Importantly, the same study showed that the IBD susceptibility gene Card9 controls the levels of indigenous microbes and their ability to produce indole derivatives; indeed, the microbiota of Card9-/- mice displayed a decrease in Adlercreutzia (genus), Actinobacteria (phylum), and Lactobacillus reuteri as compared to wild-type mice, as well as impaired production of indole-3-acetic acid. Here, CARD9 is linked to inflammatory bowel disease.