In order to investigate the potential involvement of CCL25/CCR9 and MMPs in the pathogenesis of HOR among patients diagnosed with PCOS, the correlations between CCL25/CCR9, MMPs and AMH, AFC, the number of oocytes with a diameter of ≥14 mm during COS, E2 on the HCG day, the number of oocytes retrieved, and HOMA-IR were investigated (Table 2) using Spearman's rank correlation analyses. This evidence concerns the gene CCL25 and polycystic ovary syndrome.