We recruited two case–control cohorts, from Italy (n = 1301) and Belgium (n = 2331). Subjects were genotyped for one SNP in FUT2 and two variants in ABO.
No effect on Crohn's disease risk was detected for ABO variants, whereas an association was observed between the FUT2 polymorphism and Crohn's disease susceptibility in the Belgian sample, but not in the Italian cohort. The effect of histo-blood groups was evaluated using group O as the reference. Most non-O groups had odds ratios (ORs) higher than 1 in both cohorts, and combined analysis of the two samples indicated a predisposing effect for the A and B groups (OR = 1.17, 95% CI: 1.02–1.32 and OR = 1.33, 95% CI: 1.09–1.58, respectively). In Crohn's disease patients, the non-O blood group and the non-secretor status were associated with higher risk of developing a stricturing or penetrating disease.
ABO histo-blood group might confer susceptibility to Crohn's disease and modulate disease severity.