In Logistic regression analyses (Table 2), MetS was significantly associated with immunoglobulin E {crude odds ratio (OR) [95% confidence interval (95% CI)] 0.980 (0.964–0.996); adjusted OR (95% CI) 0.981 (0.966–0.997); P < 0.05 for all} and complement C3 levels [crude OR (95% CI) 1.022 (1.013–1.030); adjusted OR (95% CI) 1.020 (1.012–1.029); P < 0.05 for all]. This evidence concerns the gene C3 and metabolic syndrome.