Familial Mediterranean fever (FMF)-associated amyloidosis in childhood. Clinical features, course and outcome

Abstract

Objective: Familial Mediterranean fever (FMF) is an autosomal recessive disorder of childhood characterized by attacks of fever and serositis. Renal amyloidosis is the most important complication of the disease that determines the prognosis.

Methods: Forty-eight Turkish FMF patients with amyloidosis who have been followed at the two hospitals in Ankara were included in this study.

Results: All patients with amyloidosis had been symptomatic for FMF at the time of the diagnosis (Phenotype I), none had received regular colchicine therapy and all presented with proteinuria. Ten of them had asymptomatic proteinuria; 38 had nephrotic syndrome and 8 of them had renal insufficiency (CRI) as well, at the time of the diagnosis. Regular colchicine therapy was commenced to all of the patients. At the end of observation period of 4.5 +/- 2.23 years (range 2-12 yrs) on treatment, nephrotic syndrome resolved in 13 patients and proteinuria was lost in 5 of them. None but 2 of the patients who were diagnosed at proteinuric stage progressed to end stage renal failure (ESRF). Seven MEFV mutations (M694V, M680I, V726A, M694I, K695R, R761H, E148Q) were systematically investigated in 32 patients. Six of the seven studied mutations were found in these patients and clinical diagnosis was confirmed by mutation analysis in 24 patients. Eight patients were found to have mutations on one of the alleles.

Conclusion: Amyloidosis is the most serious complication of FMF. Colchicine treatment ameliorates the progression of renal disease in the patients who presented with proteinuria and even with nephrotic syndrome. No correlation between the outcome of the patients with nephrotic syndrome and the degree of proteinuria and/or serum albumin levels at the initiation of treatment were noted. Progression to ESRF seems inevitable despite colchicine therapy after the development of CRI in patients with FMF associated amyloidosis.