Thus, we conducted this case-control study to investigate the effects of SNPs in genes encoding OCM-related enzymes and AEDs (e.g., VPA, OXC, LTG or LEV monotherapy) on Hcy levels in patients with epilepsy and to further explore specific SNPs that may increase patients' susceptibility to the effects of AEDs on Hcy levels. Here, OCM is linked to epilepsy.