genetics: implications of the mthfr rs1801131 polymorphism and the methylation cycle


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- G/G: typical

- A/G: one copy of MTHFR C677T allele (heterozygous), decreased by 40%

- A/A: two copies of MTHFR C677T (homozygous), decreased by 70 – 80%




- T/T: typical

- G/T: one copy of MTHFR A1298C (heterozygous), slightly decreased enzyme function

- G/G: two copies of MTHFR A1298C (homozygous), decreased enzyme by about 20%



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