Asthma researchers have found that a gene variant known to raise the risk of childhood asthma in European children plays a similar role in white American children, but not in African American children. The new findings show the gene is involved in both milder and more severe levels of asthma in children.

In the United States, about 20 million people have been diagnosed with asthma; nearly 9 million of them are children. In fact, asthma is the most common chronic illness among children in the developed world.

Asthma is a complex disease in which a variety of genes are thought to interact with each other and with environmental influences to produce its effects. As in many other genetic diseases, researchers expect that better knowledge of gene associations will pave the way for new treatments and to customizing treatments to each patient's genetic profile.

Researchers from The Children's Hospital of Philadelphia found that variants in the ORMDL3 gene were associated with childhood-onset asthma among U.S. patients of European ancestry. In 2007 a study team based in Europe had identified the ORMDL3 gene, located on chromosome 17, as contributing to childhood asthma among British and German children.

The current study, from The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, appeared as a brief online report Aug. 29, 2008 in the Journal of Allergy and Clinical Immunology.

"We replicated the European findings among American children, and showed that the gene plays a role in asthma of any severity level," said study leader and pediatric pulmonologist Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at Children's Hospital. "The previous group had detected the association of ORMDL3 with asthma by examining families having two or three members with severe disease."

Furthermore, said Hakonarson, "Through the testing of additional markers, our data suggest that other genes outside the region occupied by ORMDL3 might have important roles in raising susceptibility to asthma." His group plans further studies to further refine this and other regions.

Drawing on patients from the Children's Hospital network, the study team analyzed DNA from 807 white children with asthma, compared to 2,583 white children without the disease. Another cohort consisted of African American children, of whom 1,456 had asthma and 1,973 were healthy controls. The researchers used highly automated gene-scanning equipment at Children's Hospital's Center for Applied Genomics, the largest pediatric genotyping program in the world.

"Because asthma is a very heterogeneous disease, the genes involved in childhood-onset asthma may be very different from those involved in asthma that first appears in adults," said Hakonarson. "Furthermore, the biological mechanisms by which genetic variants contribute to asthma are not well understood. However, we will continue our investigations, to shed light on how we might use genetic knowledge to develop more effective treatments for this common disease. These treatments will be a form of personalized medicine, better tailored to the genetic makeup of the individual patient."

An Institute Development Award from The Children's Hospital of Philadelphia supported this research. Hakonarson's co-authors, all from Children's Hospital, included Patrick M.A. Sleiman, Ph.D., Julian Allen, M.D., Jonathan Spergel, M.D., Ph.D., Robert Grundmeier, M.D., Ph.D., Michael M. Grunstein, M.D., Ph.D., and Mark Magnusson, M.D. Hans Bisgaard, M.D., from the University of Copenhagen, Denmark, also collaborated.

About The Children's Hospital of Philadelphia: The Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country, ranking third in National Institutes of Health funding. In addition, its unique family-centered care and public service programs have brought the 430-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu/. 

About Asthma

Asthma (Az-muh) is a chronic disease that affects your airways. The airways are the tubes that carry air in and out of your lungs. If you have asthma, the inside walls of your airways are inflamed (swollen). The inflammation (IN-fla-MAY-shun) makes the airways very sensitive, and they tend to react strongly to things that you are allergic to or find irritating. When the airways react, they get narrower, and less air flows through to your lung tissue. This causes symptoms like wheezing (a whistling sound when you breathe), coughing, chest tightness, and trouble breathing, especially at night and in the early morning.

• Coughing. Coughing from asthma is often worse at night or early in the morning, making it hard to sleep.
• Wheezing. Wheezing is a whistling or squeaky sound when you breathe.
• Chest tightness. This can feel like something is squeezing or sitting on your chest.
• Shortness of breath. Some people say they can't catch their breath, or they feel breathless or out of breath. You may feel like you can't get enough air in or out of your lungs.
• Faster breathing or noisy breathing.

Not all people have these symptoms, and symptoms may vary from one asthma attack to another. Symptoms can differ in how severe they are: Sometimes symptoms can be mildly annoying, other times they can be serious enough to make you stop what you are doing, and sometimes symptoms can be so serious that they are life threatening.

Symptoms also differ in how often they occur. Some people with asthma have symptoms only once every few months, others have symptoms every week, and still other people have symptoms every day. With proper treatment, however, most people with asthma can expect to have few or no symptoms.

There are things in the environment that bring on your asthma symptoms and lead to asthma attacks. Some of the more common things include exercise, allergens, irritants, and viral infections. Some people have asthma only when they exercise or have a viral infection.

The list below gives some examples of things that can bring on asthma symptoms.

Allergens

• Animal dander (from the skin, hair, or feathers of animals)
• Dust mites (contained in house dust)
• Cockroaches
• Pollen from trees and grass
• Mold (indoor and outdoor)

Irritants

• Cigarette smoke
• Air pollution
• Cold air or changes in weather
• Strong odors from painting or cooking
• Scented products
• Strong emotional expression (including crying or laughing hard) and stress

Others

• Medicines such as aspirin and beta-blockers
• Sulfites in food (dried fruit) or beverages (wine)
• A condition called gastroesophageal (GAS-tro-e-sof-o-JEE-al) reflux disease that causes heartburn and can worsen asthma symptoms, especially at night
• Irritants or allergens that you may be exposed to at your work, such as special chemicals or dusts
• Infections

This is not a complete list of all the things that can bring on asthma symptoms.

Children with asthma, like adults with asthma, should see a doctor for treatment of their asthma. Treatment may include allergy testing, finding ways to limit contact with things that bring on asthma attacks, and taking medicine. For more information on asthma and available treatments, click here.