Results: Methylenetetrahydrofolate reductase (MTHFR) rs1801133 was associated with elevated serum Hcy levels in patients with epilepsy (P < 0.001), and patients presenting the TT genotype exhibited higher serum Hcy levels than patients with the CC (P < 0.001) or CT (P < 0.001) genotype. Here, MTHFR is linked to epilepsy.