Figure 3From: Meta-analysis of tumor necrosis factor alpha -308 polymorphism and knee osteoarthritis risk Meta-analysis of TNF-α -308 genotypes and OA risk: (A) AA genotype frequency; (B) GA genotype frequency; (C) GG genotype frequency. Note: No AA genotype in Romero’s study and Valle’s study, therefore, these two studies were excluded in AA frequency analysis.Back to article page