SMAD4 and metabolic syndrome: Among the 141 tag SNPs assessed in this study (Supplementary Table S3), there were 20 tag SNPs, among those SNPs present in the SMAD2, SMAD3, SMAD4, TGFB2, TGFB3, and TGFBR2 genes, which showed evidence of an association (P < 0.05) with MetS (Table 2).