When patients were classified as HOXAlo or HOXAhi based on HOXA9 expression (Supplementary Fig. 1c), we found that HOXAloMLL-AF4 infant-ALL and HOXAhiMLL-AF4 infant-ALL did not separate based on these 617 genes, suggesting that this was a true infant-ALL-specific gene expression profile, irrespective of other molecular characteristics (Fig. 1a). This evidence concerns the gene HOXA9 and acute lymphoblastic leukemia.