OLIG2 and central nervous system cancer: Cluster 1 included six samples with expressed CNS HGNET-BCOR signature genes and cluster 2 included other samples expressing only GFAP, OLIG2 or PMP2. Two samples from the same patient, originally diagnosed as anaplastic oligodendroglioma and the relapsed sample, expressed both CNS HGNET-BCOR signature and glioma marker genes (cluster 1B).