IL-1β-511 and IL-1RN*2 polymorphisms in inflammatory bowel disease: An Italian population study and meta-analysis of European studies

Background: Several studies have tried to find possible associations between genetic polymorphisms and inflammatory bowel disease prevalence and/or phenotype. Our objectives were to test the frequency and phenotypic association of two polymorphisms of the interleukin-1 pathway, IL-1β-511 and IL-1RN*2, in inflammatory bowel disease patients and controls from an Italian population, and to compare our data with previously published similar studies in Europe. Methods: We screened 290 inflammatory bowel disease patients (178 ulcerative colitis and 112 Crohn's disease) and 106 controls for IL-1β-511 and IL-1RN*2 polymorphisms by polymerase chain reaction (PCR)-based methods. The prevalence of the IL-1β-511 and IL-1RN*2 polymorphisms in European inflammatory bowel disease patients was calculated by a meta-analysis of previously published studies using the Mantel-Haenszel method. Results: No correlation between the IL-1 polymorphisms and inflammatory bowel disease prevalence was found in our study population. Crohn's disease patients with the IL-1β-511 mutation had a higher rate of complicated disease. A trend for an association between the IL-1RN*2 mutation and a higher risk for inflammatory bowel disease has been found only in studies with Northern European populations. Conclusions: The IL-1β-511 mutation can be associated with complex disease behaviour in Italian Crohn's disease patients. The IL-1RN*2 mutation may play a role in Northern European people with inflammatory bowel disease.