IMPORTANCE OF GENETIC-FACTORS IN ADOLESCENT ASTHMA - A POPULATION-BASED TWIN-FAMILY STUDY

Gene-environment interactions and inheritance of asthma were studied i n 16-yr-old twins and their parents who participated in the nationwide Finnish Twin Cohort Study. Between 1991 and 1994, questionnaires, inc luding a question on physician-diagnosed asthma, were mailed to the me mbers of 2,483 twin families. The individual response rate ranged from 82 to 93%. Information on parental asthma status allowed the genetic modeling of asthma data in two different groups of twins. In families where one of the parents was asthmatic, as much as 87% of the variatio n in susceptibility to asthma in twins was explained by genetic factor s. On the other hand, for twins whose parents were unaffected, a model including environmental effect alone was sufficient to explain the de velopment of asthma. Genetic influences could not be totally excluded, but their role was significantly smaller. These results indicate that the presence of asthma in successive generations is more likely cause d by shared genes than shared environmental risk factors; however, sub stantial heterogeneity among families may exist. Genetic analysis, esp ecially among the families with an obvious familial component in devel opment of asthma, may enhance the chances of revealing the pathogeneti c mechanisms involved.