Correlation view based on unsupervised clustering of 215 AML specimens involving 178 differentially expressed mature human microRNAs (right section) and the relative expression levels of microRNAs that characterize each of the individual clusters (left section). In the Pearson correlation view, the red squares indicate a positive correlation and the blue squares a negative pairwise correlation between the microRNA expression signatures. Using the program Heatmapper,⁴⁰  cytologic, cytogenetic, and molecular data were plotted along the diagonal. Cytogenetic abnormalities and FAB classifications are indicated with different colors. The presence of molecular abnormalities, such as NPM1, CEBPA, FLT3-ITD, and FLT3-TKD mutations, is indicated in red and absence in green. On the left part of the figure, each individual microRNA expression cluster with a particular (cyto)genetic AML subtype is indicated (subtypes with [cyto]genetic abnormality). The total number of cases in each cluster and percentage of (cyto)genetic subtype of AML in cluster are presented in the columns. In addition, the percentages of these (cyto)genetic subtypes present within each microRNA expression cluster (thus also indicating relative proportion of cases with the abnormality that are located outside the cluster) is given (% of total [cyto]genetic subtype). The levels of expression of 178 microRNAs of each of the 22 clusters including normal bone marrow CD34⁺ cells are presented in the heatmap on the left side of the correlation view. The scale bar indicates an increase (red) or decrease (green) in the level of expression by a factor of 7 relative to the geometric mean of all samples.