MEFV rs121908005: Understanding the M694V Variant
The rs121908005 variant in the MEFV gene is a well-studied missense mutation known as p.Met694Val, which results in an amino acid substitution in the pyrin protein. This genetic change is associated with susceptibility to Familial Mediterranean Fever (FMF) and is most frequently observed in individuals of Mediterranean and Middle Eastern descent.
What each genotype means
Typical MEFV genotype
This genotype represents the absence of the specific p.Met694Val mutation in the MEFV gene. Individuals with this profile do not carry this particular genetic risk factor associated with familial Mediterranean fever.
This is the most common genotype globally, though the frequency of the alternative G allele varies significantly by ancestry.
MEFV variant carrier
This genotype indicates you carry one copy of the p.Met694Val mutation. While often associated with carrier status, some individuals with a single mutation may still experience symptoms of familial Mediterranean fever or related autoinflammatory conditions, and you should discuss any clinical concerns with a healthcare provider.
Carried by a notable percentage of individuals in Middle Eastern and Mediterranean populations, with frequencies often ranging from 2% to 5%.
Increased risk for FMF
This genotype indicates you carry two copies of the p.Met694Val mutation. This state is strongly associated with a higher risk of developing familial Mediterranean fever and may be linked to more severe clinical presentations, including an increased risk of complications like AA amyloidosis if left untreated.
This genotype is rare in the general population but is observed more frequently in specific Mediterranean and Middle Eastern communities where the variant is endemic.
Understanding the rs121908005 Variant
The rs121908005 variant, commonly referred to as M694V, represents a specific location in the human genome where a single nucleotide change occurs. In this instance, a substitution of A to G at a precise position in the MEFV gene results in the replacement of the amino acid methionine with valine at position 694 of the pyrin protein. This change is located within the B30.2/SPRY domain of the protein, a region critical for its regulatory functions. Because this occurs in the protein-coding region of the gene, it is classified as a missense mutation. Researchers track this specific change because alterations in this domain are known to impact the protein's stability and function, potentially disrupting its role in the body’s inflammatory response pathways.
The Role of the MEFV Gene
The MEFV gene provides instructions for making a protein called pyrin, which is primarily expressed in white blood cells, including neutrophils, eosinophils, and monocytes. Pyrin plays a sophisticated role in the innate immune system by acting as a sensor for cellular stress and infection. It is a core component of the inflammasome, a complex of proteins that initiates the production of inflammatory cytokines—signaling molecules that trigger inflammation to help the body fight off threats. Under normal conditions, pyrin helps regulate this process, ensuring that inflammation is activated only when necessary and turned off once the threat is resolved. When the MEFV gene contains certain variants, the resulting pyrin protein may not regulate the inflammasome effectively, which can lead to excessive or uncontrolled inflammatory responses even in the absence of an infection.
Research and Clinical Associations
The rs121908005 variant is historically significant in medical genetics due to its clinical association with Familial Mediterranean Fever (FMF). FMF is an autoinflammatory condition characterized by recurrent, self-limiting episodes of fever and painful inflammation in the abdomen, chest, or joints. Clinical research published in databases like ClinVar and PubMed consistently highlights M694V as a pathogenic variant, meaning it is widely recognized as a contributor to the development of FMF symptoms. While the evidence for its role in disease susceptibility is robust, the clinical presentation can vary greatly between individuals, even those with the same genotype. This variability is often influenced by other genetic modifiers, environmental factors, and the specific pattern of inheritance, as FMF is typically inherited in an autosomal recessive manner, though some individuals with a single copy of a variant may exhibit mild phenotypes.
Interpreting Your Results
For individuals who have identified this variant in their genetic reports, it is essential to understand that this information is for educational purposes only and is not a medical diagnosis. Genetic variants in MEFV are part of a complex picture of health; having a specific genotype does not guarantee that an individual will experience symptoms of FMF. If you are concerned about your results or have a family history of inflammatory conditions, the most appropriate step is to consult with a healthcare provider or a certified genetic counselor. They can help contextualize your genetic data alongside your personal and family medical history. Never initiate or change medications based on genetic test results without consulting a clinician. If a doctor has prescribed medication for an inflammatory condition, follow their dosing instructions precisely and discuss how your genetic status may influence your overall care plan.
How common is this variant?
The rs121908005 variant is most prevalent in populations of Mediterranean and Middle Eastern ancestry, with an allele frequency typically ranging from 0.02 to 0.05 according to gnomAD data.
Frequently asked questions
Does having the M694V variant mean I have FMF?
No, carrying this variant does not mean you have or will develop Familial Mediterranean Fever. While it is associated with an increased susceptibility, many carriers may never experience clinical symptoms, and a diagnosis of FMF requires a clinical evaluation by a physician.
Why is this variant more common in certain populations?
Genetic variants often become more common in specific groups due to historical patterns of migration, geographic isolation, or potential evolutionary advantages that these variants may have provided in the past. In the case of MEFV, the variants were historically prevalent in Mediterranean and Middle Eastern populations.
What should I do if I am a carrier?
If your genetic report indicates you are a carrier, no specific action is typically required unless you are experiencing symptoms. It is a good idea to share this information with your primary care physician during your next visit so they can keep it in your medical records.
Can I use this information to determine my risk for other diseases?
The rs121908005 variant is specifically linked to MEFV and autoinflammatory processes. It does not provide information about your risk for other unrelated conditions, and its significance is primarily limited to its role in inflammatory regulation.
Sources & further reading
Educational information only, last refreshed 9/24/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic missense variant in MEFV (p.Val726Ala) conferring carrier status or reduced-penetrance familial Mediterranean fever.
Missense substitution (c.2079A>G, p.Met694Ile) in MEFV associated with familial Mediterranean fever.
A missense variant (c.2040G>C, p.Met680Ile) in pyrin conferring carrier status for familial Mediterranean fever, widely observed across Eastern Mediterranean cohorts.
A missense substitution (c.2177T>C, p.Val726Ala) in MEFV establishing carrier status for autosomal recessive familial Mediterranean fever, common in Armenian and Arab lineages.
A missense substitution (c.1984G>A, p.Glu66Lys, often referred to as E148Q) associated with reduced penetrance for familial Mediterranean fever.
Carrier variant for Familial Mediterranean Fever (p.Met694Val), conferring carrier status for recurrent autoinflammatory febrile episodes.