CDKN2A and glioblastoma: The following alterations characteristic for GBM were detected when applying a less strict threshold for analysis: PIK3CA p.E453Q (COSMIC ID: COSM758), NF1 p.I1679_Y1680del (COSMIC ID: COSM6969872) and CDKN2A/B (p15/16) deletion, further confirming the GBM origin of the metastasis.