Genetics of asthma: the University of Toronto Program. University of Toronto Genetics of Asthma Research Group.

In 1991, we initiated a study to identify susceptibility gene(s) predisposing individuals to the development of asthma. Our strategy was to focus on the collection of inbred populations because (1) they are likely to exhibit greater homogeneity than outbred populations, potentially important in multigenic diseases, (2) there may be fewer genes explaining the asthma diathesis in families with a "founder effect," (3) it is possible to follow the pattern of inheritance more closely, and (4) environmental factors are likely to be more uniform in geographically isolated poulations. We have identified, and in some cases collected data on inbred and/or isolated populations in Brazil, China, Easter Island, Israel, and Tristan da Cunha. We have completed a genome-wide scan on samples from Tristan da Cunha based on a coverage of approximately 20 cM between markers. In addition, we have collected hundreds of outbred individuals from Canada; these data have been helpful in narrowing a linked region based on the transmission/disequilibrium test.