PTEN and central nervous system cancer: For example, IDH1 mutations are frequent events in all grade II and III gliomas and in secondary glioblastomas (sGBM, glioblastomas that progress from lower grade gliomas) whereas primary GBMs (pGBM) are usually IDHwt and frequently have genetic changes involving the EGFR locus, PTEN deletions and TERT promoter mutations [4, 6, 12].