DLBCL and MLBCL genes. (A) Permutation analyses of differentially expressed genes in MLBCL and DLBCL. The observed signal-to-noise ratios (SNRs, x-axis) of ranked genes with lower levels of expression (left) and higher levels of expression (right) (black) in MLBCL versus DLBCL are compared with those expected by chance in 99% (red), 95% (yellow), and 50% (blue) of permutations. The y-axis indicates the number of genes that are differentially expressed in each direction. (B) Comparative gene expression profiles of DLBCL and MLBCL. At the top, the actual clinical/pathologic diagnosis of DLBCL versus MLBCL (green versus red), presence or absence of mediastinal disease (pink versus light green), and molecular prediction of DLBCL versus MLBCL (green versus red) are compared. The top 50 genes that were expressed at higher levels in MLBCL are shown in the upper half of the figure and the top 50 that were more abundant in DLBCL are shown in the lower half of the figure. Red indicates high relative expression; blue, low expression. Color scale at the bottom indicates relative expression in standard deviations from the mean. Each column is a sample and each row is a gene. Genes are clustered using hierarchical clustering. Expression profiles of 176 DLBCLs are on the left; profiles of the 34 MLBCLs are on the right.