Background: Inflammatory bowel disease (IBD) is caused by a combination of genetic, immunological and environmental factors. Despite recent advances in the study of IBD pathogenesis, including the discovery of the NOD2/CARD15 mutation in 40% of Crohn's Disease (CD) patients, in most IBD patients no known mutations have yet been discovered. The interleukin (IL)-13 gene is located near the IBD5 locus on chromosome 5q31, known to be in linkage disequilibrium with CD. IL-13 has a role in the pathogenesis of several chronic inflammatory diseases including IBD. The +2044G/A mutation, which encodes an IL-13 protein with glutamine instead of arginine, has been associated with various inflammatory conditions. However, its role in IBD has not been defined.
Aim: This is a study of the role of the IL-13 gene +2044G/A mutation in the susceptibility to and phenotype of IBD.
Methods: Two hundred and eighty-five patients with CD and 111 cases of ulcerative colitis (UC) were enrolled in the study. Mutation frequency was determined using restriction fragment length polymorphism study in IBD patients and 178 healthy ethnically matched controls. The mutated allele frequency was determined in various clinical sub-groups of IBD patients. Statistical significance of the differences in allele frequency in CD and UC patients and healthy controls was determined.
Results: The +2044G/A allele frequency was similar in CD, UC and healthy controls (23.3%, 19.4%, 19.6%, respectively, p = 0.294). There was no significant association of +2044G/A mutation carriage with specific phenotypes of CD and UC.
Conclusion: The IL-13 gene +2044G/A mutation has no significant role in susceptibility to and phenotype of IBD.