Interleukin-17F gene polymorphism in patients with chronic immune thrombocytopenia

INTRODUCTION: IL-17F is a novel inflammatory cytokine and plays an important role in some autoimmune diseases. We investigated the association between chronic ITP and the frequency of the single-nucleotide polymorphism rs763780 (7488T/C), which causes a His-to-Arg substitution at amino acid 161. PATIENTS AND METHODS: We examined 102 patients (men/women, 40/62; median age, 42) diagnosed with chronic ITP and 188 healthy controls (men/women, 78/110; median age, 38). Genotyping was determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS: Compared with the control group, patients with chronic ITP had a significantly lower frequency of the IL-17F 7488CC genotype (0% vs. 4.8%, P<0.05). The number of IL-17F 7488C alleles among the patients with chronic ITP was also significantly lower than in the control group (8.7% vs. 15.2% OR=0.48, 95%CI=0.27-0.84, P=0.016). Furthermore, patients with the IL-17F 7488TT genotype showed a severe thrombocytopenic state (platelet count<10×10(9) /L) at diagnosis than those with the IL-17F 7488TC genotype (20.9% vs. 0%, P=0.04). CONCLUSION: These findings suggest that the IL-17F 7488 T allele is significantly associated with the development of chronic ITP, suggesting a role for IL-17F in the pathogenesis of chronic ITP.