Genetic risk factors of amyloidogenesis in familial Mediterranean fever.

Background/aims: Evaluation of the risk factors, and phenotype-genotype correlation of familial Mediterranean fever (FMF) gene (MEFV) and serum amyloid A1 (SAA1) gene polymorphisms in renal amyloidosis.

Methods: We investigated MEFV and SAA1 genotypes (alpha, beta, and gamma isoforms) in 50 FMF patients and 50 healthy children. Tel-Hashomer criteria were used for the diagnosis and severity scoring of FMF.

Results: The most common MEFV mutation and SAA1 genotype were M694V/M694V (n = 26/50) and SAA1 alpha/alpha (n = 26/50), respectively. Positive family history for amyloidosis was significantly higher (p < 0.001) with more severe clinical course (p = 0.006) in the amyloidosis group than the non-amyloid group. In M694V/M694V mutation, erysipelas-like skin erythema (p = 0.029), arthritis (p = 0.004), arthralgia (p < 0.001) were significantly more frequent with higher severity scores (p = 0.008) than the patients with other mutations. Comparison of the SAA1 alpha/alpha genotype with other genotypes revealed more frequent arthritis (p = 0.003) in the SAA1 alpha/alpha genotype. In amyloidosis group patients having both M694V/M694V and SAA1 alpha/alpha genotypes were the largest subgroup (n = 14, p < 0.001). Logistic regression analysis for amyloidosis corrected risk revealed a 1.2 times increase in M694V/M694V, a 2.4 times increase in SAA1 alpha/alpha genotypes and a 2.5 times increase when both are together.

Conclusion: Positive family history for amyloidosis and presence of SAA1 alpha/alpha genotype in M694V/M694V mutation may predispose to amyloidosis by increasing the clinical severity. Therefore, in such children early colchicine treatment might be recommended even if they are asymptomatic.