IDH1 and glioma: Almost mutually exclusive mutations of the TERT gene promoter in IDH-wt and IDH-O tumors on one hand, and of the ATRX gene body often in combination with mutated TP53 in IDH-A gliomas on the other hand give rise to TEL(omerase induced) and ALT(ernative)-like TM pathways, respectively [22,89].