Crohn’s disease is a debilitating chronic inflammatory disorder of the bowel caused by inappropriate activation of the innate immune system in response to normal gut flora. The interplay between host gut factors and microbiota is challenging to study in humans, so little progress has been made in developing treatments. Using two of the best-studied susceptibility genes, encoding the bacterial detector proteins NOD1 and NOD2, Oehlers et al. demonstrate that the zebrafish is a tractable model for modelling Crohn’s disease. These findings establish an efficient system for testing genotype-phenotype associations relevant to intestinal inflammatory diseases. Page 832

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