Taken together, our findings, thus, confirm lower levels of global DNA methylation as a prognostically unfavorable molecular alteration in IDH-mutant astrocytomas [42, 43, 56] that can be detected by DNA methylation arrays and other methods like LINE-1 methylation analysis using pyrosequencing, i.e., a method already established in many laboratories for the assessment of the MGMT promoter methylation status [54]. Here, IDH1 is linked to astrocytoma (excluding glioblastoma).