Unsupervised analysis of the AIEOP dataset. (A) Samples' Euclidian distance matrix. The color in each entry (y,x), where x,y = 1, …, 97 (the number of samples), represents the Euclidian distance between the expression profiles of samples x and y. It was measured after centering and normalization of each sample's expression, using 1500 probe sets with highest standard deviation. The samples are ordered by SPIN along both the x-axis and y-axis. The color bars next to both axes represent the different ALL subtypes, listed on the right of the figure. The blue marks at bottom specify DS-ALL samples with mutant JAK2 (J2m), and the red marks specify samples with high CRLF2 expression levels (CRLF2) (see “Aberrant expression of the cytokine receptor CRLF2 in DS-ALLs” section on CRLF2). (B) Projection of all samples onto the first 3 principle components of the expression. DS indicates Down syndrome ALL; J2m, Down syndrome ALL with mutated JAK2 R683; HD, high hyperdiploid; TEL, TEL-AML1; BCR, BCR-ABL; E2A, E2A-PBX1; and MLL, MLL-AF4.