Correlation and pattern of expression of genes used to determine the clinical characteristics of 58 lymphoma samples (independent validation series). (A) Correlation plot of the FL stratification profile. Correlation of the expression profile of each tumor sample with the average expression profile of all low-grade samples of the training series is depicted on the horizontal axis, and the correlation of the expression profile of each tumor with the average expression profile of all high-grade tumor samples of the training series is shown on the vertical axis. Tumors classified above the threshold are classified as molecular high-grade; tumors below the threshold are classified as molecular low-grade. (B) Expression data matrix of 81 marker genes from tumors of the indolent as well as the aggressive phases of patients with FL. Each row represents the FL stratification profile for one tumor. Each column represents the relative expression of one gene. The genes in the horizontal direction are arrayed in the same order as in Figure 2B. Tumors are rank-ordered according to the difference in correlation with the average aggressive profile and the correlation with the low-grade profile of the training set (middle panel). The yellow line is the threshold as determined in Figure 2 (see Figure 2 for color scheme). In the panel on the right morphologic and clinical features are shown of the samples similar to features shown in Figure 2B. Of the 58 samples, 4 were misclassified (93% accuracy).