Apart from the well-known risk factors triggered by IR, hyperhomocysteinemia is also present in PCOS due to the dysregulation of enzymes participating in homocysteine metabolism [i.e., Methyltetrahydrofolate Reductase (MTHFR) and hepatic Cystathione β-Synthase (CBS)] [36]. This evidence concerns the gene MTHFR and polycystic ovary syndrome.