IDH1 and glioblastoma: However, dependent on patient cohort and cfDNA extraction method, 75.0% sensitivity (95% CI: 64.1–84.0%) and 88.7% specificity (95% CI: 77.0–95.7%) has been achieved for detection of the IDH1 mutation R132H, and negativity for this mutation is a key classifier of GBM [57,58].