Fort Worth, Texas,
15:39 PM

What Do We Know About MTHFR?

The Doc Smitty talks about Methylene tetrahydrofolate reductase

A Note About MTHFR Testing

Our Genetics team, Cook Children's Clinical and Metabolic Genetics Center, does not routinely schedule patients for genetic evaluation due to MTHFR concerns, as there are two polymorphisms that are common in this gene which are not usually problematic. Thirty percent of Americans have 1 polymorphism in MTHFR and 10 percent have two polymorphisms. We recommend that your primary care pediatrician check a plasma homocysteine level and if normal, no intervention is needed. If plasma homocysteine is elevated, the child can be treated with folate and the matter can be discussed with our Genetics group. We do not recommend DNA testing for MTHFR polymorphisms as this testing is not recommended by the American College of Medial Genetics and is often not covered by insurance.

I don’t read New Beauty magazine (that often), but the most recent edition’s interview with Courtney Cox caught my eye.

I’ve been working on a long piece about MTHFR gene mutation for a while now. It’s something I get asked about a lot from parents. So, I think it’s time we take a look at MTHFR.

“"About four years ago, I found out I have something called a MTHFR gene mutation, which dictates how my body methylates," Courtney revealed. "I suffered miscarriages."

The Friends actress goes on to detail how she has to watch what she eats, avoiding anything with high levels of folic acid, such as carrots, red onions and broccoli that can complicate meythlation. A side effect of MTHFR is an increased risk of blood clots and this can be the cause of her miscarriages.

Scary and worrisome issues for any mom-to-be.

But I think what’s important here is that there’s still so much about MTHFR that we still don’t understand and there’s plenty of research that still needs to be done.

At this point, the American College of Medical Genetics and Genomics does not recommend routine testing of MTHFR for patients with blood clots, for women with recurrent pregnancy loss or for any other condition.

In instances when mutations in MTHFR cause the enzyme activity to be severely impaired, it can lead to an elevated level of an amino acid (the building blocks of protein) called homocysteine. Buildup of this amino acid may increase the risk of blood clotting and heart disease.

For a more in-depth look at MTHFR



Recent studies have cast doubt on this association and have shown that treating the elevated levels of homocysteine may not decrease the incidence of heart attacks, but we know that homocysteine does activate blood vessels and make them more likely to form clots.

Mutations that do not affect homocysteine level have not been proven to cause disease. Many variations exist at the gene level which do not appear to affect the activity of the enzyme. Without further confirmation that these cause problems, they should probably be thought of as normal variations (like eye color).

Studies have attempted to link mutations in MTHFR to more than 600 different medical conditions. There have been thousands of publications on this topic and yet, only one condition has been definitely shown to be an increased risk in children with MTHFR mutations: women with a variant known as C677T have a slightly increased risk of delivering a child with a neural tube defect (like spina bifida).

As I mentioned before, the American College of Medical Genetics and Genomics practice guideline does not recommend MTHFR testing for evaluation of increased blood clotting, recurrent pregnancy loss or at-risk family members despite the fact that these are the most plausible diseases which would be caused by MTHFR mutations. No other medical societies have endorsed MTHFR mutation testing.

Because of this and many other reasons, maybe we should really think twice before going down this pathway except in very specific cases.

And as for those many other reasons … I have so much more to say on this topic and I know many of you want to read more. Click here to read my extensive post on this where I dive deeper and answer many of the questions I get asked the most.

Get to know Justin Smith, M.D.

Justin Smith, M.D., is a pediatrician and the Medical Advisor for Digital Health for Cook Children's in Fort Worth, Texas. He has an active community on both Facebook and Twitter as @TheDocSmitty and writes weekly for Cook Children's He believes that strategic use of social media and technology by pediatricians to connect with families can deepen their relationship and provide a new level of convenience for both of their busy lifestyles.Dr. Smith’s innovative pediatric clinic, a pediatric clinic “designed by you,” is set to open in Trophy Club in 2017.

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