We investigated 10 constitutional (leukocyte) DNA samples, and 20 tumor samples, including four low-grade gliomas, one IDH-mutant astrocytoma, CNS WHO grade 4, and 15 IDH-wildtype glioblastomas for copy number (CN) alterations of chromosome 7 (Fig. 4). Here, IDH1 is linked to astrocytoma (excluding glioblastoma).