Clinical, laboratory and molecular characteristics of children with Familial Mediterranean Fever-associated vasculitis.

Familial Mediterranean Fever (FMF) is an autosomal recessive disease characterized by recurrent self-limited attacks of fever accompanied by peritonitis, pleuritis and arthritis. Approximately 5% of individuals with FMF have been reported to have Henoch-Schönlein purpura (HSP) and about 1% have polyarteritis nodosa (PAN). Protracted febrile myalgia is another vasculitis-associated clinical entity among patients with FMF. Recently, the gene responsible for FMF, MEFV, has been cloned and four missense mutations (M680I, M694V, V726A and M694I) have been described. In this report, we present clinical and laboratory findings and mutation results of 23 children with FMF-associated vasculitis. HSP, PAN and protracted febrile attacks have been diagnosed in 11, 2 and 10 children, respectively. Mutation analysis shows that 3 children are homozygotes for the M694V mutation and 11 are compound heterozygotes for 2 of the studied mutations. M694V/V726A mutations were identified in 8, M694V/M694I in 2 and M680I/M694V in 1 of these children. In six children only one mutation was found and in three none of the studied mutations were identified. This study confirms that most children with FMF-associated vasculitis have identifiable mutations in the MEFV gene. Environmental and/or other genetic factors are possibly involved in the pathogenesis of vasculitis in FMF; elucidation of these mechanisms will help to understand pathogenesis of childhood vasculitides.