To search for the SNPs with alleles that alter the putative microRNA target sites, we first searched the PITA database for the microRNAs that could target the 3′ UTR region of the IL-22 gene. For the SNP that is in the target site, we obtained its flanking sequence (+-50bp) from the UCSC genome browser according to its genomic location. We then changed the polymorphism site and obtained one sequence for each of the alleles. First, we tested whether the change of alleles also changed the microRNA-target interaction by RNAhybrid. The RNAhybrid calculates the minimum hybridization energy between the microRNA and its target. If the alleles in the polymorphic site change this energy significantly, it might enhance or repress the regulatory function of the RNA, and thus plays a role in the disease. Second, we used RNAfold to calculate the thermodynamics of the putative target site. If the alleles change the thermodynamics of the target, this might affect the chance of the microRNA binding to its target, and thus affect the function of the microRNA. SNPs with statistical significance in either target thermodynamics or microRNA-target interaction were selected for genotyping.