To test the hypothesis that the UGT1A1*28 allele is associated with lower disease susceptibility to, and disease behavior within, IBD. In addition, a possible altered risk for developing IBD-drug related side-effects was explored.
Genomic DNA of 751 patients with IBD (209 patients with ulcerative colitis and 542 patients with Crohn's disease) and 930 healthy controls was genotyped for the UGT1A1*28 promoter polymorphism, and genotype distribution was compared between patients and controls. Genotype phenotype interactions were also investigated.
Patients with Crohn's disease significantly less often bear the UGT1A1*28 homozygous genotype compared to the control group, with an odds ratio of 0.64, 95%CI: 0.42-0.98. The ulcerative colitis group showed no significant differences compared to controls.
The homozygous state of the UGT1A1*28 polymorphism, associated with higher serum bilirubin levels, may be protective for the development of Crohn's disease, suggesting that the anti-oxidant capacity of bilirubin may play a part.