Familial Mediterranean fever (FMF) is the most common familial form of periodic recurrent fever, occurring primarily among people of the southern Mediterranean. The common, classic type of familial Mediterranean fever is inherited in an autosomal recessive manner with reduced penetrance. The condition is particularly common in North Africans, Anatolian Turks, Iraqi Jews, and Armenians. The incidence is 1:2,000 in North Africans, and the heterozygote frequency reaches up to 20% regionally. Initial manifestations are seen in 70% of cases before the age of 10 years in the form of short-lasting fevers lasting 3-5 days, pleurisy and peritonitis, accompanied by pain in joints, muscles and abdomen. If left untreated, secondary amyloidosis leads to renal failure and death in 12-40% of cases. Prophylactic administration of colchicine decreases the frequency of relapses and the risk of developing secondary amyloidosis. For FMF patients who do not respond to colchicine, treatment with interleukin-1 blockers appears to be the best therapeutic option.
In the classic form of Mediterranean fever, mutations in the marenostrin/pyrin (MEFV) gene on chromosome 16 have been identified, allowing early diagnosis and appropriate treatment. Most cases are caused by a few common mutations (founder effect). However, despite mutation searches in the entire coding region of the MEFV gene, only one mutation is detectable in up to 25% of FMF patients.
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