In contrast, the abundances of the genera Odoribacter and Desulfovibrio are increased in several autoimmune diseases, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease34–36, likely due to an increased level of IL-17 and number of CD4+ Th17 cells. The gene discussed is IL17A; the disease is ankylosing spondylitis.