The MTHFR gene provides instructions for the body to make an enzyme called methylenetetrahydrofolate reductase. Normally, this enzyme changes an amino acid (homocysteine) into another amino acid (methionine). A severe decrease in the methylenetetrahydrofolate reductase enzyme, due to MTHFR mutations, can cause the homocysteine level in the blood and urine to be high (homocystinuria) and the methionine level to be low. In severe cases, this may increase the risk for nearsightedness (myopia), dislocation of the lens of the eye, abnormal blood clotting, brittle bones (osteoporosis), and learning problems. However, most MTHFR mutations are not associated with health issues.
Some common MTHFR gene changes are thought to increase the risk of other health complications, including certain birth defects that affect the brain and spinal cord of a baby (neural tube defects) as well as increase the risk of common health issues, such as heart disease, high blood pressure, stroke, and certain types of cancers. However, researchers have not been able to prove a strong connection between common MTHFR gene changes and an increased risk for these health issues.
MTHFR mutations are inherited in an autosomal recessive manner. People have two copies of the MTHFR gene and, in order to have homocystinuria, a person needs to have a mutation in both copies. If you or your child has been diagnosed with MTHFR gene mutations, talk to a doctor to decide if medical management is needed. Support groups are a good resource for additional information.