MTHFR rs1801134: Understanding This Genetic Variant
The rs1801134 variant is a specific genetic change within the MTHFR gene, which provides instructions for an enzyme involved in processing folate. It is frequently studied alongside other MTHFR variants to understand its potential influence on homocysteine levels and metabolic health.
What each genotype means
Typical enzyme baseline
You carry two copies of the reference G allele, which encodes the standard arginine amino acid at residue 594 of the MTHFR enzyme. Published biochemical and observational studies evaluate this genotype as the typical baseline, showing no alteration in enzyme kinetics or folate metabolism attributable to this locus. If you are reviewing overall folate pathway efficiency, established clinical guidelines recommend focusing on confirmed lifestyle factors and major primary variants rather than this site alone.
Carried by approximately 85% to 94% of people of European ancestry and the vast majority of non-European populations.
Mildly altered enzyme activity
You carry one copy of the A minor allele (also historically described as 1793A or Arg594Gln), which introduces an amino acid change in the regulatory domain of the MTHFR enzyme. In vitro research shows a modest decrease in baseline enzyme activity, but epidemiological studies report mixed or negligible effects on resting plasma homocysteine levels on its own. Evidence for any direct clinical risk or medication alteration remains limited and unproven, so no individual medical actions or prescription changes are warranted based on this genotype alone.
Carried by roughly 6% to 15% of individuals of European ancestry; it occurs at much lower frequencies in African and East Asian populations.
Modestly reduced enzyme activity
You carry two copies of the A minor allele, which causes an arginine-to-glutamine substitution at position 594 of the MTHFR protein. Experimental assays indicate this variant leads to reduced enzyme activity, yet published human clinical data remain very limited regarding significant standalone effects on hyperhomocysteinemia or disease susceptibility. Major clinical genetics guidelines do not consider this genotype diagnostic of a metabolic disorder; always consult a physician or pharmacist before considering dietary supplements or medication adjustments.
Very rare, observed in less than 1% of European populations and virtually absent in many other global ancestries.
What is the rs1801134 Variant?
The rs1801134 variant is a single-nucleotide polymorphism (SNP) located in the MTHFR gene. In genetic terms, this variant represents a missense mutation, specifically identified as c.1793G>A, which results in an amino acid change from arginine to glutamine at position 594 (p.Arg594Gln). SNPs are the most common type of genetic variation among people, representing a difference in a single DNA building block. While many SNPs have no effect on health, researchers study them to determine if they influence how our bodies function or respond to environmental factors. This particular variant is often evaluated in the context of folate metabolism, as the MTHFR enzyme plays a critical role in converting dietary folate into its active form, which is necessary for various cellular processes, including DNA synthesis and repair.
The Role of the MTHFR Gene
The MTHFR gene encodes the methylenetetrahydrofolate reductase enzyme. This enzyme is essential for the methylation cycle, a biochemical pathway that regulates the levels of homocysteine, an amino acid in the blood. When the MTHFR enzyme functions optimally, it helps keep homocysteine levels within a healthy range. If the enzyme's activity is reduced, it can potentially lead to elevated homocysteine levels, a condition known as hyperhomocysteinemia. While the most well-known variants in this gene are rs1801133 and rs1801131, rs1801134 is also investigated for its potential to impact enzyme stability or activity. However, it is important to note that the relationship between MTHFR variants and health outcomes is complex, often depending on dietary folate intake and other genetic or environmental factors.
Research and Evidence Strength
The evidence linking rs1801134 to specific health conditions is currently considered limited. While some studies have explored its association with folate metabolism and homocysteine levels, results have been mixed or require further validation in diverse populations. Unlike some rare, high-impact genetic mutations that directly cause disease, common MTHFR variants are generally viewed as factors that might subtly influence metabolic efficiency. Many researchers emphasize that the presence of a variant does not equate to a medical diagnosis. Because human health is influenced by a combination of genetics, diet, and lifestyle, it is difficult to isolate the effect of a single SNP. Consequently, major health organizations often caution against using MTHFR testing for routine clinical decision-making until more robust, large-scale association studies are completed.
What You Can Do With This Information
If you have received information about your MTHFR genotype, it is important to view it in the context of your overall health rather than as a standalone indicator of disease risk. Genetic variants are only one piece of a much larger puzzle. If you are concerned about your homocysteine levels or your nutritional status, the most effective approach is to consult with a healthcare provider or a registered dietitian. They can assess your blood work, dietary habits, and family history to provide personalized guidance. Avoid making significant changes to your diet or starting new supplements based solely on genetic reports without professional oversight. Always discuss any questions regarding your health, potential testing, or supplement use with a qualified clinician who can interpret these results within the framework of your specific medical needs.
How common is this variant?
The rs1801134 variant has a minor allele frequency of approximately 0.03 to 0.08 in European ancestries, making it a relatively uncommon but documented variation.
Frequently asked questions
Is MTHFR rs1801134 a disease-causing mutation?
No, rs1801134 is a common genetic variant, not a disease-causing mutation. Most people with this variant live healthy lives, and its presence does not guarantee the development of any specific health condition.
Should I get tested for MTHFR variants?
Major medical organizations generally do not recommend routine testing for MTHFR variants. The results often lack clear clinical utility and may lead to unnecessary anxiety or inappropriate supplement use.
Does this variant mean I have a folate deficiency?
Not necessarily. While MTHFR variants can influence how your body processes folate, your actual folate status is primarily determined by your dietary intake. A blood test is the only way to accurately assess your folate levels.
Can I fix my MTHFR variant with supplements?
You cannot 'fix' a genetic variant. While some people take supplements to support metabolic health, you should never start a supplement regimen based on genetic results without consulting your doctor, as high doses of certain vitamins can be harmful.
Sources & further reading
Educational information only, last refreshed 10/28/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Variant in the MTHFR locus frequently studied in association with folate metabolism and homocysteine levels.
Functional polymorphism influencing homocysteine dynamics and vascular endothelial recovery during high-intensity training.
Common variant (C677T) influencing folate metabolism and plasma homocysteine levels.
The C677T variant in the MTHFR gene is associated with reduced enzyme activity and mild hyperhomocysteinemia, particularly in individuals with low folate intake.
The MTHFR 677C>T (Ala222Val) variant encodes a thermolabile enzyme with reduced activity. While associated with elevated homocysteine levels in the presence of low folate, major professional guidelines (e.g., ACMG) advise against routine clinical testing for cardiovascular or thrombophilia risk due to lack of clinical utility.
Rare functional missense variant in MTHFR (p.Arg157Gln) associated with reduced folate pathway enzyme activity.