IDH1 and glioblastoma: Besides IDH, secondary glioblastomas are characterized by TP53, PDGF and ATRX mutations, as well as loss of chromosome 19q (30), while in the majority of IDH-wildtype, epidermal growth factor receptor (EGFR) overexpression, phosphate and tensin homolog (PTEN) mutations, and loss of chromosome 10q are common (31).