The frequency of sacroiliitis in familial Mediterranean fever and the role of HLA-B27 and MEFV mutations in the development of sacroiliitis.

The objective of this study was to investigate the frequency of sacroiliitis in familial Mediterranean fever (FMF) patients and the role of HLA-B27 and MEFV mutations in the development of sacroiliitis. The study group consisted of 256 FMF patients (male 128, female 128, mean age 27.2 +/- 6.3 years). After evaluation of the medical records, 70 patients (27.4%) were determined to have one or more of musculoskeletal manifestations. Sacroiliitis was determined in 18 (32.7%) FMF patients. The frequency of sacroiliitis among all FMF patients was found to be 7%. HLA-B27 was 47% and 6.3% in FMF patients with and without sacroiliitis, respectively. The frequency of M694V mutations in FMF patients with sacroiliitis was 93.7%. Sacroiliitis may be seen more frequently in FMF patients than expected. HLA-B27 positivity and/or M694V mutation may play a role in the development of sacroiliitis and the severity of seronegative spondyloarthropathy.