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  • Writer's pictureNancy Mullan, MD

Common Misconceptions about MTHFR Mutations

Updated: Jan 23, 2020

Anyone who has a chronic illness who is proactive about it has heard about the MTHFR mutation. Put 'MTHFR mutation' into a search engine, and an extraordinary amount of material comes up. Every third clinician claims to be an expert in treating the mutation, whether they have any background in the genetics surrounding the mutation or its biochemistry or not. Most clinicians are not even clear about what mutation they are treating, whether it is MTHFR C677T, MTHFR A1298C, or MTHFR 03. Ask them and you will see. These mutations have different consequences and need to be dealt with appropriately.

There are at least three MTHFR mutations that we know about that impact your health. They work within the context of the whole pathway that is involved in methyl group formation. You need to know the status of your particular methyl group producing pathway. You need to know which MTHFR mutation(s) you are attempting to bypass. And you need to know about any other mutations you may have that affect the efficiency of methyl group production. You find this out by testing. You can't know it without doing the genetic and biochemical tests which give you that information. Any clinician who does not ask for comprehensive genetic and biochemical testing is likely not to be able to lead you out of the mire.

If you do not have a complicated situation, if you have not been chronically ill for a long time, if you are not persistently having trouble with one organ system or another, if you are neurologically intact, then it may happen that 5 methyl folate and methyl B12 will remove symptoms and enhance your feeling of well being. Good. You just saved yourself time and money.

But if you have persistent symptoms, if you have Lyme disease, autism, neurologic or psychiatric disorder, multiple chemical sensitivity, mold toxicity, and/or other sensitivity to foods or vitamins, you need to be careful about what you put into your body. You know who you are. You have usually been struggling with your body for years. You cannot pull a bottle of methyl donors, like methyl B12 and/or methyl folate, off the shelf and do well with it. You may give yourself a reaction, like hyperactivity in a child or infection in an adult, and end up confusing yourself about which direction is up for years. You have to work in an organized fashion with a concrete plan which takes into account your biochemistry and genetics in order to do well. You have to put thought into what you are doing.

Beyond that, you have to avoid misinformation. There is a National Institutes of Health (NIH) web site that recommends against testing MTHFR because it claims that there are no clinical consequences from the mutation. They are looking at only two of the possible MTHFR genetic mutations, and they are looking at them in an extremely narrow way. They are not looking at the whole picture, the whole methyl group producing pathway and all the ramifications of having too few methyl groups. They have separated the factors down too far. Humans are more complex than the model from which they are drawing their conclusion.

This NIH study does not even look at MTHFR 03, which is a worse down regulation than MTHFR C677T, the usual mutation that people are referring to when they talk about MTHFR. They do admit that women who are MTHFR C677T +/+, that is who have a mutation in both MTHFR C677T genes, are more likely to have a child with spina bifida, a crippling spinal deformity. How's that for no clinical consequence? 

Since mainstream medical doctors take their cues from government information, do not expect your mainstream doctor to have any idea about MTHFR mutations at all. If you ask them to test, they may test only one gene, MTHFR C677T, or they may test two, MTHFR C677T and MTHFR A1298C. This does not give you anything near the full picture. For the full picture, you need to look at all three MTHFR genes AND the other genes that impact methyl group production in the methylation pathway.

If you are well and you have had very few health problems all of your life, probably you do not have an MTHFR issue and you do not have to worry about testing. People with MTHFR mutations have health issues. 98% of autistic individuals have at least one MTHFR mutation. MTHFR mutations have clinical consequences. 

I have a free, downloadable ebook at that gives you further detail about these issues. Click here to download.

If you have any questions about how your methylation mutations are being handled, you can get an Exploratory Conversation with me. It is a 30-minute conversation in which I will listen to your health issues, review your recent test results, and make recommendations about what  you should do. It will clear up any confusion you have about which direction is up, which supplements you should start first, how you should start them and what you can expect.  The fee for this service is $129. It is easy to set a time for one soon, and it can save you weeks or months of doing the wrong thing, lurching around in the dark with a clinician who isn’t that easy to reach or who doesn’t know that much about the genetics or molecular biology of MTHFR. Whether you have one or two mutations, you may be dealing with conditions in your body that are confusing and difficult to understand. You can cut through all of that and get clarifying input that gives you hope and moves you in the right direction. I look forward to being able to help you, Dr. Mullan

What people like you are saying about Dr. Mullan’s work:

I shudder at the thought of what my family would be like without Dr. Mullan. Thankfully, with her help, we have stopped my husband's chronic 30 year battle with kidney stones. He is no longer forming them and is stone free. My thyroid is now working normally, my body temperature is almost normal and my hair has grown back. My oldest daughter's Autism is in the process of being reversed and her hair pulling has stopped. The greatest blessing from our good health is the birth of my second daughter Ava, now one-year-old. At 50 years old I carried her to term. One of my doctors commented to me saying “ you are carrying this baby like a 22-year-old.” Yes, I am because of Dr. Mullan and working on my methylation pathway. One by one she is knocking off symptoms and bringing us back to health. The future is bright! Thank you, Dr. Mullan, for the work you do.


Wow. I feel great. Thank you for your help. It's amazing really. Like a light turned on. Curious to see what the next tests show. To ride this peak indefinitely is my goal. Ha. I have energy again. Yay!

Really grateful,


I am so relieved. My daughter is doing SO WELL since we started with you! We have been to so many doctors and tried so many things.Now I can start working on my own program with you....


So excellent! I literally learn something every single time and I get clarification on things that have been lingering in my mind… VB

You are giving people a huge gift by empowering them… It’s about helping the patient become their own healer by taking them to a higher level of consciousness… AL

Thank you so much, Dr. Mullan. Thank you so, so much for everything you do. MS

Wow! I have to tell you, this was such an uplifting session. It’s so nice to hear good news, especially about a child. Anxiety, OCD and a host of other mental/psychiatric symptoms have been a huge hurdle for me. So to hear this story of all those awful symptoms totally going away is such a bright light for me!!!! TR

Fantastic, caring, smart, savvy doc. I worked with Dr. Mullan for a couple of years to help MTHFR mutations and their associating expressions! To say the least! She's brilliant. At that time she had weekly calls for her patients - free - where we could ask questions and she would reply. What doctors do this? She does. She's also an animal lover and is right on about the way she practices medicine. I highly recommend her. In good health!


"Dr. Nancy Mullan is a beautiful person. She is an expert in her field and has helped our family so much. I am very grateful to her. She came highly recommended and I know why. I would recommend her and her website for information re: healing from a genetic point of view. Thank you, Dr. Mullan, for everything.”


"Dr.Mullan has helped me with issues that I have struggled with for years. She is knowledgable and practical. I would recommend her to others.”


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