Ethnic differences in asthma and associated phenotypes: Collaborative study on the genetics of asthma

Background: In the Collaborative Study on the Genetics of Asthma, 314 families with 2584 subjects were characterized for asthma and allergy. Objective: The purpose of this investigation was to examine clinical heterogeneity observed in asthma and allergic characteristics among 3 ethnic groups (African American, white, and Hispanic family members). Methods: Pulmonary function parameters and asthma-associated phenotypes were compared among the ethnic groups. Results: In comparison with the other groups, African American sibling pairs had a significantly lower baseline FEV₁percent of predicted (P =. 0001) and a higher rate of skin test reactivity to cockroach allergen (P =. 0001); Hispanic sibling pairs had significantly more skin reactivity overall (P =. 001); and white sibling pairs had significantly lower total serum IgE (P <.05). In addition, there were significantly more relatives with asthma among the African American families than among the white and the Hispanic families (P =. 001). Conclusion: Although different environmental backgrounds should be considered, these clinical differences could be due to differences in genetic susceptibility among the ethnic groups, such as those suggested by our previous genome screen.