IDH1 and glioblastoma: Of the 26.2% (17 of 65) 1p/19q codeleted cases in WUSM test set misclassified as noncodeleted, we found five CNS WHO grade 4 glioblastoma cases that were IDH-wt and had low survival (median OS 5.2 months, range 0.1–13.4 months) (Figure 4C - case2).