Unsupervised hierarchical clustering of TACI^hi and TACI^lo MMCs. The 659 genes that statistically (P = .01) distinguished (ratio 1.5 or 0.67) TACI^hi patients and TACI^lo patients are presented graphically using hierarchical clustering. The color of each cell in the tabular image represents the expression level of each gene (red, expression higher than the mean; green, expression lower than the mean; increasing color intensity represents a higher magnitude of deviation from the mean). The TACI₄₀^lo, TACI₂₅^lo, and TACI₁₅^lo subgroups were represented by graded blue color (more intense in TACI₁₅^lo) and the TACI₄₀^hi, TACI₂₅^hi, and TACI₁₅^hi) subgroups were represented with graded red color (more intense in TACI₁₅^hi). (A) Initial set of 65 patients. (B) Validation set of 40 patients.