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Test Code LAB1234609 Methylenetetrahydrofolate Reductase (MTHFR) 2 Variants

Important Note

ARUP's test code: 0055655

BILLING NOTE: This testing is not covered by Medicare and Regence Blue Cross. Patients will be responsible for the cost of this testing.

Useful For

Determines genetic contribution to hyperhomocysteinemia for individuals with elevated plasma homocysteine. Not recommended for recurrent pregnancy loss, thrombophilia screening, neural tube defect risk assessment, or testing of family members of individuals with identified MTHFR variants.

Performing Laboratory

ARUP Laboratories

Specimen Required

 

Transport 3 mL whole blood (Min: 1 mL)

Specimen Stability Information

Transport: Refrigerated.

 

Stability: Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month

Reject Due To

  • Plasma or serum
  • Heparinized specimens
  • Frozen specimens in glass collection tubes.

Day(s) Performed

Sun-Sat

Method Name

Polymerase chain reaction (PCR) and fluorescence monitoring.

CPT Code Information

81291 (Asante charge number: 3000257)

Reference Values

Negative: Neither of the MTHFR variants tested, c.665C>T (previously designated C677T) and c.1286A>C (previously designated A1298C), were detected. Other causes of elevated homocysteine levels were not evaluated

Interpretation

Background Information for Methylenetetrahydrofolate Reductase (MTHFR), 2 Variants:
Characteristics: Variants in the MTHFR gene may reduce enzyme activity contributing to hyperhomocysteinemia. Although hyperhomocysteinemia was previously reported to be a risk factor for many conditions, especially venous thrombosis and cardiovascular disease, recent meta-analysis casts doubt on whether lifelong moderate homocysteine elevation has an effect on cardiovascular disease. The American College of Medical Genetics Practice Guidelines indicate that individuals with elevated homocysteine and two copies of the c.665C>T variant have an odds ratio of 1.27 for venous thromboembolism. Thus, they recommend MTHFR genotyping not be ordered as part of a routine evaluation for recurrent pregnancy loss or thrombophilia due to questionable clinical significance.


Incidence: The allele frequency of the c.665C>T variant is 0.35 in European Caucasians, 0.5 in Hispanics, and 0.12 in African Americans.


Inheritance: Autosomal recessive; two copies of the c.665C>T variant may be a contributing factor to hyperhomocysteinemia.


Variants Tested: c.665C>T(p.Ala222Val) and c.1286A>C(p.Glu429Ala). (legacy names, C677T and A1298C, respectively).


Clinical Sensitivity: Undefined; hyperhomocysteinemia is caused by genetic, physiologic and environmental factors. MTHFR variants are only one contributing factor.

 

Analytical Sensitivity & Specificity: 99 percent.


Limitations: Only two MTHFR gene variants (c.665C>T and c.1286A>C) are tested. Diagnostic errors can occur due to rare sequence variations. 

LOINC Code Information

Component Test Code* Component Chart Name LOINC
0055657 MTHFR Mutation: c.665C>T 28005-7
0055658 MTHFR Mutation: c.1286A>C 28060-2
0055660 MTHFR Interpretation 21709-1
2001331 MTHFR PCR Specimen 31208-2

* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds

Secondary ID

  • MTHFR
  • MTHFR DNA assay