IL4 and asthma: For example, the analysis of genotyping data from a large population of German children revealed that when polymorphisms in IL4, IL13, IL4RA and STAT6 pathway genes were combined in a stepwise procedure, the risk for high serum IgE levels increased by 10.8-fold and the risk for the development of asthma increased by 16.8-fold, compared with the maximum effect of any individual SNP[26].