Interleukin-6 gene polymorphism and risk of osteoarthritis of the hip: a case-control study

OBJECTIVES: Osteoarthritis (OA) is considered a polygenic disease controlled by the expression of genetic factors. Genes encoding for cytokines have been associated with susceptibility for joint OA and interleukin (IL)-6 gene is also supposed to be involved in the cartilage degradation process. In this case-control study, we evaluated for the first time whether the risk of hip OA might be influenced by the -174 IL-6 gene polymorphism. METHODS: The distribution of IL-6 genotypes was evaluated in 75 patients affected by hip OA and in 107 age- and sex-matched controls. RESULTS: The distribution of IL-6 genotypes in (1) patients with hip OA: 33 GG, 30 GC, 12 CC and (2) control subjects: 34 GG, 40 GC, 33 CC. The frequency of the CC genotype was significantly higher in control patients (P=0.02). Logistic regression analysis indicated that the presence of the CC genotype is independently associated with a decreased risk of OA (odds ratio 0.4 [95% confidence interval 0.1-0.9], P=0.04). CONCLUSIONS: Primary OA of the hip has an important genetic component and variations of genes encoding for inflammatory cytokines, such as IL-6, may play an important role in the series of events responsible for the pathophysiology of OA.