Signs and symptoms of MTHFR

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MTHFR Symptoms

Key Takeaways

 MTHFR gene mutations may cause certain symptoms depending on the type of mutation you have

 MTHFR symptoms are usually related to health conditions that develop due to low folate levels 

 Recognizing symptoms can help you to understand whether you are affected by low folate and/or MTHFR

The MTHFR gene mutation can cause a range of symptoms, depending on the type and severity of the mutation.

Those who are heterogeneous (one copy of the C677T or A1298C mutation) are less likely to have severe symptoms because their MTHFR enzyme still functions at around 65%. Those who are homozygous for the C677T mutation have only 30% of normal enzyme function, which means they are more likely to experience symptoms 1.

Knowing how to recognize the symptoms can help you to understand whether you are affected, and what kind of treatment to seek.

List of MTHFR signs and symptoms in adults

Cardiovascular symptoms

  • High homocysteine levels (hyperhomocysteinemia)

Both C677T and A1298C have been implicated in causing elevated homocysteine levels, which is a risk factor for cardiovascular diseases and stroke.

  • Homocystinuria

Homocystinuria is an accumulation of homocysteine and its byproducts in the blood and urine due to impaired methionine metabolism.

  • Thrombosis and vascular lesions (blood clots)
  • High blood pressure
  • Migraine and headaches

Neurological symptoms

  • Depression, anxiety, and other mood disorders (bipolar disorder, schizophrenia)

Several studies have linked the C677T mutation to an increased risk for anxiety and depression 2.

  • Behavioral disorders (ADHD, autism)

Genetic research shows that MTHFR C677T is linked to the development of ADHD 3.

A recent meta-analysis has also linked autism spectrum disorders to MTHFR 4.

  • Insomnia

  • Chronic fatigue and chronic pain syndromes

MTHFR mutations can be associated with chronic pain syndromes due to folate metabolism pathways affecting nerve function over time 5.

Fertility symptoms

  • Male infertility 

MTHFR is associated with an increased risk of male infertility 6.

  • Failure to conceive and/or recurrent pregnancy loss/miscarriages

Some research shows that a homozygous MTHFR gene mutation may triple the risk of miscarriage 7.

  • Neural tube defects and congenital anomalies in children

Impaired homocysteine metabolism is a possible risk factor for NTDs and unexplained recurrent embryo losses in early pregnancy 8.

Toxicity symptoms

  • Heavy metal toxicity

MTHFR C677T has been associated with increased levels of cobalt and arsenic, while MTHFR A1298C is associated with increased levels of potassium and lead. Heavy metals and SNPs in the genes are capable of inducing toxicity even at low levels and can cause a variety of health issues 9.

  • Poor liver function

SAMe is mainly needed for methylation of a large variety of substrates (DNA, proteins, lipids and many other small molecules) and polyamine synthesis, so if SAMe levels are low (as in the case of MTHFR) the normal function of the liver will be also affected 10. 

Patients with chronic liver disease often have reduced SAMe biosynthesis.

Miscellaneous symptoms

  • Hearing loss

The MTHFR C677T mutation appears to increase the risk of hearing impairment in middle-aged and elderly people

List of MTHFR symptoms in children 

Cardiovascular symptoms

  • Neurodevelopmental disorders

The MTHFR C677T polymorphism can increase the risk of a child developing autism spectrum disorder 11.

  • Neural tube defects and congenital anomalies

MTHFR A1298C combined with MTHFR C677T has been shown to increase the risk of spina bifida in children 12.

  • Behavioral disorders

Some research has indicated a possible relationship between ADHD and MTHFR in children 13.

  • Asthma

MTHFR C677T is associated with higher susceptibility to asthma in children 14.

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When should you contact a doctor?

If you are experiencing symptoms that affect your quality of life, consult your doctor or health professional.


If you or members of your family are affected by cardiovascular issues, mental health disorders, or recurrent miscarriages, it may be helpful to find out if you have a MTHFR genetic mutation. MTHFR testing can be requested from your doctor or you can purchase an at-home test kit online.

Frequently Asked Questions about MTHFR Symptoms

What are the signs and symptoms of MTHFR?

Signs of MTHFR may include high homocysteine levels, mental health disorders such as depression, and some behavioral disorders such as autism and ADHD. Each of these conditions has its own set of symptoms.

What does MTHFR feel like?

MTHFR is different for every individual, depending on the type and severity of the mutation. People with a double mutation may be more likely to experience more significant symptoms associated with high homocysteine, such as cardiovascular disorders and depression. People with a single mutation may not experience many symptoms in their lifetime at all.

Are stork bites a sign of MTHFR?

There is no evidence that stork bites are a sign of MTHFR mutations. Stork bites (also known as a salmon patch) are a common birthmark that appear on a baby’s skin and usually disappear within 1 to 2 years 15.


The homozygous MTHFR C677T is a risk factor for having children with nonsyndromic cleft lip with or without cleft palate. MTHFR A1298C polymorphism is not a risk factor 16.


Pre-conceptional folic acid supplementation is hypothesized to increase the risk of tongue-tie (ankyloglossia) in infants, but more research is pending 17.

Is a sacral dimple a sign of MTHFR?

Sacral dimples are not a sign of MTHFR and are rarely associated with spina bifida 18.

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