Relapsing periodic arthritis, palindromic rheumatism and MEFV gene-related variants alleles in children

BACKGROUND: Relapsing periodic arthritis is a general term used for a group of diseases with recurring and periodic nature, in which the joints are intermittently involved. The aim of this study is to evaluation of the possible relationship between MEFV gene mutations in intermittent arthritis of children which has recurring and periodic nature. METHODS: In this cross-sectional study we reviewed medical records of all patients with recurrent and periodic arthritis referred to pediatric rheumatology clinic from 2003 to 2019.We excluded all patients with suspicious anamnesis and/or positive history of FMF, JIA, gout, psoriasis, IBD and SLE. The peripheral blood of these patients was screened for the 12 common pathogenic MEFV gene variants (FMF Strip Assay, Vienna lab, Vienna, Austria) according to manufacturer’s instructions. RESULTS: Among 195 recorded files, 11 patients were identified with idiopathic recurrent and periodic feature. 3 patients suffering from recurrent transient synovitis hip (RSH) and 8 patients were fully compatible with the Pasero and Barbieri modified criteria of palindromic rheumatism (PR). Their mean age at diagnosis was 6.5 and 4.6 years and the average follow-up was 2.6 and 6.6 years in PR and RSH patients, respectively. The most frequently involved joints were knees and ankles in PR patients. The mean duration of attacks was 3.3 days in RSH patients and with various courses in PR. The median number of attacks was 4.75 in PR and 3 in RSH patients per year. In PR group 7 patients showed no mutations and all patients of RSH had these mutations; V726A, R761H, A744S as in heterozygote pattern. CONCLUSION: An idiopathic relapsing periodic arthritis in children with exclusively hip involvement is a MEFV gene related arthropathy; whereas with various joint attacks it could be considered as childhood PR.