The MTHFR gene is usually found with a specially-targeted blood test called AN MTFHR mutation test, or an MTHFR DNA test, according to the American Association for Clinical Chemistry. This test is usually only performed if the patient has a family history of improper blood clotting or early-onset cardiovascular disease, or if she has a close relative with a mutated MTHFR gene.
In healthy individuals, the MTFHR gene produces an enzyme that helps the body process amino acids, turning them into useful proteins, notes the U.S. National Library of Medicine. Mutations in the MTFHR gene often mean that the affected patient is unable to process the amino acid homocystiene into methionine. This leads a build-up of homocysteine in the blood, called homocystinuria, which may lead to a variety of other health conditions.
The MTFHR gene is also responsible for processing vitamin B9, or folate, according to MTHFR Support. Doctors may order an MTFHR mutation test if the patient is deficient in folate, or if the patient has recently had a heart attack or stroke but does not display other common risk factors. The test involves drawing blood from a vein in the patient's arm and does not generally require prior preparations such as fasting, notes the American Association for Clinical Chemistry.