MTHFR
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
An MTHFR test detects common genetic variants in the MTHFR gene using a blood sample taken from a vein in the arm. It is used to help assess inherited factors that may affect folate metabolism and homocysteine levels, and may be considered in the investigation of conditions such as cardiovascular disease or recurrent pregnancy complications.
Why get tested?
To evaluate the cause of elevated homocysteine levels.
When to get tested?
When you have elevated homocysteine levels.
Sample required?
A blood sample is obtained by inserting a needle into a vein in the arm.
Test preparation needed?
No test preparation is needed.
Common questions
The methylenetetrahydrofolate reductase (MTHFR) mutation test is used to detect two relatively common mutations in the MTHFR gene that are associated with elevated levels of homocysteine in the blood. It is not routinely performed within the UK.
An MTHFR test is not recommended, nor homocysteine, in diagnostic testing for inherited high clotting risk, thrombophilia. There is also no role for testing is cardiovascular risk assessment either.
Though the MTHFR test may be used to help determine the cause of elevated homocysteine, the value of measuring homocysteine levels outside of people presenting with homocystinuria is not clear. Homocystinuria is detected by the neonatal heel prick screen therefore most people born in the UK will have had homocystinuria excluded at birth.
The MTHFR test may very rarely be requested when a person has elevated homocysteine levels but not usually within the UK.
If a person has two copies (homozygous) of MTHFR C677T, or has one copy of C677T and one of A1298C, then it is likely that elevated homocysteine levels in that person are due to these inherited mutations, or that the mutations are contributing to them. Other, rarer MTHFR genetic mutations will not be detected with typical testing.
Besides MTHFR mutations, there are other causes of elevated homocysteine levels, including deficiency of vitamins B6, B12, and/or folate; these vitamins are required for homocysteine metabolism.
MTHFR mutations are a rare cause of homocystinuria, a condition caused by a defective enzyme that disrupts methionine metabolism, leads to greatly increased amounts of homocysteine in the blood and urine, and causes a variety of complications. The most common cause of this condition is a deficiency in the cystathionine B‑synthase (CBS) enzyme. The MTHFR mutations that cause homocystinuria are typically not detected by this test.
It is not offered in every laboratory. In most cases, your blood will be sent to a reference laboratory.
No, you inherit a copy of the gene from each of your parents and they will not change over time.
Even when two people have the same MTHFR mutations, the results are often different. Many things can affect homocysteine levels, including MTHFR enzyme activity, folate levels, and a person’s health status.