Enthesopathy in Patients with Familial Mediterranean Fever: Increased Prevalence in M694 V Variant

Enthesopathy is pathology of bony insertions of tendons, ligaments or joint capsules. It is a frequent finding in rheumatic diseases, like ankylosing spondylitis (AS) and Behçet's disease. Musculoskeletal complaints are common in patients with familial Mediterranean fever (FMF), and these could be a clinical manifestation of enthesopathy. Hence, we investigated the possible association between FMF and enthesopathy. Fifty-six patients with FMF and 11 patients with FMF-associated spondyloarthropathy (FMFS) were enrolled. Forty-seven healthy individuals and 36 patients with AS formed the healthy and diseased control groups. Musculoskeletal complaints were meticulously questioned, and all patients underwent a detailed physical and ultrasonographic (US) examination of the lower limbs. US scorings of enthesopathy was performed according to the Glasgow Ultrasound Enthesitis Scoring System (GUESS). Demographic data, disease characteristics, MEFV genotypes and HLA B27 results were retrieved from the medical records. Patient-reported pain and physical examination findings consistent with enthesopathy were frequent in all groups with the highest prevalence in the FMFS group. Heel was the most common region affected in all patient groups. FMF patients harboring M694 V variant had higher GUESS scores compared to patients with other variants (2.78 ± 2.43 vs. 1.37 ± 1.67, p = 0.026). There was no statistically significant difference in the mean ± SD GUESS scores between healthy subjects and those FMF patients with genetic variants other than M694 V (1.38 ± 1.42 vs. 1.37 ± 1.67, p > 0.05). Enthesopathy may not be a feature of general FMF population; rather, it might be specifically associated with the presence of M694 V variant. Our results further support the previous evidence regarding M694 V mutation and spondyloarthropathy association.