Unsupervised hierarchical cluster analyses. (A) Thumbnail overview of an unsupervised 2-way hierarchical cluster analysis of 93 CBF AML cases (columns) and 8556 variably expressed genes (rows). Mean-centered gene-expression ratios are depicted by a log₂ pseudocolor scale (indicated). Gray denotes poorly measured data. Samples are color-coded according to the cytogenetic groups t(8;21) and inv(16). The sample dendrogram shows that CBF samples separated into 2 major subgroups, as indicated. Gene clusters characterizing the respective groups as well as t(8;21) and inv(16) are highlighted by colored bars. (B) Kaplan-Meier estimates of overall survival in the 2 CBF subgroups; the difference between groups I and II was significant (P = .029, log-rank test). The “x” symbols indicate censored data. (C,D) Kaplan-Meier estimates of overall survival of CBF subgroups based on unsupervised hierarchical cluster analysis in t(8;21) (C) and inv(16) cases only (D).