MTHFR Thermolabile Variant Analysis

Test Background

Homozygosity for the c.665C>T variant in the Methylene tetrahydrofolate reductase (MTHFR) gene may be associated with increased levels of homocysteine. Note, the c.665C>T variant is also known as the thermolabile variant, and historically as C677T.

Individuals who are homozygous for c.665C>T, but have a normal homocysteine leveI are not at increased risk for venous thromboembolism or recurrent pregnancy loss. Individuals who are homozygous for the c.665C>T variant and have an elevated homocysteine level have a mildly increased risk for either event. There is no evidence of an association with mortality caused by cardiovascular disease. Women who are homozygous for the c.665C>T variant have a moderately increased risk to have a baby with a neural tube defect.

Please note, current knowledge indicates that the presence of a single copy of the c.665C>T variant is not associated with significant health risks. Therefore, heterozygosity for the c.665C>T variant is not reported by this laboratory. In addition, this assay does not assess the c.1286A>C variant in the MTHFR gene because it is reported to have limited clinical significance.  

Gene(s): 

MTHFR

About Claritas

Claritas Genomics serves children affected with complex genetic disorders by providing timely and accurate results, resolving families’ long search for answers. By combining clinical expertise of the world’s best pediatric specialists with innovative platform solutions, Claritas is working to improve patient care and enable new discoveries. We are committed to the highest quality and accessibility of information and our interpretive services and unique approach to reporting set the standard for reliably and clearly communicating genetic information.

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