In order to determine the importance of these regions in asthma susceptibility and the impact of environmental rink factors, the investigators l) evaluated the evidence for linkage in the complete CSGA data using 2-point, multipoint and multilocus approaches for asthma and associated phenotypes (including BHR, total serum IgE and skin test reactivity to standardized allergens); 2) performed fine mapping studies of regions using additional genetic markers to obtain a < 2 cM map; 3) identified candidate genes and novel sequence variants; and 4) characterized a patient population with asthma to study identified variants with respect to asthma severity and bronchial inflammation. These studies allowed identification of asthma susceptibility genes and their variants, interactions with other genes and environmental risk factors, as well as provided insight for the development of improved treatment and ultimate prevention of asthma.