High homocysteine levels (MTHFR gene test)

Methylenetetrahydrofolate Reductase (MTHFR) is a key enzyme required to metabolise homocysteine. The most common mutation in MTHFR is called C677T.

People with two copies of this mutation are called homozygotes, and are found in 5-10% of the population. These individuals are predisposed to developing high blood levels of homocysteine, particularly when their diets are low in folate. A second mutation in the MTHFR gene called A1298C has also been implicated with high levels of homocysteine, when found together with the C677T mutation. MTHFR gene mutations found in individuals with other inherited clotting genes (eg Factor V Leiden) have a dramatically increased risk of venous thrombosis.