The musculoskeletal manifestations of Familial Mediterranean fever in children genetically diagnosed with the disease

Objective. Familial Mediterranean fever (IMF) is characterized by recurrent episodes of peritonitis, pleuritis, and synovitis. Its most common musculo skeletal manifestation is acute recurrent monarthritis, but other manifesta tions have also been described. We describe the articular and musculoskelet al manifestations in a group of patients who were found by genetic screenin g to be homozygous for the IMF gene. Methods. We surveyed 136 pediatric patients of Mediterranean extraction who were evaluated for a variety of musculoskeletal symptoms, and in whom gene tic studies confirmed a diagnosis of IMF. Two groups of patients emerged: g roup 1 contained 107 patients who displayed a classic picture of IMF, and g roup 2 comprised 29 patients whose symptoms did not fulfill the criteria fo r a clinical diagnosis of IMF. Fifty-nine patients were Sephardic Jews and 77 were Arabs. The Jewish patients were all homozygous or compound heterozy gous for the M694V mutation, while the Arab patients were homozygous or com pound heterozygous for any 1 of the 5 mutations tested (M694V, V726A, M680I , M694I, and E148Q). Results. Acute episodes of monarthritis occurred in 42 (71%) of the Jewish children and 31 (40%) of the Arab children; 70% of these patients had the M 694V mutation. Acute monarthritis occurred in 73 (68%) of the patients of g roup 1, but in none of the patients from group 2. Ten (34%) of the 29 patie nts from group 2 exhibited diverse musculoskeletal manifestations. Thirteen patients in our series (10%) presented with a variety of musculoskeletal s ymptoms, including febrile myalgia syndrome in 6 patients. Conclusion. Acute episodes of monarthritis are the most common musculoskele tal manifestation of IMF in children bearing the M964V mutation, which pred ominates among Sephardic Jews, although children with the M694V mutation ma y also present with diverse nonspecific musculoskeletal manifestations. Gen etic screening for IMF appears indicated in the evaluation of unexplained m usculoskeletal symptoms in children of Mediterranean extraction.