MEFV rs121908774: Understanding the M694V Variant
The rs121908774 variant in the MEFV gene, commonly known as p.Met694Val, is a well-studied genetic change associated with Familial Mediterranean Fever (FMF). It is primarily recognized as a pathogenic variant that, when inherited in specific patterns, can influence the body's inflammatory response.
What each genotype means
Typical autoinflammatory baseline
You carry two reference copies of the MEFV gene at this position and do not carry the p.Met694Val familial Mediterranean fever variant. Research indicates this genotype is associated with normal baseline pyrin regulation, without the elevated risk for recurrent autoinflammatory febrile attacks linked to this variant. This does not rule out other genetic variants or other causes of unexplained fever.
Carried by more than 96% to 98% of individuals in Mediterranean populations, and by over 99.9% of individuals globally.
FMF carrier status
You carry one copy of the pathogenic p.Met694Val variant, which confers carrier status for autosomal recessive familial Mediterranean fever (FMF). Published studies show that roughly 98% of heterozygous carriers remain completely asymptomatic, though a small percentage can occasionally experience mild recurrent fevers or abdominal inflammation. If you have personal or family history of unexplained periodic fevers or serositis, discuss these findings with a physician or genetic counselor.
Found in approximately 2% to 4% of individuals of Turkish, Armenian, Middle Eastern, and North African or Iraqi Jewish ancestry, but rare (<0.1%) in most other populations.
High risk for severe FMF
You carry two copies of the pathogenic p.Met694Val variant in MEFV, which is strongly associated with familial Mediterranean fever (FMF). In clinical research, individuals homozygous for this genotype typically show an early onset of recurrent febrile attacks, peritonitis, or arthritis, alongside an elevated risk of secondary amyloidosis. Because clinical severity varies and effective preventive therapies such as colchicine exist, it is essential to review these results promptly with a rheumatologist or clinical geneticist.
Rare globally, but present in roughly 1 in 500 to 1 in 2,500 individuals within Eastern Mediterranean and Jewish diaspora populations.
What is the rs121908774 Variant?
The rs121908774 variant is a specific change in the DNA sequence of the MEFV gene, located on the short arm of chromosome 16. In scientific literature, this variant is frequently referred to as p.Met694Val (or M694V), indicating that the amino acid methionine at position 694 in the resulting protein has been replaced by valine. This variant is located in exon 10 of the MEFV gene, a region where many disease-associated mutations are found. Because it involves a single nucleotide substitution, it is classified as a single nucleotide polymorphism (SNP). While the change involves amino acids with similar chemical properties, this specific alteration is widely documented in clinical genetics as having a significant impact on the function of the protein it encodes.
The Role of the MEFV Gene
The MEFV gene provides instructions for creating a protein called pyrin. Pyrin is primarily expressed in white blood cells, such as neutrophils and monocytes, which are essential components of the innate immune system. While the exact mechanisms are still being researched, current scientific consensus suggests that pyrin acts as a regulator of inflammation. It helps control the activation of the inflammasome, a complex of proteins that triggers the production of inflammatory signals like IL-1β. When the MEFV gene carries certain pathogenic variants, the threshold for activating this inflammatory response is lowered. This can lead to an overactive immune system, resulting in the recurrent, self-limiting episodes of fever and inflammation that characterize conditions like Familial Mediterranean Fever.
Clinical Associations and Evidence
The rs121908774 (M694V) variant is one of the most common and well-characterized pathogenic variants associated with Familial Mediterranean Fever. Research has consistently shown that individuals who inherit two copies of this variant (homozygotes) or a combination of this and other pathogenic variants (compound heterozygotes) are at a significantly higher risk for developing FMF. Furthermore, the M694V genotype is often associated with a more severe clinical phenotype, including a higher frequency of febrile attacks and an increased risk of secondary amyloidosis, a serious complication where abnormal protein deposits accumulate in organs like the kidneys. While the evidence for its role in FMF is strong, it is important to note that the presence of this variant does not guarantee the development of clinical symptoms, as environmental and other genetic factors also play a role.
Population Frequency
The frequency of the rs121908774 variant varies significantly across different ancestral groups. It is most commonly observed in populations from the Eastern Mediterranean, Middle East, and among individuals of Sephardic Jewish, Armenian, Arab, and Turkish descent. In these regions, the carrier frequency can be quite high, with some estimates suggesting that as many as 1 in 5 individuals may carry a single copy of a pathogenic MEFV variant. Because FMF is an autosomal recessive condition, most individuals who carry only one copy of this variant are asymptomatic 'healthy carriers.' The variant is much less common in other global populations, making it a key focus for genetic screening in specific high-prevalence groups.
Interpreting Your Results
If you have identified this variant in your genetic data, it is important to understand that this information is for educational purposes only and does not constitute a medical diagnosis. Genetic testing results should always be interpreted in the context of your personal and family medical history. If you are concerned about your carrier status or potential symptoms, you should consult with a qualified healthcare provider or a genetic counselor. They can help you understand the implications of your results, discuss the necessity of clinical testing, and provide guidance on managing any potential health risks. Never make changes to your health regimen or medication based solely on genetic reports without professional medical advice.
How common is this variant?
The M694V variant is most prevalent in Eastern Mediterranean, Middle Eastern, and Ashkenazi Jewish populations, with carrier frequencies reaching up to 1 in 5 in some specific groups.
Frequently asked questions
What is the difference between being a carrier and having FMF?
Being a carrier means you have one copy of a pathogenic variant and typically do not show symptoms. Having FMF usually requires inheriting two copies of a pathogenic variant, one from each parent, which can lead to recurrent inflammatory episodes.
Does having the M694V variant mean I will get sick?
Not necessarily. Many people with one copy of the variant are healthy carriers. Even those with two copies may experience variable symptoms, as other genetic and environmental factors influence the disease.
Should I be tested for FMF if I have this variant?
If you are concerned about symptoms or family history, you should discuss testing with a doctor. They can determine if clinical diagnostic testing is appropriate based on your specific health profile.
Is there a cure for Familial Mediterranean Fever?
While there is no cure, FMF is managed with medications like colchicine, which helps prevent inflammatory attacks and complications like amyloidosis. Always consult a clinician regarding treatment options.
Sources & further reading
Educational information only, last refreshed 9/12/2026. 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.
A missense mutation (c.2080A>G, p.Met694Val) in pyrin, a well-established pathogenic variant for familial Mediterranean fever (FMF) with high penetrance.
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.