PW01-024 – Phenotypic analysis of a MEFV negative FMF cohort

Introduction

Familial Mediterranean fever (FMF) is an inherited autosomal recessive disorder, ethnically restricted and commonly found among individuals of Mediterranean descent, caused by MEditerranean FeVer gene (MEFV) mutations on the chromosome 16. It is the most frequent periodic febrile syndrome among autoinflammatory syndromes. Eighty % of patients with FMF have MEFV mutations, while around 20% do not have mutations.

Objectives

We analysed epidemiological and clinical characteristics, as well as treatment schedules of a large cohort of FMF patients without any MEFV mutations, who responded to colchicine, in order to identify further clinical features of this specific subgroup.

Methods

Epidemiological and clinical details of 344 patients attending the Periodic Fevers Research Centre in a period of 15 years were analysed. We selected patients without MEFV mutations, in whom diagnosis was established by the Tel-Hashomer criteria. We finally compared the clinical findings of MEFV-negative population with the MEFV-positive one.

Results

Genetic testing by MEFV analysis was performed in all patients (n = 344); 41 patients (14%, 20 males and 21 females) negative for MEFV mutations were selected and studied. Similarly with MEFV positive patients, in our case-series, most MEFV- negative ones came from Southern and Central Italy. The mean age of FMF onset was 21.8 years, differently from what observed in MEFV- positive population, in which the mean age was 15. The frequency of attacks went from less than 1 attack/month (in 26%) to 1-2 attacks/month (in 54%) and more than 2 attacks/months (in 19.5%). The mean duration of each attack was 83.9 ± 8.91 hours. The typical clinical signs of FMF attacks were: fever (T max 39.4°C±0.12, present in 100% of patients), articular pain (76%), abdominal pain (63.4%), oral aphthosis (44%), and chest pain (37%). Thirty-one out of 41 patients had joint involvement in terms of arthritis (21.5%), arthralgias (25%), arthromyalgias (32%), and myalgias (21.5%). Attacks were controlled with a mean dose of colchicine of 1.5 mg/day in all patients (vs a mean dose of 1.3 mg/die in the MEFV- positive population). No statistically significant difference was detected in terms of frequency and duration of attacks, as well as in symptoms distribution and colchicine dosage between MEFV- negative and positive populations.

Conclusion

Analysis of our MEFV-negative series of Italian patients revealed a higher prevalence of late-onset FMF, whereas the percentage distribution of symptoms was similar to MEFV-positive patients. These results support the hypothesis of involvement of other low-penetrance genetic systems in the FMF clinical expression.

Disclosure of interest

None declared