What is Asthma?
Asthma is a disease of the airways – the breathing tubes that carry air into our lungs. It is an inflammatory disorder and leads to widespread airflow limitation. It is a variable disease, sometimes it is harder for a person with asthma to breathe, at other times the breathing is normal. The symptoms are dyspnea, discomfort, wheezing, anxiety and occasionally fatal respiratory arrest. The pathogenesis of asthma is highly complex and still incompletely understood. Asthma is a chronic (long-term) disease. The majority of asthma occurs on an IgE-mediated background with sensitizations to inhaled allergens (pollen, house dust mite etc …) called allergic asthma. Asthma based on a non-allergic background is termed intrinsic asthma. Clinically signs and symptoms of asthma vary from patient to patient. Although there is currently no cure, with the right knowledge and good management its symptoms can be controlled. Most people with asthma can lead full and active lives.
Genetics of asthma
Data from more than 30 studies show, that children of asthmatic mothers suffer 3 times more often from asthma. The fathers’ influence is smaller, but still 2.5. Hereditary factors clearly do play a role in the development of asthma. During the last decades an impressive number of the parts of the puzzle could be found: many genes, gene-gene interactions, gene-environment interactions, epigenetic modifications. In the early days of asthma genetics the hope was to find one single gene responsible for asthma. Meanwhile over 30 genes have been linked to asthma and the list is growing. Asthma is a complex disease with several clinical phenotypes (a phenotype results from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two).
Research has also identified genes responsible for individual differences in response to treatment. For instants variable response to treatment with β2-adrenoreceptor agonists is possible. Other genes have been suggested to modify responses to corticosteroids. Such observations may lead the way to personalized treatment of asthma. There are, however, many more biological processes involved in the development of asthma.
The effect of environmental exposures has been shown to have long-lasting effects on immune responses related to allergic disease, and even prenatal exposures have the potential to modify the development of atopic diseases during childhood.