Asthma is a disease that causes the airways of the lungs to swell and narrow. It leads to wheezing, shortness of breath, chest tightness, and coughing. When an asthma attack occurs, the lining of the air passages swells and the muscles surrounding the airways become tight. This reduces the amount of air that can pass through the airway. In people who have sensitive airways, asthma symptoms can be triggered by breathing in substances called allergens or triggers.
Many people with asthma have a personal or family history of allergies, such as hay fever or eczema. Others have no history of allergies. Common asthma triggers include: Animals (pet hair or dander), Dust mites, Aspirin and other NSAIDS, Changes in weather (most often cold weather), Chemicals in the air or in food, Exercise, Mold, Pollen, The common cold, Strong emotions (stress), Tobacco smoke.
Genome scans for asthma have identified significant linkages on 17 different chromosomes, including the chromosome housing the vitamin D receptor (VDR) gene.
Vitamin D receptors control a variety of different functions including the activity of the immune system.