Interleukin-6 (IL-6) -174 G/C polymorphism in familial Mediterranean fever patients with and without amyloidosis

Familial Mediterranean fever (FMF) is a recessive disorder characterized by attacks of fever and inflammation. A sustained inflammatory reaction is observed in the disease course, and cytokine levels such as interleukin (IL)-1, IL-6 and tumor necrosis factor-alpha (TNF-alfa) are shown to increase during and between the attacks. In this study, we investigated the role of the functionally important IL-6 -174 G/C polymorphism in the clinical outcome of FMF and amyloidosis. One hundred and fifty-six FMF patients (80 with amyloidosis) and 90 healthy controls were studied. The genotype distributions and allele frequencies of the patients and the controls were found to be similar, and the differences between the groups were not statistically significant. The results show that IL-6 -174 G/C polymorphism is not associated with FMF and amyloidosis. The increase observed in cytokine levels during and between the attacks is more likely due to the inflammatory nature of the disease.