CDKN2A and neoplasm: The six cases of IDHwt tumours without HP/GD events, harboured mutations in TP53 and CDKN2A, although alterations in these genes were not mutually exclusive with the absence of GD and HP (TP53: 3/6, 50%, CDKN2A/B: 5/6, 83%, Fig. 1D).