Gene expression profile of AML+13. (A-B) FLT3 and SPRY2 expression in AML subgroups. Boxplot showing FLT3 (A) and SPRY2 (B) expression levels in various cytogenetic AML subgroups. The boxes indicate the upper and lower quartiles. The band within the boxes represents the median. Outliers are plotted as individual points. FLT3 expression is significantly higher in AML+13 compared with all other samples (P = .04). However, in several individual samples of various cytogenetic subgroups, FLT3 was expressed at higher levels compared with AML+13. SPRY2 expression is significantly lower in AML+13 (P < .001). (C) Clustering of AML+13 using 21 probe sets. Heatmap visualizing hierarchical clustering of AML+13 samples according to the 21 most differentially expressed probe sets (log-fold change ≥ 2 or ≤ −2 and adjusted P-value < .001) compared with AML with various other cytogenetic aberrations except for +13. All AML+13 samples cluster closely together, indicating a highly homogenous expression profile of this subgroup. (D) Regional gene expression on chromosome 13 in AML+13. Expression levels of probe sets located on chromosome 13 displayed by MACAT analysis in AML+13 patients (n = 9) compared with AML with various other cytogenetic abnormalities (except +13, n = 519). Scores for probe sets are shown as black dots. The sliding average of the 0.025 and 0.975 quantiles of the permuted scores are visualized as gray lines. The sliding average permuted scores (red line), and highlighted regions (yellow-dotted), where the score exceeds the quantiles, are plotted along chromosome 13. Despite the majority of probe sets showing elevated expression levels as expected, some regions were characterized by significantly lower expression levels.