Other genetic modifiers intervene in the definition of the GBM biological signature, resulting in the amplification of the Epidermal Growth Factor Receptor (EGFR), loss of heterozygosity or entire loss of chromosome 10, where Phosphatase and tensin homolog (PTEN) maps, amplification and mutational activation of receptor tyrosine kinase (RTK) genes, O6-methylguanine-DNA methyltransferase (MGMT) promoter hypermethylation appear. The gene discussed is EGFR; the disease is glioblastoma.