- 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: Mutations in the MTHFR gene (c.665C>T and c.1286A>C) correlate with reduced enzyme activity; however, only homozygotes for c.665C>T or compound heterozygotes for c.665C>T/c.1286A>C have significantly elevated plasma homocysteine levels and 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 or compound heterozygosity for c.665C>T/c.1286A>C.
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|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