Figure 2

Unsupervised clustering of 4 oligodendrogliomas with 1p19q codeletion and 9 gliomas with EGFR amplification. Unsupervised hierarchical clustering was performed using the 1366 probe sets whose expression varied the most across the 13 samples (probe sets with a robust coefficient of variation superior to the 97.5^th percentile). Samples and genes were clustered using Ward's linkage and 1-Pearson correlation coefficient. For each probe set, data were median-centered (white), with the lowest and highest intensity values in blue and red, respectively. 1p19q = 1p19q codeletion, EGFR = EGFR amplification. The gliomas were classified into 2 groups according to their genomic profile. Gliomas with EGFR amplification were classified into one cluster irrespective of their histology (red = glioblastoma, green = grade III oligodendroglioma, blue = grade III oligoastrocytoma). Gene cluster A was enriched in genes involved in proliferation, extracellular matrix, immune response, embryonic development and angiogenesis. Gene cluster B was enriched in genes involved in synaptic transmission. Gene cluster C was enriched in genes involved in neurogenesis and synaptic transmission.