Methylene Tetrahydrofolate Reductase (MTHFR) Polymorphism

CPT Code(s):


Specimen Requirements:

One 4 mL lavender- (purple) cap tube (EDTA)

Unacceptable Conditions:
  • Frozen specimens
  • Any-other-color-capped tubes
Stability (collection to initiation of testing):
  • Ambient: 3 days
  • Refrigerated: 1 week


Methylene tetrahydrofolate reductase (MTHFR) is an NADH-dependent enzyme that converts methylene tetrahydrofolate to methyl tetrahydrofolate. Homocysteine is converted to methionine in a vitamin B12 dependent step. Reduced MTHFR activity is associated with decreased homocysteine methionine conversion and increased plasma homocysteine concentrations. Elevated homocysteine has an association with vascular thrombosis. Homozygosity for MTHFR gene mutation C677T is associated with elevated plasma homocysteine especially in the
setting of folate deficiency.


Polymerase chain reaction followed by restriction enzyme digestion and agarose gel electrophoresis


Within 10 days

Reference Values:

Negative for the methylene tetrahydrofolate reductase C677T mutation