IL23R and Cowden disease: Since replication of genome-wide association findings in populations with different genetic background is essential to confirm disease susceptibility genes [34] and in order to clarify the phenotypic consequences of the different IL23R variants in IBD, we performed a detailed genotype-phenotype analysis in a large German IBD cohort (CD: n = 833; UC: n = 456; controls: n = 1289) by analyzing all 10 IL-23R variants for which significant linkage to CD has been demonstrated in the study by Duerr et al. [12].