The MTHFR genetic test screens for variations in a specific gene that affects how the body processes folate (Vitamin B9). This gene provides instructions for producing an enzyme necessary for converting folate into its active, usable form. Test results often contain complex genetic terminology, making them confusing for many individuals. This guide simplifies the report by explaining the gene’s function, the meaning of specific variants, and the practical implications of your results. Understanding these details will help you have a more informed conversation with your healthcare provider.
Understanding the MTHFR Gene
The acronym MTHFR stands for Methylenetetrahydrofolate Reductase, the enzyme encoded by the MTHFR gene. This enzyme is central to the methylation cycle, a biochemical process fundamental to functions like DNA synthesis and repair. The MTHFR enzyme converts 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate (L-methylfolate).
L-methylfolate is the active, usable form of Vitamin B9 required for metabolism. This active folate is necessary for converting the amino acid homocysteine into methionine. Common variations in the MTHFR gene reduce the enzyme’s efficiency, slowing this conversion. Reduced activity can lead to lower levels of active folate and potentially higher levels of homocysteine in the blood.
Decoding the MTHFR Variants
The MTHFR genetic test typically screens for two common variations, or polymorphisms: C677T and A1298C. These labels represent a single nucleotide polymorphism (SNP), which is a change in a single DNA building block at a specific gene location. The numbers indicate the position, and the letters show which DNA base has been substituted.
The C677T variant involves substituting Cytosine (C) with Thymine (T) at position 677. This variation occurs in the enzyme’s catalytic domain, resulting in significantly reduced activity. The A1298C variant is a change from Adenine (A) to Cytosine (C) at position 1298, located in the regulatory domain. Due to its location, A1298C generally results in a less pronounced reduction in enzyme efficiency compared to C677T.
Interpreting Your Results Terminology
MTHFR test reports use specific genetic terms to describe the status of your C677T and A1298C variants.
Wild Type
The Wild Type result, sometimes called Normal or Clear, indicates you inherited two normal copies of the gene without the tested variation. For C677T, this is reported as C/C, and for A1298C, it is A/A.
Heterozygous
The term Heterozygous means you inherited one normal copy of the gene and one copy containing the variant. A heterozygous C677T result is C/T, resulting in a partial reduction of enzyme function. A heterozygous A1298C result is A/C.
Homozygous
The Homozygous status means you inherited the variant from both parents, resulting in two copies of the change. A homozygous C677T result is reported as T/T, and a homozygous A1298C result is C/C. These terms apply separately to each variant, meaning a person can have different results for each position.
Practical Meaning of the Gene Results
The combination of results determines the estimated reduction in enzyme efficiency and the body’s ability to produce active folate.
A heterozygous C677T variant (C/T) may reduce enzyme function by approximately 35% compared to someone with no variants. A homozygous C677T result (T/T) is associated with the most significant reduction, often estimated to be around 70% lower than typical function.
The A1298C variant alone has a milder effect. A homozygous A1298C result (C/C) generally results in about a 30% reduction in enzyme activity. The combination known as compound heterozygous (C/T and A/C) is associated with an activity reduction comparable to homozygous A1298C.
The presence of these variations is a genetic predisposition, not a disease diagnosis. The actual impact on health is influenced by diet and other genetic factors. Many individuals with these variants maintain normal health and homocysteine levels, especially with sufficient dietary folate.
Next Steps After Receiving MTHFR Results
After gaining clarity on your MTHFR test results, discuss them with a qualified healthcare professional, such as a doctor or registered dietitian. Self-treating based solely on genetic results is not recommended, as the clinical importance of these common variants is still being researched. Your provider may suggest additional testing, such as a blood test to check your current homocysteine levels. Homocysteine levels are often a more direct indicator of metabolic function than the gene variant itself.
For individuals with MTHFR variants, lifestyle and dietary adjustments are frequently recommended to support the methylation pathway. A significant consideration is the intake of folic acid, the synthetic form of B9 found in fortified foods and supplements. Since the MTHFR enzyme is needed to convert folic acid into its active form, some professionals suggest focusing on dietary folate from natural sources like leafy greens. If supplementation is beneficial, your provider may recommend L-methylfolate (5-MTHF), the active form of B9 that bypasses the need for the MTHFR enzyme entirely.