Assessment of Affymetrix data. (A) Hierarchical clustering using a simple matching similarity metric with average linkage of 127 childhood ALL patients using expression values of the 15 probe-set (14 genes). (B) Principal component analysis. Clusters indicated by green and orange correspond to hierarchical cluster dendrogram.(C) Cumulative incidence of relapse among the 127 patients for the 2 patient groups. Time is in years. Lines indicated by green and orange correspond to the clusters identified by the hierarchical dendrogram.