MTHFR is an enzyme responsible for converting 5,10-methylenetetrahydrofolate to the product 5-methyltetrahydrofolate - it is involved in the metabolism of folate and homocysteine. The product of the reaction catalyzed by MTHFR converts homocysteine (a potentially toxic amino acid) to methionine (a useful and necessary amino acid).
Certain mutations in the gene coding for MTHFR produce an enzyme that has reduced activity. Reduced activity can lead to elevated levels of homocysteine (a.k.a. hyperhomocysteinemia). High homocysteine (>13umol/L) may double the risk of developing illness or complications. MTHFR genotyping can provide information about potential causes of elevated homocysteine and approaches for addressing it.
Based on MTHFR and homocysteine results, physicians can develop dietary and medical recommendations - increased intake of folate alone or in combination with vitamins B6 and B12 are recommended.