Heterogeneity testing indicated that the above two cytokines, IL6R and CCL22, were not heterogeneous in PCOS analysis (IL6R: IVW Cochran's Q = 0.608, Pheterogeneity = 0.435; CCL22: IVW Cochran's Q = 3.251, Pheterogeneity = 0.071) (Additional File 1: Table S4). The gene discussed is CCL22; the disease is polycystic ovary syndrome.