Gene expression–based separation of MLL-rearranged infant ALL subtypes. (A) Heatmap demonstrating differential gene expression between t(4;11) (n = 29), t(11;19) (n = 22), and t(9;11)-positive (n = 8) MLL-rearranged infant ALL samples, based on the 50 most significantly up-regulated probe sets for each patient group (compared with the other patient groups combined). Columns represent patient samples, and rows represent the gene names corresponding to the probe sets. Normalized gene expression is depicted in red (high expression) or blue (low expression). (B) PCA plot clustering the t(4;11) (red dots), t(11;19) (orange dots), and t(9;11) (yellow dots) according to these 150 selected probe sets.