MDR1 polymorphisms are associated with inflammatory bowel disease in a cohort of Croatian IBD patients

Background: Inflammatory bowel diseases (IBD) are chronic diseases of unknown etiology and pathogenesis in which genetic factors contribute to development of disease. MDR1/ABCB1 is an interesting candidate gene for IBD. The role of two single nucleotide polymorphisms, C3435T and G2677T remains unclear due to contradictory results of current studies. Thus, the aims of this research were to investigate the association of MDR1 polymorphisms, C3435T and G2677T, and IBD. Methods: A total of 310 IBD patients, 199 Crohn's disease (CD) patients and 109 ulcerative colitis (UC) patients, and 120 healthy controls were included in the study. All subjects were genotyped for G2677T/A and C3435T polymorphism using RT-PCR. In IBD patients, review of medical records was performed and patients were phenotyped according to the Montreal classification. Results: Significantly higher frequency of 2677T allele (p = 0.05; OR 1.46, 95% CI (1.0-2.14)) and of the 3435TT genotype was observed among UC patients compared to controls (p = 0.02; OR 2.12; 95% CI (1.11-4.03). Heterozygous carriers for C3435T were significantly less likely to have CD (p = 0.02; OR 0.58, 95% CI (0.36-0.91)). Haplotype analysis revealed that carriers of 3435T/2677T haplotype had a significantly higher risk of having UC (p = 0.02; OR 1.55; 95% CI (1.06-2.28)). Conclusion: MDR1 polymorphisms are associated with both CD and UC with a stronger association with UC.