Gene May Protect Against Asthma
Presence appears to cut risk in half
 (HealthDay News) -- Researchers have discovered something that might protect people from developing the chronic lung disease asthma.
They identified a form of a specific gene that, when it's there, seems to protect people against asthma.
Although people without this gene variant do not always develop the breathing disorder, lack of it increases the chances that they will, the research indicated.
"This is the first gene that's been described that protects people from asthma," study author Dr. Craig M. Lilly, director of the medical intensive care unit at Brigham and Women's Hospital in Boston, told HealthDay. "If you have this protective form of the gene, you have half the asthma risk."
Asthma is a serious health problem that affects up to 25 percent of children who live in cities. It causes breathing problems that are called attacks. A person with asthma may cough a lot while exercising or after working out, experience shortness of breath, make a wheezing sound when breathing or feel tightness in the chest.
Symptoms get started or "triggered" by something that bothers the lungs. There are lots of triggers, including viruses, gases, cold air, dust, feathers and molds.
When people have an asthma attack, their airways start to close and it becomes harder to breathe. Prostaglandin is one of the chemicals that cause inflammation and contribute to the narrowing of airways. But prostaglandin can't work without the receptor PTGDR, and the gene that researchers are targeting has this receptor.
"These mutations cause them not to have as much of a critical receptor, and if you don't have the receptor, you don't have asthma," Lilly said. "People who have this genetic variant release [airway] constrictors, but can't respond to them."
Other studies identified an area of the human genome that probably had asthma susceptibility genes. "There were a lot of other studies that indicated something in this region that made people susceptible," Lilly said.
For this study, Lilly and his colleagues looked at gene variants in 598 people who had been diagnosed with asthma and compared the information with data from 220 people who did not have the disease.
The participants with asthma were about half as likely to have the gene variant, they found.
Drugs that may help are headed for clinical trials, Lilly said. "These drugs block prostaglandin D2, which is one of the substances that narrows the airways in acute asthma," he said.
But this is only one focal point in a complicated disease, and other experts warn against expecting too much from the results.
"There are many different causes of the inflammation that is central to asthma," Dr. Jonathan Field, director of the pediatric allergy immunology clinic at New York University/Bellevue Hospital, told HealthDay.
And even if a person has the gene variant, it may not be active.
"This is one potential site in the spectrum of asthma, one potential area that may be linked to the severity of asthma," Field said. "The goal with scientists and clinicians is to use this information and temper it with clinical evidence from patients, and continue doing studies with it in large populations."
On the Web
For more on asthma, visit the American Academy of Allergy, Asthma and Immunology online.
Author: Anne Thompson
SOURCES: HealthDay News; Craig M. Lilly, M.D., director, Medical Intensive Care Unit, Brigham and Women's Hospital, Boston; Jonathan Field, M.D., director, Pediatric Allergy Immunology Clinic, New York University/Bellevue Hospital, New York City; Oct. 21, 2004, New England Journal of Medicine; American Lung Association (www.lungusa.org)
Publication Date: Oct. 31, 2005
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