Association of interleukin-1 receptor antagonist gene polymorphism with response to conservative treatment of lumbar herniated nucleus pulposus

Study Design: A case-control study. Objective: To evaluate the relationship between gene polymorphism in interleukin 1 receptor antagonist (IL1RN) and response to conservative treatment of lumbar herniated nucleus pulposus (HNP). Summary of Background Data: There had been several studies on IL1RN polymorphism related with incidence of disc degeneration or back pain but, there had been no report on clinical features of lumbar HNP. Methods: We analyzed the variable number tandem repeat polymorphism of IL1RN genes in 54 single level subligamentous extruded lumbar HNP patients and compared allele frequency and incidence of heterozygote with 227 healthy adult controls. Within HNP group, we compared 2 groups; surgery group and conservative treatment group according to response to conservative treatment. Results: The prevalence of A1 (odd ratio = 0.45, P = 0.0009) and A3 (odd ratio = 3.86, P = 0.0006) was significantly higher in HNP group than control group. The allele frequency of A1, A2, A3, A4, and A5 were 84.2:84.6, 7.3:15.4, 8.5:0, 0:0, 0:0, respectively, in surgical and conservative treatment group. The allele frequency for A3 was found significantly higher in the surgery group than in he conservative treatment group. Conclusion: These results suggest that a high allele prevalence of A3 contribute to the clinical progression and the response to conservative treatment for lumbar HNP. IL1RN gene polymorphism may affect the clinical course of lumbar HNP.