Determine genetic cause for hyperhomocysteinemia and potential sensitivity to antifolate drugs. Test is not recommended for women who have recurrent pregnancy loss, thrombophilia screening, or neural tube defect risk assessment.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum. Heparinized specimens.
- Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month
Characteristics: Variants in the MTHFR gene (c.665C>T and c.1286A>C) correlate with reduced enzyme activity; however, only homozygotes for the c.665C>T variant have been significantly associated with elevated plasma homocysteine levels and with an increased risk for premature cardiovascular disease. These individuals may also show toxicity from medications (ie, methotrexate) that affect folate metabolism.
Incidence: The allele frequency of c.665C>T is 0.35 in European Caucasians and 0.12 in African Americans. The allele frequency of c.1286A>C is 0.31 in European Caucasians and 0.15 in African Americans.
Inheritance: Autosomal recessive.
Cause: Homozygosity for MTHFR gene mutation c.665C>T.
Mutations Tested: c.665C>T (previously designated C677T); p.Ala222Val and c.1286A>C (previously designated A1298C); p.Glu429Ala.
Clinical Sensitivity: Undefined. Sensitivity is dependent upon multiple contributing factors.
Methodology: Polymerase chain reaction followed by high resolution melt analysis.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Only the two MTHFR gene mutations (c.665C>T and c.1286A>C) will be targeted. Diagnostic errors can occur due to rare sequence variations.
|Component Test Code*||Component Chart Name||LOINC|
|0055657||MTHFR Mutation: c.665C>T||28005-7|
|0055658||MTHFR Mutation: c.1286A>C||28060-2|
|2001331||MTHFR PCR Specimen||31208-2|
- MTHFR DNA assay