Interaction between CTLA4 gene and IBD5 locus in Hungarian Crohn's disease patients

Backgrounds and aims The IGR2198a_1 and IGR2096a_1 variants of the IBD5 region were found to be associated with Crohn's disease (CD) in the Hungarian population, while IGR2230a_1 does not seem to confer risk for the disease. In the present study, our aim was to investigate the statistical interaction of these three IBD5 polymorphisms with the +49 A/G substitution within the cytotoxic T lymphocyte antigen-4 (CTLA4) gene, detected previously as neutral gene variant in Hungarian IBD patients. Methods A total of 305 unrelated subjects with CD and 310 healthy controls were genotyped with PCR-RFLP methods. Results In contrast with single gene effects, after genotype stratification, the IGR2198a_1 C and IGR2096a_1 T variants were found to confer susceptibility only in subjects with CTLA4 +49 AA genotype (P=0.008; OR=1.86 and P= 0.016; OR=1.74, respectively), for IGR2230a_1 no such effect on disease risk could be demonstrated. Conclusion Analysis of specific genotype combinations unfolded a possible association between the CTLA4 +49 A/ G substitution and two of the observed IBD5 variants with respect to disease risk.