Manifestations appear early in life, in half of the patients before age ten.
Although more than 25 mutations have been identified in the Pyrin gene located on chromosome 16 of FMF patients, the exact pathogenesis of the disease remains unclear. The identification of FMF is based on clinical findings, family history, physical examination and routine laboratory results obtained from patients experiencing attacks. However, in atypical cases, genetic analysis may help. The attacks are usually very severe, with tremendous pain, confining the patient to bed, or stopping his regular life. The abdomen, joints or chest are the most commonly involved sites.