Independence of association signals. PLG levels of different SNP genotypes were analyzed in the combined TSS and GABC data, which were merged after adjusting for the significant environmental factors and making sure that they already have nearly the same distributions (Kolmogorov-Smirnov test, P = .07; Mann-Whitney U test, P = .53). (A) Boxplot of the distribution of PLG levels in various genotype combinations of the top 2 independent SNPs, rs4252129 and rs1084651, showing additive effects of rs1084651 in every rs4252129 genotype. The inserted table shows the counts of nonmissing genotypes for rs4252129 (row) and rs1084651 (column). One-way analysis of variance test by coding the available genotype combinations ordered by allelic effect directions as integers 1 to 6 revealed P = 3.5E-38. (B-D) Distribution of PLG levels in various genotype combinations of the top 3 independent SNPs on Chr6 and Chr19, showing additive effects of rs41272114 (B), rs783176 (C), and rs1041297 (D) in most genotype combinations of rs4252129 and rs1084651. One-way analysis of variance tests by coding the available genotype combinations as integers revealed P values of 8.0E-40 (B), 2.8E-42 (C), and 6.6E-43 (D), respectively.