Gene Variant Offers Asthma Protection
By Amanda Gardner, HealthDay Reporter
WEDNESDAY, Oct. 20 (HealthDayNews) -- Researchers have identified a form of a particular gene that, when present, can help protect people from developing asthma.
Although people without this particular gene variant are not condemned to having the breathing disorder, it does increase the likelihood of developing it, a new study says.
"This is the first gene that's been described that protects people from asthma," said study author Dr. Craig M. Lilly, director of the medical intensive care unit at Brigham and Women's Hospital in Boston. "If you have this protective form of the gene, you have half the asthma risk."
The research appears in the Oct. 21 issue of the New England Journal of Medicine.
Asthma is a significant public health problem, affecting as many as one in four children in urban areas.
During an asthma episode, a person's airways start to close up, making it more difficult to breathe. Prostaglandin is one of the chemicals that cause inflammation and contribute to the narrowing of the airways. Prostaglandin needs a receptor, PTGDR, to work. The gene in question contains 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."
Previous studies had identified a region of the human genome that likely contained these so-called 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 variants in genes of 518 white patients and 80 black patients with asthma. This information was then compared with data from 175 white and 45 black individuals who did not have asthma.
Participants with asthma were only about half as likely to have the gene variant.
According to Lilly, drugs to block the receptor are about to enter clinical trials. "They were developed for asthma and allergic rhinitis, and are just now being tested in humans," Lilly said. "These drugs block prostaglandin D2, which is one of the substances that narrows the airways in acute asthma."
But this is only one thread in a very complicated disease, and other experts warn against reading too much into the results. "There are many different causes of the inflammation that is central to asthma," said Dr. Jonathan Field, director of the pediatric allergy immunology clinic at New York University/Bellevue Hospital. "This is another tool in our armamentarium for diagnosis and treatment, but it has to be tempered with further study and clinical evidence."
And even if a person has this particular gene variant, it is not always expressed or active. "This is one potential site in the spectrum of asthma, one potential area that may be linked to the severity of asthma," Field added. "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."
More information
For more on asthma, visit the American Academy of Allergy, Asthma and Immunology (www.aaaai.org ). 
SOURCES: 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
Copyright � 2004 ScoutNews, LLC. All rights reserved.
|
