Familial Mediterranean fever in children: report of a large series and discussion of the risk and prognostic factors of amyloidosis

Familial Mediterranean fever (FMF) is a genetically transmitted disease characterized by recurrent attacks of fever and serositis. The most important complication of this disease is the development of amyloidosis. We present our analysis of 425 FMF patients without and 180 with amyloidosis (123 FMF having amyloidosis type 1 and 57 FMF having amyloidosis type II). The male female ratio was higher in the amyloidosis population (111/69) when compared to the FMF population (225 200) (P = 0.048). Consanguinity rate was the same among FMF and amyloidosis groups. However, a family history of amyloidosis was significantly more frequent in the amyloidosis group (P = 0.00001). Multivariate analysis has revealed that in FMF patients, the presence of a family history of amyloidosis plus consanguinity has a 6.04 fold increased risk of amyloidosis (P0.0001). The 5-year chronic renal failure free survival was 43.1% and 18.7% in type I and type II amyloidosis, respectively. The time interval to develop chronic renal failure after the development of amyloidosis was 4.8 in type I and 3.0 years in type II. respectively. We found ten cases of Henoch-Schönlein Purpura and nine of polyarteritis nodosa among our patients. The significance of the association between FMF and vasculitis awaits to be clarified. Among the FMF patients put on colchicine therapy (435), only 10 (2.3%) have developed amyloidosis confirming that this drug protects from amyloidosis.Since the presence of a familial history of amyloidosis has been defined as the most important risk factor in the development of amyloidosis, we suggest that additional genetic factors may be operative in the development of amyloidosis.