Since MDP-sensing and subsequent MDP-induced CCL20 expression have been shown to be affected by Crohn’s disease-associated NOD2 mutations, all patients with Crohn’s disease were genotyped for the three main Crohn’s disease-associated NOD2 mutations: p.Arg702Trp (rs2066844), p.Gly908Arg (rs2066845), and p.Leu1007fsX1008 (rs2066847). This evidence concerns the gene CCL20 and Crohn disease.