People with common MTHFR variants can have normal or elevated levels of homocysteine in their blood
or urine. MTHFR variants and elevated homocysteine levels have been studied as
When thinking about risk factors it is important to not only think about if the variants put you at risk for a condition, but if so, how much risk. You will find many studies on MTHFR and health risks. For most of these, evidence is lacking regarding an association. Described below are conditions that are more widely recognized to be associated with the common MTHFR variants.
Studies suggest that women with two C677T
Studies have also found that men and women with two C677T gene variants and elevated homocysteine levels may be at a mildly increased risk for blood clots (venous thromboembolism).
Risks associated with having one C677T and one A1298C is the same, or possibly slightly lower than, that of having two C677T gene changes.
For the vast majority of people the overall risk associated with the common MTHFR variants is small. So small, that having them does not change treatment. This is why testing for the variants is not recommended, unless a person has very high homocysteine levels. It is important to keep in mind that neural tube defects and blood clots have many other risk factors.
Very high homocysteine levels rarely result from having the common variants alone. People with very high homocysteine levels should be carefully evaluated for other factors known to affect homocysteine, such as:
Chronic conditions (obesity, diabetes, high cholesterol, physical inactivity,
Medications (atorvastatin, fenofibrate, methotrexate, andnicotinic acid)
High homocysteine levels can also result from dietary deficiencies of folate, vitamin B6, and vitamin B12. It is very important to diagnose vitamin B12 deficiencies, as high dose folic acid supplements can mask B12 deficiencies, and put people at risk for serious and irreversible symptoms. Learn more about B12 deficiency.
If high levels of homocysteine can not be explained by factors such as those listed above, a consultation with a genetics professional may be helpful in identifying rare genetic causes of the high homocysteine. To learn more about rare genetic causes, visit: Homocystinuria due to MTHFR Deficiency.
Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.
Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question
I have two clotting disorders, antithrombin 3 deficiency and MTHFR. I also only have one kidney. My question is what are all my risks and do the risks outweigh the benefits for getting pregnant? We want to have children, but are scared with everything going on. Thank you! See answer
I just found out I have a MTHFR homozygous A1298C mutation (the C677T mutation was NOT detected). What does this mean for treatment and further testing recommendations? See answer
I have recently been diagnosed with the C677T heterozygous gene mutation. What I would most like to know is: does this mutation have any bearing or is it something I do not need to concern myself with? See answer