Joint Manifestations in Children with Familial Mediterranean Fever in Armenia: Clinical and Genetic Characteristics

Familial Mediterranean fever (FMF) is an autosomal-recessive autoinflammatory disease in the group of Hereditary periodic fever syndromes (HPFS), characterized by recurrent, self-limited attacks of fever and polyserositis, which last 2-4 days. It manifests mainly in childhood and often has early onset, resolve without sequels. Genetic testing of FMF is efficient and allows diagnosing of atypical cases. FMF is a significant health care problem in Armenia because of high frequency of carriers of MEFV mutations 1:3 - 4 (0.21) and marked FMF prevalence 54.7 per 10`000 of the total population. Articular symptoms are found in about 45% of cases. They usually manifest as acute recurrent arthritis (ARA) or arthralgia, but more rarely also chronic arthritis can be found. We aimed to investigate clinical and genetic characteristics of the joint manifestations in Armenian children with FMF. The charts of all 715 patients with proven diagnosis of FMF at the National Pediatric Center (NPC) for FMF were reviewed for joint manifestations. The diagnosis of FMF and disease severity were determined according to the Tel-Hashomer criteria and molecular-genetic detection of 12 MEFV mutations common for Armenians. The characteristics of joint manifestations and overall FMF disease were then compared to MEFV mutation analysis. There were 438 boys and 277 girls with an age at diagnosis between 3 months and 17 years (mean age: 8.64±0.17). Joint involvement was observed in 56.4% of all 715 cases. The manifestation was ARA in 30.5%, arthralgia in 21.2% and chronic arthritis (CA) in 4.7%, which would also qualify for a diagnosis of JIA. The frequency of ARA was associated with M694V mutation, mainly M694V homozygous and M694V heterozygous genotypes. The risk of CA depended on MEFV genotype of the FMF patients and was the highest in M694Vheterozygotes and M694Vhomozygotes. M694V heterozygous genotype was noticed significantly more frequently among FMF patients with spondyloarthritis in comparison to those without it. The probability of the development of CA among FMF patients without M694V mutation was significantly higher also in heterozygotes in comparison to compound-heterozygotes. We concluded, that the frequency of joint involvement among Armenian pediatric FMF patients was high - 56.4%, especially for CA. Chronic arthritis may be the first manifestation of FMF and occurred usually in patients with severe M694V mutations. Patients of Armenian origin with refractory arthritis should be asked for isolated febrile attacks, hemorrhagic vasculitis, episodes of pleuritis and family history to rule out FMF.