VDR and Crohn disease: The association between VDR and Crohn's disease has been supported by multiple studies.49, 50VDR, which codes for vitamin D receptor, is engaged in NOD2 gene transcription and signalling through NOD2 to induce expressions of β‐defensin 2 and cathelicidin.51 Variants or deletion of VDR may also change the microbiota and reduce the host defence through diminishing the production of microbicidal peptides as well as ATG16L1.52, 53 However, the interaction network among genes of interest that leads to Crohn's disease needs to be elucidated in‐depth in future studies.