RB1 and malignant glioma: Frequent gene alterations observed in adult cerebral GBMs such as mutations in the TERT promoter, PIK3CA, PTEN, and RB1 were not detected in DCGs, and the rates of chromosome 10 loss, chromosome 7 gain, and mutation or amplification of EGFR were much lower than those of common cerebral high-grade gliomas [4, 6].