Asthma

According to the Centers for Disease Control and Prevention, Asthma is "a chronic medical condition where the bronchial tubes (in the lungs) become easily irritated. This leads to constriction of the airways resulting in wheezing, coughing, difficulty breathing and production of thick mucus. The cause of asthma is not yet known but environmental triggers, drugs, allergies, exercise, infection, and stress have all been implicated." There is also strong correlating evidence of a genetic defect.