Analysis of polymorphisms in the colchicine binding site of tubulin in colchicine-resistant familial Mediterranean fever patients

Familial Mediterranean fever is a hereditary autoinflammatory syndrome. The typical treatment for the disease is colchicine. However, a subset of patients are not responsive to colchicine. In this study, polymorphisms in the colchicine-binding site of the TUBB1 gene, which encodes a tubulin isoform specific to leukocytes, were investigated in patients with colchicine-resistant disease. FMF patients who were followed in the Department of Pediatric Rheumatology at Hacettepe University were included in this study. Colchicine resistance was defined as ongoing disease activity (>= 1 attack/month over 3 months or persistently elevated CRP) while taking the maximum tolerated dose of colchicine. A total of 62 Turkish FMF patients (42 colchicine-responsive and 20 colchicine-resistant) and a control group of healthy children were included in the study. DNA was extracted for analysis of TUBB1, and the colchicine binding site was sequenced. We did not observe A248T (rs148237574) or M257V (rs759579888), two variations that were previously associated with colchicine resistance in an in silico analysis. We did detect T274M (rs35565630), R306H (rs772479017), and R307H (rs6070697) variants in the FMF patients, but there was no statistically significant difference between the colchicine-responsive and colchicine-resistant groups. This is the first study to evaluate TUBB1 gene polymorphisms in the colchicine binding site in patients with FMF. Our data do not support the hypothesis that these polymorphisms are a possible cause of colchicine resistance in FMF patients.