MTHFR Common Polymorphisms

Aug 1, 2017 | Articles, Opinion

Editor’s note:

The topic of the MTHFR gene crops up every now and then in our private support group. A medical professional who happens to also be a member of our group was concerned about unfounded fears raised by common misunderstandings about this gene. She wrote the following to clarify the facts about this gene and hopefully ease concerns.


By Jenn

The MTHFR gene that has some very common changes within it (so common that 50% of us carry 1 or 2 changes within this gene).  When this gene was first discovered it was thought to be associated with many health concerns including blood clots, pregnancy loss, anxiety, etc.  This has all since been disproven.  Now many medical associations (ACMG, ACOG, AAFP) are recommending not testing for this gene.

There are nearly 20,000 genes in the human body.  Each gene is made up of 4 DNA letters, or nucleotides: A, C, T, and G.  The combination of these DNA letters code for the instructions to make a protein.  Proteins are the molecules that perform a specific function in our body.  Every person has many changes in their DNA sequence.  It is estimated that every person has approximately 10 million genetic changes.  The vast majority of these changes are known as single nucleotide polymorphisms (SNPs).  SNPs are common changes that do not impact our health or development but are normal differences in our DNA sequence (

The MTHFR gene has two SNPs that are very common: 677C>T and 1298A>C.  When these two changes were originally identified, multiple studies were performed to determine if these SNPs were associated with a variety of health concerns including risk for blood clots, heart disease, neural tube defects, chromosome abnormalities, pregnancy loss, mental health concerns, cancer, etc.  As the knowledge of the genetic basis of human disease has expanded, it became clear that these two changes in the MTHFR were not the cause of these health concerns. It is now recommended by the American College of Medical Genetics and Genomics, American College of Obstetrics and Gynecology, and Society for Maternal Fetal Medicine that testing for these common changes NOT be performed.

There are many websites and blogs that provide misleading information about this particular gene.  For reliable information on this gene and the common genetic changes found in MTHFR please visit:

Science articles and blog posts available for the public:

%d bloggers like this: