Paneth cells play an important role in the innate regulation of the intestinal microbiota by synthesizing and secreting peptides or antimicrobial proteins such as lysozyme or α-defensins. NOD2/CARD15 mutations lead to dysregulation of host–microbe interactions, contributing to the development of inflammation in the ileum, which is characteristic of Crohn's disease [4]. Here, NOD2 is linked to Crohn disease.