IDH1 and neoplasm: Using the PMN status and the newly identified MCR, we categorised all IDH-mutant astrocytomas into 3 sub-classes: (1) “PMN-hit” tumours (those with any somatic alterations in the PMN), (2) “MCR-loss” tumours (those without any somatic alterations in the PMN but with a copy-number loss event overlapping the MCR) and (3) “WT” tumours (those with neither events).