Significant association of interleukin-4 gene intron 3 VNTR polymorphism with susceptibility to knee osteoarthritis.

ABSTRACT

OBJECTIVE: Interleukin-4 (IL-4) is a strong chondroprotective cytokine and polymorphisms within this gene may be a risk factor for osteoarthritis (OA). We aimed to investigate genotype and allele frequencies of IL-4 gene intron 3 variable number of tandem repeats (VNTR) polymorphism in patients with knee OA in a Turkish population. METHODS: The study included 202 patients with knee OA and 180 healthy controls. Genomic DNA was isolated and IL-4 gene 70 bp VNTR polymorphism determined by using polymerase chain reaction (PCR) with specific primers followed by restriction fragment length polymorphism (RFLP) analysis. RESULTS: Our result show that there was statistically significant difference between knee OA patients and control group with respect to IL-4 genotype distribution and allele frequencies (p=0.000, OR 0.20, 95% CI 0.10-0.41, OR 0.22, 95% CI 0.12-0.42, respectively). CONCLUSIONS: Our findings suggest that there is an association of IL-4 gene intron 3 VNTR polymorphism with susceptibility of a person for development of knee OA. As a result, IL-4 gene intron 3 VNTR polymorphism could be a genetic marker in OA in a Turkish study population. This is the first association study that evaluates the associations between IL-4 gene VNTR polymorphism and knee OA.