Meta-analysis of the IL-4R Q551R polymorphism showed a positive association between the polymorphism and periodontitis susceptibility in three genetic models (R versus Q: OR = 1.59, 95% CI = 1.14–2.22; QR versus QQ: OR = 1.84, 95% CI = 1.21–2.80; RR + QR versus QQ: OR = 1.82, 95% CI = 1.22–2.72) with low between-study heterogeneity (Table 6, Figure 4). This evidence concerns the gene IL4R and periodontitis.