This result suggests that these genes do not harbor susceptibility variants common to both races due to a) variation in signatures of natural selection resulting in differences in allele frequencies; b) varying linkage disequilibrium patterns at causal loci across different populations (as shown for IL4 – Figure 2); and/or (c) there may be common and distinct pathways that contribute to the development and expression of asthma phenotypes between these two groups. Here, IL4 is linked to asthma.