Comparative genetic patterns of glioblastoma multiforme: Potential diagnostic tool for tumor classification

Cytogenetic and molecular genetic studies of glioblastoma multiforme (GBM) have shown that the most frequent alterations are gains of chromosome 7, lo sses of 9p loci and chromosome 10, and gene amplification, primarily of the epidermal growth factor receptor (EGFR) gene. Although this profile is pot entially useful in distinguishing GEM from other tumor types, the technique s used tend to be labor intensive, and some can detect only gains or losses of genetic loci. Comparative genomic hybridization (CGH) is a powerful tec hnique capable of identifying both gains and losses of DNA sequences. The p resent study compares the CGH evaluation of 22 GEM with classic cytogenetic s, loss of heterozygosity by allelotyping, and gene amplification by Southe rn blot analysis to determine the reliability of CGH in the genetic charact erization of GEM. The CGH and karyotypic data were consistent in showing ga in of chromosome 7 accompanied by a loss of chromosome 10 as the most frequ ent abnormality, followed by a loss of 9p in 17 of 22 GEM cases. Loss of he terozygosity of chromosomes 10 (19/22) and 9p (9/22) loci confirmed the und errepresentation by CGH. Genomic amplifications were observed by CGH in 5 o f the 10 cases where gene amplification was detected by Southern blot analy sis. The data show that CGH is equally reliable, compared with the more est ablished genetic methods, for recognizing the prominent genetic alterations associated with GEM and support its use as a plausible adjunct to glioma c lassification.