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

OBJECTIVE: Familial Mediterranean fever (FMF) is characterized by recurrent episodes of peritonitis, pleuritis, and synovitis. Its most common musculoskeletal manifestation is acute recurrent monarthritis, but other manifestations have also been described. We describe the articular and musculoskeletal manifestations in a group of patients who were found by genetic screening to be homozygous for the FMF gene.

METHODS: We surveyed 136 pediatric patients of Mediterranean extraction who were evaluated for a variety of musculoskeletal symptoms, and in whom genetic studies confirmed a diagnosis of FMF. Two groups of patients emerged: group 1 contained 107 patients who displayed a classic picture of FMF, and group 2 comprised 29 patients whose symptoms did not fulfill the criteria for a clinical diagnosis of FMF. Fifty-nine patients were Sephardic Jews and 77 were Arabs. The Jewish patients were all homozygous or compound heterozygous for the M694V mutation, while the Arab patients were homozygous or compound 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 M694V mutation. Acute monarthritis occurred in 73 (68%) of the patients of group 1, but in none of the patients from group 2. Ten (34%) of the 29 patients from group 2 exhibited diverse musculoskeletal manifestations. Thirteen patients in our series (10%) presented with a variety of musculoskeletal symptoms, including febrile myalgia syndrome in 6 patients.

CONCLUSION: Acute episodes of monarthritis are the most common musculoskeletal manifestation of FMF in children bearing the M964V mutation, which predominates among Sephardic Jews, although children with the M694V mutation may also present with diverse nonspecific musculoskeletal manifestations. Genetic screening for FMF appears indicated in the evaluation of unexplained musculoskeletal symptoms in children of Mediterranean extraction.