Asthma is a chronic condition in which flare-ups cause the airways to swell, constrict, and fill with mucus. Asthma patients have a wide variety of substances and situations that may trigger an attack. Some patients are able to easily identify these triggers, while others struggle to find their triggers. While individual triggers may be identifiable, medical scientists are unable to say with certainty what causes a person to have asthma in the first place.
While an absolute cause of asthma has not been identified, there are elements that seem to contribute to a person’s risk of developing asthma. Smoking, exposure to polluted air, and being overweight all seem to contribute to asthma. Genetics also seem to play a role. Asthma seems to follow trends according to gender. Males are more likely to develop childhood asthma. Around age 20, new cases of asthma seem about equal between males and females. Over age 40, more females develop new cases of asthma more frequently than men. Furthermore, there is strong evidence that asthma may be inherited. It is believed that three in five cases of asthma are inherited. The Centers for Disease Control estimates that a child who has at least one parent with asthma is three to six times more likely to develop asthma himself than a child without an asthmatic patient. The risk increases even further if both parents have asthma.
Conversely, studies done with identical twins suggest that genetics cannot be entirely to blame. Identical twins share the exact same DNA, yet studies have shown that if one identical twin has asthma, the other twin only has a one in three chance of developing the disorder as well. This reinforces the belief that while heredity may play a role, the development of asthma is really more of perfect storm situation. A combination of genetic predisposition and environmental circumstances seems to be responsible for the development of asthma.