The importance of genetic influences in asthma.

Asthma is a complex genetic disorder in which the mode of inheritance is not known. Many segregation studies suggest that a major gene could be involved in asthma, but until now different genetic models have been obtained. Twin studies, too, have shown evidence for genetic influences in asthma, but have also revealed substantial evidence for environmental influences, in which nonshared environmental influences appeared to be important. Linkage, association studies and genome-wide screening suggest that multiple genes are involved in the pathogenesis of asthma. At least four regions of the human genome, chromosomes 5q31-33, 6p21.3, 11q13 and 12q14.3-24.1, contain genes consistently found to be associated with asthma and associated phenotypes. Not only genes associated with asthma but also genes which are involved in the development and outcome of asthma will be found in the future. This will probably provide greater insight into the identification of individuals at risk of asthma and early prevention and greater understanding for guiding therapeutic intervention in asthma. Exchange of information between researchers involved in the genetics of asthma is important because of mandatory agreement on phenotypes and analytical approaches. Genetics will contribute to the a better understanding and management of asthma in the future.