GeneChip Mapping 500K set and Genome-Wide Human SNP 6.0 Array for glioblastomas

High-density single nucleotide polymorphism (SNP) arrays were used to investigate genome-wide copy number (CN) alterations and loss of heterozygosity (LOH) in glioblastomas (GBM) patients; our aim focused on the identification and detailed characterization of the genetic alterations of the chromosomes altered in these tumors and the identification of subgroups of GBM with distinct cytogenetic patterns of alteration for the affected chromosomes potentially associated with the behavior of the disease. Overall, gains of chromosome 7, losses of chromosomes 9p and 10 were the most frequent chromosomal alterations. The 7p11.2 region was amplified in several cases. Based on CN alterations for chromosomes 7, 9 and 10, five different cytogenetic patterns with a significant impact on patient survival were identified; noteworthy, cases with EGFR amplification showed a better survival, specifically among patients older than 60 years. In addition, our results provide further evidence about the relevance of the EGFR, CDKN2A/B, MTAP genes, and other genes coded in chromosome 10 in the pathogenesis of GBM. Altogether, our results confirm the cytogenetic heterogeneity of GBM and suggest that stratification of these tumors into genetic subsets based on the combined assessment of cytogenetic alterations involving chromosomes 7, 9 and 10, may contribute to the prognostic evaluation of GBM. GeneChip Mapping 500K set and Genome Wide Human SNP 6.0 Array were used to profile GBM with matched blood DNA samples. Loss of heterozygosity (LOH) and copy number abnormality (CNA) profiles were derived from each tumour-blood pair.