of psychiatry at the University of Iowa, Iowa City, and her colleagues decided to test their one gene fits all theory. They presented the results at the 46th Annual Meeting of the Academy of Psychosomatic Medicine in New Orleans.

Woodman says that her colleague in Iowa, Ray R. Crowe, MD, "has been looking at anxiety disorders and their association with CCK. Since there has been some linkage between psychiatric disorders and [irritable bowel syndrome], we investigated CCK as a candidate gene to determine some genetic reason for this overlap. Previous studies have demonstrated that 30% of patients with panic disorder have this mutation of CCK while only 15% of the population has it."

She and her colleagues enrolled 33 irritable bowel syndrome (IBS) patients in the study; 31 were women. Using a specially designed interview format, Woodman and her colleagues assessed the patients for psychiatric illnesses. She says that 25 of the 33 patients "had a significant lifetime psychiatric illness, and 11 of them had anxiety disorders."

"Genetic analysis found that the percentage of IBS patients who had the CCK [mutation] was exactly one-third or 11 patients. When we compared this to the control group we found that only 6% of the control group had the mutation. This is statistically significant," she says. "Of the 11 patients who had anxiety disorder, seven had panic disorder, and six of those seven patients had the mutation."

What that adds up to, says Woodman, is "a provocative finding. We know, at least in this small sample, that this [mutation] does occur in patients with IBS and that it occurs more frequently than it does in the general population. In patients with [both] IBS and panic disorder, we found the mutation in six of seven patients." She adds, however, "the numbers are so small that it is too early to draw many conclusions. The finding needs to be replicated with larger studies. This is really a pilot study."

But Woodman says that a clinical implication may not be too far off. "The good news is that we may finally be able to target treatment [to the mutation]." She says that there is already a drug in advanced stages of testing that has shown positive results.

Vital Information:

• Irritable bowel syndrome is the most common gastrointestinal disorder in women; little is known about what causes the condition.
• New research shows that one-third of irritable bowel syndrome patients have a genetic mutation that is also linked to panic disorder.
• Pharmaceutical therapies could be developed specifically in response to this gene, alleviating symptoms in this particular subset of patients.