Hierarchic clustering of CDX2-positive AML samples according to HOX gene expression. (A) Unsupervised hierarchic clustering according to HOX gene expression demonstrates HOX gene deregulation in patients with normal karyotype with or without NPM1 mutation compared with samples with abnormal karyotype or normal bone marrow samples. The red arrows highlight the boundary between the 2 main clusters. The genes and samples were permutated. (B) Expression of individual HOX genes in CDX2-positive AML samples with normal and abnormal karyotype. Log expression levels of 6 different HOX genes in 75 clinical samples are shown in box-and-whisker plots. Expression was determined by Affymetrix HGU-133 A and B microarrays. The plots show the normalized expression values in normal BM samples (n = 11), AML with t(8;21) (n = 20), AML with t(15;17) (n = 20), and AML with normal karyotype with (n = 12) and without NPM1 mutation (n = 12). The bar indicates the median expression levels and the box shows the 25th and 75th percentiles, while the whiskers show the maximum and minimum values. Outliers (values that are more than 1.5 interquartile ranges above the 75th or below the 25th percentile) are represented by open circles.