Which are the causes of Familial Mediterranean Fever?

TL;DR: Familial Mediterranean Fever (FMF) is an autoinflammatory disorder caused by mutations in the MEFV gene, which leads to the overproduction of inflammation in the body. These genetic changes disrupt the regulation of the innate immune system, resulting in recurrent, spontaneous episodes of fever and painful inflammation without an external infection.

What causes Familial Mediterranean Fever?

Familial Mediterranean Fever is primarily a genetic condition. At its core, the disease is caused by mutations in the MEFV gene, located on the short arm of chromosome 16. This gene provides instructions for making a protein called pyrin. Think of pyrin as the body's "security guard" for the immune system; its job is to detect danger and switch off inflammatory responses once they are no longer needed. In people with Familial Mediterranean Fever, the mutated MEFV gene produces a faulty version of pyrin that fails to properly "turn off" inflammation, leading to the characteristic, unprovoked inflammatory attacks seen in the 264 members of our DiseaseMaps community.

Is Familial Mediterranean Fever hereditary?

Yes, Familial Mediterranean Fever is an inherited condition that follows an autosomal recessive pattern. This means that a person must inherit two copies of the mutated gene—one from each parent—to typically manifest the full clinical symptoms of the disease. While individuals who carry only one mutated copy (carriers) may sometimes experience milder symptoms, the classic presentation of Familial Mediterranean Fever usually requires both copies to be affected. Because it is genetic, it is present from birth, though symptoms may not appear until childhood or early adulthood.

What are the triggers and mechanisms of an attack?

While the root cause is genetic, the timing of an inflammatory flare can be influenced by various factors. The mechanism behind an attack involves the activation of the inflammasome, a complex of proteins that triggers the release of inflammatory cytokines like Interleukin-1 beta. The following factors are often cited by patients as potential triggers for a Familial Mediterranean Fever flare:

• Physical or emotional stress: Significant life changes or intense physical exertion.


• Infections: Minor viral or bacterial illnesses can sometimes act as a "spark" for the immune system.


• Hormonal changes: Many individuals note that menstrual cycles or pregnancy can influence the frequency of attacks.


• Cold exposure: Some patients report that cold environments or sudden temperature changes may precipitate symptoms.

Is the cause of Familial Mediterranean Fever fully understood?

While we have a clear understanding of the MEFV gene's role, the exact "why" behind the variability of the disease remains a major focus of current research. We know that different mutations in the MEFV gene can lead to different levels of disease severity, but we do not yet fully understand why two people with the exact same genetic mutation might have vastly different experiences. Researchers are currently investigating "modifier genes"—other genetic factors that may interact with the MEFV gene—and environmental influences that might explain why some patients experience severe complications like amyloidosis while others have a much milder form of Familial Mediterranean Fever.

What is the difference between a cause and a trigger?

It is important to distinguish between the cause and a trigger in Familial Mediterranean Fever. The cause is the permanent genetic mutation in the MEFV gene; this is the fundamental reason the disease exists in the patient. A trigger, by contrast, is an external or internal event that sets off an acute episode of inflammation. Understanding this distinction is vital for patients, as it helps in identifying personal patterns that can be managed or avoided to improve quality of life.

Next steps

• Consult a rheumatologist or a geneticist specializing in autoinflammatory diseases to confirm your specific MEFV mutation.


• Keep a detailed symptom diary to track potential triggers and share these patterns with your healthcare provider.


• Join the DiseaseMaps.org community to connect with other families living with Familial Mediterranean Fever.


• Discuss with your doctor whether daily prophylactic medication, such as colchicine, is appropriate to help manage your inflammation.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• Orphanet: Familial Mediterranean Fever (ORPHA:342)


• NIH Genetic and Rare Diseases Information Center (GARD): Familial Mediterranean Fever


• OMIM (Online Mendelian Inheritance in Man): MEFV Gene Entry (#249100)


• The Autoinflammatory Alliance: Patient Resources for FMF