Bronchial asthma is a chronic inflammatory disease based on an inappropriate stimulation of the immune system, for instance by environmental aeroallergens. It is characterised by bronchial hyperreactivity, reversible airway obstruction and mucus overproduction.During the last decades bronchial asthma has become the most common disease of childhood. Accordingly, many epidemiological and genetic studies have dealt with its origin. In fact, hundreds of genome-wide linkage analyses and association studies have identified several chromosomal regions harbouring asthma susceptibility genes like chromosome 2q, 5q, 6q, 11q, 12q and 13q. Also about 100 candidate genes for asthma have been described. However, not all of them have been confirmed in independent studies.Besides the genetic predisposition environmental factors play an important role in the development of allergic diseases. Studies predominantly performed in farmer children have shown that exposure to bacterial endotoxin early in life reduces the risk to develop asthma or atopy later on. Thus, recent studies focussed also on the interaction of genes variants with environmental factors which is summarised under the term genetic epidemiology.Further dissection of asthma genetics and its complex interaction with surrounding factors will hopefully help us in the development of new very specific drugs. In addition, the generation of a genetic risk profile for bronchial asthma should enable us for the first time to take well-directed preventive measurements early in live.
