In [21], the survival distribution of 14 glioblastoma patients (11% of total) with somatic IDH1 or IDH2 mutations was compared to the survival distribution of 115 patients with wild-type IDH1 and IDH2. The reported p-value from the asymptotic approximation is 2×10−3, while the exact permutational p-value is 5×10−4, indicating a stronger association between somatic mutations in IDH1 or IDH2 and (longer) survival than reported. Here, IDH1 is linked to glioblastoma.