Overview

Familial Mediterranean fever is a genetic autoinflammatory disorder that causes recurrent fevers and painful inflammation of your abdomen, lungs and joints.

Familial Mediterranean fever is an inherited disorder that usually occurs in people of Mediterranean origin — including those of North African, Jewish, Arab, Armenian, Turkish, Greek or Italian ancestry. But it can affect people in any ethnic group.

Familial Mediterranean fever is typically diagnosed during childhood. While there’s no cure for this disorder, you may be able to relieve signs and symptoms of familial Mediterranean fever — or even prevent them altogether — by sticking to your treatment plan.

Symptoms

Signs and symptoms of familial Mediterranean fever usually begin during childhood. They occur in bouts called attacks that last one to three days. Arthritic attacks may last for weeks or months.

Signs and symptoms of familial Mediterranean fever include:

• Fever
• Abdominal pain
• Chest pain
• Achy, swollen joints
• A red rash on your legs, especially below your knees
• Muscle aches
• A swollen, tender scrotum

Between attacks, you’ll likely feel normal. Symptom-free periods may be as short as a few days or as long as several years.

Causes

Familial Mediterranean fever is caused by a gene mutation that’s passed from parents to children. The gene mutation causes problems in regulating inflammation in the body.

In people with familial Mediterranean fever, the mutation occurs in a gene called MEFV. Many different mutations in MEFV are linked to familial Mediterranean fever. Some mutations may cause very severe cases, while others may result in milder signs and symptoms.

Risk factors

Factors that may increase the risk of familial Mediterranean fever include:

• Having a family history of the disease. If you have a family history of familial Mediterranean fever, your risk of the disease is increased.
• Being of Mediterranean ancestry. If your family can trace its history to the Mediterranean region, your risk of the disease may be increased. Familial Mediterranean fever can affect people in any ethnic group, but it may be more likely in people of North African, Jewish, Arab, Armenian, Turkish, Greek or Italian descent.

 Inheritance Pattern

• Familial Mediterranean fever is almost always inherited in an autosomal recessive pattern, which means both copies of the MEFV gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
• In rare cases, this condition appears to be inherited in an autosomal dominant pattern. An autosomal dominant inheritance pattern describes cases in which one copy of the altered gene in each cell is sufficient to cause the disorder. In autosomal dominant inheritance, affected individuals often inherit the mutation from one affected parent.
• However, another mechanism is believed to account for some cases of familial Mediterranean fever that were originally thought to be inherited in an autosomal dominant pattern. A gene mutation that occurs frequently in a population may result in a disorder with autosomal recessive inheritance appearing in multiple generations in a family, a pattern that mimics autosomal dominant inheritance. If one parent has familial Mediterranean fever (with mutations in both copies of the MEFV gene in each cell) and the other parent is an unaffected carrier (with a mutation in one copy of the MEFV gene in each cell), it may appear as if the affected child inherited the disorder only from the affected parent. This appearance of autosomal dominant inheritance when the pattern is actually autosomal recessive is called pseudodominance.

 Frequency

• Familial Mediterranean fever primarily affects populations originating in the Mediterranean region, particularly people of Armenian, Arab, Turkish, or Jewish ancestry. The disorder affects 1 in 200 to 1,000 people in these populations. It is less common in other populations.