Eight studies including 892 participants assessed circulating adiponectin, with six showing significantly lower levels in PCOS women (n = 383) versus controls (n = 355) [50,51,63,73,112,116,123] and two reporting no difference between the two groups (PCOS, n = 100; control, n = 54) (Table 3) [45,83]. This evidence concerns the gene ADIPOQ and polycystic ovary syndrome.