Systemic autoinflammatory syndromes (SAIDs) are rare genetic and acquired disorders which present with recurrent attacks of fever in childhood and adult life.
Familial Mediterranean fever (FMF) is inherited as an autosomal
recessive condition and occurs in certain ethnic groups, particularly Arabs, Turks, Armenians and Sephardic Jews. The gene, called MEFV, has been localized to chromosome 16. It encodes for pyrin (or marenostrin), a suppressor of the activation of caspase 1, which stimulates the biosynthesis of IL-1~, which drives inflammation.
Failure of suppression leads to FMF attacks.
These are characterized by recurrent episodes of fever, arthritis
and serositis. Abdominal or chest pain due to peritonitis or pleurisy occurs. The arthritis is usually monoarticular and episodes last up to 1 week. The CRP is markedly raised during the attacks. The condition may be mistaken for palindromic rheumatism (see p. 675), but such attacks are not usually accompanied by fever.
The diagnosis can be made by PCR, if available, but is based
on the clinical picture and exclusion of other conditions.
Treatment involves regular colchicine 1000-1500 μg daily,
which can usually prevent the attacks. In resistant patients,
thalidomide (see p. 601) and anakinra can be tried. In general,
the disorder is benign, but in 25% of cases, renal amyloidosis
Other systemic autoinflammatory syndromes (SAIDs} are being
increasingly recognized. These include tumour necrosis factor
receptor-associated periodic syndrome (TRAPS), mevalonate
kinase deficiency (MKD), cryopyrin-associated periodic syndrome
(CAPS), and periodic fever, aphthous stomatitis, pharyngitis and