CCL4 and polycystic ovary syndrome: For example, a case-control study involving 60 PCOS patients and 30 controls reported that serum levels of CCL4 were higher in PCOS patients compared to controls (191.85 ± 17.54 vs 165.31 ± 11.01; P > .05).[7] Other studies have reported similar results, showing that MIP-1β concentrations in follicular fluid are increased in non-obese PCOS patients.[37] Our genetic MR analysis investigated the causal relationship between CCL4 and PCOS, consistent with these findings.