Unsupervised hierarchical clustering of blood transcriptional profiles of septic patients. Transcripts with 2-fold over- or under-expression compared with the median of all samples and differential expression values greater than 200 from the median for each gene in at least 2 samples in the training set were selected for unsupervised analysis (n = 2,785 transcripts). (a) A heatmap resulting from hierarchical clustering of transcripts and conditions (subjects) was generated for the training set. (b) The same gene tree of these 2,785 transcripts was then used to generate a heatmap for the first independent test set (test set 1) using hierarchical clustering of conditions as before. The color conventions for heatmaps are as follows: red indicates over-expressed transcripts; blue represents underexpressed transcripts; and yellow indicates transcripts that do not deviate from the median. Study group is marked as follows: patients with melioidosis are indicated by pink rectangles; patients with sepsis due to other organisms by green rectangles; uninfected controls who recovered from melioidosis by black rectangles; T2D patients by purple rectangles; and healthy donors by blue rectangles. This unsupervised hierarchical clustering of blood transcriptional profiles was observed to segregate into five distinct regions in both training (regions R1 to R5) and test sets (regions R6 to R10).
Pankla et al. Genome Biology 2009 10:R127 doi:10.1186/gb-2009-10-11-r127