Wu et al. identified enriched gut Aspergillus tubingensis in patients with PCOS, and this fungus induced a PCOS-like phenotype by inhibiting IL-22 secretion from intestinal group 3 innate lymphoid cells (ILC3s) via inhibition of the Aryl hydrocarbon receptor (AhR)-interleukin (IL)-22 pathway in mice. This evidence concerns the gene IL22 and polycystic ovary syndrome.