Chronic non-bacterial osteomyelitis: another disease associated with MEFV gene mutations

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disease of unknown aetiology. The relationship between CNO and familial Mediterranean fever (FMF) is not clearly documented so far. This cross-sectional study aims to evaluate the clinical and laboratory characteristics of a cohort of CNO patients within the context of its relationship with FMF and MEFV gene mutations. Demographic and clinical data were extracted from electronic medical records of patients with CNO. The MEFV gene analysis was performed for all patients. A total number of 18 patients with CNO with a median follow-up of 36.50 (13.00-84.00) months were included in the study. Five patients (27.8%) were found to have at least one exon 10 mutations (four with M694V and one with M680I). Four of them (22.2%) had homozygous or compound heterozygous mutations of the MEFV gene. Two patients had a previous diagnosis of FMF and developed CNO while FMF was under control. Patients with MEFV mutations had an earlier onset of CNO, higher acute phase reactants, lower haemoglobin concentrations, and a higher number of bone lesions at disease onset with a persistent course of disease more frequently. Our results demonstrated an increased frequency of MEFV gene mutations in CNO and a more severe disease phenotype of CNO in patients with MEFV gene mutations. Physicians practicing in regions where FMF is prevalent should be aware of this relationship and ask about the symptoms of FMF in detail in patients with CNO. Moreover, FMF should be included in CNO-associated conditions.