IDH1 and astrocytoma (excluding glioblastoma): We also performed a comparative analysis between LINE-1 methylation levels and the assignment of tumors into the methylation classes “astrocytoma, IDH-mutant, lower grade” or “astrocytoma, IDH-mutant, high-grade” according to the Heidelberg brain tumor classified v.12b5 (www.molecularneuropathology.org) using available 450 k DNA methylome data of 85 IDH-mutant astrocytomas included in our cohort, with LINE-1 methylation data being available for 80 of these cases.