The single nucleotide polymorphism of the gene 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T (or rs1801133</span>) is the most established genetic factor that increases plasma total homocysteine (tHcy) and consequently results in hyperhomocysteinemia.
The MTHFR rs1801133 CT genotype, TT genotype and T allele; the MTHFR rs1801131 AC genotype, CC genotype and C allele; the MTRR rs1801394 GA genotype, GG genotype and G allele; and the MTRR rs162036 AG genotype and AG+GG genotypes were associated with the efficacy of folic acid therapy for HHcy (P<0·05).
Genotyping of hyperhomocysteinemia associated MTHFR polymorphisms C677T (rs1801133) and A1298C (rs1801131) was done by PCR-restriction fragment length polymorphism.