Familial Mediterranean fever (FMF) is a rare hereditary condition characterized by recurrent episodes of fever. Other symptoms include pain in the abdomen, joints, and chest.FMF typically begins in childhood. In around 90% of cases it begins before the individual is 20 years. The fever begins before age 10 years in approximately 75% of cases.
This article explains more about the symptoms of FMF and what causes it. It also looks at treatment options, when to contact a doctor, and more.
What are the symptoms of familial Mediterranean fever?
The main symptoms of FMF are recurrent episodes involving fever and pain in the abdomen, chest, or joints.
Episodes typically last for around 1–3 days. They may resolve without treatment.
Not every person with FMF will experience all symptoms. When joint pain occurs, it typically affects only one joint at any one time. This usually includes the knee or the ankle.
If a person experiences swollen joints, this typically lasts for anywhere from 5–14 days at a time. In some cases, joint swelling can become chronic.
Around one-third of people with FMF also experience a rash, usually on their ankles and feet.
In children under age 5 years, a recurring fever may be the only symptom they experience.
In rare cases, a person with FMF might also experience:
- pericarditis, which is inflammation of the outer layer of the heart
- myositis, which is inflammation of the muscle
- meningitis, which is inflammation of the membrane that surrounds the spinal cord and brain
- orchitis, which is inflammation of the testicles
What causes familial Mediterranean fever?
FMF is a genetic condition. This means that it occurs when a person inherits a gene mutation. The gene that causes FMF is the MEFV gene.
The MEFV gene is responsible for providing instructions for making the pyrin protein. The pyrin protein is present in white blood cells and helps regulate inflammation.
When the MEFV gene does not work as expected, this affects the body’s production of pyrin. In turn, this can result in an increased inflammatory response. Inflammation can cause fever and pain.
Learn about other possible causes of fever.
What are the treatments for familial Mediterranean fever?
Colchicine is the main treatment for FMF. It’s an anti-inflammatory medication that has prevented fever in up to 75% of people with FMF who consistently take the medication. Of those taking colchicine, up to 90% of them have reported noticeable symptom improvement.
If symptoms do not respond to colchicine, the doctor may recommend interleukin-1 blockers. These include:
- anakinra (Kineret)
- canakinumab (Ilaris)
- rilonacept (Arcalyst)
When should I see a doctor?
It is important to contact the child’s doctor as soon as you have concerns about FMF.
As there are numerous reasons why a child might be experiencing a fever, an accurate diagnosis can help to ensure that the doctor recommends the right treatment.
How do doctors diagnose familial Mediterranean fever?
To assist with reaching an accurate diagnosis, a doctor might begin by performing a physical examination and taking a full personal and family medical history.
They may then request blood tests to check for signs of inflammation. Genetic testing may also support the diagnosis if the MEFV gene mutation is present.
How common is familial Mediterranean fever?
The frequency of FMF varies. It affects anywhere from 1 in every 200–1,000 people in populations originating in the Mediterranean region.
FMF is less common among other populations.
What are the risk factors for familial Mediterranean fever?
The main risk factor for FMF is having a parent with the MEFV gene mutation. Only one parent needs to carry the gene mutation. In some cases, an extended family member may have FMF.
FMF occurs more frequently in people of Mediterranean descent. It also occurs more often in populations within the Mediterranean region.
In particular, this includes people of the following backgrounds:
- Sephardic Jewish
What are the possible complications of familial Mediterranean fever?
A person with FMF may be at risk of developing complications. If episodes occur close together, it may cause growth delays during childhood.
FMF may also bring about amyloidosis. Amyloidosis is a potentially serious condition that occurs when amyloid protein builds up in certain areas of the body. When this happens in the kidneys, it can result in kidney failure. Learn more about amyloidosis.
Contact your doctor if you have concerns about the possible complications of FMF.
Familial Mediterranean fever (FMF) is a rare condition that causes recurrent episodes of fever. Other symptoms of FMF include pain in the abdomen, chest, and joints.
FMF typically affects children, with up to 75% of cases beginning before the age 10. It’s a hereditary condition that most commonly affects people of Mediterranean descent.
Contact a doctor if you have concerns about FMF. They will be able to perform a physical examination and order tests to reach an accurate diagnosis and advise on treatments.