A study by Sniezawska et al. [167] showed that patients with epilepsy treated with AEDs changed not only their level of Hcy but also another risk factor for vascular diseases, ADMA, with the participation of genetic variants of genes regulating the level of Hcy, such as MTHFR, MTR, and MTHFD1. It has also been shown that pharmacotherapy of AEDs in patients with epilepsy increases Hcy concentration, especially in patients treated with polytherapy and long-term treatment. Here, MTHFD1 is linked to epilepsy.