Results from the top ten gene-gene interaction models elucidated the IL4Ra gene as a hub for gene-gene interactions on childhood asthma (Table 5), supporting that the IL4Ra gene may be the key regulatory element of the Th2 immune response. Gene-gene interaction between IL13 and IL4Ra was reported to affect asthma in white Dutch and Chinese populations [45]. Since MDR determines one optimal interaction model that can successfully predict high/low risk asthma phenotype, the combination of IL13 and IL4Ra gene may not be the optimal model in our analysis. This evidence concerns the gene IL4R and asthma.