Furthermore, to evaluate effect of PCOS on leptin system in BMI-matched subjects, the results showed that PCOS in lean subjects had significantly higher FLI and reduced leptin receptor than in the results of lean subjects without PCOS (p = 0.002 and p = 0.041), respectively, while no significant difference was detected for leptin levels in both groups (p = 0.282). This evidence concerns the gene LEP and polycystic ovary syndrome.