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Sample Requirements
Phlebotomists: Do not collect blood for MTHFR.
Notify ordering provider that this test is no longer available at Seattle Children's and we do not send this test out to other reference laboratories. Our Laboratory Stewardship Committee has determined that there is no proven, evidence-based clinical utility for this test for thrombophilia evaluation or other clinical indications.
If a provider wishes to discuss MTHFR polymorphism testing further, a Laboratory Genetic Counselor may be reached through Lab Client Services at 206-987-2617 or LabGC@seattlechildrens.org.
Clinical Utility
Analysis of the MTHFR gene for variants c.677C>T & c.1298A>C is no longer offered at Seattle Children's.
Current professional guidelines advise against routine MTHFR genetic testing for various health conditions due to a lack of evidence supporting its clinical utility. It was previously hypothesized that reduced enzyme activity of MTHFR led to mild hyperhomocysteinemia which led to an increased risk for venous thromboembolism, coronary heart disease, and recurrent pregnancy loss. Recent meta-analyses have disproven an association between hyperhomocysteinemia and risk for coronary heart disease and between MTHFR polymorphism status and risk for venous thromboembolism (Bashford, M.T., Hickey, S.E., Curry, C.J. et al. Addendum: ACMG Practice Guideline: lack of evidence for MTHFR polymorphism testing. Genet Med 22, 2125 (2020). https://doi.org/10.1038/s41436-020-0843-0 )
Current Professional Guidelines can be found here:
ACMG Practice Guideline: lack of evidence for MTHFR polymorphism testing-https://doi.org/10.1038/s41436-020-0843-0
ACOG Practice Bulletin No. 197: Inherited Thrombophilias in Pregnancy-https://doi.org/10.1097/aog.0000000000002703
Seattle Children’s does not offer MTHFR polymorphism testing for thrombophilia evaluation or other clinical indications.
Seattle Children’s does not send MTHFR polymorphism testing out to other reference laboratories because we do not perform third party billing for tests that are not clinically indicated.
If a provider wishes to discuss MTHFR testing further, a Laboratory Genetic Counselor may be reached through Lab Client Services at 206-987-2617 or LabGC@seattlechildrens.org.