Perhaps AED–gene interactions have a role in the development of hyperhomocysteinemia; patients getting CBZ or PHT have higher homocysteine levels if they were homozygous TT genotype, while those who taking valproic acid had lower levels.25 In contrast, Vurucu et al.26 did not confirm the correlation between the genotypes of 677T variants of hyperhomocysteinemia and the methylenetetrahydrofolate reductase (MTFR) gene polymorphism in patients with epilepsy and treated with valproate monotherapy and CBZ. The gene discussed is MTHFR; the disease is epilepsy.