MEFV rs121908008: Understanding the E148Q Variant
The rs121908008 variant in the MEFV gene, commonly known as E148Q, is a genetic change associated with carrier status for familial Mediterranean fever (FMF). Research into this variant has yielded mixed results, with some studies classifying it as a disease-causing variant with low penetrance, while others suggest it may be a benign polymorphism.
What each genotype means
Typical genetic profile
This genotype represents the most common sequence at this position in the MEFV gene. It is considered the reference or wild-type state, and individuals with this profile do not carry the E148Q substitution associated with familial Mediterranean fever carrier status.
This is the most common genotype found across all global populations.
Reduced penetrance carrier status
This genotype indicates you carry one copy of the E148Q variant (c.1984G>A). Research suggests this variant has low penetrance, meaning it is often found in healthy individuals and may not cause symptoms on its own, though it is sometimes associated with mild inflammatory presentations or considered a risk-modifying factor in the context of familial Mediterranean fever.
Carried by roughly 1 in 7 people of East Asian ancestry, and less frequently in South Asian and European populations.
Homozygous variant carrier
This genotype indicates you carry two copies of the E148Q variant. While some studies describe this as a disease-causing variant with low penetrance and mild symptoms, its clinical significance remains a subject of ongoing research and debate in the medical community.
This genotype is rare and observed significantly less frequently than the heterozygous state across most global populations.
What is the rs121908008 Variant?
The rs121908008 variant is a specific change in the DNA sequence of the MEFV gene, located on chromosome 16. In this variant, a guanine (G) is replaced by an adenine (A) at a specific position, resulting in a missense mutation where the amino acid glutamic acid is replaced by lysine at position 66 of the protein (p.Glu66Lys). This variant is frequently referred to in scientific literature as E148Q, a name derived from an alternate transcript of the gene. Because it is a missense mutation, it alters the primary structure of the protein produced by the gene, which has led researchers to investigate whether this change impacts the protein's normal function in the body. It is categorized in many genetic databases as a variant of uncertain significance or a low-penetrance variant, meaning that carrying the change does not guarantee the development of any specific clinical condition.
The Role of the MEFV Gene
The MEFV gene provides instructions for making a protein called pyrin, also known as marenostrin. Pyrin is primarily expressed in white blood cells and plays a critical role in the regulation of the body's inflammatory response. It acts as a sensor for certain cellular stressors and helps control the activation of the inflammasome, a complex that triggers the release of inflammatory cytokines. When the MEFV gene functions correctly, pyrin helps keep inflammation in check. Mutations in this gene are the primary cause of familial Mediterranean fever (FMF), an autoinflammatory disorder characterized by recurrent episodes of fever and inflammation of the lining of the abdomen, lungs, or joints. Because pyrin is essential for managing the immune system, variations in the MEFV gene can potentially disrupt this delicate balance, leading to an overactive inflammatory response in some individuals.
Research and Clinical Evidence
The clinical significance of the E148Q (rs121908008) variant remains a subject of ongoing debate in the medical community. Some studies have identified this variant in patients diagnosed with FMF, suggesting it may contribute to the disease, particularly when found alongside other MEFV mutations. However, other research has observed the variant in healthy individuals, leading some scientists to classify it as a benign polymorphism rather than a direct cause of disease. The evidence is considered limited because the presence of the variant does not consistently correlate with the severity or presence of FMF symptoms. Some researchers suggest that E148Q may act as a modifier, potentially influencing the clinical presentation of FMF in individuals who also carry other pathogenic mutations, but it is rarely considered sufficient on its own to cause the classic, severe form of the condition.
Population Frequency
The frequency of the rs121908008 variant varies significantly across different ancestral populations. According to data from the Genome Aggregation Database (gnomAD), the variant is most common in East Asian populations, with a frequency of approximately 0.15. It is found at lower frequencies in South Asian populations (approximately 0.03) and European populations (approximately 0.02). These differences highlight that the variant is not restricted to a single geographic region but is more prevalent in certain groups. Because the variant is relatively common in some healthy populations, its presence in a genetic test result does not necessarily indicate a high risk for disease, reinforcing the need for careful clinical interpretation by healthcare professionals who can consider the patient's full medical history and family background.
Interpreting Your Genetic Information
If you have received information about your status for the rs121908008 variant, it is important to understand that this information is not a medical diagnosis. Genetic variants are only one piece of a complex puzzle that includes environmental factors, other genes, and overall health. Because the clinical impact of E148Q is not fully established, many people who carry this variant never experience symptoms of familial Mediterranean fever. You should not make any changes to your health management or lifestyle based solely on this genetic finding. If you have concerns about your health or a family history of inflammatory conditions, the best course of action is to consult with a qualified healthcare provider or a genetic counselor. They can help you interpret these results in the context of your personal health and determine if any further clinical evaluation is necessary.
How common is this variant?
The rs121908008 variant is found at varying frequencies globally, with gnomAD reporting approximately 0.15 in East Asian, 0.03 in South Asian, and 0.02 in European populations.
Frequently asked questions
Does having the E148Q variant mean I have FMF?
No, having the E148Q variant does not mean you have familial Mediterranean fever. The variant is often found in healthy individuals, and its role in causing disease is still debated by researchers.
Should I be worried if I am a carrier of this variant?
Being a carrier of a variant does not necessarily mean you will experience health issues. Because the clinical significance of E148Q is uncertain, it is best to discuss your results with a doctor who can evaluate your specific health context.
Is there a test to confirm if I have FMF?
FMF is typically diagnosed based on clinical symptoms, family history, and physical exams, often supported by genetic testing for multiple known pathogenic mutations. A genetic test for a single variant is not a diagnostic tool for the disease.
Can I change my diet to manage this variant?
There is no evidence that specific dietary changes can alter the effects of the MEFV E148Q variant. Always consult with a healthcare professional before making significant changes to your diet or health routine.
Sources & further reading
Educational information only, last refreshed 9/23/2026. 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.
Carrier variant for Familial Mediterranean Fever (p.Met694Val), conferring carrier status for recurrent autoinflammatory febrile episodes.