Individuals homozygous for the SNP rs1801133 (MTHFR_c.665C>T(Ala222Val)) have lower MTHFR activity than CC or CT (heterozygous) individuals and therefore are predisposed to hyperhomocysteinemia associated with lower plasma folate levels (Majhi et al., 2023). This evidence concerns the gene MTHFR and hyperhomocysteinemia.