Variation in the interleukin 4-receptor alpha gene confers susceptibility to asthma and atopy in ethnically diverse populations

After a genomewide screen in the Hutterites was completed, the IL4RA gene w as examined as the 16p-linked susceptibility locus for asthma and atopy. Se ven known variants and one novel variant, representing all nonsynonymous su bstitutions in the mature protein, were examined in the Hutterites; on the basis of studies in the Hutterites, outbred white, black, and Hispanic fami lies were genotyped for selected markers. All population samples showed evi dence of association to atopy or to asthma (P values .039-.0044 for atopy a nd .029-.0000061 for asthma), but the alleles or haplotypes showing the str ongest evidence differed between the groups. Overall, these data suggest th at the IL4RA gene is an atopy- and asthma-susceptibility locus but that var iation outside the coding region of the gene influences susceptibility.