Article: Familial Mediterranean fever

What is familial Mediterranean fever?

Familial Mediterranean fever is an inherited condition characterized by recurrent episodes of painful inflammation in the abdomen, chest, or joints. These episodes are often accompanied by fever and sometimes a rash. The first episode usually occurs by the age of 20 years, but in some cases, the initial attack occurs much later in life. Typically, episodes last 12 to 72 hours and can vary in severity and in the length of time between attacks. A buildup of starchy protein deposits (amyloidosis) occurs in some cases of familial Mediterranean fever and can lead to kidney failure if left untreated.

How common is familial Mediterranean fever?

Familial Mediterranean fever primarily affects populations originating from the Mediterranean region, particularly people of Armenian, Arabic, Turkish, and North African Jewish ancestry. The frequency of affected individuals in these populations ranges from 1 in 250 to 1 in 1,000. This disorder is less common in other populations.

What genes are related to familial Mediterranean fever?

Mutations in the MEFV gene cause familial Mediterranean fever.

Normal variations in the SAA1 gene modify the course of familial Mediterranean fever.

The MEFV gene produces a protein (called pyrin or marenostrin) in white blood cells that probably helps to control the inflammation process. Mutations in the MEFV gene can lead to reduced activity of the pyrin protein, which disrupts control of the inflammation process. As a result, a full-blown inflammatory reaction occurs, usually accompanied by fever and pain in the abdomen, chest, or joints.

There is some evidence that a particular version of the SAA1 gene (called the alpha variant) may increase the risk of amyloidosis among people with familial Mediterranean fever.

How do people inherit familial Mediterranean fever?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene must be altered for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene.

In rare cases, familial Mediterranean fever is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder. In these cases, an affected person has one parent with the condition.