Besides, the production of defensin, another vital AMP, would be triggered when pathological microbes stimulated toll-like receptors and intracellular sensors, such as NOD2 and NOD-like receptor (NLRs), and the mutation of NOD2 might increase the susceptibility to Crohn’s disease due to the lack of defensins (29, 30). The gene discussed is NOD2; the disease is Crohn disease.