The methylenetetrahydrofolate reductase (MTHFR) gene mutation test is used to detect two common mutations in the MTHFR gene that are associated with elevated levels of homocysteine in the blood. This test may be used as a follow-up to a homocysteine test, if homocysteine is found to be elevated. A high level of homocysteine has been associated with a greater risk of cardiovascular disease (CVD) and can be elevated from both environmental and genetic factors.
Two common mutations of the MTHFR gene are in the C677T and A1298C alleles. If a person has two copies (homozygous) of MTHFR C677T or has one copy of C677T and one of A1298C, it is likely that elevated homocysteine levels are due to these genetic mutations. Approximately 5% of Caucasians and 1.4% of African-Americans are C677T homozygotes, and are likely to have elevated serum homocysteine levels and at a higher risk of heart disease.