Familial Mediterranean fever with a single MEFV mutation: comparison of rare and common mutations in a Turkish paediatric cohort

Objective. Presence of common MEFV gene mutations strengthened the diagnosis of FMF in addition to the typical clinical characteristics of FMF. However, there are also rare mutations. P369S, A744S, R761H, K695R, F479L are the main rare mutations in Turkish population. We aimed to evaluate FMF patients with a single allele MEFV mutation and to compare patients with common and rare mutations. Methods. We retrospectively reviewed the medical records of FMF patients with a single allele mutation who were followed up between 2008 and 2013 in six centres. We compared the patients with rare and common mutations for disease severity score, frequent exacerbations (>1 attack per month), long attack period (>3 day), symptoms, age at the onset of symptoms, gender, consanguinity, and family history. Results. Two hundred and seventeen patients (M/F=101/116) with the diagnosis of FMF and single mutation were included. Heterozygote mutations were defined as common (M694V, V726A, M6801) and rare mutations (A744S, P369S, K695R, R761H, F479L). Sixty-seven patients (27 males, 40 females) had one single rare mutation and 150 (74 males, 76 females) had one single common mutation. No difference was found between the rare and common mutations with respect to the disease severity score. There was no significant difference between common and rare heterozygote form of mutations in terms of disease severity. Conclusion. Patients with typical characteristics of FMF, with some rare mutations (A744S, P369S) should be treated in the same manner as patients with a common mutation.