IDH1 and meningioma: For quality assurance approval of our assay according to the ILAC (DAkkS) standards for inspection bodies (ISO/IEC 17020) [32, 33], we defined a QC (quality control) cohort of 17 cases comprising 4 astrocytic gliomas, IDH-mutant (WHO grade II/III/IV); 2 oligodendrogliomas, IDH-mutant and 1p/19q-codeleted (WHO grade III); 5 astrocytic gliomas, IDH-wildtype, including 3 glioblastomas (WHO grade IV) and 1 diffuse midline glioma, H3K27M-mutant (WHO grade IV); 4 meningiomas (WHO grade I/II/III) and 2 medulloblastomas (WHO grade IV), 1 WNT-activated and 1 SHH-activated.