Mutations in the gene for familial Mediterranean fever: do they predispose to inflammation?

Objective: To analyze 70 individuals who were found to have the Mediterranean fever (MEFV) gene for the presence of definite familial Mediterranean fever (FMF) and to assess if they were prone to clinical and laboratory inflammation. We also prospectively evaluated 72 patients with childhood rheumatic diseases for the presence of MEFV mutations.

Methods: Seventy patients with one MEFV gene mutation were reevaluated for the presence of a clinical FMF phenotype using a new set of criteria. They were also questioned for the presence of musculoskeletal symptoms and rheumatic diseases. They were sampled for erythrocyte sedimentation rates and C-reactive protein levels. A second group with childhood rheumatic diseases were diagnosed according to international criteria.

Results: Median age of the 70 heterozygous individuals was 12 years. About 1/3 (34.3%) were classified with clinical FMF phenotype according to the suggested criteria. Fifteen (21.4%) were classified as normal and 3 (4.3%) had recurrent abdominal pains but did not fulfill all criteria for clinical FMF. Overall, 28 (40.0%) had some form of rheumatic complaint and 15 (21.4%) had developed a rheumatic disease including Behçet's disease, a vasculitis, or acute rheumatic fever. The mean ESR and CRP levels were 45.47 +/- 33.05 mm/h and 4.00 +/- 6.73 mg/dl, respectively. Among the 72 patients with rheumatic diseases of childhood, 22 (30.5%) carried one or 2 mutations of the MEFV gene. The mutated allele frequency among patients with rheumatic diseases was significantly higher than those in controls (p < 0.05). Within this group, among the 59 patients with juvenile idiopathic arthritis 15 had mutations in the heterozygous or homozygous form.

Conclusion: We confirm the acute phase response in the carriers for MEFV mutations. We suggest that these patients may have a tendency to develop certain manifestations due to an increased baseline of inflammation, and the presence of these mutations may affect their disease course when they develop rheumatic disease.