Previous MR studies investigating the causal relationship between cytokines and PCOS identified associations between IL-17, SDF1a, and IL-4.[38] However, these associations were not confirmed in our primary and replication MR analyses, which included a large sample size of PCOS cases and the most extensive range of cytokines in GWAS to date. This evidence concerns the gene CXCL12 and polycystic ovary syndrome.